libiberty/choose-temp.c

   1 /* Utility to pick a temporary filename prefix.
   2    Copyright (C) 1996, 1997, 1998 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 /* This file exports two functions: choose_temp_base and make_temp_file.  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include "config.h"
  24 #endif
  25
  26 #include <stdio.h>      /* May get P_tmpdir.  */
  27 #include <sys/types.h>
  28 #ifdef HAVE_UNISTD_H
  29 #include <unistd.h>
  30 #endif
  31 #ifdef HAVE_STDLIB_H
  32 #include <stdlib.h>
  33 #endif
  34 #ifdef HAVE_STRING_H
  35 #include <string.h>
  36 #endif
  37 #ifdef HAVE_SYS_FILE_H
  38 #include <sys/file.h>   /* May get R_OK, etc. on some systems.  */
  39 #endif
  40
  41 #ifndef R_OK
  42 #define R_OK 4
  43 #define W_OK 2
  44 #define X_OK 1
  45 #endif
  46
  47 #include "libiberty.h"
  48 extern int mkstemps ();
  49
  50 #ifndef IN_GCC
  51 #if defined (__MSDOS__) || (defined (_WIN32) && ! defined (__CYGWIN__) && ! defined (_UWIN))
  52 #define DIR_SEPARATOR '\\'
  53 #endif
  54 #endif
  55
  56 #ifndef DIR_SEPARATOR
  57 #define DIR_SEPARATOR '/'
  58 #endif
  59
  60 /* On MSDOS, write temp files in current dir
  61    because there's no place else we can expect to use.  */
  62 /* ??? Although the current directory is tried as a last resort,
  63    this is left in so that on MSDOS it is preferred to /tmp on the
  64    off chance that someone requires this, since that was the previous
  65    behaviour.  */
  66 #ifdef __MSDOS__
  67 #ifndef P_tmpdir
  68 #define P_tmpdir "."
  69 #endif
  70 #endif
  71
  72 /* Name of temporary file.
  73    mktemp requires 6 trailing X's.  */
  74 #define TEMP_FILE "ccXXXXXX"
  75
  76 /* Subroutine of choose_temp_base.
  77    If BASE is non-NULL, return it.
  78    Otherwise it checks if DIR is a usable directory.
  79    If success, DIR is returned.
  80    Otherwise NULL is returned.  */
  81
  82 static const char *try PARAMS ((const char *, const char *));
  83
  84 static const char *
  85 try (dir, base)
  86      const char *dir, *base;
  87 {
  88   if (base != 0)
  89     return base;
  90   if (dir != 0
  91       && access (dir, R_OK | W_OK | X_OK) == 0)
  92     return dir;
  93   return 0;
  94 }
  95
  96 /* Return a prefix for temporary file names or NULL if unable to find one.
  97    The current directory is chosen if all else fails so the program is
  98    exited if a temporary directory can't be found (mktemp fails).
  99    The buffer for the result is obtained with xmalloc.
 100
 101    This function is provided for backwards compatability only.  It use
 102    is not recommended.  */
 103
 104 char *
 105 choose_temp_base ()
 106 {
 107   const char *base = 0;
 108   char *temp_filename;
 109   int len;
 110   static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
 111   static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
 112
 113   base = try (getenv ("TMPDIR"), base);
 114   base = try (getenv ("TMP"), base);
 115   base = try (getenv ("TEMP"), base);
 116
 117 #ifdef P_tmpdir
 118   base = try (P_tmpdir, base);
 119 #endif
 120
 121   /* Try /usr/tmp, then /tmp.  */
 122   base = try (usrtmp, base);
 123   base = try (tmp, base);
 124
 125   /* If all else fails, use the current directory!  */
 126   if (base == 0)
 127     base = ".";
 128
 129   len = strlen (base);
 130   temp_filename = xmalloc (len + 1 /*DIR_SEPARATOR*/
 131                            + strlen (TEMP_FILE) + 1);
 132   strcpy (temp_filename, base);
 133
 134   if (len != 0
 135       && temp_filename[len-1] != '/'
 136       && temp_filename[len-1] != DIR_SEPARATOR)
 137     temp_filename[len++] = DIR_SEPARATOR;
 138   strcpy (temp_filename + len, TEMP_FILE);
 139
 140   mktemp (temp_filename);
 141   if (strlen (temp_filename) == 0)
 142     abort ();
 143   return temp_filename;
 144 }
 145 /* Return a temporary file name (as a string) or NULL if unable to create
 146    one.  */
 147
 148 char *
 149 make_temp_file (suffix)
 150      const char *suffix;
 151 {
 152   const char *base = 0;
 153   char *temp_filename;
 154   int base_len, suffix_len;
 155   int fd;
 156   static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
 157   static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
 158
 159   base = try (getenv ("TMPDIR"), base);
 160   base = try (getenv ("TMP"), base);
 161   base = try (getenv ("TEMP"), base);
 162
 163 #ifdef P_tmpdir
 164   base = try (P_tmpdir, base);
 165 #endif
 166
 167   /* Try /usr/tmp, then /tmp.  */
 168   base = try (usrtmp, base);
 169   base = try (tmp, base);
 170
 171   /* If all else fails, use the current directory!  */
 172   if (base == 0)
 173     base = ".";
 174
 175   base_len = strlen (base);
 176
 177   if (suffix)
 178     suffix_len = strlen (suffix);
 179   else
 180     suffix_len = 0;
 181
 182   temp_filename = xmalloc (base_len + 1 /*DIR_SEPARATOR*/
 183                            + strlen (TEMP_FILE)
 184                            + suffix_len + 1);
 185   strcpy (temp_filename, base);
 186
 187   if (base_len != 0
 188       && temp_filename[base_len-1] != '/'
 189       && temp_filename[base_len-1] != DIR_SEPARATOR)
 190     temp_filename[base_len++] = DIR_SEPARATOR;
 191   strcpy (temp_filename + base_len, TEMP_FILE);
 192
 193   if (suffix)
 194     strcat (temp_filename, suffix);
 195
 196   fd = mkstemps (temp_filename, suffix_len);
 197   /* If mkstemps failed, then something bad is happening.  Maybe we should
 198      issue a message about a possible security attack in progress?  */
 199   if (fd == -1)
 200     abort ();
 201   /* Similarly if we can not close the file.  */
 202   if (close (fd))
 203     abort ();
 204   return temp_filename;
 205 }