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 source tree.
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9 | */
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10 | #include "libbb.h"
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11 |
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12 | // FEATURE_NON_POSIX_CP:
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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 (sym)link, we overwrite link 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 | /* Called if open of destination, link creation etc fails.
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24 | * errno must be set to relevant value ("why we cannot create dest?")
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25 | * to give reasonable error message */
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26 | static int ask_and_unlink(const char *dest, int flags)
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27 | {
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28 | int e = errno;
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29 |
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30 | #if !ENABLE_FEATURE_NON_POSIX_CP
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31 | if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
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32 | /* Either it exists, or the *path* doesnt exist */
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33 | bb_perror_msg("can't create '%s'", dest);
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34 | return -1;
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35 | }
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36 | #endif
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37 | // else: act as if -f is always in effect.
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38 | // We don't want "can't create" msg, we want unlink to be done
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39 | // (silently unless -i). Why? POSIX cp usually succeeds with
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40 | // O_TRUNC open of existing file, and user is left ignorantly happy.
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41 | // With above block unconditionally enabled, non-POSIX cp
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42 | // will complain a lot more than POSIX one.
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43 |
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44 | /* TODO: maybe we should do it only if ctty is present? */
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45 | if (flags & FILEUTILS_INTERACTIVE) {
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46 | // We would not do POSIX insanity. -i asks,
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47 | // then _unlinks_ the offender. Presto.
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48 | // (No "opening without O_EXCL", no "unlink only if -f")
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49 | // Or else we will end up having 3 open()s!
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50 | fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
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51 | if (!bb_ask_confirmation())
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52 | return 0; /* not allowed to overwrite */
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53 | }
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54 | if (unlink(dest) < 0) {
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55 | #if ENABLE_FEATURE_VERBOSE_CP_MESSAGE
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56 | if (e == errno && e == ENOENT) {
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57 | /* e == ENOTDIR is similar: path has non-dir component,
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58 | * but in this case we don't even reach copy_file() */
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59 | bb_error_msg("can't create '%s': Path does not exist", dest);
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60 | return -1; /* error */
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61 | }
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62 | #endif
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63 | errno = e; /* do not use errno from unlink */
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64 | bb_perror_msg("can't create '%s'", dest);
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65 | return -1; /* error */
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66 | }
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67 | return 1; /* ok (to try again) */
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68 | }
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69 |
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70 | /* Return:
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71 | * -1 error, copy not made
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72 | * 0 copy is made or user answered "no" in interactive mode
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73 | * (failures to preserve mode/owner/times are not reported in exit code)
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74 | */
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75 | int FAST_FUNC copy_file(const char *source, const char *dest, int flags)
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76 | {
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77 | /* This is a recursive function, try to minimize stack usage */
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78 | /* NB: each struct stat is ~100 bytes */
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79 | struct stat source_stat;
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80 | struct stat dest_stat;
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81 | signed char retval = 0;
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82 | signed char dest_exists = 0;
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83 | signed char ovr;
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84 |
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85 | /* Inverse of cp -d ("cp without -d") */
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86 | #define FLAGS_DEREF (flags & (FILEUTILS_DEREFERENCE + FILEUTILS_DEREFERENCE_L0))
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87 |
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88 | if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
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89 | /* This may be a dangling symlink.
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90 | * Making [sym]links to dangling symlinks works, so... */
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91 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
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92 | goto make_links;
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93 | bb_perror_msg("can't stat '%s'", source);
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94 | return -1;
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95 | }
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96 |
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97 | if (lstat(dest, &dest_stat) < 0) {
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98 | if (errno != ENOENT) {
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99 | bb_perror_msg("can't stat '%s'", dest);
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100 | return -1;
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101 | }
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102 | } else {
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103 | if (source_stat.st_dev == dest_stat.st_dev
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104 | && source_stat.st_ino == dest_stat.st_ino
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105 | ) {
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106 | bb_error_msg("'%s' and '%s' are the same file", source, dest);
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107 | return -1;
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108 | }
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109 | dest_exists = 1;
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110 | }
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111 |
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112 | #if ENABLE_SELINUX
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113 | if ((flags & FILEUTILS_PRESERVE_SECURITY_CONTEXT) && is_selinux_enabled() > 0) {
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114 | security_context_t con;
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115 | if (lgetfilecon(source, &con) >= 0) {
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116 | if (setfscreatecon(con) < 0) {
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117 | bb_perror_msg("can't set setfscreatecon %s", con);
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118 | freecon(con);
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119 | return -1;
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120 | }
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121 | } else if (errno == ENOTSUP || errno == ENODATA) {
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122 | setfscreatecon_or_die(NULL);
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123 | } else {
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124 | bb_perror_msg("can't lgetfilecon %s", source);
