libiberty/make-temp-file.c

   1 /* Utility to pick a temporary filename prefix.
   2    Copyright (C) 1996-2017 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 #if defined(_WIN32) && !defined(__CYGWIN__)
  40 #include <windows.h>
  41 #endif
  42
  43 #ifndef R_OK
  44 #define R_OK 4
  45 #define W_OK 2
  46 #define X_OK 1
  47 #endif
  48
  49 #include "libiberty.h"
  50 extern int mkstemps (char *, int);
  51
  52 /* '/' works just fine on MS-DOS based systems.  */
  53 #ifndef DIR_SEPARATOR
  54 #define DIR_SEPARATOR '/'
  55 #endif
  56
  57 /* Name of temporary file.
  58    mktemp requires 6 trailing X's.  */
  59 #define TEMP_FILE "ccXXXXXX"
  60 #define TEMP_FILE_LEN (sizeof(TEMP_FILE) - 1)
  61
  62 #if !defined(_WIN32) || defined(__CYGWIN__)
  63
  64 /* Subroutine of choose_tmpdir.
  65    If BASE is non-NULL, return it.
  66    Otherwise it checks if DIR is a usable directory.
  67    If success, DIR is returned.
  68    Otherwise NULL is returned.  */
  69
  70 static inline const char *try_dir (const char *, const char *);
  71
  72 static inline const char *
  73 try_dir (const char *dir, const char *base)
  74 {
  75   if (base != 0)
  76     return base;
  77   if (dir != 0
  78       && access (dir, R_OK | W_OK | X_OK) == 0)
  79     return dir;
  80   return 0;
  81 }
  82
  83 static const char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
  84 static const char usrtmp[] =
  85 { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  86 static const char vartmp[] =
  87 { DIR_SEPARATOR, 'v', 'a', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
  88
  89 #endif
  90
  91 static char *memoized_tmpdir;
  92
  93 /*
  94
  95 @deftypefn Replacement const char* choose_tmpdir ()
  96
  97 Returns a pointer to a directory path suitable for creating temporary
  98 files in.
  99
 100 @end deftypefn
 101
 102 */
 103
 104 const char *
 105 choose_tmpdir (void)
 106 {
 107   if (!memoized_tmpdir)
 108     {
 109 #if !defined(_WIN32) || defined(__CYGWIN__)
 110       const char *base = 0;
 111       char *tmpdir;
 112       unsigned int len;
 113
 114 #ifdef VMS
 115       /* Try VMS standard temp logical.  */
 116       base = try_dir ("/sys$scratch", base);
 117 #else
 118       base = try_dir (getenv ("TMPDIR"), base);
 119       base = try_dir (getenv ("TMP"), base);
 120       base = try_dir (getenv ("TEMP"), base);
 121 #endif
 122
 123 #ifdef P_tmpdir
 124       /* We really want a directory name here as if concatenated with say \dir
 125          we do not end up with a double \\ which defines an UNC path.  */
 126       if (strcmp (P_tmpdir, "\\") == 0)
 127         base = try_dir ("\\.", base);
 128       else
 129         base = try_dir (P_tmpdir, base);
 130 #endif
 131
 132       /* Try /var/tmp, /usr/tmp, then /tmp.  */
 133       base = try_dir (vartmp, base);
 134       base = try_dir (usrtmp, base);
 135       base = try_dir (tmp, base);
 136
 137       /* If all else fails, use the current directory!  */
 138       if (base == 0)
 139         base = ".";
 140       /* Append DIR_SEPARATOR to the directory we've chosen
 141          and return it.  */
 142       len = strlen (base);
 143       tmpdir = XNEWVEC (char, len + 2);
 144       strcpy (tmpdir, base);
 145       tmpdir[len] = DIR_SEPARATOR;
 146       tmpdir[len+1] = '\0';
 147       memoized_tmpdir = tmpdir;
 148 #else /* defined(_WIN32) && !defined(__CYGWIN__) */
 149       DWORD len;
 150
 151       /* Figure out how much space we need.  */
 152       len = GetTempPath(0, NULL);
 153       if (len)
 154         {
 155           memoized_tmpdir = XNEWVEC (char, len);
 156           if (!GetTempPath(len, memoized_tmpdir))
 157             {
 158               XDELETEVEC (memoized_tmpdir);
 159               memoized_tmpdir = NULL;
 160             }
 161         }
 162       if (!memoized_tmpdir)
 163         /* If all else fails, use the current directory.  */
 164         memoized_tmpdir = xstrdup (".\\");
 165 #endif /* defined(_WIN32) && !defined(__CYGWIN__) */
 166     }
 167
 168   return memoized_tmpdir;
 169 }
 170
 171 /*
 172
 173 @deftypefn Replacement char* make_temp_file (const char *@var{suffix})
 174
 175 Return a temporary file name (as a string) or @code{NULL} if unable to
 176 create one.  @var{suffix} is a suffix to append to the file name.  The
 177 string is @code{malloc}ed, and the temporary file has been created.
 178
 179 @end deftypefn
 180
 181 */
 182
 183 char *
 184 make_temp_file (const char *suffix)
 185 {
 186   const char *base = choose_tmpdir ();
 187   char *temp_filename;
 188   int base_len, suffix_len;
 189   int fd;
 190
 191   if (suffix == 0)
 192     suffix = "";
 193
 194   base_len = strlen (base);
 195   suffix_len = strlen (suffix);
 196
 197   temp_filename = XNEWVEC (char, base_len
 198                            + TEMP_FILE_LEN
 199                            + suffix_len + 1);
 200   strcpy (temp_filename, base);
 201   strcpy (temp_filename + base_len, TEMP_FILE);
 202   strcpy (temp_filename + base_len + TEMP_FILE_LEN, suffix);
 203
 204   fd = mkstemps (temp_filename, suffix_len);
 205   /* Mkstemps failed.  It may be EPERM, ENOSPC etc.  */
 206   if (fd == -1)
 207     {
 208       fprintf (stderr, "Cannot create temporary file in %s: %s\n",
 209                base, strerror (errno));
 210       abort ();
 211     }
 212   /* We abort on failed close out of sheer paranoia.  */
 213   if (close (fd))
 214     abort ();
 215   return temp_filename;
 216 }