lib/tmpdir.c

   1 /* Copyright (C) 1999, 2001-2002, 2006, 2009-2021 Free Software Foundation,
   2    Inc.
   3    This file is part of the GNU C Library.
   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 /* Extracted from sysdeps/posix/tempname.c.  */
  19
  20 #include <config.h>
  21
  22 /* Specification.  */
  23 #include "tmpdir.h"
  24
  25 #include <stdbool.h>
  26 #include <stdlib.h>
  27 #include <string.h>
  28
  29 #include <errno.h>
  30 #ifndef __set_errno
  31 # define __set_errno(Val) errno = (Val)
  32 #endif
  33
  34 #include <stdio.h>
  35 #ifndef P_tmpdir
  36 # ifdef _P_tmpdir /* native Windows */
  37 #  define P_tmpdir _P_tmpdir
  38 # else
  39 #  define P_tmpdir "/tmp"
  40 # endif
  41 #endif
  42
  43 #include <sys/stat.h>
  44
  45 #if defined _WIN32 && ! defined __CYGWIN__
  46 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
  47 # include <windows.h>
  48 #endif
  49
  50 #include "pathmax.h"
  51
  52 #if defined _WIN32 && ! defined __CYGWIN__
  53 /* Don't assume that UNICODE is not defined.  */
  54 # undef GetTempPath
  55 # define GetTempPath GetTempPathA
  56 #endif
  57
  58 #if _LIBC
  59 # define struct_stat64 struct stat64
  60 #else
  61 # define struct_stat64 struct stat
  62 # define __libc_secure_getenv secure_getenv
  63 # define __xstat64(version, path, buf) stat (path, buf)
  64 #endif
  65
  66 /* Pathname support.
  67    ISSLASH(C)           tests whether C is a directory separator character.
  68  */
  69 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  70   /* Native Windows, Cygwin, OS/2, DOS */
  71 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  72 #else
  73   /* Unix */
  74 # define ISSLASH(C) ((C) == '/')
  75 #endif
  76
  77
  78 /* Return nonzero if DIR is an existent directory.  */
  79 static bool
  80 direxists (const char *dir)
  81 {
  82   struct_stat64 buf;
  83   return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
  84 }
  85
  86 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
  87    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
  88    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
  89    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
  90    doesn't exist, none of the searched dirs exists, or there's not
  91    enough space in TMPL. */
  92 int
  93 path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
  94              bool try_tmpdir)
  95 {
  96   const char *d;
  97   size_t dlen, plen;
  98   bool add_slash;
  99
 100   if (!pfx || !pfx[0])
 101     {
 102       pfx = "file";
 103       plen = 4;
 104     }
 105   else
 106     {
 107       plen = strlen (pfx);
 108       if (plen > 5)
 109         plen = 5;
 110     }
 111
 112   if (try_tmpdir)
 113     {
 114       d = __libc_secure_getenv ("TMPDIR");
 115       if (d != NULL && direxists (d))
 116         dir = d;
 117       else if (dir != NULL && direxists (dir))
 118         /* nothing */ ;
 119       else
 120         dir = NULL;
 121     }
 122   if (dir == NULL)
 123     {
 124 #if defined _WIN32 && ! defined __CYGWIN__
 125       char dirbuf[PATH_MAX];
 126       DWORD retval;
 127
 128       /* Find Windows temporary file directory.
 129          We try this before P_tmpdir because Windows defines P_tmpdir to "\\"
 130          and will therefore try to put all temporary files in the root
 131          directory (unless $TMPDIR is set).  */
 132       retval = GetTempPath (PATH_MAX, dirbuf);
 133       if (retval > 0 && retval < PATH_MAX && direxists (dirbuf))
 134         dir = dirbuf;
 135       else
 136 #endif
 137       if (direxists (P_tmpdir))
 138         dir = P_tmpdir;
 139       else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
 140         dir = "/tmp";
 141       else
 142         {
 143           __set_errno (ENOENT);
 144           return -1;
 145         }
 146     }
 147
 148   dlen = strlen (dir);
 149 #ifdef __VMS
 150   add_slash = 0;
 151 #else
 152   add_slash = dlen != 0 && !ISSLASH (dir[dlen - 1]);
 153 #endif
 154
 155   /* check we have room for "${dir}/${pfx}XXXXXX\0" */
 156   if (tmpl_len < dlen + add_slash + plen + 6 + 1)
 157     {
 158       __set_errno (EINVAL);
 159       return -1;
 160     }
 161
 162   memcpy (tmpl, dir, dlen);
 163   sprintf (tmpl + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx);
 164   return 0;
 165 }