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125 | return -1;
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126 | }
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127 | }
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128 | #endif
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129 |
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130 | if (S_ISDIR(source_stat.st_mode)) {
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131 | DIR *dp;
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132 | const char *tp;
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133 | struct dirent *d;
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134 | mode_t saved_umask = 0;
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135 |
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136 | if (!(flags & FILEUTILS_RECUR)) {
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137 | bb_error_msg("omitting directory '%s'", source);
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138 | return -1;
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139 | }
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140 |
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141 | /* Did we ever create source ourself before? */
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142 | tp = is_in_ino_dev_hashtable(&source_stat);
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143 | if (tp) {
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144 | /* We did! it's a recursion! man the lifeboats... */
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145 | bb_error_msg("recursion detected, omitting directory '%s'",
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146 | source);
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147 | return -1;
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148 | }
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149 |
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150 | /* Create DEST */
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151 | if (dest_exists) {
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152 | if (!S_ISDIR(dest_stat.st_mode)) {
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153 | bb_error_msg("target '%s' is not a directory", dest);
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154 | return -1;
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155 | }
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156 | /* race here: user can substitute a symlink between
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157 | * this check and actual creation of files inside dest */
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158 | } else {
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159 | mode_t mode;
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160 | saved_umask = umask(0);
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161 |
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162 | mode = source_stat.st_mode;
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163 | if (!(flags & FILEUTILS_PRESERVE_STATUS))
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164 | mode = source_stat.st_mode & ~saved_umask;
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165 | /* Allow owner to access new dir (at least for now) */
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166 | mode |= S_IRWXU;
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167 | if (mkdir(dest, mode) < 0) {
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168 | umask(saved_umask);
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169 | bb_perror_msg("can't create directory '%s'", dest);
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170 | return -1;
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171 | }
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172 | umask(saved_umask);
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173 | /* need stat info for add_to_ino_dev_hashtable */
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174 | if (lstat(dest, &dest_stat) < 0) {
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175 | bb_perror_msg("can't stat '%s'", dest);
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176 | return -1;
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177 | }
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178 | }
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179 | /* remember (dev,inode) of each created dir.
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180 | * NULL: name is not remembered */
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181 | add_to_ino_dev_hashtable(&dest_stat, NULL);
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182 |
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183 | /* Recursively copy files in SOURCE */
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184 | dp = opendir(source);
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185 | if (dp == NULL) {
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186 | retval = -1;
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187 | goto preserve_mode_ugid_time;
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188 | }
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189 |
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190 | while ((d = readdir(dp)) != NULL) {
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191 | char *new_source, *new_dest;
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192 |
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193 | new_source = concat_subpath_file(source, d->d_name);
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194 | if (new_source == NULL)
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195 | continue;
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196 | new_dest = concat_path_file(dest, d->d_name);
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197 | if (copy_file(new_source, new_dest, flags & ~FILEUTILS_DEREFERENCE_L0) < 0)
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198 | retval = -1;
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199 | free(new_source);
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200 | free(new_dest);
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201 | }
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202 | closedir(dp);
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203 |
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204 | if (!dest_exists
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205 | && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
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206 | ) {
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207 | bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
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208 | /* retval = -1; - WRONG! copy *WAS* made */
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209 | }
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210 | goto preserve_mode_ugid_time;
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211 | }
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212 |
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213 | if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
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214 | int (*lf)(const char *oldpath, const char *newpath);
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215 | make_links:
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216 | /* Hmm... maybe
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217 | * if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
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218 | * (but realpath returns NULL on dangling symlinks...) */
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219 | lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
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220 | if (lf(source, dest) < 0) {
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221 | ovr = ask_and_unlink(dest, flags);
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222 | if (ovr <= 0)
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223 | return ovr;
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224 | if (lf(source, dest) < 0) {
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225 | bb_perror_msg("can't create link '%s'", dest);
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226 | return -1;
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227 | }
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228 | }
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229 | /* _Not_ jumping to preserve_mode_ugid_time:
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230 | * (sym)links don't have those */
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231 | return 0;
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232 | }
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233 |
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234 | if (/* "cp thing1 thing2" without -R: just open and read() from thing1 */
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235 | !(flags & FILEUTILS_RECUR)
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236 | /* "cp [-opts] regular_file thing2" */
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237 | || S_ISREG(source_stat.st_mode)
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238 | /* DEREF uses stat, which never returns S_ISLNK() == true.
