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 /* This file lives in at least two places: libiberty and gcc.
  23    Don't change one without the other.  */
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include "config.h"
  27 #endif
  28
  29 #include <stdio.h>      /* May get P_tmpdir.  */
  30 #include <sys/types.h>
  31 #ifdef HAVE_UNISTD_H
  32 #include <unistd.h>
  33 #endif
  34 #ifdef HAVE_STDLIB_H
  35 #include <stdlib.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)
  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 char *
  83 try (dir, base)
  84      char *dir, *base;
  85 {
  86   if (base != 0)
  87     return base;
  88   if (dir != 0
  89       && access (dir, R_OK | W_OK | X_OK) == 0)
  90     return dir;
  91   return 0;
  92 }
  93
  94 /* Return a prefix for temporary file names or NULL if unable to find one.
  95    The current directory is chosen if all else fails so the program is
  96    exited if a temporary directory can't be found (mktemp fails).
  97    The buffer for the result is obtained with xmalloc.
  98
  99    This function is provided for backwards compatability only.  It use
 100    is not recommended.  */
 101
 102 char *
 103 choose_temp_base ()
 104 {
 105   char *base = 0;
 106   char *temp_filename;
 107   int len;
 108   static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
 109   static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
 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   len = strlen (base);
 128   temp_filename = xmalloc (len + 1 /*DIR_SEPARATOR*/
 129                            + strlen (TEMP_FILE) + 1);
 130   strcpy (temp_filename, base);
 131
 132   if (len != 0
 133       && temp_filename[len-1] != '/'
 134       && temp_filename[len-1] != DIR_SEPARATOR)
 135     temp_filename[len++] = DIR_SEPARATOR;
 136   strcpy (temp_filename + len, TEMP_FILE);
 137
 138   mktemp (temp_filename);
 139   if (strlen (temp_filename) == 0)
 140     abort ();
 141   return temp_filename;
 142 }
 143 /* Return a temporary file name (as a string) or NULL if unable to create
 144    one.  */
 145
 146 char *
 147 make_temp_file (suffix)
 148      char *suffix;
 149 {
 150   char *base = 0;
 151   char *temp_filename;
 152   int base_len, suffix_len;
 153   int fd;
 154   static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
 155   static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
 156
 157   base = try (getenv ("TMPDIR"), base);
 158   base = try (getenv ("TMP"), base);
 159   base = try (getenv ("TEMP"), base);
 160
 161 #ifdef P_tmpdir
 162   base = try (P_tmpdir, base);
 163 #endif
 164
 165   /* Try /usr/tmp, then /tmp.  */
 166   base = try (usrtmp, base);
 167   base = try (tmp, base);
 168
 169   /* If all else fails, use the current directory!  */
 170   if (base == 0)
 171     base = ".";
 172
 173   base_len = strlen (base);
 174
 175   if (suffix)
 176     suffix_len = strlen (suffix);
 177   else
 178     suffix_len = 0;
 179
 180   temp_filename = xmalloc (base_len + 1 /*DIR_SEPARATOR*/
 181                            + strlen (TEMP_FILE)
 182                            + suffix_len + 1);
 183   strcpy (temp_filename, base);
 184
 185   if (base_len != 0
 186       && temp_filename[base_len-1] != '/'
 187       && temp_filename[base_len-1] != DIR_SEPARATOR)
 188     temp_filename[base_len++] = DIR_SEPARATOR;
 189   strcpy (temp_filename + base_len, TEMP_FILE);
 190
 191   if (suffix)
 192     strcat (temp_filename, suffix);
 193
 194   fd = mkstemps (temp_filename, suffix_len);
 195   /* If mkstemps failed, then something bad is happening.  Maybe we should
 196      issue a message about a possible security attack in progress?  */
 197   if (fd == -1)
 198     abort ();
 199   /* Similarly if we can not close the file.  */
 200   if (close (fd))
 201     abort ();
 202   return temp_filename;
 203 }