/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2007 Kai Wang
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include <sys/endian.h>
#include <sys/mman.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <archive.h>
#include <archive_entry.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <gelf.h>
#include <libgen.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "ar.h"

#define _ARMAG_LEN 8            /* length of ar magic string */
#define _ARHDR_LEN 60           /* length of ar header */
#define _INIT_AS_CAP 128        /* initial archive string table size */
#define _INIT_SYMOFF_CAP (256*(sizeof(uint64_t))) /* initial so table size */
#define _INIT_SYMNAME_CAP 1024                    /* initial sn table size */
#define _MAXNAMELEN_SVR4 15     /* max member name length in svr4 variant */
#define _TRUNCATE_LEN 15        /* number of bytes to keep for member name */

static void     add_to_ar_str_table(struct bsdar *bsdar, const char *name);
static void     add_to_ar_sym_table(struct bsdar *bsdar, const char *name);
static struct ar_obj    *create_obj_from_file(struct bsdar *bsdar,
                    const char *name, time_t mtime);
static void     create_symtab_entry(struct bsdar *bsdar, void *maddr,
                    size_t size);
static void     free_obj(struct bsdar *bsdar, struct ar_obj *obj);
static void     insert_obj(struct bsdar *bsdar, struct ar_obj *obj,
                    struct ar_obj *pos);
static void     prefault_buffer(const char *buf, size_t s);
static void     read_objs(struct bsdar *bsdar, const char *archive,
                    int checkargv);
static void     write_cleanup(struct bsdar *bsdar);
static void     write_data(struct bsdar *bsdar, struct archive *a,
                    const void *buf, size_t s);
static void     write_objs(struct bsdar *bsdar);

/*
 * Create object from file, return created obj upon success, or NULL
 * when an error occurs or the member is not newer than existing
 * one while -u is specified.
 */
static struct ar_obj *
create_obj_from_file(struct bsdar *bsdar, const char *name, time_t mtime)
{
        struct ar_obj           *obj;
        struct stat              sb;
        const char              *bname;
        char                    *tmpname;

        if (name == NULL)
                return (NULL);

        obj = malloc(sizeof(struct ar_obj));
        if (obj == NULL)
                bsdar_errc(bsdar, errno, "malloc failed");
        if ((obj->fd = open(name, O_RDONLY, 0)) < 0) {
                bsdar_warnc(bsdar, errno, "can't open file: %s", name);
                free(obj);
                return (NULL);
        }

        tmpname = strdup(name);
        if (tmpname == NULL)
                bsdar_errc(bsdar, errno, "strdup failed");
        if ((bname = basename(tmpname)) == NULL)
                bsdar_errc(bsdar, errno, "basename failed");
        if (bsdar->options & AR_TR && strlen(bname) > _TRUNCATE_LEN) {
                if ((obj->name = malloc(_TRUNCATE_LEN + 1)) == NULL)
                        bsdar_errc(bsdar, errno, "malloc failed");
                (void)strncpy(obj->name, bname, _TRUNCATE_LEN);
                obj->name[_TRUNCATE_LEN] = '\0';
        } else
                if ((obj->name = strdup(bname)) == NULL)
                    bsdar_errc(bsdar, errno, "strdup failed");
        free(tmpname);

        if (fstat(obj->fd, &sb) < 0) {
                bsdar_warnc(bsdar, errno, "can't fstat file: %s", obj->name);
                goto giveup;
        }
        if (!S_ISREG(sb.st_mode)) {
                bsdar_warnc(bsdar, 0, "%s is not an ordinary file", obj->name);
                goto giveup;
        }

        /*
         * When option '-u' is specified and member is not newer than the
         * existing one, the replacement will not happen. While if mtime == 0,
         * which indicates that this is to "replace a none exist member",
         * the replace will proceed regardless of '-u'.
         */
        if (mtime != 0 && bsdar->options & AR_U && sb.st_mtime <= mtime)
                goto giveup;

