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., 51 Franklin Street - Fifth Floor,
  18 Boston, MA 02110-1301, 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 (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 (const char *, const char *);
  65
  66 static inline const char *
  67 try (const char *dir, const char *base)
  68 {
  69   if (base != 0)
  70     return base;
  71   if (dir != 0
  72       && access (dir, R_OK | W_OK | X_OK) == 0)
  73     return dir;
  74   return 0;
  75 }
  76
  77 static const char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
  78 static const char usrtmp[] =
  79 { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  80 static const char vartmp[] =
  81 { DIR_SEPARATOR, 'v', 'a', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  82
  83 static char *memoized_tmpdir;
  84
  85 /*
  86
  87 @deftypefn Replacement char* choose_tmpdir ()
  88
  89 Returns a pointer to a directory path suitable for creating temporary
  90 files in.
  91
  92 @end deftypefn
  93
  94 */
  95
  96 char *
  97 choose_tmpdir (void)
  98 {
  99   const char *base = 0;
 100   char *tmpdir;
 101   unsigned int len;
 102
 103   if (memoized_tmpdir)
 104     return memoized_tmpdir;
 105
 106   base = try (getenv ("TMPDIR"), base);
 107   base = try (getenv ("TMP"), base);
 108   base = try (getenv ("TEMP"), base);
 109
 110 #ifdef P_tmpdir
 111   base = try (P_tmpdir, base);
 112 #endif
 113
 114   /* Try /var/tmp, /usr/tmp, then /tmp.  */
 115   base = try (vartmp, base);
 116   base = try (usrtmp, base);
 117   base = try (tmp, base);
 118
 119   /* If all else fails, use the current directory!  */
 120   if (base == 0)
 121     base = ".";
 122
 123   /* Append DIR_SEPARATOR to the directory we've chosen
 124      and return it.  */
 125   len = strlen (base);
 126   tmpdir = xmalloc (len + 2);
 127   strcpy (tmpdir, base);
 128   tmpdir[len] = DIR_SEPARATOR;
 129   tmpdir[len+1] = '\0';
 130
 131   memoized_tmpdir = tmpdir;
 132   return tmpdir;
 133 }
 134
 135 /*
 136
 137 @deftypefn Replacement char* make_temp_file (const char *@var{suffix})
 138
 139 Return a temporary file name (as a string) or @code{NULL} if unable to
 140 create one.  @var{suffix} is a suffix to append to the file name.  The
 141 string is @code{malloc}ed, and the temporary file has been created.
 142
 143 @end deftypefn
 144
 145 */
 146
 147 char *
 148 make_temp_file (const char *suffix)
 149 {
 150   const char *base = choose_tmpdir ();
 151   char *temp_filename;
 152   int base_len, suffix_len;
 153   int fd;
 154
 155   if (suffix == 0)
 156     suffix = "";
 157
 158   base_len = strlen (base);
 159   suffix_len = strlen (suffix);
 160
 161   temp_filename = xmalloc (base_len
 162                            + TEMP_FILE_LEN
 163                            + suffix_len + 1);
 164   strcpy (temp_filename, base);
 165   strcpy (temp_filename + base_len, TEMP_FILE);
 166   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 167
 168   fd = mkstemps (temp_filename, suffix_len);
 169   /* If mkstemps failed, then something bad is happening.  Maybe we should
 170      issue a message about a possible security attack in progress?  */
 171   if (fd == -1)
 172     abort ();
 173   /* Similarly if we can not close the file.  */
 174   if (close (fd))
 175     abort ();
 176   return temp_filename;
 177 }