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 #include <errno.h>
  27 #ifdef HAVE_UNISTD_H
  28 #include <unistd.h>
  29 #endif
  30 #ifdef HAVE_STDLIB_H
  31 #include <stdlib.h>
  32 #endif
  33 #ifdef HAVE_STRING_H
  34 #include <string.h>
  35 #endif
  36 #ifdef HAVE_SYS_FILE_H
  37 #include <sys/file.h>   /* May get R_OK, etc. on some systems.  */
  38 #endif
  39
  40 #ifndef R_OK
  41 #define R_OK 4
  42 #define W_OK 2
  43 #define X_OK 1
  44 #endif
  45
  46 #include "libiberty.h"
  47 extern int mkstemps (char *, int);
  48
  49 /* '/' works just fine on MS-DOS based systems.  */
  50 #ifndef DIR_SEPARATOR
  51 #define DIR_SEPARATOR '/'
  52 #endif
  53
  54 /* Name of temporary file.
  55    mktemp requires 6 trailing X's.  */
  56 #define TEMP_FILE "ccXXXXXX"
  57 #define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
  58
  59 /* Subroutine of choose_tmpdir.
  60    If BASE is non-NULL, return it.
  61    Otherwise it checks if DIR is a usable directory.
  62    If success, DIR is returned.
  63    Otherwise NULL is returned.  */
  64
  65 static inline const char *try_dir (const char *, const char *);
  66
  67 static inline const char *
  68 try_dir (const char *dir, const char *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 (void)
  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_dir (getenv ("TMPDIR"), base);
 108   base = try_dir (getenv ("TMP"), base);
 109   base = try_dir (getenv ("TEMP"), base);
 110
 111 #ifdef P_tmpdir
 112   base = try_dir (P_tmpdir, base);
 113 #endif
 114
 115   /* Try /var/tmp, /usr/tmp, then /tmp.  */
 116   base = try_dir (vartmp, base);
 117   base = try_dir (usrtmp, base);
 118   base = try_dir (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 = XNEWVEC (char, 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 (const char *suffix)
 150 {
 151   const char *base = choose_tmpdir ();
 152   char *temp_filename;
 153   int base_len, suffix_len;
 154   int fd;
 155
 156   if (suffix == 0)
 157     suffix = "";
 158
 159   base_len = strlen (base);
 160   suffix_len = strlen (suffix);
 161
 162   temp_filename = XNEWVEC (char, base_len
 163                            + TEMP_FILE_LEN
 164                            + suffix_len + 1);
 165   strcpy (temp_filename, base);
 166   strcpy (temp_filename + base_len, TEMP_FILE);
 167   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 168
 169   fd = mkstemps (temp_filename, suffix_len);
 170   /* Mkstemps failed.  It may be EPERM, ENOSPC etc.  */
 171   if (fd == -1)
 172     {
 173       fprintf (stderr, "Cannot create temporary file in %s: %s\n",
 174                base, strerror (errno));
 175       abort ();
 176     }
 177   /* We abort on failed close out of sheer paranoia.  */
 178   if (close (fd))
 179     abort ();
 180   return temp_filename;
 181 }