        /*
         * When option '-D' is specified, mtime and UID / GID from the file
         * will be replaced with 0, and file mode with 644. This ensures that
         * checksums will match for two archives containing the exact same
         * files.
         */
        if (bsdar->options & AR_D) {
                obj->uid = 0;
                obj->gid = 0;
                obj->mtime = 0;
                obj->md = S_IFREG | 0644;
        } else {
                obj->uid = sb.st_uid;
                obj->gid = sb.st_gid;
                obj->mtime = sb.st_mtime;
                obj->md = sb.st_mode;
        }
        obj->size = sb.st_size;
        obj->dev = sb.st_dev;
        obj->ino = sb.st_ino;

        if (obj->size == 0) {
                obj->maddr = NULL;
                return (obj);
        }

        if ((obj->maddr = mmap(NULL, obj->size, PROT_READ,
            MAP_PRIVATE, obj->fd, (off_t)0)) == MAP_FAILED) {
                bsdar_warnc(bsdar, errno, "can't mmap file: %s", obj->name);
                goto giveup;
        }
        if (close(obj->fd) < 0)
                bsdar_errc(bsdar, errno, "close failed: %s",
                    obj->name);

        return (obj);

giveup:
        if (close(obj->fd) < 0)
                bsdar_errc(bsdar, errno, "close failed: %s",
                    obj->name);
        free(obj->name);
        free(obj);
        return (NULL);
}

/*
 * Free object itself and its associated allocations.
 */
static void
free_obj(struct bsdar *bsdar, struct ar_obj *obj)
{
        if (obj->fd == -1)
                free(obj->maddr);
        else
                if (obj->maddr != NULL && munmap(obj->maddr, obj->size))
                        bsdar_warnc(bsdar, errno,
                            "can't munmap file: %s", obj->name);
        free(obj->name);
        free(obj);
}

/*
 * Insert obj to the tail, or before/after the pos obj.
 */
static void
insert_obj(struct bsdar *bsdar, struct ar_obj *obj, struct ar_obj *pos)
{
        if (obj == NULL)
                bsdar_errc(bsdar, 0, "try to insert a null obj");

        if (pos == NULL || obj == pos)
                /*
                 * If the object to move happens to be the position obj,
                 * or if there is not a pos obj, move it to tail.
                 */
                goto tail;

        if (bsdar->options & AR_B) {
                TAILQ_INSERT_BEFORE(pos, obj, objs);
                return;
        }
        if (bsdar->options & AR_A) {
                TAILQ_INSERT_AFTER(&bsdar->v_obj, pos, obj, objs);
                return;
        }

tail:
        TAILQ_INSERT_TAIL(&bsdar->v_obj, obj, objs);

}

/*
 * Read objects from archive into v_obj list. Note that checkargv is
 * set when read_objs is used to read objects from the target of
 * ADDLIB command (ar script mode), in this case argv array possibly
 * specifies the members ADDLIB want.
 */
static void
read_objs(struct bsdar *bsdar, const char *archive, int checkargv)
{
        struct archive           *a;
        struct archive_entry     *entry;
        struct ar_obj            *obj;
        const char               *name;
        const char               *bname;
        char                     *buff;
        char                    **av;
        size_t                    size;
        int                       i, r, find;

        if ((a = archive_read_new()) == NULL)
                bsdar_errc(bsdar, 0, "archive_read_new failed");
        archive_read_support_format_ar(a);
        AC(archive_read_open_filename(a, archive, DEF_BLKSZ));
        for (;;) {
                r = archive_read_next_header(a, &entry);
                if (r == ARCHIVE_FATAL)
                        bsdar_errc(bsdar, archive_errno(a), "%s",
                            archive_error_string(a));
                if (r == ARCHIVE_EOF)
                        break;
                if (r == ARCHIVE_WARN || r == ARCHIVE_RETRY)
                        bsdar_warnc(bsdar, archive_errno(a), "%s",
                            archive_error_string(a));
                if (r == ARCHIVE_RETRY) {
                        bsdar_warnc(bsdar, 0, "Retrying...");
                        continue;
                }

                name = archive_entry_pathname(entry);

