stdio-common/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 2.1 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 #if defined _WIN32 && ! defined __CYGWIN__
  50 /* Don't assume that UNICODE is not defined.  */
  51 # undef GetTempPath
  52 # define GetTempPath GetTempPathA
  53 #endif
  54
  55 #if _LIBC
  56 # define struct_stat64 struct __stat64_t64
  57 #else
  58 # include "pathmax.h"
  59 # define struct_stat64 struct stat
  60 # define __libc_secure_getenv secure_getenv
  61 # define __stat64_time64(path, buf) stat (path, buf)
  62 #endif
  63
  64 /* Pathname support.
  65    ISSLASH(C)           tests whether C is a directory separator character.
  66  */
  67 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  68   /* Native Windows, Cygwin, OS/2, DOS */
  69 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  70 #else
  71   /* Unix */
  72 # define ISSLASH(C) ((C) == '/')
  73 #endif
  74
  75
  76 /* Return nonzero if DIR is an existent directory.  */
  77 static bool
  78 direxists (const char *dir)
  79 {
  80   struct_stat64 buf;
  81   return __stat64_time64 (dir, &buf) == 0 && S_ISDIR (buf.st_mode);
  82 }
  83
  84 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
  85    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
  86    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
  87    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
  88    doesn't exist, none of the searched dirs exists, or there's not
  89    enough space in TMPL. */
  90 int
  91 __path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
  92                bool try_tmpdir)
  93 {
  94   const char *d;
  95   size_t dlen, plen;
  96   bool add_slash;
  97
  98   if (!pfx || !pfx[0])
  99     {
 100       pfx = "file";
 101       plen = 4;
 102     }
 103   else
 104     {
 105       plen = strlen (pfx);
 106       if (plen > 5)
 107         plen = 5;
 108     }
 109
 110   if (try_tmpdir)
 111     {
 112       d = __libc_secure_getenv ("TMPDIR");
 113       if (d != NULL && direxists (d))
 114         dir = d;
 115       else if (dir != NULL && direxists (dir))
 116         /* nothing */ ;
 117       else
 118         dir = NULL;
 119     }
 120   if (dir == NULL)
 121     {
 122 #if defined _WIN32 && ! defined __CYGWIN__
 123       char dirbuf[PATH_MAX];
 124       DWORD retval;
 125
 126       /* Find Windows temporary file directory.
 127          We try this before P_tmpdir because Windows defines P_tmpdir to "\\"
 128          and will therefore try to put all temporary files in the root
 129          directory (unless $TMPDIR is set).  */
 130       retval = GetTempPath (PATH_MAX, dirbuf);
 131       if (retval > 0 && retval < PATH_MAX && direxists (dirbuf))
 132         dir = dirbuf;
 133       else
 134 #endif
 135       if (direxists (P_tmpdir))
 136         dir = P_tmpdir;
 137       else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
 138         dir = "/tmp";
 139       else
 140         {
 141           __set_errno (ENOENT);
 142           return -1;
 143         }
 144     }
 145
 146   dlen = strlen (dir);
 147 #ifdef __VMS
 148   add_slash = 0;
 149 #else
 150   add_slash = dlen != 0 && !ISSLASH (dir[dlen - 1]);
 151 #endif
 152
 153   /* check we have room for "${dir}/${pfx}XXXXXX\0" */
 154   if (tmpl_len < dlen + add_slash + plen + 6 + 1)
 155     {
 156       __set_errno (EINVAL);
 157       return -1;
 158     }
 159
 160   memcpy (tmpl, dir, dlen);
 161   sprintf (tmpl + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx);
 162   return 0;
 163 }