lib/tmpdir.c

   1 /* Copyright (C) 1999, 2001-2002, 2006, 2009-2019 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 _LIBC
  53 # define struct_stat64 struct stat64
  54 #else
  55 # define struct_stat64 struct stat
  56 # define __libc_secure_getenv secure_getenv
  57 # define __xstat64(version, path, buf) stat (path, buf)
  58 #endif
  59
  60 /* Pathname support.
  61    ISSLASH(C)           tests whether C is a directory separator character.
  62  */
  63 #if defined _WIN32 || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
  64   /* Native Windows, Cygwin, OS/2, DOS */
  65 # define ISSLASH(C) ((C) == '/' || (C) == '\\')
  66 #else
  67   /* Unix */
  68 # define ISSLASH(C) ((C) == '/')
  69 #endif
  70
  71
  72 /* Return nonzero if DIR is an existent directory.  */
  73 static bool
  74 direxists (const char *dir)
  75 {
  76   struct_stat64 buf;
  77   return __xstat64 (_STAT_VER, dir, &buf) == 0 && S_ISDIR (buf.st_mode);
  78 }
  79
  80 /* Path search algorithm, for tmpnam, tmpfile, etc.  If DIR is
  81    non-null and exists, uses it; otherwise uses the first of $TMPDIR,
  82    P_tmpdir, /tmp that exists.  Copies into TMPL a template suitable
  83    for use with mk[s]temp.  Will fail (-1) if DIR is non-null and
  84    doesn't exist, none of the searched dirs exists, or there's not
  85    enough space in TMPL. */
  86 int
  87 path_search (char *tmpl, size_t tmpl_len, const char *dir, const char *pfx,
  88              bool try_tmpdir)
  89 {
  90   const char *d;
  91   size_t dlen, plen;
  92   bool add_slash;
  93
  94   if (!pfx || !pfx[0])
  95     {
  96       pfx = "file";
  97       plen = 4;
  98     }
  99   else
 100     {
 101       plen = strlen (pfx);
 102       if (plen > 5)
 103         plen = 5;
 104     }
 105
 106   if (try_tmpdir)
 107     {
 108       d = __libc_secure_getenv ("TMPDIR");
 109       if (d != NULL && direxists (d))
 110         dir = d;
 111       else if (dir != NULL && direxists (dir))
 112         /* nothing */ ;
 113       else
 114         dir = NULL;
 115     }
 116   if (dir == NULL)
 117     {
 118 #if defined _WIN32 && ! defined __CYGWIN__
 119       char dirbuf[PATH_MAX];
 120       DWORD retval;
 121
 122       /* Find Windows temporary file directory.
 123          We try this before P_tmpdir because Windows defines P_tmpdir to "\\"
 124          and will therefore try to put all temporary files in the root
 125          directory (unless $TMPDIR is set).  */
 126       retval = GetTempPath (PATH_MAX, dirbuf);
 127       if (retval > 0 && retval < PATH_MAX && direxists (dirbuf))
 128         dir = dirbuf;
 129       else
 130 #endif
 131       if (direxists (P_tmpdir))
 132         dir = P_tmpdir;
 133       else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
 134         dir = "/tmp";
 135       else
 136         {
 137           __set_errno (ENOENT);
 138           return -1;
 139         }
 140     }
 141
 142   dlen = strlen (dir);
 143 #ifdef __VMS
 144   add_slash = 0;
 145 #else
 146   add_slash = dlen != 0 && !ISSLASH (dir[dlen - 1]);
 147 #endif
 148
 149   /* check we have room for "${dir}/${pfx}XXXXXX\0" */
 150   if (tmpl_len < dlen + add_slash + plen + 6 + 1)
 151     {
 152       __set_errno (EINVAL);
 153       return -1;
 154     }
 155
 156   memcpy (tmpl, dir, dlen);
 157   sprintf (tmpl + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx);
 158   return 0;
 159 }