[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Mini copy_file implementation for busybox
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| 4 | *
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| 5 | * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
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[1765] | 6 | * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
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[821] | 7 | *
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| 8 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 9 | *
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| 10 | */
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| 11 |
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| 12 | #include "libbb.h"
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| 13 |
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[1765] | 14 | // POSIX: if exists and -i, ask (w/o -i assume yes).
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| 15 | // Then open w/o EXCL (yes, not unlink!).
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| 16 | // If open still fails and -f, try unlink, then try open again.
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| 17 | // Result: a mess:
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| 18 | // If dest is a softlink, we overwrite softlink's destination!
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| 19 | // (or fail, if it points to dir/nonexistent location/etc).
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| 20 | // This is strange, but POSIX-correct.
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| 21 | // coreutils cp has --remove-destination to override this...
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| 22 | //
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| 23 | // NB: we have special code which still allows for "cp file /dev/node"
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| 24 | // to work POSIX-ly (the only realistic case where it makes sense)
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| 25 |
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| 26 | #define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */
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| 27 |
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| 28 | // errno must be set to relevant value ("why we cannot create dest?")
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| 29 | // for POSIX mode to give reasonable error message
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| 30 | static int ask_and_unlink(const char *dest, int flags)
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| 31 | {
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| 32 | #if DO_POSIX_CP
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| 33 | if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
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| 34 | // Either it exists, or the *path* doesnt exist
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| 35 | bb_perror_msg("cannot create '%s'", dest);
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| 36 | return -1;
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| 37 | }
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| 38 | #endif
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| 39 | // If !DO_POSIX_CP, act as if -f is always in effect - we don't want
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| 40 | // "cannot create" msg, we want unlink to be done (silently unless -i).
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| 41 |
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| 42 | // TODO: maybe we should do it only if ctty is present?
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| 43 | if (flags & FILEUTILS_INTERACTIVE) {
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| 44 | // We would not do POSIX insanity. -i asks,
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| 45 | // then _unlinks_ the offender. Presto.
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| 46 | // (No "opening without O_EXCL", no "unlink only if -f")
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| 47 | // Or else we will end up having 3 open()s!
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| 48 | fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
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| 49 | if (!bb_ask_confirmation())
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| 50 | return 0; // not allowed to overwrite
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| 51 | }
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| 52 | if (unlink(dest) < 0) {
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| 53 | bb_perror_msg("cannot remove '%s'", dest);
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| 54 | return -1; // error
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| 55 | }
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| 56 | return 1; // ok (to try again)
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| 57 | }
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| 58 |
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| 59 | /* Return:
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| 60 | * -1 error, copy not made
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| 61 | * 0 copy is made or user answered "no" in interactive mode
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| 62 | * (failures to preserve mode/owner/times are not reported in exit code)
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| 63 | */
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[821] | 64 | int copy_file(const char *source, const char *dest, int flags)
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| 65 | {
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[1765] | 66 | /* This is a recursive function, try to minimize stack usage */
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| 67 | /* NB: each struct stat is ~100 bytes */
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[821] | 68 | struct stat source_stat;
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| 69 | struct stat dest_stat;
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[1765] | 70 | signed char retval = 0;
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| 71 | signed char dest_exists = 0;
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| 72 | signed char ovr;
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[821] | 73 |
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[1765] | 74 | #define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
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| 75 |
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| 76 | if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
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| 77 | // This may be a dangling symlink.
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| 78 | // Making [sym]links to dangling symlinks works, so...