                /*
                 * skip pseudo members.
                 */
                if (strcmp(name, "/") == 0 || strcmp(name, "//") == 0)
                        continue;

                /*
                 * If checkargv is set, only read those members specified
                 * in argv.
                 */
                if (checkargv && bsdar->argc > 0) {
                        find = 0;
                        for(i = 0; i < bsdar->argc; i++) {
                                av = &bsdar->argv[i];
                                if (*av == NULL)
                                        continue;
                                if ((bname = basename(*av)) == NULL)
                                        bsdar_errc(bsdar, errno,
                                            "basename failed");
                                if (strcmp(bname, name) != 0)
                                        continue;

                                *av = NULL;
                                find = 1;
                                break;
                        }
                        if (!find)
                                continue;
                }

                size = archive_entry_size(entry);

                if (size > 0) {
                        if ((buff = malloc(size)) == NULL)
                                bsdar_errc(bsdar, errno, "malloc failed");
                        if (archive_read_data(a, buff, size) != (ssize_t)size) {
                                bsdar_warnc(bsdar, archive_errno(a), "%s",
                                    archive_error_string(a));
                                free(buff);
                                continue;
                        }
                } else
                        buff = NULL;

                obj = malloc(sizeof(struct ar_obj));
                if (obj == NULL)
                        bsdar_errc(bsdar, errno, "malloc failed");
                obj->maddr = buff;
                if ((obj->name = strdup(name)) == NULL)
                        bsdar_errc(bsdar, errno, "strdup failed");
                obj->size = size;
                obj->uid = archive_entry_uid(entry);
                obj->gid = archive_entry_gid(entry);
                obj->md = archive_entry_mode(entry);
                obj->mtime = archive_entry_mtime(entry);
                obj->dev = 0;
                obj->ino = 0;

                /*
                 * Objects from archive have obj->fd set to -1,
                 * for the ease of cleaning up.
                 */
                obj->fd = -1;
                TAILQ_INSERT_TAIL(&bsdar->v_obj, obj, objs);
        }
        AC(archive_read_close(a));
        AC(archive_read_free(a));
}

/*
 * Determine the constitution of resulting archive.
 */
int
ar_write_archive(struct bsdar *bsdar, int mode)
{
        struct ar_obj            *nobj, *obj, *obj_temp, *pos;
        struct stat               sb;
        const char               *bname;
        char                    **av;
        int                       exitcode, i;

        TAILQ_INIT(&bsdar->v_obj);
        exitcode = EXIT_SUCCESS;
        nobj = NULL;
        pos = NULL;
        memset(&sb, 0, sizeof(sb));

        assert(mode == 'A' || mode == 'd' || mode == 'm' || mode == 'q' ||
            mode == 'r' || mode == 's');

        /*
         * Test if the specified archive exists, to figure out
         * whether we are creating one here.
         */
        if (stat(bsdar->filename, &sb) != 0) {
                if (errno != ENOENT) {
                        bsdar_warnc(bsdar, 0, "stat %s failed",
                            bsdar->filename);
                        return (EXIT_FAILURE);
                }

                /* We do not create archive in mode 'd', 'm' and 's'.  */
                if (mode != 'r' && mode != 'q') {
                        bsdar_warnc(bsdar, 0, "%s: no such file",
                            bsdar->filename);
                        return (EXIT_FAILURE);
                }

                /* Issue a warning if -c is not specified when creating. */
                if (!(bsdar->options & AR_C))
                        bsdar_warnc(bsdar, 0, "creating %s", bsdar->filename);
                goto new_archive;
        }

