1  /* Copyright (C) 1999, 2001-2002, 2006, 2009-2023 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  }