root/usr.bin/ssh/sftp-client.c
/* $OpenBSD: sftp-client.c,v 1.185 2026/03/03 09:57:25 dtucker Exp $ */
/*
 * Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/* XXX: memleaks */
/* XXX: signed vs unsigned */
/* XXX: remove all logging, only return status codes */
/* XXX: copy between two remote sites */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/statvfs.h>
#include <sys/uio.h>

#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "ssherr.h"
#include "sshbuf.h"
#include "log.h"
#include "atomicio.h"
#include "progressmeter.h"
#include "misc.h"
#include "utf8.h"

#include "sftp.h"
#include "sftp-common.h"
#include "sftp-client.h"

extern volatile sig_atomic_t interrupted;
extern int showprogress;

/* Default size of buffer for up/download (fix sftp.1 scp.1 if changed) */
#define DEFAULT_COPY_BUFLEN     32768

/* Default number of concurrent xfer requests (fix sftp.1 scp.1 if changed) */
#define DEFAULT_NUM_REQUESTS    64

/* Minimum amount of data to read at a time */
#define MIN_READ_SIZE   512

/* Maximum depth to descend in directory trees */
#define MAX_DIR_DEPTH 64

struct sftp_conn {
        int fd_in;
        int fd_out;
        u_int download_buflen;
        u_int upload_buflen;
        u_int num_requests;
        u_int version;
        u_int msg_id;
#define SFTP_EXT_POSIX_RENAME           0x00000001
#define SFTP_EXT_STATVFS                0x00000002
#define SFTP_EXT_FSTATVFS               0x00000004
#define SFTP_EXT_HARDLINK               0x00000008
#define SFTP_EXT_FSYNC                  0x00000010
#define SFTP_EXT_LSETSTAT               0x00000020
#define SFTP_EXT_LIMITS                 0x00000040
#define SFTP_EXT_PATH_EXPAND            0x00000080
#define SFTP_EXT_COPY_DATA              0x00000100
#define SFTP_EXT_GETUSERSGROUPS_BY_ID   0x00000200
        u_int exts;
        uint64_t limit_kbps;
        struct bwlimit bwlimit_in, bwlimit_out;
};

/* Tracks in-progress requests during file transfers */
struct request {
        u_int id;
        size_t len;
        uint64_t offset;
        TAILQ_ENTRY(request) tq;
};
TAILQ_HEAD(requests, request);

static u_char *
get_handle(struct sftp_conn *conn, u_int expected_id, size_t *len,
    const char *errfmt, ...) __attribute__((format(printf, 4, 5)));

static struct request *
request_enqueue(struct requests *requests, u_int id, size_t len,
    uint64_t offset)
{
        struct request *req;

        req = xcalloc(1, sizeof(*req));
        req->id = id;
        req->len = len;
        req->offset = offset;
        TAILQ_INSERT_TAIL(requests, req, tq);
        return req;
}

static struct request *
request_find(struct requests *requests, u_int id)
{
        struct request *req;

        for (req = TAILQ_FIRST(requests);
            req != NULL && req->id != id;
            req = TAILQ_NEXT(req, tq))
                ;
        return req;
}

static int
sftpio(void *_bwlimit, size_t amount)
{
        struct bwlimit *bwlimit = (struct bwlimit *)_bwlimit;

        refresh_progress_meter(0);
        if (bwlimit != NULL)
                bandwidth_limit(bwlimit, amount);
        return 0;
}

static void
send_msg(struct sftp_conn *conn, struct sshbuf *m)
{
        u_char mlen[4];
        struct iovec iov[2];

        if (sshbuf_len(m) > SFTP_MAX_MSG_LENGTH)
                fatal("Outbound message too long %zu", sshbuf_len(m));

        /* Send length first */
        put_u32(mlen, sshbuf_len(m));
        iov[0].iov_base = mlen;
        iov[0].iov_len = sizeof(mlen);
        iov[1].iov_base = (u_char *)sshbuf_ptr(m);
        iov[1].iov_len = sshbuf_len(m);

        if (atomiciov6(writev, conn->fd_out, iov, 2, sftpio,
            conn->limit_kbps > 0 ? &conn->bwlimit_out : NULL) !=
            sshbuf_len(m) + sizeof(mlen))
                fatal("Couldn't send packet: %s", strerror(errno));

        sshbuf_reset(m);
}

static void
get_msg_extended(struct sftp_conn *conn, struct sshbuf *m, int initial)
{
        u_int msg_len;
        u_char *p;
        int r;

        sshbuf_reset(m);
        if ((r = sshbuf_reserve(m, 4, &p)) != 0)
                fatal_fr(r, "reserve");
        if (atomicio6(read, conn->fd_in, p, 4, sftpio,
            conn->limit_kbps > 0 ? &conn->bwlimit_in : NULL) != 4) {
                if (errno == EPIPE || errno == ECONNRESET)
                        fatal("Connection closed");
                else
                        fatal("Couldn't read packet: %s", strerror(errno));
        }

        if ((r = sshbuf_get_u32(m, &msg_len)) != 0)
                fatal_fr(r, "sshbuf_get_u32");
        if (msg_len > SFTP_MAX_MSG_LENGTH) {
                do_log2(initial ? SYSLOG_LEVEL_ERROR : SYSLOG_LEVEL_FATAL,
                    "Received message too long %u", msg_len);
                fatal("Ensure the remote shell produces no output "
                    "for non-interactive sessions.");
        }

        if ((r = sshbuf_reserve(m, msg_len, &p)) != 0)
                fatal_fr(r, "reserve");
        if (atomicio6(read, conn->fd_in, p, msg_len, sftpio,
            conn->limit_kbps > 0 ? &conn->bwlimit_in : NULL)
            != msg_len) {
                if (errno == EPIPE)
                        fatal("Connection closed");
                else
                        fatal("Read packet: %s", strerror(errno));
        }
}

static void
get_msg(struct sftp_conn *conn, struct sshbuf *m)
{
        get_msg_extended(conn, m, 0);
}

static void
send_string_request(struct sftp_conn *conn, u_int id, u_int code, const char *s,
    u_int len)
{
        struct sshbuf *msg;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, code)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_string(msg, s, len)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message fd %d T:%u I:%u", conn->fd_out, code, id);
        sshbuf_free(msg);
}

static void
send_string_attrs_request(struct sftp_conn *conn, u_int id, u_int code,
    const void *s, u_int len, Attrib *a)
{
        struct sshbuf *msg;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, code)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_string(msg, s, len)) != 0 ||
            (r = encode_attrib(msg, a)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message fd %d T:%u I:%u F:0x%04x M:%05o",
            conn->fd_out, code, id, a->flags, a->perm);
        sshbuf_free(msg);
}

static u_int
get_status(struct sftp_conn *conn, u_int expected_id)
{
        struct sshbuf *msg;
        u_char type;
        u_int id, status;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        get_msg(conn, msg);
        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "compose");

        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);
        if (type != SSH2_FXP_STATUS)
                fatal("Expected SSH2_FXP_STATUS(%u) packet, got %u",
                    SSH2_FXP_STATUS, type);

        if ((r = sshbuf_get_u32(msg, &status)) != 0)
                fatal_fr(r, "parse");
        sshbuf_free(msg);

        debug3("SSH2_FXP_STATUS %u", status);

        return status;
}

static u_char *
get_handle(struct sftp_conn *conn, u_int expected_id, size_t *len,
    const char *errfmt, ...)
{
        struct sshbuf *msg;
        u_int id, status;
        u_char type;
        u_char *handle;
        char errmsg[256];
        va_list args;
        int r;

        va_start(args, errfmt);
        if (errfmt != NULL)
                vsnprintf(errmsg, sizeof(errmsg), errfmt, args);
        va_end(args);

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        get_msg(conn, msg);
        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");

        if (id != expected_id)
                fatal("%s: ID mismatch (%u != %u)",
                    errfmt == NULL ? __func__ : errmsg, id, expected_id);
        if (type == SSH2_FXP_STATUS) {
                if ((r = sshbuf_get_u32(msg, &status)) != 0)
                        fatal_fr(r, "parse status");
                if (errfmt != NULL)
                        error("%s: %s", errmsg, fx2txt(status));
                sshbuf_free(msg);
                return(NULL);
        } else if (type != SSH2_FXP_HANDLE)
                fatal("%s: Expected SSH2_FXP_HANDLE(%u) packet, got %u",
                    errfmt == NULL ? __func__ : errmsg, SSH2_FXP_HANDLE, type);

        if ((r = sshbuf_get_string(msg, &handle, len)) != 0)
                fatal_fr(r, "parse handle");
        sshbuf_free(msg);

        return handle;
}

static int
get_decode_stat(struct sftp_conn *conn, u_int expected_id, int quiet, Attrib *a)
{
        struct sshbuf *msg;
        u_int id;
        u_char type;
        int r;
        Attrib attr;

        if (a != NULL)
                memset(a, '\0', sizeof(*a));
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        get_msg(conn, msg);

        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");

        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);
        if (type == SSH2_FXP_STATUS) {
                u_int status;

                if ((r = sshbuf_get_u32(msg, &status)) != 0)
                        fatal_fr(r, "parse status");
                if (quiet)
                        debug("stat remote: %s", fx2txt(status));
                else
                        error("stat remote: %s", fx2txt(status));
                sshbuf_free(msg);
                return -1;
        } else if (type != SSH2_FXP_ATTRS) {
                fatal("Expected SSH2_FXP_ATTRS(%u) packet, got %u",
                    SSH2_FXP_ATTRS, type);
        }
        if ((r = decode_attrib(msg, &attr)) != 0) {
                error_fr(r, "decode_attrib");
                sshbuf_free(msg);
                return -1;
        }
        /* success */
        if (a != NULL)
                *a = attr;
        debug3("Received stat reply T:%u I:%u F:0x%04x M:%05o",
            type, id, attr.flags, attr.perm);
        sshbuf_free(msg);

        return 0;
}

static int
get_decode_statvfs(struct sftp_conn *conn, struct sftp_statvfs *st,
    u_int expected_id, int quiet)
{
        struct sshbuf *msg;
        u_char type;
        u_int id;
        uint64_t flag;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        get_msg(conn, msg);

        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");

        debug3("Received statvfs reply T:%u I:%u", type, id);
        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);
        if (type == SSH2_FXP_STATUS) {
                u_int status;

                if ((r = sshbuf_get_u32(msg, &status)) != 0)
                        fatal_fr(r, "parse status");
                if (quiet)
                        debug("remote statvfs: %s", fx2txt(status));
                else
                        error("remote statvfs: %s", fx2txt(status));
                sshbuf_free(msg);
                return -1;
        } else if (type != SSH2_FXP_EXTENDED_REPLY) {
                fatal("Expected SSH2_FXP_EXTENDED_REPLY(%u) packet, got %u",
                    SSH2_FXP_EXTENDED_REPLY, type);
        }

        memset(st, 0, sizeof(*st));
        if ((r = sshbuf_get_u64(msg, &st->f_bsize)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_frsize)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_blocks)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_bfree)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_bavail)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_files)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_ffree)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_favail)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_fsid)) != 0 ||
            (r = sshbuf_get_u64(msg, &flag)) != 0 ||
            (r = sshbuf_get_u64(msg, &st->f_namemax)) != 0)
                fatal_fr(r, "parse statvfs");

        st->f_flag = (flag & SSH2_FXE_STATVFS_ST_RDONLY) ? ST_RDONLY : 0;
        st->f_flag |= (flag & SSH2_FXE_STATVFS_ST_NOSUID) ? ST_NOSUID : 0;

        sshbuf_free(msg);

        return 0;
}

struct sftp_conn *
sftp_init(int fd_in, int fd_out, u_int transfer_buflen, u_int num_requests,
    uint64_t limit_kbps)
{
        u_char type;
        struct sshbuf *msg;
        struct sftp_conn *ret;
        int r;

        ret = xcalloc(1, sizeof(*ret));
        ret->msg_id = 1;
        ret->fd_in = fd_in;
        ret->fd_out = fd_out;
        ret->download_buflen = ret->upload_buflen =
            transfer_buflen ? transfer_buflen : DEFAULT_COPY_BUFLEN;
        ret->num_requests =
            num_requests ? num_requests : DEFAULT_NUM_REQUESTS;
        ret->exts = 0;
        ret->limit_kbps = 0;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_INIT)) != 0 ||
            (r = sshbuf_put_u32(msg, SSH2_FILEXFER_VERSION)) != 0)
                fatal_fr(r, "parse");

        send_msg(ret, msg);

        get_msg_extended(ret, msg, 1);