        /*
         * First read members from existing archive.
         */
        read_objs(bsdar, bsdar->filename, 0);

        /*
         * For mode 's', no member will be moved, deleted or replaced.
         */
        if (mode == 's')
                goto write_objs;

        /*
         * For mode 'q', we don't need to adjust existing members either.
         * Also, -a, -b and -i are ignored in this mode. New members are
         * always inserted at tail.
         */
        if (mode == 'q')
                goto new_archive;

        /*
         * Mode 'A' adds the contents of another archive to the tail of
         * current archive. Note that mode 'A' is a special mode for the
         * ADDLIB command of the ar script mode. Currently there is no
         * access to this function from the ar command line mode.
         */
        if (mode == 'A') {
                /*
                 * Read objects from the target archive of ADDLIB command.
                 * If there are members specified in argv, read those members
                 * only, otherwise the entire archive will be read.
                 */
                read_objs(bsdar, bsdar->addlib, 1);
                goto write_objs;
        }

        /*
         * Try to find the position member specified by user.
         */
        if (bsdar->options & AR_A || bsdar->options & AR_B) {
                TAILQ_FOREACH(obj, &bsdar->v_obj, objs) {
                        if (strcmp(obj->name, bsdar->posarg) == 0) {
                                pos = obj;
                                break;
                        }
                }

                /*
                 * If can't find `pos' specified by user,
                 * silently insert objects at tail.
                 */
                if (pos == NULL)
                        bsdar->options &= ~(AR_A | AR_B);
        }

        for (i = 0; i < bsdar->argc; i++) {
                av = &bsdar->argv[i];

                TAILQ_FOREACH_SAFE(obj, &bsdar->v_obj, objs, obj_temp) {
                        if ((bname = basename(*av)) == NULL)
                                bsdar_errc(bsdar, errno, "basename failed");
                        if (bsdar->options & AR_TR) {
                                if (strncmp(bname, obj->name, _TRUNCATE_LEN))
                                        continue;
                        } else
                                if (strcmp(bname, obj->name) != 0)
                                        continue;

                        if (mode == 'r') {
                                /*
                                 * if the new member is not qualified
                                 * to replace the old one, skip it.
                                 */
                                nobj = create_obj_from_file(bsdar, *av,
                                    obj->mtime);
                                if (nobj == NULL) {
                                        exitcode = EXIT_FAILURE;
                                        goto skip_obj;
                                }
                        }

                        if (bsdar->options & AR_V)
                                (void)fprintf(stdout, "%c - %s\n", mode,
                                    *av);

                        TAILQ_REMOVE(&bsdar->v_obj, obj, objs);
                        if (mode == 'd' || mode == 'r')
                                free_obj(bsdar, obj);

                        if (mode == 'm')
                                insert_obj(bsdar, obj, pos);
                        if (mode == 'r')
                                insert_obj(bsdar, nobj, pos);

                skip_obj:
                        *av = NULL;
                        break;
                }

        }

new_archive:
        /*
         * When operating in mode 'r', directly add those user specified
         * objects which do not exist in current archive. When operating
         * in mode 'q', all objects specified in command line args are
         * appended to the archive, without comparing with existing ones.
         */
        for (i = 0; i < bsdar->argc; i++) {
                av = &bsdar->argv[i];
                if (*av != NULL && (mode == 'r' || mode == 'q')) {
                        nobj = create_obj_from_file(bsdar, *av, 0);
                        if (nobj == NULL) {
                                exitcode = EXIT_FAILURE;
                                *av = NULL;
                                continue;
                        }
                        insert_obj(bsdar, nobj, pos);
                        if (bsdar->options & AR_V && nobj != NULL)
                                (void)fprintf(stdout, "a - %s\n", *av);
                        *av = NULL;
                }
        }

write_objs:
        write_objs(bsdar);
        write_cleanup(bsdar);

        return (exitcode);
}

/*
 * Memory cleaning up.
 */
static void
write_cleanup(struct bsdar *bsdar)
{
        struct ar_obj           *obj, *obj_temp;

