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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6 | * SELinux support by Yuichi Nakamura <ynakam@hitachisoft.jp>
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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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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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64 | int copy_file(const char *source, const char *dest, int flags)
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65 | {
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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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68 | struct stat source_stat;
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69 | struct stat dest_stat;
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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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73 |
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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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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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87 | bb_perror_msg("cannot stat '%s'", dest);
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88 | return -1;
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89 | }
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90 | } else {
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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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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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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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118 | if (S_ISDIR(source_stat.st_mode)) {
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119 | DIR *dp;
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120 | const char *tp;
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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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125 | bb_error_msg("omitting directory '%s'", source);
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126 | return -1;
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127 | }
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128 |
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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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139 | if (dest_exists) {
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140 | if (!S_ISDIR(dest_stat.st_mode)) {
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141 | bb_error_msg("target '%s' is not a directory", dest);
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142 | return -1;
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143 | }
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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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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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153 | /* Allow owner to access new dir (at least for now) */
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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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157 | bb_perror_msg("cannot create directory '%s'", dest);
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158 | return -1;
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159 | }
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160 | umask(saved_umask);
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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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166 | }
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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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170 |
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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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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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182 | if (new_source == NULL)
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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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186 | retval = -1;
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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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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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197 | }
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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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226 | int src_fd;
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227 | int dst_fd;
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228 |
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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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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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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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250 |
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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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268 | }
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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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272 | close(src_fd);
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273 | return -1;
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274 | }
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275 | }
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276 |
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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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285 | return -1;
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286 | }
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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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294 | }
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295 | }
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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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308 |
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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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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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328 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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329 | }
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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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341 | } else {
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342 | bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
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343 | return -1;
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344 | }
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345 |
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346 | preserve_mode_ugid_time:
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347 |
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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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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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356 | /* BTW, utimes sets usec-precision time - just FYI */
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357 | if (utime(dest, ×) < 0)
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358 | bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
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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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361 | bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
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362 | }
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363 | if (chmod(dest, source_stat.st_mode) < 0)
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364 | bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
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365 | }
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366 |
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367 | return retval;
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368 | }
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