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| 79 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
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| 80 | goto make_links;
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| 81 | bb_perror_msg("cannot stat '%s'", source);
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[821] | 82 | return -1;
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| 83 | }
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| 84 |
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| 85 | if (lstat(dest, &dest_stat) < 0) {
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| 86 | if (errno != ENOENT) {
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[1765] | 87 | bb_perror_msg("cannot stat '%s'", dest);
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[821] | 88 | return -1;
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| 89 | }
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| 90 | } else {
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[1765] | 91 | if (source_stat.st_dev == dest_stat.st_dev
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| 92 | && source_stat.st_ino == dest_stat.st_ino
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| 93 | ) {
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| 94 | bb_error_msg("'%s' and '%s' are the same file", source, dest);
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[821] | 95 | return -1;
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| 96 | }
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| 97 | dest_exists = 1;
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| 98 | }
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| 99 |
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[1765] | 100 | #if ENABLE_SELINUX
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| 101 | if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
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| 102 | security_context_t con;
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| 103 | if (lgetfilecon(source, &con) >= 0) {
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| 104 | if (setfscreatecon(con) < 0) {
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| 105 | bb_perror_msg("cannot set setfscreatecon %s", con);
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| 106 | freecon(con);
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| 107 | return -1;
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| 108 | }
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| 109 | } else if (errno == ENOTSUP || errno == ENODATA) {
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| 110 | setfscreatecon_or_die(NULL);
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| 111 | } else {
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| 112 | bb_perror_msg("cannot lgetfilecon %s", source);
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| 113 | return -1;
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| 114 | }
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| 115 | }
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| 116 | #endif
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| 117 |
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[821] | 118 | if (S_ISDIR(source_stat.st_mode)) {
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| 119 | DIR *dp;
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[1765] | 120 | const char *tp;
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[821] | 121 | struct dirent *d;
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| 122 | mode_t saved_umask = 0;
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| 123 |
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| 124 | if (!(flags & FILEUTILS_RECUR)) {
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[1765] | 125 | bb_error_msg("omitting directory '%s'", source);
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[821] | 126 | return -1;
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| 127 | }
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| 128 |
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[1765] | 129 | /* Did we ever create source ourself before? */
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| 130 | tp = is_in_ino_dev_hashtable(&source_stat);
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| 131 | if (tp) {
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| 132 | /* We did! it's a recursion! man the lifeboats... */
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| 133 | bb_error_msg("recursion detected, omitting directory '%s'",
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| 134 | source);
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| 135 | return -1;
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| 136 | }
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| 137 |
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| 138 | /* Create DEST */
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[821] | 139 | if (dest_exists) {
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| 140 | if (!S_ISDIR(dest_stat.st_mode)) {
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[1765] | 141 | bb_error_msg("target '%s' is not a directory", dest);
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[821] | 142 | return -1;
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| 143 | }
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[1765] | 144 | /* race here: user can substitute a symlink between
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| 145 | * this check and actual creation of files inside dest */
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[821] | 146 | } else {
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| 147 | mode_t mode;
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| 148 | saved_umask = umask(0);
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| 149 |
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| 150 | mode = source_stat.st_mode;
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| 151 | if (!(flags & FILEUTILS_PRESERVE_STATUS))
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| 152 | mode = source_stat.st_mode & ~saved_umask;
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[1765] | 153 | /* Allow owner to access new dir (at least for now) */
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[821] | 154 | mode |= S_IRWXU;
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| 155 | if (mkdir(dest, mode) < 0) {
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| 156 | umask(saved_umask);
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[1765] | 157 | bb_perror_msg("cannot create directory '%s'", dest);
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[821] | 158 | return -1;
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| 159 | }
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| 160 | umask(saved_umask);
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[1765] | 161 | /* need stat info for add_to_ino_dev_hashtable */
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| 162 | if (lstat(dest, &dest_stat) < 0) {
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| 163 | bb_perror_msg("cannot stat '%s'", dest);
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| 164 | return -1;
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| 165 | }
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[821] | 166 | }
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[1765] | 167 | /* remember (dev,inode) of each created dir.
