gnulib/import/rename.c

   1 /* Work around rename bugs in some systems.
   2
   3    Copyright (C) 2001-2003, 2005-2006, 2009-2022 Free Software Foundation, Inc.
   4
   5    This file is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    This file 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 Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser 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 /* Don't assume that UNICODE is not defined.  */
  43 # undef MoveFileEx
  44 # define MoveFileEx MoveFileExA
  45
  46 /* Rename the file SRC to DST.  This replacement is necessary on
  47    Windows, on which the system rename function will not replace
  48    an existing DST.  */
  49 int
  50 rpl_rename (char const *src, char const *dst)
  51 {
  52   int error;
  53   size_t src_len = strlen (src);
  54   size_t dst_len = strlen (dst);
  55   char *src_base = last_component (src);
  56   char *dst_base = last_component (dst);
  57   bool src_slash;
  58   bool dst_slash;
  59   bool dst_exists;
  60   struct stat src_st;
  61   struct stat dst_st;
  62
  63   /* Filter out dot as last component.  */
  64   if (!src_len || !dst_len)
  65     {
  66       errno = ENOENT;
  67       return -1;
  68     }
  69   if (*src_base == '.')
  70     {
  71       size_t len = base_len (src_base);
  72       if (len == 1 || (len == 2 && src_base[1] == '.'))
  73         {
  74           errno = EINVAL;
  75           return -1;
  76         }
  77     }
  78   if (*dst_base == '.')
  79     {
  80       size_t len = base_len (dst_base);
  81       if (len == 1 || (len == 2 && dst_base[1] == '.'))
  82         {
  83           errno = EINVAL;
  84           return -1;
  85         }
  86     }
  87
  88   /* Presence of a trailing slash requires directory semantics.  If
  89      the source does not exist, or if the destination cannot be turned
  90      into a directory, give up now.  Otherwise, strip trailing slashes
  91      before calling rename.  There are no symlinks on mingw, so stat
  92      works instead of lstat.  */
  93   src_slash = ISSLASH (src[src_len - 1]);
  94   dst_slash = ISSLASH (dst[dst_len - 1]);
  95   if (stat (src, &src_st))
  96     return -1;
  97   if (stat (dst, &dst_st))
  98     {
  99       if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
 100         return -1;
 101       dst_exists = false;
 102     }
 103   else
 104     {
 105       if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
 106         {
 107           errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
 108           return -1;
 109         }
 110       dst_exists = true;
 111     }
 112
 113   /* There are no symlinks, so if a file existed with a trailing
 114      slash, it must be a directory, and we don't have to worry about
 115      stripping strip trailing slash.  However, mingw refuses to
 116      replace an existing empty directory, so we have to help it out.
 117      And canonicalize_file_name is not yet ported to mingw; however,
 118      for directories, getcwd works as a viable alternative.  Ensure
 119      that we can get back to where we started before using it; later
 120      attempts to return are fatal.  Note that we can end up losing a
 121      directory if rename then fails, but it was empty, so not much
 122      damage was done.  */
 123   if (dst_exists && S_ISDIR (dst_st.st_mode))
 124     {
 125       char *cwd = getcwd (NULL, 0);
 126       char *src_temp;
 127       char *dst_temp;
 128       if (!cwd || chdir (cwd))
 129         return -1;
 130       if (IS_ABSOLUTE_FILE_NAME (src))
 131         {
 132           dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
 133           src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
 134         }
 135       else
 136         {
 137           src_temp = chdir (src) ? NULL : getcwd (NULL, 0);
 138           if (!IS_ABSOLUTE_FILE_NAME (dst) && chdir (cwd))
 139             abort ();
 140           dst_temp = chdir (dst) ? NULL : getcwd (NULL, 0);
 141         }
 142       if (chdir (cwd))
 143         abort ();
 144       free (cwd);
 145       if (!src_temp || !dst_temp)
 146         {
 147           free (src_temp);
 148           free (dst_temp);
 149           errno = ENOMEM;
 150           return -1;
 151         }
 152       src_len = strlen (src_temp);
 153       if (strncmp (src_temp, dst_temp, src_len) == 0
 154           && (ISSLASH (dst_temp[src_len]) || dst_temp[src_len] == '\0'))
 155         {
 156           error = dst_temp[src_len];
 157           free (src_temp);
 158           free (dst_temp);
 159           if (error)
 160             {
 161               errno = EINVAL;
 162               return -1;
 163             }
 164           return 0;
 165         }
 166       if (rmdir (dst))
 167         {
 168           free (src_temp);
 169           free (dst_temp);
 170           return -1;
 171         }
 172       free (src_temp);
 173       free (dst_temp);
 174     }
 175
 176   /* MoveFileEx works if SRC is a directory without any flags, but
 177      fails with MOVEFILE_REPLACE_EXISTING, so try without flags first.
