/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1991, 1993, 1994
 *      The Regents of the University of California.  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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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/param.h>
#include <sys/acl.h>
#include <sys/stat.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <fts.h>
#include <limits.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>

#include "extern.h"

#define cp_pct(x, y)    ((y == 0) ? 0 : (int)(100.0 * (x) / (y)))

/*
 * Memory strategy threshold, in pages: if physmem is larger then this, use a 
 * large buffer.
 */
#define PHYSPAGES_THRESHOLD (32*1024)

/* Maximum buffer size in bytes - do not allow it to grow larger than this. */
#define BUFSIZE_MAX (2*1024*1024)

/*
 * Small (default) buffer size in bytes. It's inefficient for this to be
 * smaller than MAXPHYS.
 */
#define BUFSIZE_SMALL (MAXPHYS)

/*
 * Prompt used in -i case.
 */
#define YESNO "(y/n [n]) "

static ssize_t
copy_fallback(int from_fd, int to_fd)
{
        static char *buf = NULL;
        static size_t bufsize;
        ssize_t rcount, wresid, wcount = 0;
        char *bufp;

        if (buf == NULL) {
                if (sysconf(_SC_PHYS_PAGES) > PHYSPAGES_THRESHOLD)
                        bufsize = MIN(BUFSIZE_MAX, MAXPHYS * 8);
                else
                        bufsize = BUFSIZE_SMALL;
                buf = malloc(bufsize);
                if (buf == NULL)
                        err(1, "Not enough memory");
        }
        rcount = read(from_fd, buf, bufsize);
        if (rcount <= 0)
                return (rcount);
        for (bufp = buf, wresid = rcount; ; bufp += wcount, wresid -= wcount) {
                wcount = write(to_fd, bufp, wresid);
                if (wcount <= 0)
                        break;
                if (wcount >= wresid)
                        break;
        }
        return (wcount < 0 ? wcount : rcount);
}

int
copy_file(const FTSENT *entp, bool dne, bool beneath)
{
        struct stat sb, *fs;
        ssize_t wcount;
        off_t wtotal;
        int ch, checkch, from_fd, rval, to_fd;
        bool use_copy_file_range = true;

        fs = entp->fts_statp;
        from_fd = to_fd = -1;
        if (!lflag && !sflag) {
                if ((from_fd = open(entp->fts_path, O_RDONLY, 0)) < 0 ||
                    fstat(from_fd, &sb) != 0) {
                        warn("%s", entp->fts_path);
                        if (from_fd >= 0)
                                (void)close(from_fd);
                        return (1);
                }
                /*
                 * Check that the file hasn't been replaced with one of a
                 * different type.  This can happen if we've been asked to
                 * copy something which is actively being modified and
                 * lost the race, or if we've been asked to copy something
                 * like /proc/X/fd/Y which stat(2) reports as S_IFREG but
                 * is actually something else once you open it.
                 */
                if ((sb.st_mode & S_IFMT) != (fs->st_mode & S_IFMT)) {
                        warnx("%s: File changed", entp->fts_path);
                        (void)close(from_fd);
                        return (1);
                }
        }

        /*
         * If the file exists and we're interactive, verify with the user.
         * If the file DNE, set the mode to be the from file, minus setuid
         * bits, modified by the umask; arguably wrong, but it makes copying
         * executables work right and it's been that way forever.  (The
         * other choice is 666 or'ed with the execute bits on the from file
         * modified by the umask.)
         */
        if (!dne) {
                if (nflag) {
                        if (vflag)
                                printf("%s%s not overwritten\n",
                                    to.base, to.path);
                        rval = 1;
                        goto done;
                } else if (iflag) {
                        (void)fprintf(stderr, "overwrite %s%s? %s",
                            to.base, to.path, YESNO);
                        checkch = ch = getchar();
                        while (ch != '\n' && ch != EOF)
                                ch = getchar();
                        if (checkch != 'y' && checkch != 'Y') {
                                (void)fprintf(stderr, "not overwritten\n");
                                rval = 1;
                                goto done;
                        }
                }

                if (fflag) {
                        /* remove existing destination file */
                        (void)unlinkat(to.dir, to.path,
                            beneath ? AT_RESOLVE_BENEATH : 0);
                        dne = 1;
                }
        }

        rval = 0;

        if (lflag) {
                if (linkat(AT_FDCWD, entp->fts_path, to.dir, to.path, 0) != 0) {
                        warn("%s%s", to.base, to.path);
                        rval = 1;
                }
                goto done;
        }

        if (sflag) {
                if (symlinkat(entp->fts_path, to.dir, to.path) != 0) {
                        warn("%s%s", to.base, to.path);
                        rval = 1;
                }
                goto done;
        }

        if (!dne) {
                /* overwrite existing destination file */
                to_fd = openat(to.dir, to.path,
                    O_WRONLY | O_TRUNC | (beneath ? O_RESOLVE_BENEATH : 0), 0);
        } else {
                /* create new destination file */
                to_fd = openat(to.dir, to.path,
                    O_WRONLY | O_TRUNC | O_CREAT |
                    (beneath ? O_RESOLVE_BENEATH : 0),
                    fs->st_mode & ~(S_ISUID | S_ISGID));
        }
        if (to_fd == -1) {
                warn("%s%s", to.base, to.path);
                rval = 1;
                goto done;
        }