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| 168 | * NULL: name is not remembered */
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| 169 | add_to_ino_dev_hashtable(&dest_stat, NULL);
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[821] | 170 |
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[1765] | 171 | /* Recursively copy files in SOURCE */
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| 172 | dp = opendir(source);
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| 173 | if (dp == NULL) {
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| 174 | retval = -1;
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| 175 | goto preserve_mode_ugid_time;
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[821] | 176 | }
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| 177 |
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| 178 | while ((d = readdir(dp)) != NULL) {
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| 179 | char *new_source, *new_dest;
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| 180 |
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| 181 | new_source = concat_subpath_file(source, d->d_name);
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[1765] | 182 | if (new_source == NULL)
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[821] | 183 | continue;
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| 184 | new_dest = concat_path_file(dest, d->d_name);
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| 185 | if (copy_file(new_source, new_dest, flags) < 0)
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[1765] | 186 | retval = -1;
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[821] | 187 | free(new_source);
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| 188 | free(new_dest);
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| 189 | }
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| 190 | closedir(dp);
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| 191 |
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[1765] | 192 | if (!dest_exists
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| 193 | && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
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| 194 | ) {
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| 195 | bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
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| 196 | /* retval = -1; - WRONG! copy *WAS* made */
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[821] | 197 | }
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[1765] | 198 | goto preserve_mode_ugid_time;
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| 199 | }
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| 200 |
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| 201 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
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| 202 | int (*lf)(const char *oldpath, const char *newpath);
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| 203 | make_links:
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| 204 | // Hmm... maybe
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| 205 | // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
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| 206 | // (but realpath returns NULL on dangling symlinks...)
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| 207 | lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
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| 208 | if (lf(source, dest) < 0) {
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| 209 | ovr = ask_and_unlink(dest, flags);
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| 210 | if (ovr <= 0)
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| 211 | return ovr;
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| 212 | if (lf(source, dest) < 0) {
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| 213 | bb_perror_msg("cannot create link '%s'", dest);
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| 214 | return -1;
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| 215 | }
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| 216 | }
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| 217 | /* _Not_ jumping to preserve_mode_ugid_time:
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| 218 | * hard/softlinks don't have those */
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| 219 | return 0;
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| 220 | }
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| 221 |
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| 222 | if (S_ISREG(source_stat.st_mode)
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| 223 | /* DEREF uses stat, which never returns S_ISLNK() == true. */
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| 224 | /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
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| 225 | ) {
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[821] | 226 | int src_fd;
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| 227 | int dst_fd;
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| 228 |
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[1765] | 229 | if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
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| 230 | const char *link_target;
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| 231 | link_target = is_in_ino_dev_hashtable(&source_stat);
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| 232 | if (link_target) {
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| 233 | if (link(link_target, dest) < 0) {
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| 234 | ovr = ask_and_unlink(dest, flags);
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| 235 | if (ovr <= 0)
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| 236 | return ovr;
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| 237 | if (link(link_target, dest) < 0) {
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| 238 | bb_perror_msg("cannot create link '%s'", dest);
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| 239 | return -1;
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| 240 | }
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[821] | 241 | }
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| 242 | return 0;
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| 243 | }
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| 244 | add_to_ino_dev_hashtable(&source_stat, dest);
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| 245 | }
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| 246 |
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[1765] | 247 | src_fd = open_or_warn(source, O_RDONLY);
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| 248 | if (src_fd < 0)
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| 249 | return -1;
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[821] | 250 |
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[1765] | 251 | /* POSIX way is a security problem versus symlink attacks,
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| 252 | * we do it only for non-symlinks, and only for non-recursive,
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| 253 | * non-interactive cp. NB: it is still racy
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| 254 | * for "cp file /home/bad_user/file" case
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| 255 | * (user can rm file and create a link to /etc/passwd) */
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| 256 | if (DO_POSIX_CP
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| 257 | || (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
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| 258 | && !S_ISLNK(dest_stat.st_mode))
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| 259 | ) {
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| 260 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
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| 261 | } else /* safe way: */
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| 262 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
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| 263 | if (dst_fd == -1) {
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| 264 | ovr = ask_and_unlink(dest, flags);
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| 265 | if (ovr <= 0) {
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| 266 | close(src_fd);
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| 267 | return ovr;
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[821] | 268 | }