        TAILQ_FOREACH_SAFE(obj, &bsdar->v_obj, objs, obj_temp) {
                TAILQ_REMOVE(&bsdar->v_obj, obj, objs);
                free_obj(bsdar, obj);
        }

        free(bsdar->as);
        free(bsdar->s_so);
        free(bsdar->s_sn);
        bsdar->as = NULL;
        bsdar->s_so = NULL;
        bsdar->s_so_max = 0;
        bsdar->s_sn = NULL;
}

/*
 * Fault in the buffer prior to writing as a workaround for poor performance
 * due to interaction with kernel fs deadlock avoidance code. See the comment
 * above vn_io_fault_doio() in sys/kern/vfs_vnops.c for details of the issue.
 */
static void
prefault_buffer(const char *buf, size_t s)
{
        volatile const char *p;
        size_t page_size;

        if (s == 0)
                return;
        page_size = sysconf(_SC_PAGESIZE);
        for (p = buf; p < buf + s; p += page_size)
                *p;
        /*
         * Ensure we touch the last page as well, in case the buffer is not
         * page-aligned.
         */
        *(volatile const char *)(buf + s - 1);
}

/*
 * Wrapper for archive_write_data().
 */
static void
write_data(struct bsdar *bsdar, struct archive *a, const void *buf, size_t s)
{
        ssize_t written;

        prefault_buffer(buf, s);
        while (s > 0) {
                written = archive_write_data(a, buf, s);
                if (written < 0)
                        bsdar_errc(bsdar, archive_errno(a), "%s",
                            archive_error_string(a));
                buf = (const char *)buf + written;
                s -= written;
        }
}

/*
 * Write the resulting archive members.
 */
static void
write_objs(struct bsdar *bsdar)
{
        struct ar_obj           *obj;
        struct archive          *a;
        struct archive_entry    *entry;
        size_t s_sz;            /* size of archive symbol table. */
        size_t pm_sz;           /* size of pseudo members */
        size_t w_sz;            /* size of words in symbol table */
        size_t                   i;
        uint64_t                 nr;
        uint32_t                 nr32;

        if (elf_version(EV_CURRENT) == EV_NONE)
                bsdar_errc(bsdar, 0, "ELF library initialization failed: %s",
                    elf_errmsg(-1));

        bsdar->rela_off = 0;

        /* Create archive symbol table and archive string table, if need. */
        TAILQ_FOREACH(obj, &bsdar->v_obj, objs) {
                if (!(bsdar->options & AR_SS) && obj->maddr != NULL)
                        create_symtab_entry(bsdar, obj->maddr, obj->size);
                if (strlen(obj->name) > _MAXNAMELEN_SVR4)
                        add_to_ar_str_table(bsdar, obj->name);
                bsdar->rela_off += _ARHDR_LEN + obj->size + obj->size % 2;
        }

        /*
         * Pad the symbol name string table. It is treated specially because
         * symbol name table should be padded by a '\0', not the common '\n'
         * for other members. The size of sn table includes the pad bit.
         */
        if (bsdar->s_cnt != 0 && bsdar->s_sn_sz % 2 != 0)
                bsdar->s_sn[bsdar->s_sn_sz++] = '\0';

        /*
         * Archive string table is padded by a "\n" as the normal members.
         * The difference is that the size of archive string table counts
         * in the pad bit, while normal members' size fields do not.
         */
        if (bsdar->as != NULL && bsdar->as_sz % 2 != 0)
                bsdar->as[bsdar->as_sz++] = '\n';

