mirror of
https://github.com/topjohnwu/ndk-busybox.git
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f24e1f40e0
Add doc on POSIX's rules on -i and -f (insane!). ln: make "ln dangling_symlink new_link" work.
283 lines
7.3 KiB
C
283 lines
7.3 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* Mini copy_file implementation for busybox
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*
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* Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
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*
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*
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*/
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#include "libbb.h"
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static int retry_overwrite(const char *dest, int flags)
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{
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if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
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fprintf(stderr, "'%s' exists\n", dest);
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return -1;
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}
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if (flags & FILEUTILS_INTERACTIVE) {
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fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
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if (!bb_ask_confirmation())
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return 0; // not allowed to overwrite
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}
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if (unlink(dest) < 0) {
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bb_perror_msg("cannot remove '%s'", dest);
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return -1; // error
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}
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return 1; // ok (to try again)
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}
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int copy_file(const char *source, const char *dest, int flags)
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{
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struct stat source_stat;
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struct stat dest_stat;
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int status = 0;
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signed char dest_exists = 0;
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signed char ovr;
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#define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
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if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
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// This may be a dangling symlink.
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// Making [sym]links to dangling symlinks works, so...
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if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
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goto make_links;
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bb_perror_msg("cannot stat '%s'", source);
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return -1;
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}
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if (lstat(dest, &dest_stat) < 0) {
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if (errno != ENOENT) {
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bb_perror_msg("cannot stat '%s'", dest);
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return -1;
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}
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} else {
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if (source_stat.st_dev == dest_stat.st_dev
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&& source_stat.st_ino == dest_stat.st_ino
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) {
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bb_error_msg("'%s' and '%s' are the same file", source, dest);
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return -1;
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}
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dest_exists = 1;
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}
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if (S_ISDIR(source_stat.st_mode)) {
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DIR *dp;
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struct dirent *d;
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mode_t saved_umask = 0;
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if (!(flags & FILEUTILS_RECUR)) {
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bb_error_msg("omitting directory '%s'", source);
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return -1;
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}
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/* Create DEST. */
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if (dest_exists) {
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if (!S_ISDIR(dest_stat.st_mode)) {
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bb_error_msg("target '%s' is not a directory", dest);
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return -1;
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}
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} else {
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mode_t mode;
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saved_umask = umask(0);
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mode = source_stat.st_mode;
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if (!(flags & FILEUTILS_PRESERVE_STATUS))
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mode = source_stat.st_mode & ~saved_umask;
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mode |= S_IRWXU;
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if (mkdir(dest, mode) < 0) {
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umask(saved_umask);
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bb_perror_msg("cannot create directory '%s'", dest);
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return -1;
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}
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umask(saved_umask);
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}
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/* Recursively copy files in SOURCE. */
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dp = opendir(source);
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if (dp == NULL) {
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status = -1;
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goto preserve_status;
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}
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while ((d = readdir(dp)) != NULL) {
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char *new_source, *new_dest;
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new_source = concat_subpath_file(source, d->d_name);
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if (new_source == NULL)
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continue;
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new_dest = concat_path_file(dest, d->d_name);
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if (copy_file(new_source, new_dest, flags) < 0)
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status = -1;
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free(new_source);
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free(new_dest);
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}
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closedir(dp);
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if (!dest_exists
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&& chmod(dest, source_stat.st_mode & ~saved_umask) < 0
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) {
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bb_perror_msg("cannot change permissions of '%s'", dest);
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status = -1;
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}
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} else if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
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int (*lf)(const char *oldpath, const char *newpath);
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make_links:
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// Hmm... maybe
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// if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
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// (but realpath returns NULL on dangling symlinks...)
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lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
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if (lf(source, dest) < 0) {
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ovr = retry_overwrite(dest, flags);
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if (ovr <= 0)
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return ovr;
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if (lf(source, dest) < 0) {
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bb_perror_msg("cannot create link '%s'", dest);
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return -1;
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}
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}
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return 0;
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} else if (S_ISREG(source_stat.st_mode)
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// Huh? DEREF uses stat, which never returns links IIRC...
