lib/rename.c

   1 /* Work around rename bugs in some systems.
   2
   3    Copyright (C) 2001-2003, 2005-2006, 2009-2018 Free Software Foundation, Inc.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 /* Written by Volker Borchert, Eric Blake.  */
  19
  20 #include <config.h>
  21
  22 #include <stdio.h>
  23
  24 #undef rename
  25
  26 #if defined _WIN32 && ! defined __CYGWIN__
  27 /* The mingw rename has problems with trailing slashes; it also
  28    requires use of native Windows calls to allow atomic renames over
  29    existing files.  */
  30
  31 # include <errno.h>
  32 # include <stdbool.h>
  33 # include <stdlib.h>
  34 # include <sys/stat.h>
  35 # include <unistd.h>
  36
  37 # define WIN32_LEAN_AND_MEAN
  38 # include <windows.h>
  39
  40 # include "dirname.h"
  41
  42 /* Rename the file SRC to DST.  This replacement is necessary on
  43    Windows, on which the system rename function will not replace
  44    an existing DST.  */
  45 int
  46 rpl_rename (char const *src, char const *dst)
  47 {
  48   int error;
  49   size_t src_len = strlen (src);
  50   size_t dst_len = strlen (dst);
  51   char *src_base = last_component (src);
  52   char *dst_base = last_component (dst);
  53   bool src_slash;
  54   bool dst_slash;
  55   bool dst_exists;
  56   struct stat src_st;
  57   struct stat dst_st;
  58
  59   /* Filter out dot as last component.  */
  60   if (!src_len || !dst_len)
  61     {
  62       errno = ENOENT;
  63       return -1;
  64     }
  65   if (*src_base == '.')
  66     {
  67       size_t len = base_len (src_base);
  68       if (len == 1 || (len == 2 && src_base[1] == '.'))
  69         {
  70           errno = EINVAL;
  71           return -1;
  72         }
  73     }
  74   if (*dst_base == '.')
  75     {
  76       size_t len = base_len (dst_base);
  77       if (len == 1 || (len == 2 && dst_base[1] == '.'))
  78         {
  79           errno = EINVAL;
  80           return -1;
  81         }
  82     }
  83
  84   /* Presence of a trailing slash requires directory semantics.  If
  85      the source does not exist, or if the destination cannot be turned
  86      into a directory, give up now.  Otherwise, strip trailing slashes
  87      before calling rename.  There are no symlinks on mingw, so stat
  88      works instead of lstat.  */
  89   src_slash = ISSLASH (src[src_len - 1]);
  90   dst_slash = ISSLASH (dst[dst_len - 1]);
  91   if (stat (src, &src_st))
  92     return -1;
  93   if (stat (dst, &dst_st))
  94     {
  95       if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
  96         return -1;
  97       dst_exists = false;
  98     }
  99   else
 100     {
 101       if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
 102         {
 103           errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
 104           return -1;
 105         }
 106       dst_exists = true;
 107     }
 108
 109   /* There are no symlinks, so if a file existed with a trailing
 110      slash, it must be a directory, and we don't have to worry about
 111      stripping strip trailing slash.  However, mingw refuses to
 112      replace an existing empty directory, so we have to help it out.