        /* Expecting a VERSION reply */
        if ((r = sshbuf_get_u8(msg, &type)) != 0)
                fatal_fr(r, "parse type");
        if (type != SSH2_FXP_VERSION) {
                error("Invalid packet back from SSH2_FXP_INIT (type %u)",
                    type);
                sshbuf_free(msg);
                free(ret);
                return(NULL);
        }
        if ((r = sshbuf_get_u32(msg, &ret->version)) != 0)
                fatal_fr(r, "parse version");

        debug2("Remote version: %u", ret->version);

        /* Check for extensions */
        while (sshbuf_len(msg) > 0) {
                char *name;
                u_char *value;
                size_t vlen;
                int known = 0;

                if ((r = sshbuf_get_cstring(msg, &name, NULL)) != 0 ||
                    (r = sshbuf_get_string(msg, &value, &vlen)) != 0)
                        fatal_fr(r, "parse extension");
                if (strcmp(name, "posix-rename@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_POSIX_RENAME;
                        known = 1;
                } else if (strcmp(name, "statvfs@openssh.com") == 0 &&
                    strcmp((char *)value, "2") == 0) {
                        ret->exts |= SFTP_EXT_STATVFS;
                        known = 1;
                } else if (strcmp(name, "fstatvfs@openssh.com") == 0 &&
                    strcmp((char *)value, "2") == 0) {
                        ret->exts |= SFTP_EXT_FSTATVFS;
                        known = 1;
                } else if (strcmp(name, "hardlink@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_HARDLINK;
                        known = 1;
                } else if (strcmp(name, "fsync@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_FSYNC;
                        known = 1;
                } else if (strcmp(name, "lsetstat@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_LSETSTAT;
                        known = 1;
                } else if (strcmp(name, "limits@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_LIMITS;
                        known = 1;
                } else if (strcmp(name, "expand-path@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_PATH_EXPAND;
                        known = 1;
                } else if (strcmp(name, "copy-data") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_COPY_DATA;
                        known = 1;
                } else if (strcmp(name,
                    "users-groups-by-id@openssh.com") == 0 &&
                    strcmp((char *)value, "1") == 0) {
                        ret->exts |= SFTP_EXT_GETUSERSGROUPS_BY_ID;
                        known = 1;
                }
                if (known) {
                        debug2("Server supports extension \"%s\" revision %s",
                            name, value);
                } else {
                        debug2("Unrecognised server extension \"%s\"", name);
                }
                free(name);
                free(value);
        }

        sshbuf_free(msg);

        /* Query the server for its limits */
        if (ret->exts & SFTP_EXT_LIMITS) {
                struct sftp_limits limits;
                if (sftp_get_limits(ret, &limits) != 0)
                        fatal_f("limits failed");

                /* If the caller did not specify, find a good value */
                if (transfer_buflen == 0) {
                        ret->download_buflen = MINIMUM(limits.read_length,
                            SFTP_MAX_MSG_LENGTH - 1024);
                        ret->upload_buflen = MINIMUM(limits.write_length,
                            SFTP_MAX_MSG_LENGTH - 1024);
                        ret->download_buflen = MAXIMUM(ret->download_buflen, 64);
                        ret->upload_buflen = MAXIMUM(ret->upload_buflen, 64);
                        debug3("server upload/download buffer sizes "
                            "%llu / %llu; using %u / %u",
                            (unsigned long long)limits.write_length,
                            (unsigned long long)limits.read_length,
                            ret->upload_buflen, ret->download_buflen);
                }
        }

        /* Some filexfer v.0 servers don't support large packets */
        if (ret->version == 0) {
                ret->download_buflen = MINIMUM(ret->download_buflen, 20480);
                ret->upload_buflen = MINIMUM(ret->upload_buflen, 20480);
        }

        ret->limit_kbps = limit_kbps;
        if (ret->limit_kbps > 0) {
                bandwidth_limit_init(&ret->bwlimit_in, ret->limit_kbps,
                    ret->download_buflen);
                bandwidth_limit_init(&ret->bwlimit_out, ret->limit_kbps,
                    ret->upload_buflen);
        }

        return ret;
}

void
sftp_free(struct sftp_conn *conn)
{
        if (conn == NULL)
                return;
        freezero(conn, sizeof(*conn));
}

u_int
sftp_proto_version(struct sftp_conn *conn)
{
        return conn->version;
}

int
sftp_get_limits(struct sftp_conn *conn, struct sftp_limits *limits)
{
        u_int id, msg_id;
        u_char type;
        struct sshbuf *msg;
        int r;

        if ((conn->exts & SFTP_EXT_LIMITS) == 0) {
                error("Server does not support limits@openssh.com extension");
                return -1;
        }

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "limits@openssh.com")) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message limits@openssh.com I:%u", id);

        get_msg(conn, msg);

        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &msg_id)) != 0)
                fatal_fr(r, "parse");

        debug3("Received limits reply T:%u I:%u", type, msg_id);
        if (id != msg_id)
                fatal("ID mismatch (%u != %u)", msg_id, id);
        if (type != SSH2_FXP_EXTENDED_REPLY) {
                debug_f("expected SSH2_FXP_EXTENDED_REPLY(%u) packet, got %u",
                    SSH2_FXP_EXTENDED_REPLY, type);
                /* Disable the limits extension */
                conn->exts &= ~SFTP_EXT_LIMITS;
                sshbuf_free(msg);
                return -1;
        }

        memset(limits, 0, sizeof(*limits));
        if ((r = sshbuf_get_u64(msg, &limits->packet_length)) != 0 ||
            (r = sshbuf_get_u64(msg, &limits->read_length)) != 0 ||
            (r = sshbuf_get_u64(msg, &limits->write_length)) != 0 ||
            (r = sshbuf_get_u64(msg, &limits->open_handles)) != 0)
                fatal_fr(r, "parse limits");

        sshbuf_free(msg);

        return 0;
}

int
sftp_close(struct sftp_conn *conn, const u_char *handle, u_int handle_len)
{
        u_int id, status;
        struct sshbuf *msg;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_CLOSE)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_string(msg, handle, handle_len)) != 0)
                fatal_fr(r, "parse");
        send_msg(conn, msg);
        debug3("Sent message SSH2_FXP_CLOSE I:%u", id);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("close remote: %s", fx2txt(status));

        sshbuf_free(msg);

        return status == SSH2_FX_OK ? 0 : -1;
}


static int
sftp_lsreaddir(struct sftp_conn *conn, const char *path, int print_flag,
    SFTP_DIRENT ***dir)
{
        struct sshbuf *msg;
        u_int count, id, i, expected_id, ents = 0;
        size_t handle_len;
        u_char type, *handle;
        int status = SSH2_FX_FAILURE;
        int r;

        if (dir)
                *dir = NULL;

        id = conn->msg_id++;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_OPENDIR)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, path)) != 0)
                fatal_fr(r, "compose OPENDIR");
        send_msg(conn, msg);

        handle = get_handle(conn, id, &handle_len,
            "remote readdir(\"%s\")", path);
        if (handle == NULL) {
                sshbuf_free(msg);
                return -1;
        }

        if (dir) {
                ents = 0;
                *dir = xcalloc(1, sizeof(**dir));
                (*dir)[0] = NULL;
        }

        for (; !interrupted;) {
                id = expected_id = conn->msg_id++;

                debug3("Sending SSH2_FXP_READDIR I:%u", id);

                sshbuf_reset(msg);
                if ((r = sshbuf_put_u8(msg, SSH2_FXP_READDIR)) != 0 ||
                    (r = sshbuf_put_u32(msg, id)) != 0 ||
                    (r = sshbuf_put_string(msg, handle, handle_len)) != 0)
                        fatal_fr(r, "compose READDIR");
                send_msg(conn, msg);

                sshbuf_reset(msg);

                get_msg(conn, msg);

                if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
                    (r = sshbuf_get_u32(msg, &id)) != 0)
                        fatal_fr(r, "parse");

                debug3("Received reply T:%u I:%u", type, id);

                if (id != expected_id)
                        fatal("ID mismatch (%u != %u)", id, expected_id);

                if (type == SSH2_FXP_STATUS) {
                        u_int rstatus;

                        if ((r = sshbuf_get_u32(msg, &rstatus)) != 0)
                                fatal_fr(r, "parse status");
                        debug3("Received SSH2_FXP_STATUS %d", rstatus);
                        if (rstatus == SSH2_FX_EOF)
                                break;
                        error("Couldn't read directory: %s", fx2txt(rstatus));
                        goto out;
                } else if (type != SSH2_FXP_NAME)
                        fatal("Expected SSH2_FXP_NAME(%u) packet, got %u",
                            SSH2_FXP_NAME, type);

                if ((r = sshbuf_get_u32(msg, &count)) != 0)
                        fatal_fr(r, "parse count");
                if (count > SSHBUF_SIZE_MAX)
                        fatal_f("nonsensical number of entries");
                if (count == 0)
                        break;
                debug3("Received %d SSH2_FXP_NAME responses", count);
                for (i = 0; i < count; i++) {
                        char *filename, *longname;
                        Attrib a;

                        if ((r = sshbuf_get_cstring(msg, &filename,
                            NULL)) != 0 ||
                            (r = sshbuf_get_cstring(msg, &longname,
                            NULL)) != 0)
                                fatal_fr(r, "parse filenames");
                        if ((r = decode_attrib(msg, &a)) != 0) {
                                error_fr(r, "couldn't decode attrib");
                                free(filename);
                                free(longname);
                                goto out;
                        }

                        if (print_flag)
                                mprintf("%s\n", longname);

                        /*
                         * Directory entries should never contain '/'
                         * These can be used to attack recursive ops
                         * (e.g. send '../../../../etc/passwd')
                         */
                        if (strchr(filename, '/') != NULL) {
                                error("Server sent suspect path \"%s\" "
                                    "during readdir of \"%s\"", filename, path);
                        } else if (dir) {
                                *dir = xreallocarray(*dir, ents + 2, sizeof(**dir));
                                (*dir)[ents] = xcalloc(1, sizeof(***dir));
                                (*dir)[ents]->filename = xstrdup(filename);
                                (*dir)[ents]->longname = xstrdup(longname);
                                memcpy(&(*dir)[ents]->a, &a, sizeof(a));
                                (*dir)[++ents] = NULL;
                        }
                        free(filename);
                        free(longname);
                }
        }
        status = 0;

 out:
        sshbuf_free(msg);
        sftp_close(conn, handle, handle_len);
        free(handle);

        if (status != 0 && dir != NULL) {
                /* Don't return results on error */
                sftp_free_dirents(*dir);
                *dir = NULL;
        } else if (interrupted && dir != NULL && *dir != NULL) {
                /* Don't return partial matches on interrupt */
                sftp_free_dirents(*dir);
                *dir = xcalloc(1, sizeof(**dir));
                **dir = NULL;
        }

