libiberty/choose-temp.c

   1 /* Utility to pick a temporary filename prefix.
   2    Copyright (C) 1996, 1997, 1998 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 /* This file exports one function: choose_temp_base.  */
  21
  22 /* This file lives in at least two places: libiberty and gcc.
  23    Don't change one without the other.  */
  24
  25 #if defined (IN_GCC) || defined (HAVE_CONFIG_H)
  26 #include "config.h"
  27 #endif
  28
  29 #ifdef IN_GCC
  30 #include "system.h"
  31 #else
  32
  33 /* If we are in gcc, system.h has handled everything.  When not in
  34    gcc, if we have a config.h we assume that HAVE_SYS_FILE_H tells us
  35    whether to include sys/file.h.  However, libiberty does not have a
  36    config.h, and instead arranges to define NO_SYS_FILE_H on the
  37    command line when there is no sys/file.h.  */
  38
  39 #if defined (HAVE_CONFIG_H) ? defined (HAVE_SYS_FILE_H) : ! defined (NO_SYS_FILE_H)
  40 #include <sys/types.h>
  41 #include <sys/file.h>   /* May get R_OK, etc. on some systems.  */
  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 <stdio.h>      /* May get P_tmpdir.  */
  51 #endif /* IN_GCC */
  52
  53 #ifdef IN_GCC
  54 #include "gansidecl.h"
  55 extern char *xmalloc ();
  56 #else
  57 #include "ansidecl.h"
  58 #include "libiberty.h"
  59 #if defined (__MSDOS__) || defined (_WIN32)
  60 #define DIR_SEPARATOR '\\'
  61 #endif
  62 #endif
  63
  64 #ifndef DIR_SEPARATOR
  65 #define DIR_SEPARATOR '/'
  66 #endif
  67
  68 /* On MSDOS, write temp files in current dir
  69    because there's no place else we can expect to use.  */
  70 /* ??? Although the current directory is tried as a last resort,
  71    this is left in so that on MSDOS it is preferred to /tmp on the
  72    off chance that someone requires this, since that was the previous
  73    behaviour.  */
  74 #ifdef __MSDOS__
  75 #ifndef P_tmpdir
  76 #define P_tmpdir "."
  77 #endif
  78 #endif
  79
  80 /* Name of temporary file.
  81    mktemp requires 6 trailing X's.  */
  82 #define TEMP_FILE "ccXXXXXX"
  83
  84 /* Subroutine of choose_temp_base.
  85    If BASE is non-NULL, return it.
  86    Otherwise it checks if DIR is a usable directory.
  87    If success, DIR is returned.
  88    Otherwise NULL is returned.  */
  89
  90 static char *
  91 try (dir, base)
  92      char *dir, *base;
  93 {
  94   if (base != 0)
  95     return base;
  96   if (dir != 0
  97       && access (dir, R_OK | W_OK | X_OK) == 0)
  98     return dir;
  99   return 0;
 100 }
 101
 102 /* Return a prefix for temporary file names or NULL if unable to find one.
 103    The current directory is chosen if all else fails so the program is
 104    exited if a temporary directory can't be found (mktemp fails).
 105    The buffer for the result is obtained with xmalloc.  */
 106
 107 char *
 108 choose_temp_base ()
 109 {
 110   char *base = 0;
 111   char *temp_filename;
 112   int len;
 113   static char tmp[] = { DIR_SEPARATOR, 't', 'm', 'p', 0 };
 114   static char usrtmp[] = { DIR_SEPARATOR, 'u', 's', 'r', DIR_SEPARATOR, 't', 'm', 'p', 0 };
 115
 116 #ifndef MPW
 117   base = try (getenv ("TMPDIR"), base);
 118   base = try (getenv ("TMP"), base);
 119   base = try (getenv ("TEMP"), base);
 120
 121 #ifdef P_tmpdir
 122   base = try (P_tmpdir, base);
 123 #endif
 124
 125   /* Try /usr/tmp, then /tmp.  */
 126   base = try (usrtmp, base);
 127   base = try (tmp, base);
 128
 129   /* If all else fails, use the current directory!  */
 130   if (base == 0)
 131     base = ".";
 132
 133 #else /* MPW */
 134   base = ":";
 135 #endif
 136
 137   len = strlen (base);
 138   temp_filename = xmalloc (len + 1 /*DIR_SEPARATOR*/
 139                            + strlen (TEMP_FILE) + 1);
 140   strcpy (temp_filename, base);
 141
 142 #ifndef MPW
 143   if (len != 0
 144       && temp_filename[len-1] != '/'
 145       && temp_filename[len-1] != DIR_SEPARATOR)
 146     temp_filename[len++] = DIR_SEPARATOR;
 147 #else /* MPW */
 148   if (temp_filename[len-1] != ':')
 149     temp_filename[len++] = ':';
 150 #endif /* MPW */
 151   strcpy (temp_filename + len, TEMP_FILE);
 152
 153   mktemp (temp_filename);
 154   if (strlen (temp_filename) == 0)
 155     abort ();
 156   return temp_filename;
 157 }