1  /* Copyright (C) 1999, 2001-2002, 2006, 2009-2022 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 <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  }