lib/creat.c

   1 /* Create a file.
   2    Copyright (C) 2007-2020 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* If the user's config.h happens to include <fcntl.h>, let it include only
  18    the system's <fcntl.h> here, so that orig_creat doesn't recurse to
  19    rpl_creat.  */
  20 #define __need_system_fcntl_h
  21 #include <config.h>
  22
  23 /* Get the original definition of creat.  It might be defined as a macro.  */
  24 #include <fcntl.h>
  25 #include <sys/types.h>
  26 #undef __need_system_fcntl_h
  27
  28 static int
  29 orig_creat (const char *filename, mode_t mode)
  30 {
  31 #if defined _WIN32 && !defined __CYGWIN__
  32   return _creat (filename, mode);
  33 #else
  34   return creat (filename, mode);
  35 #endif
  36 }
  37
  38 /* Specification.  */
  39 /* Write "fcntl.h" here, not <fcntl.h>, otherwise OSF/1 5.1 DTK cc eliminates
  40    this include because of the preliminary #include <fcntl.h> above.  */
  41 #include "fcntl.h"
  42
  43 #include <errno.h>
  44 #include <string.h>
  45 #include <sys/types.h>
  46
  47 int
  48 creat (const char *filename, mode_t mode)
  49 {
  50 #if OPEN_TRAILING_SLASH_BUG
  51   /* Fail if the filename ends in a slash,
  52      as POSIX says such a filename must name a directory
  53      <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>:
  54        "A pathname that contains at least one non-<slash> character and that
  55         ends with one or more trailing <slash> characters shall not be resolved
  56         successfully unless the last pathname component before the trailing
  57         <slash> characters names an existing directory"
  58      creat() is defined as being equivalent to open() with flags
  59      O_CREAT | O_TRUNC | O_WRONLY.  Therefore:
  60      If the named file already exists as a directory, then creat() must fail
  61      with errno = EISDIR.
  62      If the named file does not exist or does not name a directory, then
  63      creat() must fail since creat() cannot create directories.  */
  64   {
  65     size_t len = strlen (filename);
  66     if (len > 0 && filename[len - 1] == '/')
  67       {
  68         errno = EISDIR;
  69         return -1;
  70       }
  71   }
  72 #endif
  73
  74 #if defined _WIN32 && !defined __CYGWIN__
  75   /* Remap the 'x' bits to the 'r' bits.  */
  76   mode = (mode & ~0111) | ((mode & 0111) << 2);
  77 #endif
  78
  79   return orig_creat (filename, mode);
  80 }