 178      Thankfully, MoveFileEx handles hard links correctly, even though
 179      rename() does not.  */
 180   if (MoveFileEx (src, dst, 0))
 181     return 0;
 182
 183   /* Retry with MOVEFILE_REPLACE_EXISTING if the move failed
 184      due to the destination already existing.  */
 185   error = GetLastError ();
 186   if (error == ERROR_FILE_EXISTS || error == ERROR_ALREADY_EXISTS)
 187     {
 188       if (MoveFileEx (src, dst, MOVEFILE_REPLACE_EXISTING))
 189         return 0;
 190
 191       error = GetLastError ();
 192     }
 193
 194   switch (error)
 195     {
 196     case ERROR_FILE_NOT_FOUND:
 197     case ERROR_PATH_NOT_FOUND:
 198     case ERROR_BAD_PATHNAME:
 199     case ERROR_DIRECTORY:
 200       errno = ENOENT;
 201       break;
 202
 203     case ERROR_ACCESS_DENIED:
 204     case ERROR_SHARING_VIOLATION:
 205       errno = EACCES;
 206       break;
 207
 208     case ERROR_OUTOFMEMORY:
 209       errno = ENOMEM;
 210       break;
 211
 212     case ERROR_CURRENT_DIRECTORY:
 213       errno = EBUSY;
 214       break;
 215
 216     case ERROR_NOT_SAME_DEVICE:
 217       errno = EXDEV;
 218       break;
 219
 220     case ERROR_WRITE_PROTECT:
 221       errno = EROFS;
 222       break;
 223
 224     case ERROR_WRITE_FAULT:
 225     case ERROR_READ_FAULT:
 226     case ERROR_GEN_FAILURE:
 227       errno = EIO;
 228       break;
 229
 230     case ERROR_HANDLE_DISK_FULL:
 231     case ERROR_DISK_FULL:
 232     case ERROR_DISK_TOO_FRAGMENTED:
 233       errno = ENOSPC;
 234       break;
 235
 236     case ERROR_FILE_EXISTS:
 237     case ERROR_ALREADY_EXISTS:
 238       errno = EEXIST;
 239       break;
 240
 241     case ERROR_BUFFER_OVERFLOW:
 242     case ERROR_FILENAME_EXCED_RANGE:
 243       errno = ENAMETOOLONG;
 244       break;
 245
 246     case ERROR_INVALID_NAME:
 247     case ERROR_DELETE_PENDING:
 248       errno = EPERM;        /* ? */
 249       break;
 250
 251 # ifndef ERROR_FILE_TOO_LARGE
 252 /* This value is documented but not defined in all versions of windows.h.  */
 253 #  define ERROR_FILE_TOO_LARGE 223
 254 # endif
 255     case ERROR_FILE_TOO_LARGE:
 256       errno = EFBIG;
 257       break;
 258
 259     default:
 260       errno = EINVAL;
 261       break;
 262     }
 263
 264   return -1;
 265 }
 266
 267 #else /* ! W32 platform */
 268
 269 # include <errno.h>
 270 # include <stdio.h>
 271 # include <stdlib.h>
 272 # include <string.h>
 273 # include <sys/stat.h>
 274 # include <unistd.h>
 275
 276 # include "dirname.h"
 277 # include "same-inode.h"
 278
 279 /* Rename the file SRC to DST, fixing any trailing slash bugs.  */
 280
 281 int
 282 rpl_rename (char const *src, char const *dst)
 283 {
 284   size_t src_len = strlen (src);
 285   size_t dst_len = strlen (dst);
 286   char *src_temp = (char *) src;
 287   char *dst_temp = (char *) dst;
 288   bool src_slash;
 289   bool dst_slash;
 290   _GL_UNUSED bool dst_exists;
 291   int ret_val = -1;
 292   int rename_errno = ENOTDIR;
