src/libs/libgroff/tmpfile.cc

   1 // -*- C++ -*-
   2 /* Copyright (C) 1989, 1990, 1991, 1992 Free Software Foundation, Inc.
   3      Written by James Clark (jjc@jclark.com)
   4
   5 This file is part of groff.
   6
   7 groff is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License along
  18 with groff; see the file COPYING.  If not, write to the Free Software
  19 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
  20
  21 #include <stdio.h>
  22 #include <errno.h>
  23 #include <string.h>
  24 #include <stdlib.h>
  25
  26 #include "posix.h"
  27 #include "lib.h"
  28 #include "errarg.h"
  29 #include "error.h"
  30 #include "nonposix.h"
  31
  32 extern "C" {
  33   // Solaris 2.5.1 has these functions,
  34   // but its stdlib.h fails to declare them.
  35   char *mktemp(char *);
  36   int mkstemp(char *);
  37 }
  38
  39 // If this is set, create temporary files there
  40 #define GROFF_TMPDIR_ENVVAR "GROFF_TMPDIR"
  41 // otherwise if this is set, create temporary files there
  42 #define TMPDIR_ENVVAR "TMPDIR"
  43 // otherwise if P_tmpdir is defined, create temporary files there
  44 #ifdef P_tmpdir
  45 # define DEFAULT_TMPDIR P_tmpdir
  46 #else
  47 // otherwise create temporary files here.
  48 # define DEFAULT_TMPDIR "/tmp"
  49 #endif
  50 // Use this as the prefix for temporary filenames.
  51 #define TMPFILE_PREFIX  "groff"
  52
  53 /*
  54  *  Generate a temporary name template with a postfix
  55  *  immediately after the TMPFILE_PREFIX.
  56  *  It uses the groff preferences for a temporary directory.
  57  *  Note that no file name is either created or opened,
  58  *  only the *template* is returned.
  59  */
  60
  61 char *xtmptemplate(char *postfix)
  62 {
  63   const char *dir = getenv(GROFF_TMPDIR_ENVVAR);
  64   int postlen = 0;
  65
  66   if (postfix)
  67     postlen = strlen(postfix);
  68
  69   if (!dir) {
  70     dir = getenv(TMPDIR_ENVVAR);
  71     if (!dir)
  72       dir = DEFAULT_TMPDIR;
  73   }
  74
  75   size_t dir_len = strlen(dir);
  76   const char *dir_end = dir + dir_len - 1;
  77   int needs_slash = strchr(DIR_SEPS, *dir_end) == NULL;
  78   char *templ = new char[strlen(dir) + needs_slash
  79                 + sizeof(TMPFILE_PREFIX) - 1 + 6 + 1 + postlen];
  80   strcpy(templ, dir);
  81   if (needs_slash)
  82     strcat(templ, "/");
  83   strcat(templ, TMPFILE_PREFIX);
  84   if (postlen > 0)
  85     strcat(templ, postfix);
  86   strcat(templ, "XXXXXX");
  87
  88   return( templ );
  89 }
  90
  91 // The trick with unlinking the temporary file while it is still in
  92 // use is not portable, it will fail on MS-DOS and most MS-Windows
  93 // filesystems.  So it cannot be used on non-Posix systems.
  94 // Instead, we maintain a list of files to be deleted on exit, and
  95 // register an atexit function that will remove them all in one go.
  96 // This should be portable to all platforms.
  97
  98 static struct xtmpfile_list {
  99   struct xtmpfile_list *next;
 100   char *fname;
 101 } *xtmpfiles_to_delete;
 102
 103 static void remove_tmp_files(void)
 104 {
 105   struct xtmpfile_list *p = xtmpfiles_to_delete;
 106
 107   while (p)
 108     {
 109       if (unlink(p->fname) < 0)
 110         error("cannot unlink `%1': %2", p->fname, strerror(errno));
 111       a_delete p->fname;
 112       struct xtmpfile_list *old = p;
 113       p = p->next;
 114       free(old);
 115     }
 116 }
 117
 118 static void add_tmp_file(const char *name)
 119 {
 120   if (xtmpfiles_to_delete == NULL)
 121     atexit(remove_tmp_files);
 122
 123   char *fname = new char[FILENAME_MAX];
 124   struct xtmpfile_list *p
 125     = (struct xtmpfile_list *)malloc(sizeof(struct xtmpfile_list));
 126   if (p == NULL)
 127     {
 128       error("cannot unlink `%1': %2", name, strerror(errno));
 129       return;
 130     }
 131   p->next = xtmpfiles_to_delete;
 132   p->fname = strcpy(fname, name);
 133   xtmpfiles_to_delete = p;
 134 }
 135
 136 // Open a temporary file and with fatal error on failure.
 137
 138 #ifndef _MSC_VER
 139
 140 FILE *xtmpfile(char **namep, char *postfix, int do_unlink)
 141 {
 142   char *templ = xtmptemplate(postfix);
 143
 144 #ifdef HAVE_MKSTEMP
 145   errno = 0;
 146   int fd = mkstemp(templ);
 147   if (fd < 0)
 148     fatal("cannot create temporary file: %1", strerror(errno));
 149   errno = 0;
 150   FILE *fp = fdopen(fd, FOPEN_RWB); // many callers of xtmpfile use binary I/O
 151   if (!fp)
 152     fatal("fdopen: %1", strerror(errno));
 153 #else /* not HAVE_MKSTEMP */
 154   if (!mktemp(templ) || !templ[0])
 155     fatal("cannot create file name for temporary file");
 156   errno = 0;
 157   FILE *fp = fopen(templ, FOPEN_RWB);
 158   if (!fp)
 159     fatal("cannot open `%1': %2", templ, strerror(errno));
 160 #endif /* not HAVE_MKSTEMP */
 161   if (do_unlink)
 162     add_tmp_file(templ);
 163   if ((namep != 0) && ((*namep) != 0)) {
 164     *namep = templ;
 165   } else {
 166     a_delete templ;
 167   }
 168   return fp;
 169 }
 170
 171 #else
 172
 173 // FIXME: does MSVC have mktemp or mkstemp?  If so, it should now
 174 //        use the version above, as it no longer removes an open file.
 175 //        The version below will NOT work with grohtml, since grohtml
 176 //        wants to know the name of the file opened by xtmpfile!!
 177
 178 // If you're not running Unix, the following will do:
 179 FILE *xtmpfile(char **namep, char *postfix, int do_unlink)
 180 {
 181   FILE *fp = tmpfile();
 182   if (!fp)
 183     fatal("couldn't create temporary file");
 184   return fp;
 185 }
 186
 187 #endif /* _MSC_VER */