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_readdir(struct sftp_conn *conn, const char *path, SFTP_DIRENT ***dir)
{
        return sftp_lsreaddir(conn, path, 0, dir);
}

void sftp_free_dirents(SFTP_DIRENT **s)
{
        int i;

        if (s == NULL)
                return;
        for (i = 0; s[i]; i++) {
                free(s[i]->filename);
                free(s[i]->longname);
                free(s[i]);
        }
        free(s);
}

int
sftp_rm(struct sftp_conn *conn, const char *path)
{
        u_int status, id;

        debug2("Sending SSH2_FXP_REMOVE \"%s\"", path);

        id = conn->msg_id++;
        send_string_request(conn, id, SSH2_FXP_REMOVE, path, strlen(path));
        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote delete %s: %s", path, fx2txt(status));
        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_mkdir(struct sftp_conn *conn, const char *path, Attrib *a, int print_flag)
{
        u_int status, id;

        debug2("Sending SSH2_FXP_MKDIR \"%s\"", path);

        id = conn->msg_id++;
        send_string_attrs_request(conn, id, SSH2_FXP_MKDIR, path,
            strlen(path), a);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK && print_flag)
                error("remote mkdir \"%s\": %s", path, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_rmdir(struct sftp_conn *conn, const char *path)
{
        u_int status, id;

        debug2("Sending SSH2_FXP_RMDIR \"%s\"", path);

        id = conn->msg_id++;
        send_string_request(conn, id, SSH2_FXP_RMDIR, path,
            strlen(path));

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote rmdir \"%s\": %s", path, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_stat(struct sftp_conn *conn, const char *path, int quiet, Attrib *a)
{
        u_int id;

        debug2("Sending SSH2_FXP_STAT \"%s\"", path);

        id = conn->msg_id++;

        send_string_request(conn, id,
            conn->version == 0 ? SSH2_FXP_STAT_VERSION_0 : SSH2_FXP_STAT,
            path, strlen(path));

        return get_decode_stat(conn, id, quiet, a);
}

int
sftp_lstat(struct sftp_conn *conn, const char *path, int quiet, Attrib *a)
{
        u_int id;

        if (conn->version == 0) {
                do_log2(quiet ? SYSLOG_LEVEL_DEBUG1 : SYSLOG_LEVEL_INFO,
                    "Server version does not support lstat operation");
                return sftp_stat(conn, path, quiet, a);
        }

        id = conn->msg_id++;
        send_string_request(conn, id, SSH2_FXP_LSTAT, path,
            strlen(path));

        return get_decode_stat(conn, id, quiet, a);
}

#ifdef notyet
int
sftp_fstat(struct sftp_conn *conn, const u_char *handle, u_int handle_len,
    int quiet, Attrib *a)
{
        u_int id;

        debug2("Sending SSH2_FXP_FSTAT \"%s\"");

        id = conn->msg_id++;
        send_string_request(conn, id, SSH2_FXP_FSTAT, handle,
            handle_len);

        return get_decode_stat(conn, id, quiet, a);
}
#endif

int
sftp_setstat(struct sftp_conn *conn, const char *path, Attrib *a)
{
        u_int status, id;

        debug2("Sending SSH2_FXP_SETSTAT \"%s\"", path);

        id = conn->msg_id++;
        send_string_attrs_request(conn, id, SSH2_FXP_SETSTAT, path,
            strlen(path), a);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote setstat \"%s\": %s", path, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_fsetstat(struct sftp_conn *conn, const u_char *handle, u_int handle_len,
    Attrib *a)
{
        u_int status, id;

        debug2("Sending SSH2_FXP_FSETSTAT");

        id = conn->msg_id++;
        send_string_attrs_request(conn, id, SSH2_FXP_FSETSTAT, handle,
            handle_len, a);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote fsetstat: %s", fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

/* Implements both the realpath and expand-path operations */
static char *
sftp_realpath_expand(struct sftp_conn *conn, const char *path, int expand)
{
        struct sshbuf *msg;
        u_int expected_id, count, id;
        char *filename, *longname;
        Attrib a;
        u_char type;
        int r;
        const char *what = "SSH2_FXP_REALPATH";

        if (expand)
                what = "expand-path@openssh.com";
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        expected_id = id = conn->msg_id++;
        if (expand) {
                debug2("Sending SSH2_FXP_EXTENDED(expand-path@openssh.com) "
                    "\"%s\"", path);
                if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
                    (r = sshbuf_put_u32(msg, id)) != 0 ||
                    (r = sshbuf_put_cstring(msg,
                    "expand-path@openssh.com")) != 0 ||
                    (r = sshbuf_put_cstring(msg, path)) != 0)
                        fatal_fr(r, "compose %s", what);
                send_msg(conn, msg);
        } else {
                debug2("Sending SSH2_FXP_REALPATH \"%s\"", path);
                send_string_request(conn, id, SSH2_FXP_REALPATH,
                    path, strlen(path));
        }
        get_msg(conn, msg);
        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");

        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);

        if (type == SSH2_FXP_STATUS) {
                u_int status;
                char *errmsg;

                if ((r = sshbuf_get_u32(msg, &status)) != 0 ||
                    (r = sshbuf_get_cstring(msg, &errmsg, NULL)) != 0)
                        fatal_fr(r, "parse status");
                error("%s %s: %s", expand ? "expand" : "realpath",
                    path, *errmsg == '\0' ? fx2txt(status) : errmsg);
                free(errmsg);
                sshbuf_free(msg);
                return NULL;
        } else if (type != SSH2_FXP_NAME)
                fatal("Expected SSH2_FXP_NAME(%u) packet, got %u",
                    SSH2_FXP_NAME, type);

        if ((r = sshbuf_get_u32(msg, &count)) != 0)
                fatal_fr(r, "parse count");
        if (count != 1)
                fatal("Got multiple names (%d) from %s", count, what);

        if ((r = sshbuf_get_cstring(msg, &filename, NULL)) != 0 ||
            (r = sshbuf_get_cstring(msg, &longname, NULL)) != 0 ||
            (r = decode_attrib(msg, &a)) != 0)
                fatal_fr(r, "parse filename/attrib");

        debug3("%s %s -> %s", what, path, filename);

        free(longname);

        sshbuf_free(msg);

        return(filename);
}

char *
sftp_realpath(struct sftp_conn *conn, const char *path)
{
        return sftp_realpath_expand(conn, path, 0);
}

int
sftp_can_expand_path(struct sftp_conn *conn)
{
        return (conn->exts & SFTP_EXT_PATH_EXPAND) != 0;
}

char *
sftp_expand_path(struct sftp_conn *conn, const char *path)
{
        if (!sftp_can_expand_path(conn)) {
                debug3_f("no server support, fallback to realpath");
                return sftp_realpath_expand(conn, path, 0);
        }
        return sftp_realpath_expand(conn, path, 1);
}

int
sftp_copy(struct sftp_conn *conn, const char *oldpath, const char *newpath)
{
        Attrib junk, attr;
        struct sshbuf *msg;
        u_char *old_handle, *new_handle;
        u_int mode, status, id;
        size_t old_handle_len, new_handle_len;
        int r;

        /* Return if the extension is not supported */
        if ((conn->exts & SFTP_EXT_COPY_DATA) == 0) {
                error("Server does not support copy-data extension");
                return -1;
        }

        /* Make sure the file exists, and we can copy its perms */
        if (sftp_stat(conn, oldpath, 0, &attr) != 0)
                return -1;

        /* Do not preserve set[ug]id here, as we do not preserve ownership */
        if (attr.flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
                mode = attr.perm & 0777;

                if (!S_ISREG(attr.perm)) {
                        error("Cannot copy non-regular file: %s", oldpath);
                        return -1;
                }
        } else {
                /* NB: The user's umask will apply to this */
                mode = 0666;
        }

        /* Set up the new perms for the new file */
        attrib_clear(&attr);
        attr.perm = mode;
        attr.flags |= SSH2_FILEXFER_ATTR_PERMISSIONS;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        attrib_clear(&junk); /* Send empty attributes */

        /* Open the old file for reading */
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_OPEN)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, oldpath)) != 0 ||
            (r = sshbuf_put_u32(msg, SSH2_FXF_READ)) != 0 ||
            (r = encode_attrib(msg, &junk)) != 0)
                fatal_fr(r, "buffer error");
        send_msg(conn, msg);
        debug3("Sent message SSH2_FXP_OPEN I:%u P:%s", id, oldpath);

        sshbuf_reset(msg);

        old_handle = get_handle(conn, id, &old_handle_len,
            "remote open(\"%s\")", oldpath);
        if (old_handle == NULL) {
                sshbuf_free(msg);
                return -1;
        }

        /* Open the new file for writing */
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_OPEN)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, newpath)) != 0 ||
            (r = sshbuf_put_u32(msg, SSH2_FXF_WRITE|SSH2_FXF_CREAT|
            SSH2_FXF_TRUNC)) != 0 ||
            (r = encode_attrib(msg, &attr)) != 0)
                fatal_fr(r, "buffer error");
        send_msg(conn, msg);
        debug3("Sent message SSH2_FXP_OPEN I:%u P:%s", id, newpath);

        sshbuf_reset(msg);

        new_handle = get_handle(conn, id, &new_handle_len,
            "remote open(\"%s\")", newpath);
        if (new_handle == NULL) {
                sshbuf_free(msg);
                free(old_handle);
                return -1;
        }

        /* Copy the file data */
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "copy-data")) != 0 ||
            (r = sshbuf_put_string(msg, old_handle, old_handle_len)) != 0 ||
            (r = sshbuf_put_u64(msg, 0)) != 0 ||
            (r = sshbuf_put_u64(msg, 0)) != 0 ||
            (r = sshbuf_put_string(msg, new_handle, new_handle_len)) != 0 ||
            (r = sshbuf_put_u64(msg, 0)) != 0)
                fatal_fr(r, "buffer error");
        send_msg(conn, msg);
        debug3("Sent message copy-data \"%s\" 0 0 -> \"%s\" 0",
               oldpath, newpath);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("Couldn't copy file \"%s\" to \"%s\": %s", oldpath,
                    newpath, fx2txt(status));

        /* Clean up everything */
        sshbuf_free(msg);
        sftp_close(conn, old_handle, old_handle_len);
        sftp_close(conn, new_handle, new_handle_len);
        free(old_handle);
        free(new_handle);

