libiberty/make-temp-file.c

   1 /* Utility to pick a temporary filename prefix.
   2    Copyright (C) 1996, 1997, 1998, 2001 Free Software Foundation, Inc.
   3
   4 This file is part of the libiberty library.
   5 Libiberty is free software; you can redistribute it and/or
   6 modify it under the terms of the GNU Library General Public
   7 License as published by the Free Software Foundation; either
   8 version 2 of the License, or (at your option) any later version.
   9
  10 Libiberty 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 GNU
  13 Library General Public License for more details.
  14
  15 You should have received a copy of the GNU Library General Public
  16 License along with libiberty; see the file COPYING.LIB.  If not,
  17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18 Boston, MA 02111-1307, USA.  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #include "config.h"
  22 #endif
  23
  24 #include <stdio.h>      /* May get P_tmpdir.  */
  25 #include <sys/types.h>
  26 #ifdef HAVE_UNISTD_H
  27 #include <unistd.h>
  28 #endif
  29 #ifdef HAVE_STDLIB_H
  30 #include <stdlib.h>
  31 #endif
  32 #ifdef HAVE_STRING_H
  33 #include <string.h>
  34 #endif
  35 #ifdef HAVE_SYS_FILE_H
  36 #include <sys/file.h>   /* May get R_OK, etc. on some systems.  */
  37 #endif
  38
  39 #ifndef R_OK
  40 #define R_OK 4
  41 #define W_OK 2
  42 #define X_OK 1
  43 #endif
  44
  45 #include "libiberty.h"
  46 extern int mkstemps PARAMS ((char *, int));
  47
  48 #ifndef IN_GCC
  49 #if defined (__MSDOS__) || (defined (_WIN32) && ! defined (__CYGWIN__) && ! defined (_UWIN))
  50 #define DIR_SEPARATOR '\\'
  51 #endif
  52 #endif
  53
  54 #ifndef DIR_SEPARATOR
  55 #define DIR_SEPARATOR '/'
  56 #endif
  57
  58 /* On MSDOS, write temp files in current dir
  59    because there's no place else we can expect to use.  */
  60 /* ??? Although the current directory is tried as a last resort,
  61    this is left in so that on MSDOS it is preferred to /tmp on the
  62    off chance that someone requires this, since that was the previous
  63    behaviour.  */
  64 #ifdef __MSDOS__
  65 #ifndef P_tmpdir
  66 #define P_tmpdir "."
  67 #endif
  68 #endif
  69
  70 /* Name of temporary file.
  71    mktemp requires 6 trailing X's.  */
  72 #define TEMP_FILE "ccXXXXXX"
  73 #define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
  74
  75 /* Subroutine of choose_tmpdir.
  76    If BASE is non-NULL, return it.
  77    Otherwise it checks if DIR is a usable directory.
  78    If success, DIR is returned.
  79    Otherwise NULL is returned.  */
  80
  81 static const char *try PARAMS ((const char *, const char *));
  82
  83 static const char *
  84 try (dir, base)
  85      const char *dir, *base;
  86 {
  87   if (base != 0)
  88     return base;
  89   if (dir != 0
  90       && access (dir, R_OK | W_OK | X_OK) == 0)
  91     return dir;
  92   return 0;
  93 }
  94
  95 static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
  96 static char usrtmp[] =
  97 { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  98
  99 static char *memoized_tmpdir;
 100
 101 char *
 102 choose_tmpdir ()
 103 {
 104   const char *base = 0;
 105   char *tmpdir;
 106   unsigned int len;
 107
 108   if (memoized_tmpdir)
 109     return memoized_tmpdir;
 110
 111   base = try (getenv ("TMPDIR"), base);
 112   base = try (getenv ("TMP"), base);
 113   base = try (getenv ("TEMP"), base);
 114
 115 #ifdef P_tmpdir
 116   base = try (P_tmpdir, base);
 117 #endif
 118
 119   /* Try /usr/tmp, then /tmp.  */
 120   base = try (usrtmp, base);
 121   base = try (tmp, base);
 122
 123   /* If all else fails, use the current directory!  */
 124   if (base == 0)
 125     base = ".";
 126
 127   /* Append DIR_SEPARATOR to the directory we've chosen
 128      and return it.  */
 129   len = strlen (base);
 130   tmpdir = xmalloc (len + 2);
 131   strcpy (tmpdir, base);
 132   tmpdir[len] = DIR_SEPARATOR;
 133   tmpdir[len+1] = '\0';
 134
 135   memoized_tmpdir = tmpdir;
 136   return tmpdir;
 137 }
 138
 139 /* Return a temporary file name (as a string) or NULL if unable to create
 140    one.  SUFFIX is a suffix to append to the file name.  The string is
 141    malloced, and the temporary file has been created.  */
 142
 143 char *
 144 make_temp_file (suffix)
 145      const char *suffix;
 146 {
 147   const char *base = choose_tmpdir ();
 148   char *temp_filename;
 149   int base_len, suffix_len;
 150   int fd;
 151
 152   if (suffix == 0)
 153     suffix = "";
 154
 155   base_len = strlen (base);
 156   suffix_len = strlen (suffix);
 157
 158   temp_filename = xmalloc (base_len
 159                            + TEMP_FILE_LEN
 160                            + suffix_len + 1);
 161   strcpy (temp_filename, base);
 162   strcpy (temp_filename + base_len, TEMP_FILE);
 163   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 164
 165   fd = mkstemps (temp_filename, suffix_len);
 166   /* If mkstemps failed, then something bad is happening.  Maybe we should
 167      issue a message about a possible security attack in progress?  */
 168   if (fd == -1)
 169     abort ();
 170   /* Similarly if we can not close the file.  */
 171   if (close (fd))
 172     abort ();
 173   return temp_filename;
 174 }