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 /* '/' works just fine on MS-DOS based systems.  */
  49 #ifndef DIR_SEPARATOR
  50 #define DIR_SEPARATOR '/'
  51 #endif
  52
  53 /* Name of temporary file.
  54    mktemp requires 6 trailing X's.  */
  55 #define TEMP_FILE "ccXXXXXX"
  56 #define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
  57
  58 /* Subroutine of choose_tmpdir.
  59    If BASE is non-NULL, return it.
  60    Otherwise it checks if DIR is a usable directory.
  61    If success, DIR is returned.
  62    Otherwise NULL is returned.  */
  63
  64 static inline const char *try PARAMS ((const char *, const char *));
  65
  66 static inline const char *
  67 try (dir, base)
  68      const char *dir, *base;
  69 {
  70   if (base != 0)
  71     return base;
  72   if (dir != 0
  73       && access (dir, R_OK | W_OK | X_OK) == 0)
  74     return dir;
  75   return 0;
  76 }
  77
  78 static const char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
  79 static const char usrtmp[] =
  80 { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  81 static const char vartmp[] =
  82 { DIR_SEPARATOR, 'v', 'a', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  83
  84 static char *memoized_tmpdir;
  85
  86 /*
  87
  88 @deftypefn Replacement char* choose_tmpdir ()
  89
  90 Returns a pointer to a directory path suitable for creating temporary
  91 files in.
  92
  93 @end deftypefn
  94
  95 */
  96
  97 char *
  98 choose_tmpdir ()
  99 {
 100   const char *base = 0;
 101   char *tmpdir;
 102   unsigned int len;
 103
 104   if (memoized_tmpdir)
 105     return memoized_tmpdir;
 106
 107   base = try (getenv ("TMPDIR"), base);
 108   base = try (getenv ("TMP"), base);
 109   base = try (getenv ("TEMP"), base);
 110
 111 #ifdef P_tmpdir
 112   base = try (P_tmpdir, base);
 113 #endif
 114
 115   /* Try /var/tmp, /usr/tmp, then /tmp.  */
 116   base = try (vartmp, base);
 117   base = try (usrtmp, base);
 118   base = try (tmp, base);
 119
 120   /* If all else fails, use the current directory!  */
 121   if (base == 0)
 122     base = ".";
 123
 124   /* Append DIR_SEPARATOR to the directory we've chosen
 125      and return it.  */
 126   len = strlen (base);
 127   tmpdir = xmalloc (len + 2);
 128   strcpy (tmpdir, base);
 129   tmpdir[len] = DIR_SEPARATOR;
 130   tmpdir[len+1] = '\0';
 131
 132   memoized_tmpdir = tmpdir;
 133   return tmpdir;
 134 }
 135
 136 /*
 137
 138 @deftypefn Replacement char* make_temp_file (const char *@var{suffix})
 139
 140 Return a temporary file name (as a string) or @code{NULL} if unable to
 141 create one.  @var{suffix} is a suffix to append to the file name.  The
 142 string is @code{malloc}ed, and the temporary file has been created.
 143
 144 @end deftypefn
 145
 146 */
 147
 148 char *
 149 make_temp_file (suffix)
 150      const char *suffix;
 151 {
 152   const char *base = choose_tmpdir ();
 153   char *temp_filename;
 154   int base_len, suffix_len;
 155   int fd;
 156
 157   if (suffix == 0)
 158     suffix = "";
 159
 160   base_len = strlen (base);
 161   suffix_len = strlen (suffix);
 162
 163   temp_filename = xmalloc (base_len
 164                            + TEMP_FILE_LEN
 165                            + suffix_len + 1);
 166   strcpy (temp_filename, base);
 167   strcpy (temp_filename + base_len, TEMP_FILE);
 168   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 169
 170   fd = mkstemps (temp_filename, suffix_len);
 171   /* If mkstemps failed, then something bad is happening.  Maybe we should
 172      issue a message about a possible security attack in progress?  */
 173   if (fd == -1)
 174     abort ();
 175   /* Similarly if we can not close the file.  */
 176   if (close (fd))
 177     abort ();
 178   return temp_filename;
 179 }