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_rename(struct sftp_conn *conn, const char *oldpath, const char *newpath,
    int force_legacy)
{
        struct sshbuf *msg;
        u_int status, id;
        int r, use_ext = (conn->exts & SFTP_EXT_POSIX_RENAME) && !force_legacy;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        /* Send rename request */
        id = conn->msg_id++;
        if (use_ext) {
                debug2("Sending SSH2_FXP_EXTENDED(posix-rename@openssh.com) "
                    "\"%s\" to \"%s\"", oldpath, newpath);
                if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
                    (r = sshbuf_put_u32(msg, id)) != 0 ||
                    (r = sshbuf_put_cstring(msg,
                    "posix-rename@openssh.com")) != 0)
                        fatal_fr(r, "compose posix-rename");
        } else {
                debug2("Sending SSH2_FXP_RENAME \"%s\" to \"%s\"",
                    oldpath, newpath);
                if ((r = sshbuf_put_u8(msg, SSH2_FXP_RENAME)) != 0 ||
                    (r = sshbuf_put_u32(msg, id)) != 0)
                        fatal_fr(r, "compose rename");
        }
        if ((r = sshbuf_put_cstring(msg, oldpath)) != 0 ||
            (r = sshbuf_put_cstring(msg, newpath)) != 0)
                fatal_fr(r, "compose paths");
        send_msg(conn, msg);
        debug3("Sent message %s \"%s\" -> \"%s\"",
            use_ext ? "posix-rename@openssh.com" :
            "SSH2_FXP_RENAME", oldpath, newpath);
        sshbuf_free(msg);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote rename \"%s\" to \"%s\": %s", oldpath,
                    newpath, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_hardlink(struct sftp_conn *conn, const char *oldpath, const char *newpath)
{
        struct sshbuf *msg;
        u_int status, id;
        int r;

        if ((conn->exts & SFTP_EXT_HARDLINK) == 0) {
                error("Server does not support hardlink@openssh.com extension");
                return -1;
        }
        debug2("Sending SSH2_FXP_EXTENDED(hardlink@openssh.com) "
            "\"%s\" to \"%s\"", oldpath, newpath);

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        /* Send link request */
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "hardlink@openssh.com")) != 0 ||
            (r = sshbuf_put_cstring(msg, oldpath)) != 0 ||
            (r = sshbuf_put_cstring(msg, newpath)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message hardlink@openssh.com \"%s\" -> \"%s\"",
            oldpath, newpath);
        sshbuf_free(msg);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote link \"%s\" to \"%s\": %s", oldpath,
                    newpath, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_symlink(struct sftp_conn *conn, const char *oldpath, const char *newpath)
{
        struct sshbuf *msg;
        u_int status, id;
        int r;

        if (conn->version < 3) {
                error("This server does not support the symlink operation");
                return(SSH2_FX_OP_UNSUPPORTED);
        }
        debug2("Sending SSH2_FXP_SYMLINK \"%s\" to \"%s\"", oldpath, newpath);

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        /* Send symlink request */
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_SYMLINK)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, oldpath)) != 0 ||
            (r = sshbuf_put_cstring(msg, newpath)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message SSH2_FXP_SYMLINK \"%s\" -> \"%s\"", oldpath,
            newpath);
        sshbuf_free(msg);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote symlink file \"%s\" to \"%s\": %s", oldpath,
                    newpath, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

int
sftp_fsync(struct sftp_conn *conn, u_char *handle, u_int handle_len)
{
        struct sshbuf *msg;
        u_int status, id;
        int r;

        /* Silently return if the extension is not supported */
        if ((conn->exts & SFTP_EXT_FSYNC) == 0)
                return -1;
        debug2("Sending SSH2_FXP_EXTENDED(fsync@openssh.com)");

        /* Send fsync request */
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "fsync@openssh.com")) != 0 ||
            (r = sshbuf_put_string(msg, handle, handle_len)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        debug3("Sent message fsync@openssh.com I:%u", id);
        sshbuf_free(msg);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote fsync: %s", fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

#ifdef notyet
char *
sftp_readlink(struct sftp_conn *conn, const char *path)
{
        struct sshbuf *msg;
        u_int expected_id, count, id;
        char *filename, *longname;
        Attrib a;
        u_char type;
        int r;

        debug2("Sending SSH2_FXP_READLINK \"%s\"", path);

        expected_id = id = conn->msg_id++;
        send_string_request(conn, id, SSH2_FXP_READLINK, path, strlen(path));

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        get_msg(conn, msg);
        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");

        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);

        if (type == SSH2_FXP_STATUS) {
                u_int status;

                if ((r = sshbuf_get_u32(msg, &status)) != 0)
                        fatal_fr(r, "parse status");
                error("Couldn't readlink: %s", fx2txt(status));
                sshbuf_free(msg);
                return(NULL);
        } else if (type != SSH2_FXP_NAME)
                fatal("Expected SSH2_FXP_NAME(%u) packet, got %u",
                    SSH2_FXP_NAME, type);

        if ((r = sshbuf_get_u32(msg, &count)) != 0)
                fatal_fr(r, "parse count");
        if (count != 1)
                fatal("Got multiple names (%d) from SSH_FXP_READLINK", count);

        if ((r = sshbuf_get_cstring(msg, &filename, NULL)) != 0 ||
            (r = sshbuf_get_cstring(msg, &longname, NULL)) != 0 ||
            (r = decode_attrib(msg, &a)) != 0)
                fatal_fr(r, "parse filenames/attrib");

        debug3("SSH_FXP_READLINK %s -> %s", path, filename);

        free(longname);

        sshbuf_free(msg);

        return filename;
}
#endif

int
sftp_statvfs(struct sftp_conn *conn, const char *path, struct sftp_statvfs *st,
    int quiet)
{
        struct sshbuf *msg;
        u_int id;
        int r;

        if ((conn->exts & SFTP_EXT_STATVFS) == 0) {
                error("Server does not support statvfs@openssh.com extension");
                return -1;
        }

        debug2("Sending SSH2_FXP_EXTENDED(statvfs@openssh.com) \"%s\"", path);

        id = conn->msg_id++;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "statvfs@openssh.com")) != 0 ||
            (r = sshbuf_put_cstring(msg, path)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        sshbuf_free(msg);

        return get_decode_statvfs(conn, st, id, quiet);
}

#ifdef notyet
int
sftp_fstatvfs(struct sftp_conn *conn, const u_char *handle, u_int handle_len,
    struct sftp_statvfs *st, int quiet)
{
        struct sshbuf *msg;
        u_int id;

        if ((conn->exts & SFTP_EXT_FSTATVFS) == 0) {
                error("Server does not support fstatvfs@openssh.com extension");
                return -1;
        }

        debug2("Sending SSH2_FXP_EXTENDED(fstatvfs@openssh.com)");

        id = conn->msg_id++;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "fstatvfs@openssh.com")) != 0 ||
            (r = sshbuf_put_string(msg, handle, handle_len)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        sshbuf_free(msg);

        return get_decode_statvfs(conn, st, id, quiet);
}
#endif

int
sftp_lsetstat(struct sftp_conn *conn, const char *path, Attrib *a)
{
        struct sshbuf *msg;
        u_int status, id;
        int r;

        if ((conn->exts & SFTP_EXT_LSETSTAT) == 0) {
                error("Server does not support lsetstat@openssh.com extension");
                return -1;
        }

        debug2("Sending SSH2_FXP_EXTENDED(lsetstat@openssh.com) \"%s\"", path);

        id = conn->msg_id++;
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, "lsetstat@openssh.com")) != 0 ||
            (r = sshbuf_put_cstring(msg, path)) != 0 ||
            (r = encode_attrib(msg, a)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        sshbuf_free(msg);

        status = get_status(conn, id);
        if (status != SSH2_FX_OK)
                error("remote lsetstat \"%s\": %s", path, fx2txt(status));

        return status == SSH2_FX_OK ? 0 : -1;
}

static void
send_read_request(struct sftp_conn *conn, u_int id, uint64_t offset,
    u_int len, const u_char *handle, u_int handle_len)
{
        struct sshbuf *msg;
        int r;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_READ)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_string(msg, handle, handle_len)) != 0 ||
            (r = sshbuf_put_u64(msg, offset)) != 0 ||
            (r = sshbuf_put_u32(msg, len)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        sshbuf_free(msg);
}

static int
send_open(struct sftp_conn *conn, const char *path, const char *tag,
    u_int openmode, Attrib *a, u_char **handlep, size_t *handle_lenp)
{
        Attrib junk;
        u_char *handle;
        size_t handle_len;
        struct sshbuf *msg;
        int r;
        u_int id;

        debug2("Sending SSH2_FXP_OPEN \"%s\"", path);

        *handlep = NULL;
        *handle_lenp = 0;

        if (a == NULL) {
                attrib_clear(&junk); /* Send empty attributes */
                a = &junk;
        }
        /* Send open request */
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        id = conn->msg_id++;
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_OPEN)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg, path)) != 0 ||
            (r = sshbuf_put_u32(msg, openmode)) != 0 ||
            (r = encode_attrib(msg, a)) != 0)
                fatal_fr(r, "compose %s open", tag);
        send_msg(conn, msg);
        sshbuf_free(msg);
        debug3("Sent %s message SSH2_FXP_OPEN I:%u P:%s M:0x%04x",
            tag, id, path, openmode);
        if ((handle = get_handle(conn, id, &handle_len,
            "%s open \"%s\"", tag, path)) == NULL)
                return -1;
        /* success */
        *handlep = handle;
        *handle_lenp = handle_len;
        return 0;
}

static const char *
progress_meter_path(const char *path)
{
        const char *progresspath;

        if ((progresspath = strrchr(path, '/')) == NULL)
                return path;
        progresspath++;
        if (*progresspath == '\0')
                return path;
        return progresspath;
}

int
sftp_download(struct sftp_conn *conn, const char *remote_path,
    const char *local_path, Attrib *a, int preserve_flag, int resume_flag,
    int fsync_flag, int inplace_flag)
{
        struct sshbuf *msg;
        u_char *handle;
        int local_fd = -1, write_error;
        int read_error, write_errno, lmodified = 0, reordered = 0, r;
        uint64_t offset = 0, size, highwater = 0, maxack = 0;
        u_int mode, id, buflen, num_req, max_req, status = SSH2_FX_OK;
        off_t progress_counter;
        size_t handle_len;
        struct stat st;
        struct requests requests;
        struct request *req;
        u_char type;
        Attrib attr;

        debug2_f("download remote \"%s\" to local \"%s\"",
            remote_path, local_path);

        TAILQ_INIT(&requests);

        if (a == NULL) {
                if (sftp_stat(conn, remote_path, 0, &attr) != 0)
                        return -1;
                a = &attr;
        }

        /* Do not preserve set[ug]id here, as we do not preserve ownership */
        if (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS)
                mode = a->perm & 0777;
        else
                mode = 0666;

        if ((a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) &&
            (!S_ISREG(a->perm))) {
                error("download %s: not a regular file", remote_path);
                return(-1);
        }

        if (a->flags & SSH2_FILEXFER_ATTR_SIZE)
                size = a->size;
        else
                size = 0;

        buflen = conn->download_buflen;

        /* Send open request */
        if (send_open(conn, remote_path, "remote", SSH2_FXF_READ, NULL,
            &handle, &handle_len) != 0)
                return -1;

        local_fd = open(local_path, O_WRONLY | O_CREAT |
        ((resume_flag || inplace_flag) ? 0 : O_TRUNC), mode | S_IWUSR);
        if (local_fd == -1) {
                error("open local \"%s\": %s", local_path, strerror(errno));
                goto fail;
        }
        if (resume_flag) {
                if (fstat(local_fd, &st) == -1) {
                        error("stat local \"%s\": %s",
                            local_path, strerror(errno));
                        goto fail;
                }
                if (st.st_size < 0) {
                        error("\"%s\" has negative size", local_path);
                        goto fail;
                }
                if ((uint64_t)st.st_size > size) {
                        error("Unable to resume download of \"%s\": "
                            "local file is larger than remote", local_path);
 fail:
                        sftp_close(conn, handle, handle_len);
                        free(handle);
                        if (local_fd != -1)
                                close(local_fd);
                        return -1;
                }
                offset = highwater = maxack = st.st_size;
        }