        /*
         * If there is a symbol table, calculate the size of pseudo members,
         * convert previously stored relative offsets to absolute ones, and
         * then make them Big Endian.
         *
         * absolute_offset = htobe32(relative_offset + size_of_pseudo_members)
         */
        w_sz = sizeof(uint32_t);
        if (bsdar->s_cnt != 0) {
                s_sz = (bsdar->s_cnt + 1) * sizeof(uint32_t) + bsdar->s_sn_sz;
                pm_sz = _ARMAG_LEN + (_ARHDR_LEN + s_sz);
                if (bsdar->as != NULL)
                        pm_sz += _ARHDR_LEN + bsdar->as_sz;
                /* Use the 64-bit word size format if necessary. */
                if (bsdar->s_so_max > UINT32_MAX - pm_sz) {
                        w_sz = sizeof(uint64_t);
                        pm_sz -= s_sz;
                        s_sz = (bsdar->s_cnt + 1) * sizeof(uint64_t) +
                            bsdar->s_sn_sz;
                        pm_sz += s_sz;
                        /* Convert to big-endian. */
                        for (i = 0; i < bsdar->s_cnt; i++)
                                bsdar->s_so[i] =
                                    htobe64(bsdar->s_so[i] + pm_sz);
                } else {
                        /*
                         * Convert to big-endian and shuffle in-place to
                         * the front of the allocation. XXX UB
                         */
                        for (i = 0; i < bsdar->s_cnt; i++)
                                ((uint32_t *)(bsdar->s_so))[i] =
                                    htobe32(bsdar->s_so[i] + pm_sz);
                }
        }

        if ((a = archive_write_new()) == NULL)
                bsdar_errc(bsdar, 0, "archive_write_new failed");

        archive_write_set_format_ar_svr4(a);

        AC(archive_write_open_filename(a, bsdar->filename));

        /*
         * write the archive symbol table, if there is one.
         * If options -s is explicitly specified or we are invoked
         * as ranlib, write the symbol table even if it is empty.
         */
        if ((bsdar->s_cnt != 0 && !(bsdar->options & AR_SS)) ||
            bsdar->options & AR_S) {
                entry = archive_entry_new();
                if (entry == NULL)
                        bsdar_errc(bsdar, 0, "archive_entry_new failed");
                if (w_sz == sizeof(uint64_t))
                        archive_entry_copy_pathname(entry, "/SYM64/");
                else
                        archive_entry_copy_pathname(entry, "/");
                if ((bsdar->options & AR_D) == 0)
                        archive_entry_set_mtime(entry, time(NULL), 0);
                archive_entry_set_size(entry, (bsdar->s_cnt + 1) * w_sz +
                    bsdar->s_sn_sz);
                AC(archive_write_header(a, entry));
                if (w_sz == sizeof(uint64_t)) {
                        nr = htobe64(bsdar->s_cnt);
                        write_data(bsdar, a, &nr, sizeof(nr));
                } else {
                        nr32 = htobe32((uint32_t)bsdar->s_cnt);
                        write_data(bsdar, a, &nr32, sizeof(nr32));
                }
                write_data(bsdar, a, bsdar->s_so, w_sz * bsdar->s_cnt);
                write_data(bsdar, a, bsdar->s_sn, bsdar->s_sn_sz);
                archive_entry_free(entry);
        }

        /* write the archive string table, if any. */
        if (bsdar->as != NULL) {
                entry = archive_entry_new();
                if (entry == NULL)
                        bsdar_errc(bsdar, 0, "archive_entry_new failed");
                archive_entry_copy_pathname(entry, "//");
                archive_entry_set_size(entry, bsdar->as_sz);
                AC(archive_write_header(a, entry));
                write_data(bsdar, a, bsdar->as, bsdar->as_sz);
                archive_entry_free(entry);
        }