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[1765] | 269 | /* It shouldn't exist. If it exists, do not open (symlink attack?) */
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| 270 | dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
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| 271 | if (dst_fd < 0) {
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[821] | 272 | close(src_fd);
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[1765] | 273 | return -1;
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[821] | 274 | }
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| 275 | }
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| 276 |
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[1765] | 277 | #if ENABLE_SELINUX
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| 278 | if (((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT)
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| 279 | || (flags & FILEUTILS_SET_SECURITY_CONTEXT))
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| 280 | && is_selinux_enabled() > 0
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| 281 | ) {
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| 282 | security_context_t con;
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| 283 | if (getfscreatecon(&con) == -1) {
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| 284 | bb_perror_msg("getfscreatecon");
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[821] | 285 | return -1;
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| 286 | }
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[1765] | 287 | if (con) {
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| 288 | if (setfilecon(dest, con) == -1) {
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| 289 | bb_perror_msg("setfilecon:%s,%s", dest, con);
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| 290 | freecon(con);
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| 291 | return -1;
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| 292 | }
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| 293 | freecon(con);
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[821] | 294 | }
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| 295 | }
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[1765] | 296 | #endif
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| 297 | if (bb_copyfd_eof(src_fd, dst_fd) == -1)
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| 298 | retval = -1;
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| 299 | /* Ok, writing side I can understand... */
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| 300 | if (close(dst_fd) < 0) {
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| 301 | bb_perror_msg("cannot close '%s'", dest);
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| 302 | retval = -1;
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| 303 | }
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| 304 | /* ...but read size is already checked by bb_copyfd_eof */
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| 305 | close(src_fd);
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| 306 | goto preserve_mode_ugid_time;
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| 307 | }
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[821] | 308 |
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[1765] | 309 | /* Source is a symlink or a special file */
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| 310 | /* We are lazy here, a bit lax with races... */
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| 311 | if (dest_exists) {
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| 312 | errno = EEXIST;
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| 313 | ovr = ask_and_unlink(dest, flags);
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| 314 | if (ovr <= 0)
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| 315 | return ovr;
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| 316 | }
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| 317 | if (S_ISLNK(source_stat.st_mode)) {
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| 318 | char *lpath = xmalloc_readlink_or_warn(source);
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| 319 | if (lpath) {
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| 320 | int r = symlink(lpath, dest);
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| 321 | free(lpath);
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| 322 | if (r < 0) {
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| 323 | bb_perror_msg("cannot create symlink '%s'", dest);
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[821] | 324 | return -1;
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| 325 | }
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| 326 | if (flags & FILEUTILS_PRESERVE_STATUS)
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| 327 | if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
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[1765] | 328 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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[821] | 329 | }
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[1765] | 330 | /* _Not_ jumping to preserve_mode_ugid_time:
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| 331 | * symlinks don't have those */
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| 332 | return 0;
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| 333 | }
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| 334 | if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
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| 335 | || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
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| 336 | ) {
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| 337 | if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
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| 338 | bb_perror_msg("cannot create '%s'", dest);
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| 339 | return -1;
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| 340 | }
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[821] | 341 | } else {
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[1765] | 342 | bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
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[821] | 343 | return -1;
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| 344 | }
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| 345 |
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[1765] | 346 | preserve_mode_ugid_time:
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[821] | 347 |
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[1765] | 348 | if (flags & FILEUTILS_PRESERVE_STATUS
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| 349 | /* Cannot happen: */
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| 350 | /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
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| 351 | ) {
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[821] | 352 | struct utimbuf times;
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| 353 |
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| 354 | times.actime = source_stat.st_atime;
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| 355 | times.modtime = source_stat.st_mtime;
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[1765] | 356 | /* BTW, utimes sets usec-precision time - just FYI */
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[821] | 357 | if (utime(dest, ×) < 0)
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[1765] | 358 | bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
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[821] | 359 | if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
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| 360 | source_stat.st_mode &= ~(S_ISUID | S_ISGID);
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[1765] | 361 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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[821] | 362 | }
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| 363 | if (chmod(dest, source_stat.st_mode) < 0)
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[1765] | 364 | bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
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[821] | 365 | }
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| 366 |
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[1765] | 367 | return retval;
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[821] | 368 | }
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