        /* Read from remote and write to local */
        write_error = read_error = write_errno = num_req = 0;
        max_req = 1;
        progress_counter = offset;

        if (showprogress && size != 0) {
                start_progress_meter(progress_meter_path(remote_path),
                    size, &progress_counter);
        }

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        while (num_req > 0 || max_req > 0) {
                u_char *data;
                size_t len;

                /*
                 * Simulate EOF on interrupt: stop sending new requests and
                 * allow outstanding requests to drain gracefully
                 */
                if (interrupted) {
                        if (num_req == 0) /* If we haven't started yet... */
                                break;
                        max_req = 0;
                }

                /* Send some more requests */
                while (num_req < max_req) {
                        debug3("Request range %llu -> %llu (%d/%d)",
                            (unsigned long long)offset,
                            (unsigned long long)offset + buflen - 1,
                            num_req, max_req);
                        req = request_enqueue(&requests, conn->msg_id++,
                            buflen, offset);
                        offset += buflen;
                        num_req++;
                        send_read_request(conn, req->id, req->offset,
                            req->len, handle, handle_len);
                }

                sshbuf_reset(msg);
                get_msg(conn, msg);
                if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
                    (r = sshbuf_get_u32(msg, &id)) != 0)
                        fatal_fr(r, "parse");
                debug3("Received reply T:%u I:%u R:%d", type, id, max_req);

                /* Find the request in our queue */
                if ((req = request_find(&requests, id)) == NULL)
                        fatal("Unexpected reply %u", id);

                switch (type) {
                case SSH2_FXP_STATUS:
                        if ((r = sshbuf_get_u32(msg, &status)) != 0)
                                fatal_fr(r, "parse status");
                        if (status != SSH2_FX_EOF)
                                read_error = 1;
                        max_req = 0;
                        TAILQ_REMOVE(&requests, req, tq);
                        free(req);
                        num_req--;
                        break;
                case SSH2_FXP_DATA:
                        if ((r = sshbuf_get_string(msg, &data, &len)) != 0)
                                fatal_fr(r, "parse data");
                        debug3("Received data %llu -> %llu",
                            (unsigned long long)req->offset,
                            (unsigned long long)req->offset + len - 1);
                        if (len > req->len)
                                fatal("Received more data than asked for "
                                    "%zu > %zu", len, req->len);
                        lmodified = 1;
                        if ((lseek(local_fd, req->offset, SEEK_SET) == -1 ||
                            atomicio(vwrite, local_fd, data, len) != len) &&
                            !write_error) {
                                write_errno = errno;
                                write_error = 1;
                                max_req = 0;
                        } else {
                                /*
                                 * Track both the highest offset acknowledged
                                 * and the highest *contiguous* offset
                                 * acknowledged.
                                 * We'll need the latter for ftruncate()ing
                                 * interrupted transfers.
                                 */
                                if (maxack < req->offset + len)
                                        maxack = req->offset + len;
                                if (!reordered && req->offset <= highwater)
                                        highwater = maxack;
                                else if (!reordered && req->offset > highwater)
                                        reordered = 1;
                        }
                        progress_counter += len;
                        free(data);

                        if (len == req->len) {
                                TAILQ_REMOVE(&requests, req, tq);
                                free(req);
                                num_req--;
                        } else {
                                /* Resend the request for the missing data */
                                debug3("Short data block, re-requesting "
                                    "%llu -> %llu (%2d)",
                                    (unsigned long long)req->offset + len,
                                    (unsigned long long)req->offset +
                                    req->len - 1, num_req);
                                req->id = conn->msg_id++;
                                req->len -= len;
                                req->offset += len;
                                send_read_request(conn, req->id,
                                    req->offset, req->len, handle, handle_len);
                                /* Reduce the request size */
                                if (len < buflen)
                                        buflen = MAXIMUM(MIN_READ_SIZE, len);
                        }
                        if (max_req > 0) { /* max_req = 0 iff EOF received */
                                if (size > 0 && offset > size) {
                                        /* Only one request at a time
                                         * after the expected EOF */
                                        debug3("Finish at %llu (%2d)",
                                            (unsigned long long)offset,
                                            num_req);
                                        max_req = 1;
                                } else if (max_req < conn->num_requests) {
                                        ++max_req;
                                }
                        }
                        break;
                default:
                        fatal("Expected SSH2_FXP_DATA(%u) packet, got %u",
                            SSH2_FXP_DATA, type);
                }
        }

        if (showprogress && size)
                stop_progress_meter();

        /* Sanity check */
        if (TAILQ_FIRST(&requests) != NULL)
                fatal("Transfer complete, but requests still in queue");

        if (!read_error && !write_error && !interrupted) {
                /* we got everything */
                highwater = maxack;
        }

        /*
         * Truncate at highest contiguous point to avoid holes on interrupt,
         * or unconditionally if writing in place.
         */
        if (inplace_flag || read_error || write_error || interrupted) {
                if (reordered && resume_flag &&
                    (read_error || write_error || interrupted)) {
                        error("Unable to resume download of \"%s\": "
                            "server reordered requests", local_path);
                }
                debug("truncating at %llu", (unsigned long long)highwater);
                if (ftruncate(local_fd, highwater) == -1)
                        error("local ftruncate \"%s\": %s", local_path,
                            strerror(errno));
        }
        if (read_error) {
                error("read remote \"%s\" : %s", remote_path, fx2txt(status));
                status = -1;
                sftp_close(conn, handle, handle_len);
        } else if (write_error) {
                error("write local \"%s\": %s", local_path,
                    strerror(write_errno));
                status = SSH2_FX_FAILURE;
                sftp_close(conn, handle, handle_len);
        } else {
                if (sftp_close(conn, handle, handle_len) != 0 || interrupted)
                        status = SSH2_FX_FAILURE;
                else
                        status = SSH2_FX_OK;
                /* Override umask and utimes if asked */
                if (preserve_flag && fchmod(local_fd, mode) == -1)
                        error("local chmod \"%s\": %s", local_path,
                            strerror(errno));
                if (preserve_flag &&
                    (a->flags & SSH2_FILEXFER_ATTR_ACMODTIME)) {
                        struct timeval tv[2];
                        tv[0].tv_sec = a->atime;
                        tv[1].tv_sec = a->mtime;
                        tv[0].tv_usec = tv[1].tv_usec = 0;
                        if (utimes(local_path, tv) == -1)
                                error("local set times \"%s\": %s",
                                    local_path, strerror(errno));
                }
                if (resume_flag && !lmodified)
                        logit("File \"%s\" was not modified", local_path);
                else if (fsync_flag) {
                        debug("syncing \"%s\"", local_path);
                        if (fsync(local_fd) == -1)
                                error("local sync \"%s\": %s",
                                    local_path, strerror(errno));
                }
        }
        close(local_fd);
        sshbuf_free(msg);
        free(handle);

        return status == SSH2_FX_OK ? 0 : -1;
}

static int
download_dir_internal(struct sftp_conn *conn, const char *src, const char *dst,
    int depth, Attrib *dirattrib, int preserve_flag, int print_flag,
    int resume_flag, int fsync_flag, int follow_link_flag, int inplace_flag)
{
        int i, ret = 0;
        SFTP_DIRENT **dir_entries;
        char *filename, *new_src = NULL, *new_dst = NULL;
        mode_t mode = 0777, tmpmode = mode;
        Attrib *a, ldirattrib, lsym;

        if (depth >= MAX_DIR_DEPTH) {
                error("Maximum directory depth exceeded: %d levels", depth);
                return -1;
        }

        debug2_f("download dir remote \"%s\" to local \"%s\"", src, dst);

        if (dirattrib == NULL) {
                if (sftp_stat(conn, src, 1, &ldirattrib) != 0) {
                        error("stat remote \"%s\" directory failed", src);
                        return -1;
                }
                dirattrib = &ldirattrib;
        }
        if (!S_ISDIR(dirattrib->perm)) {
                error("\"%s\" is not a directory", src);
                return -1;
        }
        if (print_flag && print_flag != SFTP_PROGRESS_ONLY)
                mprintf("Retrieving %s\n", src);

        if (dirattrib->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
                mode = dirattrib->perm & 01777;
                tmpmode = mode | (S_IWUSR|S_IXUSR);
        } else {
                debug("download remote \"%s\": server "
                    "did not send permissions", dst);
        }

        if (mkdir(dst, tmpmode) == -1 && errno != EEXIST) {
                error("mkdir %s: %s", dst, strerror(errno));
                return -1;
        }

        if (sftp_readdir(conn, src, &dir_entries) == -1) {
                error("remote readdir \"%s\" failed", src);
                return -1;
        }

        for (i = 0; dir_entries[i] != NULL && !interrupted; i++) {
                free(new_dst);
                free(new_src);

                filename = dir_entries[i]->filename;
                new_dst = sftp_path_append(dst, filename);
                new_src = sftp_path_append(src, filename);

                a = &dir_entries[i]->a;
                if (S_ISLNK(a->perm)) {
                        if (!follow_link_flag) {
                                logit("download \"%s\": not a regular file",
                                    new_src);
                                continue;
                        }
                        /* Replace the stat contents with the symlink target */
                        if (sftp_stat(conn, new_src, 1, &lsym) != 0) {
                                logit("remote stat \"%s\" failed", new_src);
                                ret = -1;
                                continue;
                        }
                        a = &lsym;
                }

                if (S_ISDIR(a->perm)) {
                        if (strcmp(filename, ".") == 0 ||
                            strcmp(filename, "..") == 0)
                                continue;
                        if (download_dir_internal(conn, new_src, new_dst,
                            depth + 1, a, preserve_flag,
                            print_flag, resume_flag,
                            fsync_flag, follow_link_flag, inplace_flag) == -1)
                                ret = -1;
                } else if (S_ISREG(a->perm)) {
                        if (sftp_download(conn, new_src, new_dst, a,
                            preserve_flag, resume_flag, fsync_flag,
                            inplace_flag) == -1) {
                                error("Download of file %s to %s failed",
                                    new_src, new_dst);
                                ret = -1;
                        }
                } else
                        logit("download \"%s\": not a regular file", new_src);