 293   struct stat src_st;
 294   struct stat dst_st;
 295
 296   if (!src_len || !dst_len)
 297     return rename (src, dst); /* Let strace see the ENOENT failure.  */
 298
 299 # if RENAME_DEST_EXISTS_BUG
 300   {
 301     char *src_base = last_component (src);
 302     char *dst_base = last_component (dst);
 303     if (*src_base == '.')
 304       {
 305         size_t len = base_len (src_base);
 306         if (len == 1 || (len == 2 && src_base[1] == '.'))
 307           {
 308             errno = EINVAL;
 309             return -1;
 310           }
 311       }
 312     if (*dst_base == '.')
 313       {
 314         size_t len = base_len (dst_base);
 315         if (len == 1 || (len == 2 && dst_base[1] == '.'))
 316           {
 317             errno = EINVAL;
 318             return -1;
 319           }
 320       }
 321   }
 322 # endif /* RENAME_DEST_EXISTS_BUG */
 323
 324   src_slash = src[src_len - 1] == '/';
 325   dst_slash = dst[dst_len - 1] == '/';
 326
 327 # if !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG
 328   /* If there are no trailing slashes, then trust the native
 329      implementation unless we also suspect issues with hard link
 330      detection or file/directory conflicts.  */
 331   if (!src_slash && !dst_slash)
 332     return rename (src, dst);
 333 # endif /* !RENAME_HARD_LINK_BUG && !RENAME_DEST_EXISTS_BUG */
 334
 335   /* Presence of a trailing slash requires directory semantics.  If
 336      the source does not exist, or if the destination cannot be turned
 337      into a directory, give up now.  Otherwise, strip trailing slashes
 338      before calling rename.  */
 339   if (lstat (src, &src_st))
 340     return -1;
 341   if (lstat (dst, &dst_st))
 342     {
 343       if (errno != ENOENT || (!S_ISDIR (src_st.st_mode) && dst_slash))
 344         return -1;
 345       dst_exists = false;
 346     }
 347   else
 348     {
 349       if (S_ISDIR (dst_st.st_mode) != S_ISDIR (src_st.st_mode))
 350         {
 351           errno = S_ISDIR (dst_st.st_mode) ? EISDIR : ENOTDIR;
 352           return -1;
 353         }
 354 # if RENAME_HARD_LINK_BUG
 355       if (SAME_INODE (src_st, dst_st))
 356         return 0;
 357 # endif /* RENAME_HARD_LINK_BUG */
 358       dst_exists = true;
 359     }
 360
 361 # if (RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG        \
 362       || RENAME_HARD_LINK_BUG)
 363   /* If the only bug was that a trailing slash was allowed on a
 364      non-existing file destination, as in Solaris 10, then we've
 365      already covered that situation.  But if there is any problem with
 366      a trailing slash on an existing source or destination, as in
 367      Solaris 9, or if a directory can overwrite a symlink, as on
 368      Cygwin 1.5, or if directories cannot be created with trailing
 369      slash, as on NetBSD 1.6, then we must strip the offending slash
 370      and check that we have not encountered a symlink instead of a
 371      directory.