 113      And canonicalize_file_name is not yet ported to mingw; however,
 114      for directories, getcwd works as a viable alternative.  Ensure
 115      that we can get back to where we started before using it; later
 116      attempts to return are fatal.  Note that we can end up losing a
 117      directory if rename then fails, but it was empty, so not much
 118      damage was done.  */
 119   if (dst_exists && S_ISDIR (dst_st.st_mode))
 120     {
 121       char *cwd = getcwd (NULL, 0);
 122       char *src_temp;
 123       char *dst_temp;
 124       if (!cwd || chdir (cwd))
 125         return -1;
 126       if (IS_ABSOLUTE_FILE_NAME (src))
 127         {
 128           dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
 129           src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
 130         }
 131       else
 132         {
 133           src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
 134           if (!IS_ABSOLUTE_FILE_NAME (dst) && chdir (cwd))
 135             abort ();
 136           dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
 137         }
 138       if (chdir (cwd))
 139         abort ();
 140       free (cwd);
 141       if (!src_temp || !dst_temp)
 142         {
 143           free (src_temp);
 144           free (dst_temp);
 145           errno = ENOMEM;
 146           return -1;
 147         }
 148       src_len = strlen (src_temp);
 149       if (strncmp (src_temp, dst_temp, src_len) == 0
 150           && (ISSLASH (dst_temp[src_len]) || dst_temp[src_len] == '\0'))
 151         {
 152           error = dst_temp[src_len];
 153           free (src_temp);
 154           free (dst_temp);
 155           if (error)
 156             {
 157               errno = EINVAL;
 158               return -1;
 159             }
 160           return 0;
 161         }
 162       if (rmdir (dst))
 163         {
 164           error = errno;
 165           free (src_temp);
 166           free (dst_temp);
 167           errno = error;
 168           return -1;
 169         }
 170       free (src_temp);
 171       free (dst_temp);
 172     }
 173
 174   /* MoveFileEx works if SRC is a directory without any flags, but
 175      fails with MOVEFILE_REPLACE_EXISTING, so try without flags first.
 176      Thankfully, MoveFileEx handles hard links correctly, even though
 177      rename() does not.  */
 178   if (MoveFileEx (src, dst, 0))
 179     return 0;
 180
 181   /* Retry with MOVEFILE_REPLACE_EXISTING if the move failed
 182      due to the destination already existing.  */
 183   error = GetLastError ();
 184   if (error == ERROR_FILE_EXISTS || error == ERROR_ALREADY_EXISTS)
 185     {
 186       if (MoveFileEx (src, dst, MOVEFILE_REPLACE_EXISTING))
 187         return 0;
 188
 189       error = GetLastError ();
 190     }
 191
 192   switch (error)
 193     {
 194     case ERROR_FILE_NOT_FOUND:
 195     case ERROR_PATH_NOT_FOUND:
 196     case ERROR_BAD_PATHNAME:
 197     case ERROR_DIRECTORY:
 198       errno = ENOENT;
 199       break;
 200
 201     case ERROR_ACCESS_DENIED:
 202     case ERROR_SHARING_VIOLATION:
 203       errno = EACCES;
 204       break;
 205
 206     case ERROR_OUTOFMEMORY:
 207       errno = ENOMEM;
 208       break;
 209
 210     case ERROR_CURRENT_DIRECTORY:
 211       errno = EBUSY;
 212       break;
 213
 214     case ERROR_NOT_SAME_DEVICE:
 215       errno = EXDEV;
 216       break;
 217
 218     case ERROR_WRITE_PROTECT:
 219       errno = EROFS;
 220       break;
 221
 222     case ERROR_WRITE_FAULT:
 223     case ERROR_READ_FAULT:
 224     case ERROR_GEN_FAILURE:
 225       errno = EIO;
 226       break;
 227
 228     case ERROR_HANDLE_DISK_FULL:
 229     case ERROR_DISK_FULL:
 230     case ERROR_DISK_TOO_FRAGMENTED:
 231       errno = ENOSPC;
 232       break;
 233
 234     case ERROR_FILE_EXISTS:
 235     case ERROR_ALREADY_EXISTS:
 236       errno = EEXIST;
 237       break;
 238
 239     case ERROR_BUFFER_OVERFLOW:
 240     case ERROR_FILENAME_EXCED_RANGE:
 241       errno = ENAMETOOLONG;
 242       break;
 243
 244     case ERROR_INVALID_NAME:
 245     case ERROR_DELETE_PENDING:
 246       errno = EPERM;        /* ? */
 247       break;
 248
 249 # ifndef ERROR_FILE_TOO_LARGE
 250 /* This value is documented but not defined in all versions of windows.h.  */
 251 #  define ERROR_FILE_TOO_LARGE 223
 252 # endif
 253     case ERROR_FILE_TOO_LARGE:
 254       errno = EFBIG;
 255       break;
 256
 257     default:
 258       errno = EINVAL;
 259       break;
 260     }
 261
 262   return -1;
 263 }
 264
 265 #else /* ! W32 platform */
 266
 267 # include <errno.h>
 268 # include <stdio.h>
 269 # include <stdlib.h>
 270 # include <string.h>
 271 # include <sys/stat.h>
 272 # include <unistd.h>
 273
 274 # include "dirname.h"
 275 # include "same-inode.h"
 276
 277 /* Rename the file SRC to DST, fixing any trailing slash bugs.  */
 278
 279 int
 280 rpl_rename (char const *src, char const *dst)
 281 {
 282   size_t src_len = strlen (src);
 283   size_t dst_len = strlen (dst);
 284   char *src_temp = (char *) src;
 285   char *dst_temp = (char *) dst;
 286   bool src_slash;
 287   bool dst_slash;
 288   bool dst_exists _GL_UNUSED;
 289   int ret_val = -1;
 290   int rename_errno = ENOTDIR;
 291   struct stat src_st;
 292   struct stat dst_st;
 293
 294   if (!src_len || !dst_len)
 295     return rename (src, dst); /* Let strace see the ENOENT failure.  */
 296
 297 # if RENAME_DEST_EXISTS_BUG
 298   {
 299     char *src_base = last_component (src);
 300     char *dst_base = last_component (dst);
 301     if (*src_base == '.')
 302       {
 303         size_t len = base_len (src_base);
 304         if (len == 1 || (len == 2 && src_base[1] == '.'))
 305           {
 306             errno = EINVAL;
 307             return -1;
 308           }
 309       }
 310     if (*dst_base == '.')
 311       {
 312         size_t len = base_len (dst_base);
 313         if (len == 1 || (len == 2 && dst_base[1] == '.'))
 314           {
 315             errno = EINVAL;
 316             return -1;
 317           }
 318       }
 319   }
 320 # endif /* RENAME_DEST_EXISTS_BUG */
 321
 322   src_slash = src[src_len - 1] == '/';
 323   dst_slash = dst[dst_len - 1] == '/';
 324
 325 # if !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG
 326   /* If there are no trailing slashes, then trust the native
 327      implementation unless we also suspect issues with hard link
 328      detection or file/directory conflicts.  */
 329   if (!src_slash && !dst_slash)
 330     return rename (src, dst);
 331 # endif /* !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG */
 332
 333   /* Presence of a trailing slash requires directory semantics.  If
 334      the source does not exist, or if the destination cannot be turned
 335      into a directory, give up now.  Otherwise, strip trailing slashes
 336      before calling rename.  */
 337   if (lstat (src, &src_st))
 338     return -1;
 339   if (lstat (dst, &dst_st))
 340     {
 341       if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
 342         return -1;
 343       dst_exists = false;
 344     }
 345   else
 346     {
 347       if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
 348         {
 349           errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
 350           return -1;
 351         }
 352 # if RENAME_HARD_LINK_BUG
 353       if (SAME_INODE (src_st, dst_st))
 354         return 0;
 355 # endif /* RENAME_HARD_LINK_BUG */
 356       dst_exists = true;
 357     }
 358
 359 # if (RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG        \
 360       || RENAME_HARD_LINK_BUG)
 361   /* If the only bug was that a trailing slash was allowed on a
 362      non-existing file destination, as in Solaris 10, then we've
 363      already covered that situation.  But if there is any problem with
 364      a trailing slash on an existing source or destination, as in
 365      Solaris 9, or if a directory can overwrite a symlink, as on
 366      Cygwin 1.5, or if directories cannot be created with trailing
 367      slash, as on NetBSD 1.6, then we must strip the offending slash
 368      and check that we have not encountered a symlink instead of a
 369      directory.