        wtotal = 0;
        do {
                if (use_copy_file_range) {
                        wcount = copy_file_range(from_fd, NULL,
                            to_fd, NULL, SSIZE_MAX, 0);
                        if (wcount < 0 && errno == EINVAL) {
                                /* probably a non-seekable descriptor */
                                use_copy_file_range = false;
                        }
                }
                if (!use_copy_file_range) {
                        wcount = copy_fallback(from_fd, to_fd);
                }
                if (wcount >= 0)
                        wtotal += wcount;
                else if (errno != EINTR)
                        break;
                if (info) {
                        info = 0;
                        (void)fprintf(stderr,
                            "%s -> %s%s %3d%%\n",
                            entp->fts_path, to.base, to.path,
                            cp_pct(wtotal, fs->st_size));
                }
        } while (wcount != 0);
        if (wcount < 0) {
                warn("%s", entp->fts_path);
                rval = 1;
        }

        /*
         * Don't remove the target even after an error.  The target might
         * not be a regular file, or its attributes might be important,
         * or its contents might be irreplaceable.  It would only be safe
         * to remove it if we created it and its length is 0.
         */
        if (pflag && setfile(fs, to_fd, beneath))
                rval = 1;
        if (pflag && preserve_fd_acls(from_fd, to_fd) != 0)
                rval = 1;
        if (close(to_fd)) {
                warn("%s%s", to.base, to.path);
                rval = 1;
        }

done:
        if (from_fd != -1)
                (void)close(from_fd);
        return (rval);
}

int
copy_link(const FTSENT *p, bool dne, bool beneath)
{
        ssize_t len;
        int atflags = beneath ? AT_RESOLVE_BENEATH : 0;
        char llink[PATH_MAX];

        if (!dne && nflag) {
                if (vflag)
                        printf("%s%s not overwritten\n", to.base, to.path);
                return (1);
        }
        if ((len = readlink(p->fts_path, llink, sizeof(llink) - 1)) == -1) {
                warn("readlink: %s", p->fts_path);
                return (1);
        }
        llink[len] = '\0';
        if (!dne && unlinkat(to.dir, to.path, atflags) != 0) {
                warn("unlink: %s%s", to.base, to.path);
                return (1);
        }
        if (symlinkat(llink, to.dir, to.path) != 0) {
                warn("symlink: %s", llink);
                return (1);
        }
        return (pflag ? setfile(p->fts_statp, -1, beneath) : 0);
}

int
copy_fifo(struct stat *from_stat, bool dne, bool beneath)
{
        int atflags = beneath ? AT_RESOLVE_BENEATH : 0;

        if (!dne && nflag) {
                if (vflag)
                        printf("%s%s not overwritten\n", to.base, to.path);
                return (1);
        }
        if (!dne && unlinkat(to.dir, to.path, atflags) != 0) {
                warn("unlink: %s%s", to.base, to.path);
                return (1);
        }
        if (mkfifoat(to.dir, to.path, from_stat->st_mode) != 0) {
                warn("mkfifo: %s%s", to.base, to.path);
                return (1);
        }
        return (pflag ? setfile(from_stat, -1, beneath) : 0);
}

int
copy_special(struct stat *from_stat, bool dne, bool beneath)
{
        int atflags = beneath ? AT_RESOLVE_BENEATH : 0;

        if (!dne && nflag) {
                if (vflag)
                        printf("%s%s not overwritten\n", to.base, to.path);
                return (1);
        }
        if (!dne && unlinkat(to.dir, to.path, atflags) != 0) {
                warn("unlink: %s%s", to.base, to.path);
                return (1);
        }
        if (mknodat(to.dir, to.path, from_stat->st_mode, from_stat->st_rdev) != 0) {
                warn("mknod: %s%s", to.base, to.path);
                return (1);
        }
        return (pflag ? setfile(from_stat, -1, beneath) : 0);
}

int
setfile(struct stat *fs, int fd, bool beneath)
{
        static struct timespec tspec[2];
        struct stat ts;
        int atflags = beneath ? AT_RESOLVE_BENEATH : 0;
        int rval, gotstat, islink, fdval;

        rval = 0;
        fdval = fd != -1;
        islink = !fdval && S_ISLNK(fs->st_mode);
        if (islink)
                atflags |= AT_SYMLINK_NOFOLLOW;
        fs->st_mode &= S_ISUID | S_ISGID | S_ISVTX |
            S_IRWXU | S_IRWXG | S_IRWXO;