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239 | * So the below is never true: */
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240 | /* || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) */
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241 | ) {
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242 | int src_fd;
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243 | int dst_fd;
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244 | mode_t new_mode;
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245 |
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246 | if (!FLAGS_DEREF && S_ISLNK(source_stat.st_mode)) {
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247 | /* "cp -d symlink dst": create a link */
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248 | goto dont_cat;
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249 | }
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250 |
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251 | if (ENABLE_FEATURE_PRESERVE_HARDLINKS && !FLAGS_DEREF) {
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252 | const char *link_target;
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253 | link_target = is_in_ino_dev_hashtable(&source_stat);
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254 | if (link_target) {
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255 | if (link(link_target, dest) < 0) {
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256 | ovr = ask_and_unlink(dest, flags);
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257 | if (ovr <= 0)
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258 | return ovr;
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259 | if (link(link_target, dest) < 0) {
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260 | bb_perror_msg("can't create link '%s'", dest);
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261 | return -1;
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262 | }
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263 | }
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264 | return 0;
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265 | }
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266 | add_to_ino_dev_hashtable(&source_stat, dest);
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267 | }
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268 |
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269 | src_fd = open_or_warn(source, O_RDONLY);
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270 | if (src_fd < 0)
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271 | return -1;
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272 |
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273 | /* Do not try to open with weird mode fields */
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274 | new_mode = source_stat.st_mode;
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275 | if (!S_ISREG(source_stat.st_mode))
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276 | new_mode = 0666;
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277 |
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278 | // POSIX way is a security problem versus (sym)link attacks
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279 | if (!ENABLE_FEATURE_NON_POSIX_CP) {
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280 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode);
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281 | } else { /* safe way: */
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282 | dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
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283 | }
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284 | if (dst_fd == -1) {
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285 | ovr = ask_and_unlink(dest, flags);
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286 | if (ovr <= 0) {
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287 | close(src_fd);
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288 | return ovr;
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289 | }
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290 | /* It shouldn't exist. If it exists, do not open (symlink attack?) */
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291 | dst_fd = open3_or_warn(dest, O_WRONLY|O_CREAT|O_EXCL, new_mode);
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292 | if (dst_fd < 0) {
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293 | close(src_fd);
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294 | return -1;
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295 | }
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296 | }
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297 |
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298 | #if ENABLE_SELINUX
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299 | if ((flags & (FILEUTILS_PRESERVE_SECURITY_CONTEXT|FILEUTILS_SET_SECURITY_CONTEXT))
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300 | && is_selinux_enabled() > 0
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301 | ) {
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302 | security_context_t con;
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303 | if (getfscreatecon(&con) == -1) {
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304 | bb_perror_msg("getfscreatecon");
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305 | return -1;
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306 | }
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307 | if (con) {
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308 | if (setfilecon(dest, con) == -1) {
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309 | bb_perror_msg("setfilecon:%s,%s", dest, con);
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310 | freecon(con);
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311 | return -1;
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312 | }
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313 | freecon(con);
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314 | }
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315 | }
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316 | #endif
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317 | if (bb_copyfd_eof(src_fd, dst_fd) == -1)
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318 | retval = -1;
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319 | /* Careful with writing... */
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320 | if (close(dst_fd) < 0) {
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321 | bb_perror_msg("error writing to '%s'", dest);
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322 | retval = -1;
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323 | }
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324 | /* ...but read size is already checked by bb_copyfd_eof */
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325 | close(src_fd);
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326 | /* "cp /dev/something new_file" should not
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327 | * copy mode of /dev/something */
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328 | if (!S_ISREG(source_stat.st_mode))
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329 | return retval;
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330 | goto preserve_mode_ugid_time;
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331 | }
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332 | dont_cat:
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333 |
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334 | /* Source is a symlink or a special file */
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335 | /* We are lazy here, a bit lax with races... */
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336 | if (dest_exists) {
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337 | errno = EEXIST;
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338 | ovr = ask_and_unlink(dest, flags);
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339 | if (ovr <= 0)
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340 | return ovr;
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341 | }
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342 | if (S_ISLNK(source_stat.st_mode)) {
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343 | char *lpath = xmalloc_readlink_or_warn(source);
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344 | if (lpath) {
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345 | int r = symlink(lpath, dest);
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346 | free(lpath);
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347 | if (r < 0) {
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348 | bb_perror_msg("can't create symlink '%s'", dest);
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349 | return -1;
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350 | }
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351 | if (flags & FILEUTILS_PRESERVE_STATUS)
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352 | if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
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353 | bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
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354 | }
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355 | /* _Not_ jumping to preserve_mode_ugid_time:
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356 | * symlinks don't have those */
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357 | return 0;
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358 | }
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359 | if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
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360 | || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
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361 | ) {
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362 | if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
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363 | bb_perror_msg("can't create '%s'", dest);
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364 | return -1;
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365 | }
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366 | } else {
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367 | bb_error_msg("unrecognized file '%s' with mode %x", source, source_stat.st_mode);
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368 | return -1;
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369 | }
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370 |
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371 | preserve_mode_ugid_time:
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372 |
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373 | if (flags & FILEUTILS_PRESERVE_STATUS
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374 | /* Cannot happen: */
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375 | /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
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376 | ) {
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377 | struct timeval times[2];
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378 |
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379 | times[1].tv_sec = times[0].tv_sec = source_stat.st_mtime;
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380 | times[1].tv_usec = times[0].tv_usec = 0;
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381 | /* BTW, utimes sets usec-precision time - just FYI */
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382 | if (utimes(dest, times) < 0)
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383 | bb_perror_msg("can't preserve %s of '%s'", "times", dest);
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384 | if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
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385 | source_stat.st_mode &= ~(S_ISUID | S_ISGID);
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386 | bb_perror_msg("can't preserve %s of '%s'", "ownership", dest);
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387 | }
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388 | if (chmod(dest, source_stat.st_mode) < 0)
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389 | bb_perror_msg("can't preserve %s of '%s'", "permissions", dest);
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390 | }
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391 |
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392 | return retval;
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393 | }
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