        }
        free(new_dst);
        free(new_src);

        if (preserve_flag) {
                if (dirattrib->flags & SSH2_FILEXFER_ATTR_ACMODTIME) {
                        struct timeval tv[2];
                        tv[0].tv_sec = dirattrib->atime;
                        tv[1].tv_sec = dirattrib->mtime;
                        tv[0].tv_usec = tv[1].tv_usec = 0;
                        if (utimes(dst, tv) == -1)
                                error("local set times on \"%s\": %s",
                                    dst, strerror(errno));
                } else
                        debug("Server did not send times for directory "
                            "\"%s\"", dst);
        }

        if (mode != tmpmode && chmod(dst, mode) == -1)
                error("local chmod directory \"%s\": %s", dst,
                    strerror(errno));

        sftp_free_dirents(dir_entries);

        return ret;
}

int
sftp_download_dir(struct sftp_conn *conn, const char *src, const char *dst,
    Attrib *dirattrib, int preserve_flag, int print_flag, int resume_flag,
    int fsync_flag, int follow_link_flag, int inplace_flag)
{
        char *src_canon;
        int ret;

        if ((src_canon = sftp_realpath(conn, src)) == NULL) {
                error("download \"%s\": path canonicalization failed", src);
                return -1;
        }

        ret = download_dir_internal(conn, src_canon, dst, 0,
            dirattrib, preserve_flag, print_flag, resume_flag, fsync_flag,
            follow_link_flag, inplace_flag);
        free(src_canon);
        return ret;
}

int
sftp_upload(struct sftp_conn *conn, const char *local_path,
    const char *remote_path, int preserve_flag, int resume,
    int fsync_flag, int inplace_flag)
{
        int r, local_fd;
        u_int openmode, id, status = SSH2_FX_OK, status2, reordered = 0;
        off_t offset, progress_counter;
        u_char type, *handle, *data;
        struct sshbuf *msg;
        struct stat sb;
        Attrib a, t, c;
        uint32_t startid, ackid;
        uint64_t highwater = 0, maxack = 0;
        struct request *ack = NULL;
        struct requests acks;
        size_t handle_len;

        debug2_f("upload local \"%s\" to remote \"%s\"",
            local_path, remote_path);

        TAILQ_INIT(&acks);

        if ((local_fd = open(local_path, O_RDONLY)) == -1) {
                error("open local \"%s\": %s", local_path, strerror(errno));
                return(-1);
        }
        if (fstat(local_fd, &sb) == -1) {
                error("fstat local \"%s\": %s", local_path, strerror(errno));
                close(local_fd);
                return(-1);
        }
        if (!S_ISREG(sb.st_mode)) {
                error("local \"%s\" is not a regular file", local_path);
                close(local_fd);
                return(-1);
        }
        stat_to_attrib(&sb, &a);

        a.flags &= ~SSH2_FILEXFER_ATTR_SIZE;
        a.flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
        a.perm &= 0777;
        if (!preserve_flag)
                a.flags &= ~SSH2_FILEXFER_ATTR_ACMODTIME;

        if (resume) {
                /* Get remote file size if it exists */
                if (sftp_stat(conn, remote_path, 0, &c) != 0) {
                        close(local_fd);
                        return -1;
                }

                if ((off_t)c.size >= sb.st_size) {
                        error("resume \"%s\": destination file "
                            "same size or larger", local_path);
                        close(local_fd);
                        return -1;
                }

                if (lseek(local_fd, (off_t)c.size, SEEK_SET) == -1) {
                        close(local_fd);
                        return -1;
                }
                highwater = c.size;
        }

        openmode = SSH2_FXF_WRITE|SSH2_FXF_CREAT;
        if (resume)
                openmode |= SSH2_FXF_APPEND;
        else if (!inplace_flag)
                openmode |= SSH2_FXF_TRUNC;

        /* Send open request */
        if (send_open(conn, remote_path, "dest", openmode, &a,
            &handle, &handle_len) != 0) {
                close(local_fd);
                return -1;
        }

        id = conn->msg_id;
        startid = ackid = id + 1;
        data = xmalloc(conn->upload_buflen);

        /* Read from local and write to remote */
        offset = progress_counter = (resume ? c.size : 0);
        if (showprogress) {
                start_progress_meter(progress_meter_path(local_path),
                    sb.st_size, &progress_counter);
        }

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        for (;;) {
                int len;

                /*
                 * Can't use atomicio here because it returns 0 on EOF,
                 * thus losing the last block of the file.
                 * Simulate an EOF on interrupt, allowing ACKs from the
                 * server to drain.
                 */
                if (interrupted || status != SSH2_FX_OK)
                        len = 0;
                else do
                        len = read(local_fd, data, conn->upload_buflen);
                while ((len == -1) && (errno == EINTR || errno == EAGAIN));

                if (len == -1) {
                        fatal("read local \"%s\": %s",
                            local_path, strerror(errno));
                } else if (len != 0) {
                        ack = request_enqueue(&acks, ++id, len, offset);
                        sshbuf_reset(msg);
                        if ((r = sshbuf_put_u8(msg, SSH2_FXP_WRITE)) != 0 ||
                            (r = sshbuf_put_u32(msg, ack->id)) != 0 ||
                            (r = sshbuf_put_string(msg, handle,
                            handle_len)) != 0 ||
                            (r = sshbuf_put_u64(msg, offset)) != 0 ||
                            (r = sshbuf_put_string(msg, data, len)) != 0)
                                fatal_fr(r, "compose");
                        send_msg(conn, msg);
                        debug3("Sent message SSH2_FXP_WRITE I:%u O:%llu S:%u",
                            id, (unsigned long long)offset, len);
                } else if (TAILQ_FIRST(&acks) == NULL)
                        break;

                if (ack == NULL)
                        fatal("Unexpected ACK %u", id);

                if (id == startid || len == 0 ||
                    id - ackid >= conn->num_requests) {
                        u_int rid;

                        sshbuf_reset(msg);
                        get_msg(conn, msg);
                        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
                            (r = sshbuf_get_u32(msg, &rid)) != 0)
                                fatal_fr(r, "parse");

                        if (type != SSH2_FXP_STATUS)
                                fatal("Expected SSH2_FXP_STATUS(%d) packet, "
                                    "got %d", SSH2_FXP_STATUS, type);

                        if ((r = sshbuf_get_u32(msg, &status2)) != 0)
                                fatal_fr(r, "parse status");
                        debug3("SSH2_FXP_STATUS %u", status2);
                        if (status2 != SSH2_FX_OK)
                                status = status2; /* remember errors */

                        /* Find the request in our queue */
                        if ((ack = request_find(&acks, rid)) == NULL)
                                fatal("Can't find request for ID %u", rid);
                        TAILQ_REMOVE(&acks, ack, tq);
                        debug3("In write loop, ack for %u %zu bytes at %lld",
                            ack->id, ack->len, (unsigned long long)ack->offset);
                        ++ackid;
                        progress_counter += ack->len;
                        /*
                         * Track both the highest offset acknowledged and the
                         * highest *contiguous* offset acknowledged.
                         * We'll need the latter for ftruncate()ing
                         * interrupted transfers.
                         */
                        if (maxack < ack->offset + ack->len)
                                maxack = ack->offset + ack->len;
                        if (!reordered && ack->offset <= highwater)
                                highwater = maxack;
                        else if (!reordered && ack->offset > highwater) {
                                debug3_f("server reordered ACKs");
                                reordered = 1;
                        }
                        free(ack);
                }
                offset += len;
                if (offset < 0)
                        fatal_f("offset < 0");
        }
        sshbuf_free(msg);

        if (showprogress)
                stop_progress_meter();
        free(data);

        if (status == SSH2_FX_OK && !interrupted) {
                /* we got everything */
                highwater = maxack;
        }
        if (status != SSH2_FX_OK) {
                error("write remote \"%s\": %s", remote_path, fx2txt(status));
                status = SSH2_FX_FAILURE;
        }

        if (inplace_flag || (resume && (status != SSH2_FX_OK || interrupted))) {
                debug("truncating at %llu", (unsigned long long)highwater);
                attrib_clear(&t);
                t.flags = SSH2_FILEXFER_ATTR_SIZE;
                t.size = highwater;
                sftp_fsetstat(conn, handle, handle_len, &t);
        }

        if (close(local_fd) == -1) {
                error("close local \"%s\": %s", local_path, strerror(errno));
                status = SSH2_FX_FAILURE;
        }

        /* Override umask and utimes if asked */
        if (preserve_flag)
                sftp_fsetstat(conn, handle, handle_len, &a);

        if (fsync_flag)
                (void)sftp_fsync(conn, handle, handle_len);

        if (sftp_close(conn, handle, handle_len) != 0)
                status = SSH2_FX_FAILURE;

        free(handle);

        return status == SSH2_FX_OK ? 0 : -1;
}

static int
upload_dir_internal(struct sftp_conn *conn, const char *src, const char *dst,
    int depth, int preserve_flag, int print_flag, int resume, int fsync_flag,
    int follow_link_flag, int inplace_flag)
{
        int created = 0, ret = 0;
        DIR *dirp;
        struct dirent *dp;
        char *filename, *new_src = NULL, *new_dst = NULL;
        struct stat sb;
        Attrib a, dirattrib;
        uint32_t saved_perm;

        debug2_f("upload local dir \"%s\" to remote \"%s\"", src, dst);

        if (depth >= MAX_DIR_DEPTH) {
                error("Maximum directory depth exceeded: %d levels", depth);
                return -1;
        }

        if (stat(src, &sb) == -1) {
                error("stat local \"%s\": %s", src, strerror(errno));
                return -1;
        }
        if (!S_ISDIR(sb.st_mode)) {
                error("\"%s\" is not a directory", src);
                return -1;
        }
        if (print_flag && print_flag != SFTP_PROGRESS_ONLY)
                mprintf("Entering %s\n", src);

        stat_to_attrib(&sb, &a);
        a.flags &= ~SSH2_FILEXFER_ATTR_SIZE;
        a.flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
        a.perm &= 01777;
        if (!preserve_flag)
                a.flags &= ~SSH2_FILEXFER_ATTR_ACMODTIME;

        /*
         * sftp lacks a portable status value to match errno EEXIST,
         * so if we get a failure back then we must check whether
         * the path already existed and is a directory.  Ensure we can
         * write to the directory we create for the duration of the transfer.
         */
        saved_perm = a.perm;
        a.perm |= (S_IWUSR|S_IXUSR);
        if (sftp_mkdir(conn, dst, &a, 0) == 0)
                created = 1;
        else {
                if (sftp_stat(conn, dst, 0, &dirattrib) != 0)
                        return -1;
                if (!S_ISDIR(dirattrib.perm)) {
                        error("\"%s\" exists but is not a directory", dst);
                        return -1;
                }
        }
        a.perm = saved_perm;

        if ((dirp = opendir(src)) == NULL) {
                error("local opendir \"%s\": %s", src, strerror(errno));
                return -1;
        }

        while (((dp = readdir(dirp)) != NULL) && !interrupted) {
                if (dp->d_ino == 0)
                        continue;
                free(new_dst);
                free(new_src);
                filename = dp->d_name;
                new_dst = sftp_path_append(dst, filename);
                new_src = sftp_path_append(src, filename);

                if (strcmp(filename, ".") == 0 || strcmp(filename, "..") == 0)
                        continue;
                if (lstat(new_src, &sb) == -1) {
                        logit("local lstat \"%s\": %s", filename,
                            strerror(errno));
                        ret = -1;
                        continue;
                }
                if (S_ISLNK(sb.st_mode)) {
                        if (!follow_link_flag) {
                                logit("%s: not a regular file", filename);
                                continue;
                        }
                        /* Replace the stat contents with the symlink target */
                        if (stat(new_src, &sb) == -1) {
                                logit("local stat \"%s\": %s", filename,
                                    strerror(errno));
                                ret = -1;
                                continue;
                        }
                }
                if (S_ISDIR(sb.st_mode)) {
                        if (upload_dir_internal(conn, new_src, new_dst,
                            depth + 1, preserve_flag, print_flag, resume,
                            fsync_flag, follow_link_flag, inplace_flag) == -1)
                                ret = -1;
                } else if (S_ISREG(sb.st_mode)) {
                        if (sftp_upload(conn, new_src, new_dst,
                            preserve_flag, resume, fsync_flag,
                            inplace_flag) == -1) {
                                error("upload \"%s\" to \"%s\" failed",
                                    new_src, new_dst);
                                ret = -1;
                        }
                } else
                        logit("%s: not a regular file", filename);
        }
        free(new_dst);
        free(new_src);

        if (created || preserve_flag)
                sftp_setstat(conn, dst, &a);