        tspec[0] = fs->st_atim;
        tspec[1] = fs->st_mtim;
        if (fdval ? futimens(fd, tspec) :
            utimensat(to.dir, to.path, tspec, atflags)) {
                warn("utimensat: %s%s", to.base, to.path);
                rval = 1;
        }
        if (fdval ? fstat(fd, &ts) :
            fstatat(to.dir, to.path, &ts, atflags)) {
                gotstat = 0;
        } else {
                gotstat = 1;
                ts.st_mode &= S_ISUID | S_ISGID | S_ISVTX |
                    S_IRWXU | S_IRWXG | S_IRWXO;
        }
        /*
         * Changing the ownership probably won't succeed, unless we're root
         * or POSIX_CHOWN_RESTRICTED is not set.  Set uid/gid before setting
         * the mode; current BSD behavior is to remove all setuid bits on
         * chown.  If chown fails, lose setuid/setgid bits.
         */
        if (!gotstat || fs->st_uid != ts.st_uid || fs->st_gid != ts.st_gid) {
                if (fdval ? fchown(fd, fs->st_uid, fs->st_gid) :
                    fchownat(to.dir, to.path, fs->st_uid, fs->st_gid, atflags)) {
                        if (errno != EPERM) {
                                warn("chown: %s%s", to.base, to.path);
                                rval = 1;
                        }
                        fs->st_mode &= ~(S_ISUID | S_ISGID);
                }
        }

        if (!gotstat || fs->st_mode != ts.st_mode) {
                if (fdval ? fchmod(fd, fs->st_mode) :
                    fchmodat(to.dir, to.path, fs->st_mode, atflags)) {
                        warn("chmod: %s%s", to.base, to.path);
                        rval = 1;
                }
        }

        if (!Nflag && (!gotstat || fs->st_flags != ts.st_flags)) {
                if (fdval ? fchflags(fd, fs->st_flags) :
                    chflagsat(to.dir, to.path, fs->st_flags, atflags)) {
                        /*
                         * NFS doesn't support chflags; ignore errors unless
                         * there's reason to believe we're losing bits.  (Note,
                         * this still won't be right if the server supports
                         * flags and we were trying to *remove* flags on a file
                         * that we copied, i.e., that we didn't create.)
                         */
                        if (errno != EOPNOTSUPP || fs->st_flags != 0) {
                                warn("chflags: %s%s", to.base, to.path);
                                rval = 1;
                        }
                }
        }

        return (rval);
}

int
preserve_fd_acls(int source_fd, int dest_fd)
{
        acl_t acl;
        acl_type_t acl_type;
        int acl_supported = 0, ret, trivial;

        ret = fpathconf(source_fd, _PC_ACL_NFS4);
        if (ret > 0 ) {
                acl_supported = 1;
                acl_type = ACL_TYPE_NFS4;
        } else if (ret < 0 && errno != EINVAL) {
                warn("fpathconf(..., _PC_ACL_NFS4) failed for %s%s",
                    to.base, to.path);
                return (-1);
        }
        if (acl_supported == 0) {
                ret = fpathconf(source_fd, _PC_ACL_EXTENDED);
                if (ret > 0 ) {
                        acl_supported = 1;
                        acl_type = ACL_TYPE_ACCESS;
                } else if (ret < 0 && errno != EINVAL) {
                        warn("fpathconf(..., _PC_ACL_EXTENDED) failed for %s%s",
                            to.base, to.path);
                        return (-1);
                }
        }
        if (acl_supported == 0)
                return (0);

        acl = acl_get_fd_np(source_fd, acl_type);
        if (acl == NULL) {
                warn("failed to get acl entries while setting %s%s",
                    to.base, to.path);
                return (-1);
        }
        if (acl_is_trivial_np(acl, &trivial)) {
                warn("acl_is_trivial() failed for %s%s",
                    to.base, to.path);
                acl_free(acl);
                return (-1);
        }
        if (trivial) {
                acl_free(acl);
                return (0);
        }
        if (acl_set_fd_np(dest_fd, acl, acl_type) < 0) {
                warn("failed to set acl entries for %s%s",
                    to.base, to.path);
                acl_free(acl);
                return (-1);
        }
        acl_free(acl);
        return (0);
}

int
preserve_dir_acls(const char *source_dir, const char *dest_dir)
{
        int source_fd = -1, dest_fd = -1, ret;

        if ((source_fd = open(source_dir, O_DIRECTORY | O_RDONLY)) < 0) {
                warn("%s: failed to copy ACLs", source_dir);
                return (-1);
        }
        dest_fd = (*dest_dir == '\0') ? to.dir :
            openat(to.dir, dest_dir, O_DIRECTORY, AT_RESOLVE_BENEATH);
        if (dest_fd < 0) {
                warn("%s: failed to copy ACLs to %s%s", source_dir,
                    to.base, dest_dir);
                close(source_fd);
                return (-1);
        }
        if ((ret = preserve_fd_acls(source_fd, dest_fd)) != 0) {
                /* preserve_fd_acls() already printed a message */
        }
        if (dest_fd != to.dir)
                close(dest_fd);
        close(source_fd);
        return (ret);
}

void
usage(void)
{

        (void)fprintf(stderr, "%s\n%s\n",
            "usage: cp [-R [-H | -L | -P]] [-f | -i | -n] [-alpsvx] "
            "source_file target_file",
            "       cp [-R [-H | -L | -P]] [-f | -i | -n] [-alpsvx] "
            "source_file ... "
            "target_directory");
        exit(EX_USAGE);
}