libiberty/make-temp-file.c

   1 /* Utility to pick a temporary filename prefix.
   2    Copyright (C) 1996, 1997, 1998, 2001, 2009, 2010
   3    Free Software Foundation, Inc.
   4
   5 This file is part of the libiberty library.
   6 Libiberty is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public
   8 License as published by the Free Software Foundation; either
   9 version 2 of the License, or (at your option) any later version.
  10
  11 Libiberty is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with libiberty; see the file COPYING.LIB.  If not,
  18 write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  19 Boston, MA 02110-1301, USA.  */
  20
  21 #ifdef HAVE_CONFIG_H
  22 #include "config.h"
  23 #endif
  24
  25 #include <stdio.h>      /* May get P_tmpdir.  */
  26 #include <sys/types.h>
  27 #include <errno.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 #if defined(_WIN32) && !defined(__CYGWIN__)
  41 #include <windows.h>
  42 #endif
  43
  44 #ifndef R_OK
  45 #define R_OK 4
  46 #define W_OK 2
  47 #define X_OK 1
  48 #endif
  49
  50 #include "libiberty.h"
  51 extern int mkstemps (char *, int);
  52
  53 /* '/' works just fine on MS-DOS based systems.  */
  54 #ifndef DIR_SEPARATOR
  55 #define DIR_SEPARATOR '/'
  56 #endif
  57
  58 /* Name of temporary file.
  59    mktemp requires 6 trailing X's.  */
  60 #define TEMP_FILE "ccXXXXXX"
  61 #define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
  62
  63 #if !defined(_WIN32) || defined(__CYGWIN__)
  64
  65 /* Subroutine of choose_tmpdir.
  66    If BASE is non-NULL, return it.
  67    Otherwise it checks if DIR is a usable directory.
  68    If success, DIR is returned.
  69    Otherwise NULL is returned.  */
  70
  71 static inline const char *try_dir (const char *, const char *);
  72
  73 static inline const char *
  74 try_dir (const char *dir, const char *base)
  75 {
  76   if (base != 0)
  77     return base;
  78   if (dir != 0
  79       && access (dir, R_OK | W_OK | X_OK) == 0)
  80     return dir;
  81   return 0;
  82 }
  83
  84 static const char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
  85 static const char usrtmp[] =
  86 { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  87 static const char vartmp[] =
  88 { DIR_SEPARATOR, 'v', 'a', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  89
  90 #endif
  91
  92 static char *memoized_tmpdir;
  93
  94 /*
  95
  96 @deftypefn Replacement const char* choose_tmpdir ()
  97
  98 Returns a pointer to a directory path suitable for creating temporary
  99 files in.
 100
 101 @end deftypefn
 102
 103 */
 104
 105 const char *
 106 choose_tmpdir (void)
 107 {
 108   if (!memoized_tmpdir)
 109     {
 110 #if !defined(_WIN32) || defined(__CYGWIN__)
 111       const char *base = 0;
 112       char *tmpdir;
 113       unsigned int len;
 114
 115 #ifdef VMS
 116       /* Try VMS standard temp logical.  */
 117       base = try_dir ("/sys$scratch", base);
 118 #else
 119       base = try_dir (getenv ("TMPDIR"), base);
 120       base = try_dir (getenv ("TMP"), base);
 121       base = try_dir (getenv ("TEMP"), base);
 122 #endif
 123
 124 #ifdef P_tmpdir
 125       /* We really want a directory name here as if concatenated with say \dir
 126          we do not end up with a double \\ which defines an UNC path.  */
 127       if (strcmp (P_tmpdir, "\\") == 0)
 128         base = try_dir ("\\.", base);
 129       else
 130         base = try_dir (P_tmpdir, base);
 131 #endif
 132
 133       /* Try /var/tmp, /usr/tmp, then /tmp.  */
 134       base = try_dir (vartmp, base);
 135       base = try_dir (usrtmp, base);
 136       base = try_dir (tmp, base);
 137
 138       /* If all else fails, use the current directory!  */
 139       if (base == 0)
 140         base = ".";
 141       /* Append DIR_SEPARATOR to the directory we've chosen
 142          and return it.  */
 143       len = strlen (base);
 144       tmpdir = XNEWVEC (char, len + 2);
 145       strcpy (tmpdir, base);
 146       tmpdir[len] = DIR_SEPARATOR;
 147       tmpdir[len+1] = '\0';
 148       memoized_tmpdir = tmpdir;
 149 #else /* defined(_WIN32) && !defined(__CYGWIN__) */
 150       DWORD len;
 151
 152       /* Figure out how much space we need.  */
 153       len = GetTempPath(0, NULL);
 154       if (len)
 155         {
 156           memoized_tmpdir = XNEWVEC (char, len);
 157           if (!GetTempPath(len, memoized_tmpdir))
 158             {
 159               XDELETEVEC (memoized_tmpdir);
 160               memoized_tmpdir = NULL;
 161             }
 162         }
 163       if (!memoized_tmpdir)
 164         /* If all else fails, use the current directory.  */
 165         memoized_tmpdir = xstrdup (".\\");
 166 #endif /* defined(_WIN32) && !defined(__CYGWIN__) */
 167     }
 168
 169   return memoized_tmpdir;
 170 }
 171
 172 /*
 173
 174 @deftypefn Replacement char* make_temp_file (const char *@var{suffix})
 175
 176 Return a temporary file name (as a string) or @code{NULL} if unable to
 177 create one.  @var{suffix} is a suffix to append to the file name.  The
 178 string is @code{malloc}ed, and the temporary file has been created.
 179
 180 @end deftypefn
 181
 182 */
 183
 184 char *
 185 make_temp_file (const char *suffix)
 186 {
 187   const char *base = choose_tmpdir ();
 188   char *temp_filename;
 189   int base_len, suffix_len;
 190   int fd;
 191
 192   if (suffix == 0)
 193     suffix = "";
 194
 195   base_len = strlen (base);
 196   suffix_len = strlen (suffix);
 197
 198   temp_filename = XNEWVEC (char, base_len
 199                            + TEMP_FILE_LEN
 200                            + suffix_len + 1);
 201   strcpy (temp_filename, base);
 202   strcpy (temp_filename + base_len, TEMP_FILE);
 203   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 204
 205   fd = mkstemps (temp_filename, suffix_len);
 206   /* Mkstemps failed.  It may be EPERM, ENOSPC etc.  */
 207   if (fd == -1)
 208     {
 209       fprintf (stderr, "Cannot create temporary file in %s: %s\n",
 210                base, strerror (errno));
 211       abort ();
 212     }
 213   /* We abort on failed close out of sheer paranoia.  */
 214   if (close (fd))
 215     abort ();
 216   return temp_filename;
 217 }