libbb/copy_file.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini copy_file implementation for busybox
   4  *
   5  * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8  *
   9  */
  10
  11 #include "libbb.h"
  12
  13 static int retry_overwrite(const char *dest, int flags)
  14 {
  15         if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) {
  16                 fprintf(stderr, "'%s' exists\n", dest);
  17                 return -1;
  18         }
  19         if (flags & FILEUTILS_INTERACTIVE) {
  20                 fprintf(stderr, "%s: overwrite '%s'? ", applet_name, dest);
  21                 if (!bb_ask_confirmation())
  22                         return 0; // not allowed to overwrite
  23         }
  24         if (unlink(dest) < 0) {
  25                 bb_perror_msg("cannot remove '%s'", dest);
  26                 return -1; // error
  27         }
  28         return 1; // ok (to try again)
  29 }
  30
  31 int copy_file(const char *source, const char *dest, int flags)
  32 {
  33         struct stat source_stat;
  34         struct stat dest_stat;
  35         int status = 0;
  36         signed char dest_exists = 0;
  37         signed char ovr;
  38
  39 #define FLAGS_DEREF (flags & FILEUTILS_DEREFERENCE)
  40
  41         if ((FLAGS_DEREF ? stat : lstat)(source, &source_stat) < 0) {
  42                 // This may be a dangling symlink.
  43                 // Making [sym]links to dangling symlinks works, so...
  44                 if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK))
  45                         goto make_links;
  46                 bb_perror_msg("cannot stat '%s'", source);
  47                 return -1;
  48         }
  49
  50         if (lstat(dest, &dest_stat) < 0) {
  51                 if (errno != ENOENT) {
  52                         bb_perror_msg("cannot stat '%s'", dest);
  53                         return -1;
  54                 }
  55         } else {
  56                 if (source_stat.st_dev == dest_stat.st_dev
  57                  && source_stat.st_ino == dest_stat.st_ino
  58                 ) {
  59                         bb_error_msg("'%s' and '%s' are the same file", source, dest);
  60                         return -1;
  61                 }
  62                 dest_exists = 1;
  63         }
  64
  65         if (S_ISDIR(source_stat.st_mode)) {
  66                 DIR *dp;
  67                 struct dirent *d;
  68                 mode_t saved_umask = 0;
  69
  70                 if (!(flags & FILEUTILS_RECUR)) {
  71                         bb_error_msg("omitting directory '%s'", source);
  72                         return -1;
  73                 }
  74
  75                 /* Create DEST.  */
  76                 if (dest_exists) {
  77                         if (!S_ISDIR(dest_stat.st_mode)) {
  78                                 bb_error_msg("target '%s' is not a directory", dest);
  79                                 return -1;
  80                         }
  81                 } else {
  82                         mode_t mode;
  83                         saved_umask = umask(0);
  84
  85                         mode = source_stat.st_mode;
  86                         if (!(flags & FILEUTILS_PRESERVE_STATUS))
  87                                 mode = source_stat.st_mode & ~saved_umask;
  88                         mode |= S_IRWXU;
  89
  90                         if (mkdir(dest, mode) < 0) {
  91                                 umask(saved_umask);
  92                                 bb_perror_msg("cannot create directory '%s'", dest);
  93                                 return -1;
  94                         }
  95
  96                         umask(saved_umask);
  97                 }
  98
  99                 /* Recursively copy files in SOURCE.  */
 100                 dp = opendir(source);
 101                 if (dp == NULL) {
 102                         status = -1;
 103                         goto preserve_status;
 104                 }
 105
 106                 while ((d = readdir(dp)) != NULL) {
 107                         char *new_source, *new_dest;
 108
 109                         new_source = concat_subpath_file(source, d->d_name);
 110                         if (new_source == NULL)
 111                                 continue;
 112                         new_dest = concat_path_file(dest, d->d_name);
 113                         if (copy_file(new_source, new_dest, flags) < 0)
 114                                 status = -1;
 115                         free(new_source);
 116                         free(new_dest);
 117                 }
 118                 closedir(dp);
 119
 120                 if (!dest_exists
 121                  && chmod(dest, source_stat.st_mode & ~saved_umask) < 0
 122                 ) {
 123                         bb_perror_msg("cannot change permissions of '%s'", dest);
 124                         status = -1;
 125                 }
 126
 127         } else if (flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) {
 128                 int (*lf)(const char *oldpath, const char *newpath);
 129  make_links:
 130                 // Hmm... maybe
 131                 // if (DEREF && MAKE_SOFTLINK) source = realpath(source) ?
 132                 // (but realpath returns NULL on dangling symlinks...)
 133                 lf = (flags & FILEUTILS_MAKE_SOFTLINK) ? symlink : link;
 134                 if (lf(source, dest) < 0) {
 135                         ovr = retry_overwrite(dest, flags);
 136                         if (ovr <= 0)
 137                                 return ovr;
 138                         if (lf(source, dest) < 0) {
 139                                 bb_perror_msg("cannot create link '%s'", dest);
 140                                 return -1;
 141                         }
 142                 }
 143                 return 0;
 144
 145         } else if (S_ISREG(source_stat.st_mode)
 146         // Huh? DEREF uses stat, which never returns links IIRC...