        (void) closedir(dirp);
        return ret;
}

int
sftp_upload_dir(struct sftp_conn *conn, const char *src, const char *dst,
    int preserve_flag, int print_flag, int resume, int fsync_flag,
    int follow_link_flag, int inplace_flag)
{
        char *dst_canon;
        int ret;

        if ((dst_canon = sftp_realpath(conn, dst)) == NULL) {
                error("upload \"%s\": path canonicalization failed", dst);
                return -1;
        }

        ret = upload_dir_internal(conn, src, dst_canon, 0, preserve_flag,
            print_flag, resume, fsync_flag, follow_link_flag, inplace_flag);

        free(dst_canon);
        return ret;
}

static void
handle_dest_replies(struct sftp_conn *to, const char *to_path, int synchronous,
    u_int *nreqsp, u_int *write_errorp)
{
        struct sshbuf *msg;
        u_char type;
        u_int id, status;
        int r;
        struct pollfd pfd;

        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");

        /* Try to eat replies from the upload side */
        while (*nreqsp > 0) {
                debug3_f("%u outstanding replies", *nreqsp);
                if (!synchronous) {
                        /* Bail out if no data is ready to be read */
                        pfd.fd = to->fd_in;
                        pfd.events = POLLIN;
                        if ((r = poll(&pfd, 1, 0)) == -1) {
                                if (errno == EINTR)
                                        break;
                                fatal_f("poll: %s", strerror(errno));
                        } else if (r == 0)
                                break; /* fd not ready */
                }
                sshbuf_reset(msg);
                get_msg(to, msg);

                if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
                    (r = sshbuf_get_u32(msg, &id)) != 0)
                        fatal_fr(r, "dest parse");
                debug3("Received dest reply T:%u I:%u R:%u", type, id, *nreqsp);
                if (type != SSH2_FXP_STATUS) {
                        fatal_f("Expected SSH2_FXP_STATUS(%d) packet, got %d",
                            SSH2_FXP_STATUS, type);
                }
                if ((r = sshbuf_get_u32(msg, &status)) != 0)
                        fatal_fr(r, "parse dest status");
                debug3("dest SSH2_FXP_STATUS %u", status);
                if (status != SSH2_FX_OK) {
                        /* record first error */
                        if (*write_errorp == 0)
                                *write_errorp = status;
                }
                /*
                 * XXX this doesn't do full reply matching like sftp_upload and
                 * so cannot gracefully truncate terminated uploads at a
                 * high-water mark. ATM the only caller of this function (scp)
                 * doesn't support transfer resumption, so this doesn't matter
                 * a whole lot.
                 *
                 * To be safe, sftp_crossload truncates the destination file to
                 * zero length on upload failure, since we can't trust the
                 * server not to have reordered replies that could have
                 * inserted holes where none existed in the source file.
                 *
                 * XXX we could get a more accurate progress bar if we updated
                 * the counter based on the reply from the destination...
                 */
                (*nreqsp)--;
        }
        debug3_f("done: %u outstanding replies", *nreqsp);
        sshbuf_free(msg);
}

int
sftp_crossload(struct sftp_conn *from, struct sftp_conn *to,
    const char *from_path, const char *to_path,
    Attrib *a, int preserve_flag)
{
        struct sshbuf *msg;
        int write_error, read_error, r;
        uint64_t offset = 0, size;
        u_int id, buflen, num_req, max_req, status = SSH2_FX_OK;
        u_int num_upload_req;
        off_t progress_counter;
        u_char *from_handle, *to_handle;
        size_t from_handle_len, to_handle_len;
        struct requests requests;
        struct request *req;
        u_char type;
        Attrib attr;

        debug2_f("crossload src \"%s\" to dst \"%s\"", from_path, to_path);

        TAILQ_INIT(&requests);

        if (a == NULL) {
                if (sftp_stat(from, from_path, 0, &attr) != 0)
                        return -1;
                a = &attr;
        }

        if ((a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) &&
            (!S_ISREG(a->perm))) {
                error("download \"%s\": not a regular file", from_path);
                return(-1);
        }
        if (a->flags & SSH2_FILEXFER_ATTR_SIZE)
                size = a->size;
        else
                size = 0;

        buflen = from->download_buflen;
        if (buflen > to->upload_buflen)
                buflen = to->upload_buflen;

        /* Send open request to read side */
        if (send_open(from, from_path, "origin", SSH2_FXF_READ, NULL,
            &from_handle, &from_handle_len) != 0)
                return -1;

        /* Send open request to write side */
        a->flags &= ~SSH2_FILEXFER_ATTR_SIZE;
        a->flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
        a->perm &= 0777;
        if (!preserve_flag)
                a->flags &= ~SSH2_FILEXFER_ATTR_ACMODTIME;
        if (send_open(to, to_path, "dest",
            SSH2_FXF_WRITE|SSH2_FXF_CREAT|SSH2_FXF_TRUNC, a,
            &to_handle, &to_handle_len) != 0) {
                sftp_close(from, from_handle, from_handle_len);
                return -1;
        }

        /* Read from remote "from" and write to remote "to" */
        offset = 0;
        write_error = read_error = num_req = num_upload_req = 0;
        max_req = 1;
        progress_counter = 0;

        if (showprogress && size != 0) {
                start_progress_meter(progress_meter_path(from_path),
                    size, &progress_counter);
        }
        if ((msg = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        while (num_req > 0 || max_req > 0) {
                u_char *data;
                size_t len;

                /*
                 * Simulate EOF on interrupt: stop sending new requests and
                 * allow outstanding requests to drain gracefully
                 */
                if (interrupted) {
                        if (num_req == 0) /* If we haven't started yet... */
                                break;
                        max_req = 0;
                }

                /* Send some more requests */
                while (num_req < max_req) {
                        debug3("Request range %llu -> %llu (%d/%d)",
                            (unsigned long long)offset,
                            (unsigned long long)offset + buflen - 1,
                            num_req, max_req);
                        req = request_enqueue(&requests, from->msg_id++,
                            buflen, offset);
                        offset += buflen;
                        num_req++;
                        send_read_request(from, req->id, req->offset,
                            req->len, from_handle, from_handle_len);
                }

                /* Try to eat replies from the upload side (nonblocking) */
                handle_dest_replies(to, to_path, 0,
                    &num_upload_req, &write_error);

                sshbuf_reset(msg);
                get_msg(from, msg);
                if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
                    (r = sshbuf_get_u32(msg, &id)) != 0)
                        fatal_fr(r, "parse");
                debug3("Received origin reply T:%u I:%u R:%d",
                    type, id, max_req);

                /* Find the request in our queue */
                if ((req = request_find(&requests, id)) == NULL)
                        fatal("Unexpected reply %u", id);

                switch (type) {
                case SSH2_FXP_STATUS:
                        if ((r = sshbuf_get_u32(msg, &status)) != 0)
                                fatal_fr(r, "parse status");
                        if (status != SSH2_FX_EOF)
                                read_error = 1;
                        max_req = 0;
                        TAILQ_REMOVE(&requests, req, tq);
                        free(req);
                        num_req--;
                        break;
                case SSH2_FXP_DATA:
                        if ((r = sshbuf_get_string(msg, &data, &len)) != 0)
                                fatal_fr(r, "parse data");
                        debug3("Received data %llu -> %llu",
                            (unsigned long long)req->offset,
                            (unsigned long long)req->offset + len - 1);
                        if (len > req->len)
                                fatal("Received more data than asked for "
                                    "%zu > %zu", len, req->len);

                        /* Write this chunk out to the destination */
                        sshbuf_reset(msg);
                        if ((r = sshbuf_put_u8(msg, SSH2_FXP_WRITE)) != 0 ||
                            (r = sshbuf_put_u32(msg, to->msg_id++)) != 0 ||
                            (r = sshbuf_put_string(msg, to_handle,
                            to_handle_len)) != 0 ||
                            (r = sshbuf_put_u64(msg, req->offset)) != 0 ||
                            (r = sshbuf_put_string(msg, data, len)) != 0)
                                fatal_fr(r, "compose write");
                        send_msg(to, msg);
                        debug3("Sent message SSH2_FXP_WRITE I:%u O:%llu S:%zu",
                            id, (unsigned long long)offset, len);
                        num_upload_req++;
                        progress_counter += len;
                        free(data);

                        if (len == req->len) {
                                TAILQ_REMOVE(&requests, req, tq);
                                free(req);
                                num_req--;
                        } else {
                                /* Resend the request for the missing data */
                                debug3("Short data block, re-requesting "
                                    "%llu -> %llu (%2d)",
                                    (unsigned long long)req->offset + len,
                                    (unsigned long long)req->offset +
                                    req->len - 1, num_req);
                                req->id = from->msg_id++;
                                req->len -= len;
                                req->offset += len;
                                send_read_request(from, req->id,
                                    req->offset, req->len,
                                    from_handle, from_handle_len);
                                /* Reduce the request size */
                                if (len < buflen)
                                        buflen = MAXIMUM(MIN_READ_SIZE, len);
                        }
                        if (max_req > 0) { /* max_req = 0 iff EOF received */
                                if (size > 0 && offset > size) {
                                        /* Only one request at a time
                                         * after the expected EOF */
                                        debug3("Finish at %llu (%2d)",
                                            (unsigned long long)offset,
                                            num_req);
                                        max_req = 1;
                                } else if (max_req < from->num_requests) {
                                        ++max_req;
                                }
                        }
                        break;
                default:
                        fatal("Expected SSH2_FXP_DATA(%u) packet, got %u",
                            SSH2_FXP_DATA, type);
                }
        }

        if (showprogress && size)
                stop_progress_meter();

        /* Drain replies from the server (blocking) */
        debug3_f("waiting for %u replies from destination", num_upload_req);
        handle_dest_replies(to, to_path, 1, &num_upload_req, &write_error);

