lib/stat.c

   1 /* Work around platform bugs in stat.
   2    Copyright (C) 2009-2017 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 <http://www.gnu.org/licenses/>.  */
  16
  17 /* written by Eric Blake */
  18
  19 /* If the user's config.h happens to include <sys/stat.h>, let it include only
  20    the system's <sys/stat.h> here, so that orig_stat doesn't recurse to
  21    rpl_stat.  */
  22 #define __need_system_sys_stat_h
  23 #include <config.h>
  24
  25 /* Get the original definition of stat.  It might be defined as a macro.  */
  26 #include <sys/types.h>
  27 #include <sys/stat.h>
  28 #undef __need_system_sys_stat_h
  29
  30 #if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__
  31 # if _GL_WINDOWS_64_BIT_ST_SIZE
  32 #  undef stat /* avoid warning on mingw64 with _FILE_OFFSET_BITS=64 */
  33 #  define stat _stati64
  34 #  define REPLACE_FUNC_STAT_DIR 1
  35 #  undef REPLACE_FUNC_STAT_FILE
  36 # elif REPLACE_FUNC_STAT_FILE
  37 /* mingw64 has a broken stat() function, based on _stat(), in libmingwex.a.
  38    Bypass it.  */
  39 #  define stat _stat
  40 #  define REPLACE_FUNC_STAT_DIR 1
  41 #  undef REPLACE_FUNC_STAT_FILE
  42 # endif
  43 #endif
  44
  45 static int
  46 orig_stat (const char *filename, struct stat *buf)
  47 {
  48   return stat (filename, buf);
  49 }
  50
  51 /* Specification.  */
  52 /* Write "sys/stat.h" here, not <sys/stat.h>, otherwise OSF/1 5.1 DTK cc
  53    eliminates this include because of the preliminary #include <sys/stat.h>
  54    above.  */
  55 #include "sys/stat.h"
  56
  57 #include <errno.h>
  58 #include <limits.h>
  59 #include <stdbool.h>
  60 #include <string.h>
  61 #include "dosname.h"
  62 #include "verify.h"
  63
  64 #if REPLACE_FUNC_STAT_DIR
  65 # include "pathmax.h"
  66   /* The only known systems where REPLACE_FUNC_STAT_DIR is needed also
  67      have a constant PATH_MAX.  */
  68 # ifndef PATH_MAX
  69 #  error "Please port this replacement to your platform"
  70 # endif
  71 #endif
  72
  73 /* Store information about NAME into ST.  Work around bugs with
  74    trailing slashes.  Mingw has other bugs (such as st_ino always
  75    being 0 on success) which this wrapper does not work around.  But
  76    at least this implementation provides the ability to emulate fchdir
  77    correctly.  */
  78
  79 int
  80 rpl_stat (char const *name, struct stat *st)
  81 {
  82   int result = orig_stat (name, st);
  83 #if REPLACE_FUNC_STAT_FILE
  84   /* Solaris 9 mistakenly succeeds when given a non-directory with a
  85      trailing slash.  */
  86   if (result == 0 && !S_ISDIR (st->st_mode))
  87     {
  88       size_t len = strlen (name);
  89       if (ISSLASH (name[len - 1]))
  90         {
  91           errno = ENOTDIR;
  92           return -1;
  93         }
  94     }
  95 #endif /* REPLACE_FUNC_STAT_FILE */
  96 #if REPLACE_FUNC_STAT_DIR
  97
  98   if (result == -1 && errno == ENOENT)
  99     {
 100       /* Due to mingw's oddities, there are some directories (like
 101          c:\) where stat() only succeeds with a trailing slash, and
 102          other directories (like c:\windows) where stat() only
 103          succeeds without a trailing slash.  But we want the two to be
 104          synonymous, since chdir() manages either style.  Likewise, Mingw also
 105          reports ENOENT for names longer than PATH_MAX, when we want
 106          ENAMETOOLONG, and for stat("file/"), when we want ENOTDIR.
 107          Fortunately, mingw PATH_MAX is small enough for stack
 108          allocation.  */
 109       char fixed_name[PATH_MAX + 1] = {0};
 110       size_t len = strlen (name);
 111       bool check_dir = false;
 112       verify (PATH_MAX <= 4096);
 113       if (PATH_MAX <= len)
 114         errno = ENAMETOOLONG;
 115       else if (len)
 116         {
 117           strcpy (fixed_name, name);
 118           if (ISSLASH (fixed_name[len - 1]))
 119             {
 120               check_dir = true;
 121               while (len && ISSLASH (fixed_name[len - 1]))
 122                 fixed_name[--len] = '\0';
 123               if (!len)
 124                 fixed_name[0] = '/';
 125             }
 126           else
 127             fixed_name[len++] = '/';
 128           result = orig_stat (fixed_name, st);
 129           if (result == 0 && check_dir && !S_ISDIR (st->st_mode))
 130             {
 131               result = -1;
 132               errno = ENOTDIR;
 133             }
 134         }
 135     }
 136 #endif /* REPLACE_FUNC_STAT_DIR */
 137   return result;
 138 }