 147          || (FLAGS_DEREF && S_ISLNK(source_stat.st_mode))
 148         ) {
 149                 int src_fd;
 150                 int dst_fd;
 151                 if (ENABLE_FEATURE_PRESERVE_HARDLINKS) {
 152                         char *link_name;
 153
 154                         if (!FLAGS_DEREF
 155                          && is_in_ino_dev_hashtable(&source_stat, &link_name)
 156                         ) {
 157                                 if (link(link_name, dest) < 0) {
 158                                         ovr = retry_overwrite(dest, flags);
 159                                         if (ovr <= 0)
 160                                                 return ovr;
 161                                         if (link(link_name, dest) < 0) {
 162                                                 bb_perror_msg("cannot create link '%s'", dest);
 163                                                 return -1;
 164                                         }
 165                                 }
 166                                 return 0;
 167                         }
 168                         // TODO: probably is_in_.. and add_to_...
 169                         // can be combined: find_or_add_...
 170                         add_to_ino_dev_hashtable(&source_stat, dest);
 171                 }
 172
 173                 src_fd = open(source, O_RDONLY);
 174                 if (src_fd == -1) {
 175                         bb_perror_msg("cannot open '%s'", source);
 176                         return -1;
 177                 }
 178
 179                 // POSIX: if exists and -i, ask (w/o -i assume yes).
 180                 // Then open w/o EXCL.
 181                 // If open still fails and -f, try unlink, then try open again.
 182                 // Result: a mess:
 183                 // If dest is a softlink, we overwrite softlink's destination!
 184                 // (or fail, if it points to dir/nonexistent location/etc).
 185                 // This is strange, but POSIX-correct.
 186                 // coreutils cp has --remove-destination to override this...
 187                 dst_fd = open(dest, (flags & FILEUTILS_INTERACTIVE)
 188                                 ? O_WRONLY|O_CREAT|O_TRUNC|O_EXCL
 189                                 : O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
 190                 if (dst_fd == -1) {
 191                         // We would not do POSIX insanity. -i asks,
 192                         // then _unlinks_ the offender. Presto.
 193                         // Or else we will end up having 3 open()s!
 194                         ovr = retry_overwrite(dest, flags);
 195                         if (ovr <= 0) {
 196                                 close(src_fd);
 197                                 return ovr;
 198                         }
 199                         dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
 200                         if (dst_fd == -1) {
 201                                 bb_perror_msg("cannot open '%s'", dest);
 202                                 close(src_fd);
 203                                 return -1;
 204                         }
 205                 }
 206
 207                 if (bb_copyfd_eof(src_fd, dst_fd) == -1)
 208                         status = -1;
 209                 if (close(dst_fd) < 0) {
 210                         bb_perror_msg("cannot close '%s'", dest);
 211                         status = -1;
 212                 }
 213                 if (close(src_fd) < 0) {
 214                         bb_perror_msg("cannot close '%s'", source);
 215                         status = -1;
 216                 }
 217
 218         } else if (S_ISBLK(source_stat.st_mode) || S_ISCHR(source_stat.st_mode)
 219          || S_ISSOCK(source_stat.st_mode) || S_ISFIFO(source_stat.st_mode)
 220          || S_ISLNK(source_stat.st_mode)
 221         ) {
 222                 // We are lazy here, a bit lax with races...
 223                 if (dest_exists) {
 224                         ovr = retry_overwrite(dest, flags);
 225                         if (ovr <= 0)
 226                                 return ovr;
 227                 }
 228                 if (S_ISFIFO(source_stat.st_mode)) {
 229                         if (mkfifo(dest, source_stat.st_mode) < 0) {
 230                                 bb_perror_msg("cannot create fifo '%s'", dest);
 231                                 return -1;
 232                         }
 233                 } else if (S_ISLNK(source_stat.st_mode)) {
 234                         char *lpath;
 235
 236                         lpath = xmalloc_readlink_or_warn(source);
 237                         if (symlink(lpath, dest) < 0) {
 238                                 bb_perror_msg("cannot create symlink '%s'", dest);
 239                                 free(lpath);
 240                                 return -1;
 241                         }
 242                         free(lpath);
 243
 244                         if (flags & FILEUTILS_PRESERVE_STATUS)
 245                                 if (lchown(dest, source_stat.st_uid, source_stat.st_gid) < 0)
 246                                         bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
 247
 248                         return 0;
 249
 250                 } else {
 251                         if (mknod(dest, source_stat.st_mode, source_stat.st_rdev) < 0) {
 252                                 bb_perror_msg("cannot create '%s'", dest);
 253                                 return -1;
 254                         }
 255                 }
 256         } else {
 257                 bb_error_msg("internal error: unrecognized file type");
 258                 return -1;
 259         }
 260
 261  preserve_status:
 262
 263         if (flags & FILEUTILS_PRESERVE_STATUS
 264         /* Cannot happen: */
 265         /* && !(flags & (FILEUTILS_MAKE_SOFTLINK|FILEUTILS_MAKE_HARDLINK)) */
 266         ) {
 267                 struct utimbuf times;
 268
 269                 times.actime = source_stat.st_atime;
 270                 times.modtime = source_stat.st_mtime;
 271                 if (utime(dest, &times) < 0)
 272                         bb_perror_msg("cannot preserve %s of '%s'", "times", dest);
 273                 if (chown(dest, source_stat.st_uid, source_stat.st_gid) < 0) {
 274                         source_stat.st_mode &= ~(S_ISUID | S_ISGID);
 275                         bb_perror_msg("cannot preserve %s of '%s'", "ownership", dest);
 276                 }
 277                 if (chmod(dest, source_stat.st_mode) < 0)
 278                         bb_perror_msg("cannot preserve %s of '%s'", "permissions", dest);
 279         }
 280
 281         return status;
 282 }