        /* Sanity check */
        if (TAILQ_FIRST(&requests) != NULL)
                fatal("Transfer complete, but requests still in queue");
        /* Truncate at 0 length on interrupt or error to avoid holes at dest */
        if (read_error || write_error || interrupted) {
                debug("truncating \"%s\" at 0", to_path);
                sftp_close(to, to_handle, to_handle_len);
                free(to_handle);
                if (send_open(to, to_path, "dest",
                    SSH2_FXF_WRITE|SSH2_FXF_CREAT|SSH2_FXF_TRUNC, a,
                    &to_handle, &to_handle_len) != 0) {
                        error("dest truncate \"%s\" failed", to_path);
                        to_handle = NULL;
                }
        }
        if (read_error) {
                error("read origin \"%s\": %s", from_path, fx2txt(status));
                status = -1;
                sftp_close(from, from_handle, from_handle_len);
                if (to_handle != NULL)
                        sftp_close(to, to_handle, to_handle_len);
        } else if (write_error) {
                error("write dest \"%s\": %s", to_path, fx2txt(write_error));
                status = SSH2_FX_FAILURE;
                sftp_close(from, from_handle, from_handle_len);
                if (to_handle != NULL)
                        sftp_close(to, to_handle, to_handle_len);
        } else {
                if (sftp_close(from, from_handle, from_handle_len) != 0 ||
                    interrupted)
                        status = -1;
                else
                        status = SSH2_FX_OK;
                if (to_handle != NULL) {
                        /* Need to resend utimes after write */
                        if (preserve_flag)
                                sftp_fsetstat(to, to_handle, to_handle_len, a);
                        sftp_close(to, to_handle, to_handle_len);
                }
        }
        sshbuf_free(msg);
        free(from_handle);
        free(to_handle);

        return status == SSH2_FX_OK ? 0 : -1;
}

static int
crossload_dir_internal(struct sftp_conn *from, struct sftp_conn *to,
    const char *from_path, const char *to_path,
    int depth, Attrib *dirattrib, int preserve_flag, int print_flag,
    int follow_link_flag)
{
        int i, ret = 0, created = 0;
        SFTP_DIRENT **dir_entries;
        char *filename, *new_from_path = NULL, *new_to_path = NULL;
        mode_t mode = 0777;
        Attrib *a, curdir, ldirattrib, newdir, lsym;

        debug2_f("crossload dir src \"%s\" to dst \"%s\"", from_path, to_path);

        if (depth >= MAX_DIR_DEPTH) {
                error("Maximum directory depth exceeded: %d levels", depth);
                return -1;
        }

        if (dirattrib == NULL) {
                if (sftp_stat(from, from_path, 1, &ldirattrib) != 0) {
                        error("stat remote \"%s\" failed", from_path);
                        return -1;
                }
                dirattrib = &ldirattrib;
        }
        if (!S_ISDIR(dirattrib->perm)) {
                error("\"%s\" is not a directory", from_path);
                return -1;
        }
        if (print_flag && print_flag != SFTP_PROGRESS_ONLY)
                mprintf("Retrieving %s\n", from_path);

        curdir = *dirattrib; /* dirattrib will be clobbered */
        curdir.flags &= ~SSH2_FILEXFER_ATTR_SIZE;
        curdir.flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
        if ((curdir.flags & SSH2_FILEXFER_ATTR_PERMISSIONS) == 0) {
                debug("Origin did not send permissions for "
                    "directory \"%s\"", to_path);
                curdir.perm = S_IWUSR|S_IXUSR;
                curdir.flags |= SSH2_FILEXFER_ATTR_PERMISSIONS;
        }
        /* We need to be able to write to the directory while we transfer it */
        mode = curdir.perm & 01777;
        curdir.perm = mode | (S_IWUSR|S_IXUSR);

        /*
         * sftp lacks a portable status value to match errno EEXIST,
         * so if we get a failure back then we must check whether
         * the path already existed and is a directory.  Ensure we can
         * write to the directory we create for the duration of the transfer.
         */
        if (sftp_mkdir(to, to_path, &curdir, 0) == 0)
                created = 1;
        else {
                if (sftp_stat(to, to_path, 0, &newdir) != 0)
                        return -1;
                if (!S_ISDIR(newdir.perm)) {
                        error("\"%s\" exists but is not a directory", to_path);
                        return -1;
                }
        }
        curdir.perm = mode;

        if (sftp_readdir(from, from_path, &dir_entries) == -1) {
                error("origin readdir \"%s\" failed", from_path);
                return -1;
        }

        for (i = 0; dir_entries[i] != NULL && !interrupted; i++) {
                free(new_from_path);
                free(new_to_path);

                filename = dir_entries[i]->filename;
                new_from_path = sftp_path_append(from_path, filename);
                new_to_path = sftp_path_append(to_path, filename);

                a = &dir_entries[i]->a;
                if (S_ISLNK(a->perm)) {
                        if (!follow_link_flag) {
                                logit("%s: not a regular file", filename);
                                continue;
                        }
                        /* Replace the stat contents with the symlink target */
                        if (sftp_stat(from, new_from_path, 1, &lsym) != 0) {
                                logit("remote stat \"%s\" failed",
                                    new_from_path);
                                ret = -1;
                                continue;
                        }
                        a = &lsym;
                }
                if (S_ISDIR(a->perm)) {
                        if (strcmp(filename, ".") == 0 ||
                            strcmp(filename, "..") == 0)
                                continue;
                        if (crossload_dir_internal(from, to,
                            new_from_path, new_to_path,
                            depth + 1, a, preserve_flag,
                            print_flag, follow_link_flag) == -1)
                                ret = -1;
                } else if (S_ISREG(a->perm)) {
                        if (sftp_crossload(from, to, new_from_path,
                            new_to_path, a, preserve_flag) == -1) {
                                error("crossload \"%s\" to \"%s\" failed",
                                    new_from_path, new_to_path);
                                ret = -1;
                        }
                } else {
                        logit("origin \"%s\": not a regular file",
                            new_from_path);
                }
        }
        free(new_to_path);
        free(new_from_path);

        if (created || preserve_flag)
                sftp_setstat(to, to_path, &curdir);

        sftp_free_dirents(dir_entries);

        return ret;
}

int
sftp_crossload_dir(struct sftp_conn *from, struct sftp_conn *to,
    const char *from_path, const char *to_path,
    Attrib *dirattrib, int preserve_flag, int print_flag, int follow_link_flag)
{
        char *from_path_canon;
        int ret;

        if ((from_path_canon = sftp_realpath(from, from_path)) == NULL) {
                error("crossload \"%s\": path canonicalization failed",
                    from_path);
                return -1;
        }

        ret = crossload_dir_internal(from, to, from_path_canon, to_path, 0,
            dirattrib, preserve_flag, print_flag, follow_link_flag);
        free(from_path_canon);
        return ret;
}

int
sftp_can_get_users_groups_by_id(struct sftp_conn *conn)
{
        return (conn->exts & SFTP_EXT_GETUSERSGROUPS_BY_ID) != 0;
}

int
sftp_get_users_groups_by_id(struct sftp_conn *conn,
    const u_int *uids, u_int nuids,
    const u_int *gids, u_int ngids,
    char ***usernamesp, char ***groupnamesp)
{
        struct sshbuf *msg, *uidbuf, *gidbuf;
        u_int i, expected_id, id;
        char *name, **usernames = NULL, **groupnames = NULL;
        u_char type;
        int r;

        *usernamesp = *groupnamesp = NULL;
        if (!sftp_can_get_users_groups_by_id(conn))
                return SSH_ERR_FEATURE_UNSUPPORTED;

        if ((msg = sshbuf_new()) == NULL ||
            (uidbuf = sshbuf_new()) == NULL ||
            (gidbuf = sshbuf_new()) == NULL)
                fatal_f("sshbuf_new failed");
        expected_id = id = conn->msg_id++;
        debug2("Sending SSH2_FXP_EXTENDED(users-groups-by-id@openssh.com)");
        for (i = 0; i < nuids; i++) {
                if ((r = sshbuf_put_u32(uidbuf, uids[i])) != 0)
                        fatal_fr(r, "compose uids");
        }
        for (i = 0; i < ngids; i++) {
                if ((r = sshbuf_put_u32(gidbuf, gids[i])) != 0)
                        fatal_fr(r, "compose gids");
        }
        if ((r = sshbuf_put_u8(msg, SSH2_FXP_EXTENDED)) != 0 ||
            (r = sshbuf_put_u32(msg, id)) != 0 ||
            (r = sshbuf_put_cstring(msg,
            "users-groups-by-id@openssh.com")) != 0 ||
            (r = sshbuf_put_stringb(msg, uidbuf)) != 0 ||
            (r = sshbuf_put_stringb(msg, gidbuf)) != 0)
                fatal_fr(r, "compose");
        send_msg(conn, msg);
        get_msg(conn, msg);
        if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
            (r = sshbuf_get_u32(msg, &id)) != 0)
                fatal_fr(r, "parse");
        if (id != expected_id)
                fatal("ID mismatch (%u != %u)", id, expected_id);
        if (type == SSH2_FXP_STATUS) {
                u_int status;
                char *errmsg;

                if ((r = sshbuf_get_u32(msg, &status)) != 0 ||
                    (r = sshbuf_get_cstring(msg, &errmsg, NULL)) != 0)
                        fatal_fr(r, "parse status");
                error("users-groups-by-id %s",
                    *errmsg == '\0' ? fx2txt(status) : errmsg);
                free(errmsg);
                sshbuf_free(msg);
                sshbuf_free(uidbuf);
                sshbuf_free(gidbuf);
                return -1;
        } else if (type != SSH2_FXP_EXTENDED_REPLY)
                fatal("Expected SSH2_FXP_EXTENDED_REPLY(%u) packet, got %u",
                    SSH2_FXP_EXTENDED_REPLY, type);

        /* reuse */
        sshbuf_free(uidbuf);
        sshbuf_free(gidbuf);
        uidbuf = gidbuf = NULL;
        if ((r = sshbuf_froms(msg, &uidbuf)) != 0 ||
            (r = sshbuf_froms(msg, &gidbuf)) != 0)
                fatal_fr(r, "parse response");
        if (nuids > 0) {
                usernames = xcalloc(nuids, sizeof(*usernames));
                for (i = 0; i < nuids; i++) {
                        if ((r = sshbuf_get_cstring(uidbuf, &name, NULL)) != 0)
                                fatal_fr(r, "parse user name");
                        /* Handle unresolved names */
                        if (*name == '\0') {
                                free(name);
                                name = NULL;
                        }
                        usernames[i] = name;
                }
        }
        if (ngids > 0) {
                groupnames = xcalloc(ngids, sizeof(*groupnames));
                for (i = 0; i < ngids; i++) {
                        if ((r = sshbuf_get_cstring(gidbuf, &name, NULL)) != 0)
                                fatal_fr(r, "parse user name");
                        /* Handle unresolved names */
                        if (*name == '\0') {
                                free(name);
                                name = NULL;
                        }
                        groupnames[i] = name;
                }
        }
        if (sshbuf_len(uidbuf) != 0)
                fatal_f("unexpected extra username data");
        if (sshbuf_len(gidbuf) != 0)
                fatal_f("unexpected extra groupname data");
        sshbuf_free(uidbuf);
        sshbuf_free(gidbuf);
        sshbuf_free(msg);
        /* success */
        *usernamesp = usernames;
        *groupnamesp = groupnames;
        return 0;
}

char *
sftp_path_append(const char *p1, const char *p2)
{
        char *ret;
        size_t len = strlen(p1) + strlen(p2) + 2;

        ret = xmalloc(len);
        strlcpy(ret, p1, len);
        if (p1[0] != '\0' && p1[strlen(p1) - 1] != '/')
                strlcat(ret, "/", len);
        strlcat(ret, p2, len);

        return(ret);
}

/*
 * Arg p must be dynamically allocated.  It will either be returned or
 * freed and a replacement allocated.  Caller must free returned string.
 */
char *
sftp_make_absolute(char *p, const char *pwd)
{
        char *abs_str;

        /* Derelativise */
        if (p && !path_absolute(p)) {
                abs_str = sftp_path_append(pwd, p);
                free(p);
                return(abs_str);
        } else
                return(p);
}

int
sftp_remote_is_dir(struct sftp_conn *conn, const char *path)
{
        Attrib a;

        /* XXX: report errors? */
        if (sftp_stat(conn, path, 1, &a) != 0)
                return(0);
        if (!(a.flags & SSH2_FILEXFER_ATTR_PERMISSIONS))
                return(0);
        return S_ISDIR(a.perm);
}


/* Check whether path returned from glob(..., GLOB_MARK, ...) is a directory */
int
sftp_globpath_is_dir(const char *pathname)
{
        size_t l = strlen(pathname);

        return l > 0 && pathname[l - 1] == '/';
}