 370
 371      Stripping a trailing slash interferes with POSIX semantics, where
 372      rename behavior on a symlink with a trailing slash operates on
 373      the corresponding target directory.  We prefer the GNU semantics
 374      of rejecting any use of a symlink with trailing slash, but do not
 375      enforce them, since Solaris 10 is able to obey POSIX semantics
 376      and there might be clients expecting it, as counter-intuitive as
 377      those semantics are.
 378
 379      Technically, we could also follow the POSIX behavior by chasing a
 380      readlink trail, but that is harder to implement.  */
 381   if (src_slash)
 382     {
 383       src_temp = strdup (src);
 384       if (!src_temp)
 385         {
 386           /* Rather than rely on strdup-posix, we set errno ourselves.  */
 387           rename_errno = ENOMEM;
 388           goto out;
 389         }
 390       strip_trailing_slashes (src_temp);
 391       if (lstat (src_temp, &src_st))
 392         {
 393           rename_errno = errno;
 394           goto out;
 395         }
 396       if (S_ISLNK (src_st.st_mode))
 397         goto out;
 398     }
 399   if (dst_slash)
 400     {
 401       dst_temp = strdup (dst);
 402       if (!dst_temp)
 403         {
 404           rename_errno = ENOMEM;
 405           goto out;
 406         }
 407       strip_trailing_slashes (dst_temp);
 408       if (lstat (dst_temp, &dst_st))
 409         {
 410           if (errno != ENOENT)
 411             {
 412               rename_errno = errno;
 413               goto out;
 414             }
 415         }
 416       else if (S_ISLNK (dst_st.st_mode))
 417         goto out;
 418     }
 419 # endif /* RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG
 420            || RENAME_HARD_LINK_BUG */
 421
 422 # if RENAME_DEST_EXISTS_BUG
 423   /* Cygwin 1.5 sometimes behaves oddly when moving a non-empty
 424      directory on top of an empty one (the old directory name can
 425      reappear if the new directory tree is removed).  Work around this
 426      by removing the target first, but don't remove the target if it
 427      is a subdirectory of the source.  Note that we can end up losing
 428      a directory if rename then fails, but it was empty, so not much
 429      damage was done.  */
 430   if (dst_exists && S_ISDIR (dst_st.st_mode))
 431     {
 432       if (src_st.st_dev != dst_st.st_dev)
 433         {
 434           rename_errno = EXDEV;
 435           goto out;
 436         }
 437       if (src_temp != src)
 438         free (src_temp);
 439       src_temp = canonicalize_file_name (src);
 440       if (dst_temp != dst)
 441         free (dst_temp);
 442       dst_temp = canonicalize_file_name (dst);
 443       if (!src_temp || !dst_temp)
 444         {
 445           rename_errno = ENOMEM;
 446           goto out;
 447         }
 448       src_len = strlen (src_temp);
 449       if (strncmp (src_temp, dst_temp, src_len) == 0
 450           && dst_temp[src_len] == '/')
 451         {
 452           rename_errno = EINVAL;
 453           goto out;
 454         }
 455       if (rmdir (dst))
 456         {
 457           rename_errno = errno;
 458           goto out;
 459         }
 460     }
 461 # endif /* RENAME_DEST_EXISTS_BUG */
 462
 463   ret_val = rename (src_temp, dst_temp);
 464   rename_errno = errno;
 465
 466  out: _GL_UNUSED_LABEL;
 467
 468   if (src_temp != src)
 469     free (src_temp);
 470   if (dst_temp != dst)
 471     free (dst_temp);
 472   errno = rename_errno;
 473   return ret_val;
 474 }
 475 #endif /* ! W32 platform */