 372
 373      Stripping a trailing slash interferes with POSIX semantics, where
 374      rename behavior on a symlink with a trailing slash operates on
 375      the corresponding target directory.  We prefer the GNU semantics
 376      of rejecting any use of a symlink with trailing slash, but do not
 377      enforce them, since Solaris 10 is able to obey POSIX semantics
 378      and there might be clients expecting it, as counter-intuitive as
 379      those semantics are.
 380
 381      Technically, we could also follow the POSIX behavior by chasing a
 382      readlink trail, but that is harder to implement.  */
 383   if (src_slash)
 384     {
 385       src_temp = strdup (src);
 386       if (!src_temp)
 387         {
 388           /* Rather than rely on strdup-posix, we set errno ourselves.  */
 389           rename_errno = ENOMEM;
 390           goto out;
 391         }
 392       strip_trailing_slashes (src_temp);
 393       if (lstat (src_temp, &src_st))
 394         {
 395           rename_errno = errno;
 396           goto out;
 397         }
 398       if (S_ISLNK (src_st.st_mode))
 399         goto out;
 400     }
 401   if (dst_slash)
 402     {
 403       dst_temp = strdup (dst);
 404       if (!dst_temp)
 405         {
 406           rename_errno = ENOMEM;
 407           goto out;
 408         }
 409       strip_trailing_slashes (dst_temp);
 410       if (lstat (dst_temp, &dst_st))
 411         {
 412           if (errno != ENOENT)
 413             {
 414               rename_errno = errno;
 415               goto out;
 416             }
 417         }
 418       else if (S_ISLNK (dst_st.st_mode))
 419         goto out;
 420     }
 421 # endif /* RENAME_TRAILING_SLASH_SOURCE_BUG || RENAME_DEST_EXISTS_BUG
 422            || RENAME_HARD_LINK_BUG */
 423
 424 # if RENAME_DEST_EXISTS_BUG
 425   /* Cygwin 1.5 sometimes behaves oddly when moving a non-empty
 426      directory on top of an empty one (the old directory name can
 427      reappear if the new directory tree is removed).  Work around this
 428      by removing the target first, but don't remove the target if it
 429      is a subdirectory of the source.  Note that we can end up losing
 430      a directory if rename then fails, but it was empty, so not much
 431      damage was done.  */
 432   if (dst_exists && S_ISDIR (dst_st.st_mode))
 433     {
 434       if (src_st.st_dev != dst_st.st_dev)
 435         {
 436           rename_errno = EXDEV;
 437           goto out;
 438         }
 439       if (src_temp != src)
 440         free (src_temp);
 441       src_temp = canonicalize_file_name (src);
 442       if (dst_temp != dst)
 443         free (dst_temp);
 444       dst_temp = canonicalize_file_name (dst);
 445       if (!src_temp || !dst_temp)
 446         {
 447           rename_errno = ENOMEM;
 448           goto out;
 449         }
 450       src_len = strlen (src_temp);
 451       if (strncmp (src_temp, dst_temp, src_len) == 0
 452           && dst_temp[src_len] == '/')
 453         {
 454           rename_errno = EINVAL;
 455           goto out;
 456         }
 457       if (rmdir (dst))
 458         {
 459           rename_errno = errno;
 460           goto out;
 461         }
 462     }
 463 # endif /* RENAME_DEST_EXISTS_BUG */
 464
 465   ret_val = rename (src_temp, dst_temp);
 466   rename_errno = errno;
 467
 468  out: _GL_UNUSED_LABEL;
 469
 470   if (src_temp != src)
 471     free (src_temp);
 472   if (dst_temp != dst)
 473     free (dst_temp);
 474   errno = rename_errno;
 475   return ret_val;
 476 }
 477 #endif /* ! W32 platform */