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|| (FLAGS_DEREF && S_ISLNK(source_stat.st_mode))
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) {
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int src_fd;
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int dst_fd;
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if (ENABLE_FEATURE_PRESERVE_HARDLINKS) {
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char *link_name;
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if (!FLAGS_DEREF
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&& is_in_ino_dev_hashtable(&source_stat, &link_name)
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) {
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if (link(link_name, dest) < 0) {
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ovr = retry_overwrite(dest, flags);
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if (ovr <= 0)
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return ovr;
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if (link(link_name, dest) < 0) {
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bb_perror_msg("cannot create link '%s'", dest);
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return -1;
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}
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}
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return 0;
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}
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// TODO: probably is_in_.. and add_to_...
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// can be combined: find_or_add_...
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add_to_ino_dev_hashtable(&source_stat, dest);
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}
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src_fd = open(source, O_RDONLY);
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if (src_fd == -1) {
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bb_perror_msg("cannot open '%s'", source);
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return -1;
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}
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// POSIX: if exists and -i, ask (w/o -i assume yes).
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// Then open w/o EXCL.
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// If open still fails and -f, try unlink, then try open again.
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// Result: a mess:
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// If dest is a softlink, we overwrite softlink's destination!
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// (or fail, if it points to dir/nonexistent location/etc).
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// This is strange, but POSIX-correct.
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// coreutils cp has --remove-destination to override this...
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dst_fd = open(dest, (flags & FILEUTILS_INTERACTIVE)
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? O_WRONLY|O_CREAT|O_TRUNC|O_EXCL
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: O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
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if (dst_fd == -1) {
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// We would not do POSIX insanity. -i asks,
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// then _unlinks_ the offender. Presto.
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// Or else we will end up having 3 open()s!
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ovr = retry_overwrite(dest, flags);
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if (ovr <= 0) {
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close(src_fd);
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return ovr;
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}
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dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
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if (dst_fd == -1) {
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bb_perror_msg("cannot open '%s'", dest);
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close(src_fd);
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return -1;
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}
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}
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if (bb_copyfd_eof(src_fd, dst_fd) == -1)
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status = -1;
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if (close(dst_fd) < 0) {
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bb_perror_msg("cannot close '%s'", dest);
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status = -1;
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}
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if (close(src_fd) < 0) {
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bb_perror_msg("cannot close '%s'", source);
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status = -1;
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}
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} else if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
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|| S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
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|| S_ISLNK(source_stat.st_mode)
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) {
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// We are lazy here, a bit lax with races...
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if (dest_exists) {
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ovr = retry_overwrite(dest, flags);
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if (ovr <= 0)
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return ovr;
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}
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if (S_ISFIFO(source_stat.st_mode)) {
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if (mkfifo(dest, source_stat.st_mode) < 0) {
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bb_perror_msg("cannot create fifo '%s'", dest);
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return -1;
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}
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} else if (S_ISLNK(source_stat.st_mode)) {
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char *lpath;
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lpath = xreadlink(source);
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if (symlink(lpath, dest) < 0) {
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bb_perror_msg("cannot create symlink '%s'", dest);
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free(lpath);
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return -1;
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}
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free(lpath);
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if (flags & FILEUTILS_PRESERVE_STATUS)
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if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
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bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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return 0;
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} else {
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if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
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bb_perror_msg("cannot create '%s'", dest);
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return -1;
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}
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}
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} else {
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bb_error_msg("internal error: unrecognized file type");
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return -1;
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}
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preserve_status:
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if (flags & FILEUTILS_PRESERVE_STATUS
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/* Cannot happen: */
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/* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
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) {
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struct utimbuf times;
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times.actime = source_stat.st_atime;
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times.modtime = source_stat.st_mtime;
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if (utime(dest, ×) < 0)
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bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
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if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
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source_stat.st_mode &= ~(S_ISUID | S_ISGID);
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bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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}
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if (chmod(dest, source_stat.st_mode) < 0)
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bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
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}
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return status;
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}
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