root/maint/gnulib/lib/truncate.c

/* */

DEFINITIONS

1. orig_truncate
2. truncate

   1 /* truncate emulations for native Windows.
   2    Copyright (C) 2017-2021 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, or (at your option)
   7    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 along
  15    with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16 
  17 /* If the user's config.h happens to include <unistd.h>, let it include only
  18    the system's <unistd.h> here, so that orig_faccessat doesn't recurse to
  19    rpl_faccessat.  */
  20 #define _GL_INCLUDING_UNISTD_H
  21 #include <config.h>
  22 
  23 /* Specification.  */
  24 #include <unistd.h>
  25 
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <string.h>
  29 #include <sys/stat.h>
  30 #undef _GL_INCLUDING_UNISTD_H
  31 
  32 #if TRUNCATE_TRAILING_SLASH_BUG
  33 static int
  34 orig_truncate (const char *filename, off_t length)
     /*  */
  35 {
  36   return truncate (filename, length);
  37 }
  38 #endif
  39 
  40 /* Write "unistd.h" here, not <unistd.h>, otherwise OSF/1 5.1 DTK cc
  41    eliminates this include because of the preliminary #include <unistd.h>
  42    above.  */
  43 #include "unistd.h"
  44 
  45 int
  46 truncate (const char *filename, off_t length)
     /*  */
  47 {
  48 #if TRUNCATE_TRAILING_SLASH_BUG
  49   /* Use the original truncate(), but correct the trailing slash handling.  */
  50   size_t len = strlen (filename);
  51   if (len && filename[len - 1] == '/')
  52     {
  53       struct stat st;
  54       if (stat (filename, &st) == 0)
  55         errno = (S_ISDIR (st.st_mode) ? EISDIR : ENOTDIR);
  56       return -1;
  57     }
  58   return orig_truncate (filename, length);
  59 #else
  60   int fd;
  61 
  62   if (length == 0)
  63     {
  64       fd = open (filename, O_WRONLY | O_TRUNC | O_CLOEXEC);
  65       if (fd < 0)
  66         return -1;
  67     }
  68   else
  69     {
  70       fd = open (filename, O_WRONLY | O_CLOEXEC);
  71       if (fd < 0)
  72         return -1;
  73       if (ftruncate (fd, length) < 0)
  74         {
  75           int saved_errno = errno;
  76           close (fd);
  77           errno = saved_errno;
  78           return -1;
  79         }
  80     }
  81   close (fd);
  82   return 0;
  83 #endif
  84 }

/* */