400 lines
11 KiB
C
400 lines
11 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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* SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
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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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// POSIX: if exists and -i, ask (w/o -i assume yes).
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// Then open w/o EXCL (yes, not unlink!).
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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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//
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// NB: we have special code which still allows for "cp file /dev/node"
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// to work POSIX-ly (the only realistic case where it makes sense)
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#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */
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// errno must be set to relevant value ("why we cannot create dest?")
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// for POSIX mode to give reasonable error message
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static int ask_and_unlink(const char *dest, int flags)
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{
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int e = errno;
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#if DO_POSIX_CP
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if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
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// Either it exists, or the *path* doesnt exist
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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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#endif
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// If !DO_POSIX_CP, act as if -f is always in effect - we don't want
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// "cannot create" msg, we want unlink to be done (silently unless -i).
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// TODO: maybe we should do it only if ctty is present?
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if (flags & FILEUTILS_INTERACTIVE) {
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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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// (No "opening without O_EXCL", no "unlink only if -f")
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// Or else we will end up having 3 open()s!
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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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#if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
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if (e == errno && e == ENOENT) {
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/* e == ENOTDIR is similar: path has non-dir component,
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* but in this case we don't even reach copy_file() */
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bb_error_msg("cannot create '%s': Path does not exist", dest);
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return -1; // error
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}
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#endif
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errno = e;
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bb_perror_msg("cannot create '%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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/* Return:
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* -1 error, copy not made
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* 0 copy is made or user answered "no" in interactive mode
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* (failures to preserve mode/owner/times are not reported in exit code)
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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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/* This is a recursive function, try to minimize stack usage */
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/* NB: each struct stat is ~100 bytes */
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struct stat source_stat;
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struct stat dest_stat;
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signed char retval = 0;
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signed char dest_exists = 0;
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signed char ovr;
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/* Inverse of cp -d ("cp without -d") */
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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 ENABLE_SELINUX
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if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
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security_context_t con;
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if (lgetfilecon(source, &con) >= 0) {
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if (setfscreatecon(con) < 0) {
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bb_perror_msg("cannot set setfscreatecon %s", con);
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freecon(con);
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return -1;
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}
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} else if (errno == ENOTSUP || errno == ENODATA) {
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setfscreatecon_or_die(NULL);
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} else {
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bb_perror_msg("cannot lgetfilecon %s", source);
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return -1;
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}
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}
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#endif
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if (S_ISDIR(source_stat.st_mode)) {
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DIR *dp;
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const char *tp;
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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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/* Did we ever create source ourself before? */
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tp = is_in_ino_dev_hashtable(&source_stat);
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if (tp) {
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/* We did! it's a recursion! man the lifeboats... */
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bb_error_msg("recursion detected, omitting directory '%s'",
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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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/* race here: user can substitute a symlink between
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* this check and actual creation of files inside dest */
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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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/* Allow owner to access new dir (at least for now) */
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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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/* need stat info for add_to_ino_dev_hashtable */
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if (lstat(dest, &dest_stat) < 0) {
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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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}
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/* remember (dev,inode) of each created dir.
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* NULL: name is not remembered */
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add_to_ino_dev_hashtable(&dest_stat, NULL);
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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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retval = -1;
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goto preserve_mode_ugid_time;
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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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retval = -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 preserve %s of '%s'", "permissions", dest);
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/* retval = -1; - WRONG! copy *WAS* made */
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}
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goto preserve_mode_ugid_time;
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}
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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 = ask_and_unlink(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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/* _Not_ jumping to preserve_mode_ugid_time:
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* hard/softlinks don't have those */
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return 0;
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}
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if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
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!(flags & FILEUTILS_RECUR)
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/* "cp [-opts] regular_file thing2" */
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|| S_ISREG(source_stat.st_mode)
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/* DEREF uses stat, which never returns S_ISLNK() == true.
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* So the below is never true: */
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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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mode_t new_mode;
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if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
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/* "cp -d symlink dst": create a link */
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goto dont_cat;
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}
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if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
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const char *link_target;
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link_target = is_in_ino_dev_hashtable(&source_stat);
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if (link_target) {
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if (link(link_target, dest) < 0) {
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ovr = ask_and_unlink(dest, flags);
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if (ovr <= 0)
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return ovr;
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if (link(link_target, 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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add_to_ino_dev_hashtable(&source_stat, dest);
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}
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src_fd = open_or_warn(source, O_RDONLY);
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if (src_fd < 0)
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return -1;
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/* Do not try to open with weird mode fields */
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new_mode = source_stat.st_mode;
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if (!S_ISREG(source_stat.st_mode))
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new_mode = 0666;
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/* POSIX way is a security problem versus symlink attacks,
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* we do it only for non-symlinks, and only for non-recursive,
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* non-interactive cp. NB: it is still racy
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* for "cp file /home/bad_user/file" case
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* (user can rm file and create a link to /etc/passwd) */
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if (DO_POSIX_CP
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|| (dest_exists
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&& !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
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&& !S_ISLNK(dest_stat.st_mode))
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) {
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dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
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} else /* safe way: */
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dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
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if (dst_fd == -1) {
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ovr = ask_and_unlink(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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/* It shouldn't exist. If it exists, do not open (symlink attack?) */
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dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
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if (dst_fd < 0) {
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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 ENABLE_SELINUX
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if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
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&& is_selinux_enabled() > 0
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) {
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security_context_t con;
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if (getfscreatecon(&con) == -1) {
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bb_perror_msg("getfscreatecon");
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return -1;
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}
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if (con) {
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if (setfilecon(dest, con) == -1) {
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bb_perror_msg("setfilecon:%s,%s", dest, con);
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freecon(con);
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return -1;
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}
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freecon(con);
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}
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}
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#endif
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if (bb_copyfd_eof(src_fd, dst_fd) == -1)
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retval = -1;
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/* Ok, writing side I can understand... */
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if (close(dst_fd) < 0) {
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bb_perror_msg("cannot close '%s'", dest);
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retval = -1;
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}
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/* ...but read size is already checked by bb_copyfd_eof */
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close(src_fd);
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/* "cp /dev/something new_file" should not
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* copy mode of /dev/something */
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if (!S_ISREG(source_stat.st_mode))
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return retval;
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goto preserve_mode_ugid_time;
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}
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dont_cat:
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/* Source is a symlink or a special file */
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/* We are lazy here, a bit lax with races... */
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if (dest_exists) {
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errno = EEXIST;
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ovr = ask_and_unlink(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_ISLNK(source_stat.st_mode)) {
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char *lpath = xmalloc_readlink_or_warn(source);
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if (lpath) {
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int r = symlink(lpath, dest);
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free(lpath);
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if (r < 0) {
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bb_perror_msg("cannot create symlink '%s'", dest);
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return -1;
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}
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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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}
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/* _Not_ jumping to preserve_mode_ugid_time:
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* symlinks don't have those */
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return 0;
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}
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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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) {
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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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} else {
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bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
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return -1;
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}
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preserve_mode_ugid_time:
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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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/* BTW, utimes sets usec-precision time - just FYI */
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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 retval;
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}
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