        /* write normal members. */
        TAILQ_FOREACH(obj, &bsdar->v_obj, objs) {
                entry = archive_entry_new();
                if (entry == NULL)
                        bsdar_errc(bsdar, 0, "archive_entry_new failed");
                archive_entry_copy_pathname(entry, obj->name);
                archive_entry_set_uid(entry, obj->uid);
                archive_entry_set_gid(entry, obj->gid);
                archive_entry_set_mode(entry, obj->md);
                archive_entry_set_size(entry, obj->size);
                archive_entry_set_mtime(entry, obj->mtime, 0);
                archive_entry_set_dev(entry, obj->dev);
                archive_entry_set_ino(entry, obj->ino);
                archive_entry_set_filetype(entry, AE_IFREG);
                AC(archive_write_header(a, entry));
                write_data(bsdar, a, obj->maddr, obj->size);
                archive_entry_free(entry);
        }

        AC(archive_write_close(a));
        AC(archive_write_free(a));
}

/*
 * Extract global symbols from ELF binary members.
 */
static void
create_symtab_entry(struct bsdar *bsdar, void *maddr, size_t size)
{
        Elf             *e;
        Elf_Scn         *scn;
        GElf_Shdr        shdr;
        GElf_Sym         sym;
        Elf_Data        *data;
        char            *name;
        size_t           n, shstrndx;
        int              elferr, tabndx, len, i;

        if ((e = elf_memory(maddr, size)) == NULL) {
                bsdar_warnc(bsdar, 0, "elf_memory() failed: %s",
                     elf_errmsg(-1));
                return;
        }
        if (elf_kind(e) != ELF_K_ELF) {
                /* Silently ignore non-elf member. */
                elf_end(e);
                return;
        }
        if (elf_getshstrndx(e, &shstrndx) == 0) {
                bsdar_warnc(bsdar, 0, "elf_getshstrndx failed: %s",
                     elf_errmsg(-1));
                elf_end(e);
                return;
        }

        tabndx = -1;
        scn = NULL;
        while ((scn = elf_nextscn(e, scn)) != NULL) {
                if (gelf_getshdr(scn, &shdr) != &shdr) {
                        bsdar_warnc(bsdar, 0,
                            "elf_getshdr failed: %s", elf_errmsg(-1));
                        continue;
                }
                if ((name = elf_strptr(e, shstrndx, shdr.sh_name)) == NULL) {
                        bsdar_warnc(bsdar, 0,
                            "elf_strptr failed: %s", elf_errmsg(-1));
                        continue;
                }
                if (strcmp(name, ".strtab") == 0) {
                        tabndx = elf_ndxscn(scn);
                        break;
                }
        }
        elferr = elf_errno();
        if (elferr != 0)
                bsdar_warnc(bsdar, 0, "elf_nextscn failed: %s",
                     elf_errmsg(elferr));
        if (tabndx == -1) {
                bsdar_warnc(bsdar, 0, "can't find .strtab section");
                elf_end(e);
                return;
        }

        scn = NULL;
        while ((scn = elf_nextscn(e, scn)) != NULL) {
                if (gelf_getshdr(scn, &shdr) != &shdr) {
                        bsdar_warnc(bsdar, 0, "elf_getshdr failed: %s",
                            elf_errmsg(-1));
                        continue;
                }
                if (shdr.sh_type != SHT_SYMTAB)
                        continue;

                data = NULL;
                n = 0;
                while (n < shdr.sh_size &&
                    (data = elf_getdata(scn, data)) != NULL) {
                        len = data->d_size / shdr.sh_entsize;
                        for (i = 0; i < len; i++) {
                                if (gelf_getsym(data, i, &sym) != &sym) {
                                        bsdar_warnc(bsdar, 0,
                                            "gelf_getsym failed: %s",
                                             elf_errmsg(-1));
                                        continue;
                                }

                                /* keep only global or weak symbols */
                                if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL &&
                                    GELF_ST_BIND(sym.st_info) != STB_WEAK)
                                        continue;

                                /* keep only defined symbols */
                                if (sym.st_shndx == SHN_UNDEF)
                                        continue;

