lib/tmpdir.c

   1 /* Copyright (C) 1999, 2001-2002, 2006, 2009-2024 Free Software Foundation,
   2    Inc.
   3    This file is part of the GNU C Library.
   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 3 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 /* Extracted from sysdeps/posix/tempname.c.  */
  19
  20 #include <config.h>
  21
  22 /* Specification.  */
  23 #include "tmpdir.h"
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 #include <errno.h>
  29 #ifndef __set_errno
  30 # define __set_errno(Val) errno = (Val)
  31 #endif
  32
  33 #include <stdio.h>
  34 #ifndef P_tmpdir
  35 # ifdef _P_tmpdir /* native Windows */
  36 #  define P_tmpdir _P_tmpdir
  37 # else
  38 #  define P_tmpdir "/tmp"
  39 # endif
  40 #endif
  41
  42 #include <sys/stat.h>
  43
  44 #if defined _WIN32 && ! defined __CYGWIN__
  45 # define WIN32_LEAN_AND_MEAN  /* avoid including junk */
  46 # include <windows.h>
  47 #endif
  48
  49 #include "pathmax.h"
  50
  51 #if defined _WIN32 && ! defined __CYGWIN__
  52 /* Don't assume that UNICODE is not defined.  */
  53 # undef GetTempPath
  54 # define GetTempPath GetTempPathA
  55 #endif
  56
  57 #if _LIBC
  58 # define struct_stat64 struct stat64
  59 #else
  60 # define struct_stat64 struct stat
  61 # define __libc_secure_getenv secure_getenv
  62 # define __xstat64(version, path, buf) stat (path, buf)
  63 #endif
  64
  65 /* Pathname support.
  66    ISSLASH(C)           tests whether C is a directory separator character.
  67  */
  68 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  69   /* Native Windows, Cygwin, OS/2, DOS */
  70 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  71 #else
  72   /* Unix */
  73 # define ISSLASH(C) ((C) == '/')
  74 #endif
  75
  76
  77 /* Return nonzero if DIR is an existent directory.  */
  78 static bool
  79 direxists (const char *dir)
  80 {
  81   struct_stat64 buf;
  82   return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
  83 }
  84
  85 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
  86    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
  87    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
  88    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
  89    doesn't exist, none of the searched dirs exists, or there's not
  90    enough space in TMPL. */
  91 int
  92 path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
  93              bool try_tmpdir)
  94 {
  95   const char *d;
  96   size_t dlen, plen;
  97   bool add_slash;
  98
  99   if (!pfx || !pfx[0])
 100     {
 101       pfx = "file";
 102       plen = 4;
 103     }
 104   else
 105     {
 106       plen = strlen (pfx);
 107       if (plen > 5)
 108         plen = 5;
 109     }
 110
 111   if (try_tmpdir)
 112     {
 113       d = __libc_secure_getenv ("TMPDIR");
 114       if (d != NULL && direxists (d))
 115         dir = d;
 116       else if (dir != NULL && direxists (dir))
 117         /* nothing */ ;
 118       else
 119         dir = NULL;
 120     }
 121   if (dir == NULL)
 122     {
 123 #if defined _WIN32 && ! defined __CYGWIN__
 124       char dirbuf[PATH_MAX];
 125       DWORD retval;
 126
 127       /* Find Windows temporary file directory.
 128          We try this before P_tmpdir because Windows defines P_tmpdir to "\\"
 129          and will therefore try to put all temporary files in the root
 130          directory (unless $TMPDIR is set).  */
 131       retval = GetTempPath (PATH_MAX, dirbuf);
 132       if (retval > 0 && retval < PATH_MAX && direxists (dirbuf))
 133         dir = dirbuf;
 134       else
 135 #endif
 136       if (direxists (P_tmpdir))
 137         dir = P_tmpdir;
 138       else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
 139         dir = "/tmp";
 140       else
 141         {
 142           __set_errno (ENOENT);
 143           return -1;
 144         }
 145     }
 146
 147   dlen = strlen (dir);
 148 #ifdef __VMS
 149   add_slash = 0;
 150 #else
 151   add_slash = dlen != 0 && !ISSLASH (dir[dlen - 1]);
 152 #endif
 153
 154   /* check we have room for "${dir}/${pfx}XXXXXX\0" */
 155   if (tmpl_len < dlen + add_slash + plen + 6 + 1)
 156     {
 157       __set_errno (EINVAL);
 158       return -1;
 159     }
 160
 161   memcpy (tmpl, dir, dlen);
 162   sprintf (tmpl + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx);
 163   return 0;
 164 }