                                if ((name = elf_strptr(e, tabndx,
                                    sym.st_name)) == NULL) {
                                        bsdar_warnc(bsdar, 0,
                                            "elf_strptr failed: %s",
                                             elf_errmsg(-1));
                                        continue;
                                }

                                add_to_ar_sym_table(bsdar, name);
                        }
                }
        }
        elferr = elf_errno();
        if (elferr != 0)
                bsdar_warnc(bsdar, 0, "elf_nextscn failed: %s",
                     elf_errmsg(elferr));

        elf_end(e);
}

/*
 * Append to the archive string table buffer.
 */
static void
add_to_ar_str_table(struct bsdar *bsdar, const char *name)
{

        if (bsdar->as == NULL) {
                bsdar->as_cap = _INIT_AS_CAP;
                bsdar->as_sz = 0;
                if ((bsdar->as = malloc(bsdar->as_cap)) == NULL)
                        bsdar_errc(bsdar, errno, "malloc failed");
        }

        /*
         * The space required for holding one member name in as table includes:
         * strlen(name) + (1 for '/') + (1 for '\n') + (possibly 1 for padding).
         */
        while (bsdar->as_sz + strlen(name) + 3 > bsdar->as_cap) {
                bsdar->as_cap *= 2;
                bsdar->as = realloc(bsdar->as, bsdar->as_cap);
                if (bsdar->as == NULL)
                        bsdar_errc(bsdar, errno, "realloc failed");
        }
        strncpy(&bsdar->as[bsdar->as_sz], name, strlen(name));
        bsdar->as_sz += strlen(name);
        bsdar->as[bsdar->as_sz++] = '/';
        bsdar->as[bsdar->as_sz++] = '\n';
}

/*
 * Append to the archive symbol table buffer.
 */
static void
add_to_ar_sym_table(struct bsdar *bsdar, const char *name)
{

        if (bsdar->s_so == NULL) {
                if ((bsdar->s_so = malloc(_INIT_SYMOFF_CAP)) ==
                    NULL)
                        bsdar_errc(bsdar, errno, "malloc failed");
                bsdar->s_so_cap = _INIT_SYMOFF_CAP;
                bsdar->s_cnt = 0;
        }

        if (bsdar->s_sn == NULL) {
                if ((bsdar->s_sn = malloc(_INIT_SYMNAME_CAP)) == NULL)
                        bsdar_errc(bsdar, errno, "malloc failed");
                bsdar->s_sn_cap = _INIT_SYMNAME_CAP;
                bsdar->s_sn_sz = 0;
        }

        if (bsdar->s_cnt * sizeof(uint64_t) >= bsdar->s_so_cap) {
                bsdar->s_so_cap *= 2;
                bsdar->s_so = realloc(bsdar->s_so, bsdar->s_so_cap);
                if (bsdar->s_so == NULL)
                        bsdar_errc(bsdar, errno, "realloc failed");
        }
        bsdar->s_so[bsdar->s_cnt] = bsdar->rela_off;
        if ((uint64_t)bsdar->rela_off > bsdar->s_so_max)
                bsdar->s_so_max = (uint64_t)bsdar->rela_off;
        bsdar->s_cnt++;

        /*
         * The space required for holding one symbol name in sn table includes:
         * strlen(name) + (1 for '\n') + (possibly 1 for padding).
         */
        while (bsdar->s_sn_sz + strlen(name) + 2 > bsdar->s_sn_cap) {
                bsdar->s_sn_cap *= 2;
                bsdar->s_sn = realloc(bsdar->s_sn, bsdar->s_sn_cap);
                if (bsdar->s_sn == NULL)
                        bsdar_errc(bsdar, errno, "realloc failed");
        }
        strncpy(&bsdar->s_sn[bsdar->s_sn_sz], name, strlen(name));
        bsdar->s_sn_sz += strlen(name);
        bsdar->s_sn[bsdar->s_sn_sz++] = '\0';
}