src/libs/libgroff/tmpfile.cpp

   1 // -*- C++ -*-
   2 /* Copyright (C) 1989, 1990, 1991, 1992, 2000, 2001, 2003
   3    Free Software Foundation, Inc.
   4      Written by James Clark (jjc@jclark.com)
   5
   6 This file is part of groff.
   7
   8 groff is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 2, or (at your option) any later
  11 version.
  12
  13 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License along
  19 with groff; see the file COPYING.  If not, write to the Free Software
  20 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
  21
  22 #include "lib.h"
  23
  24 #include <errno.h>
  25 #include <stdlib.h>
  26
  27 #include "posix.h"
  28 #include "errarg.h"
  29 #include "error.h"
  30 #include "nonposix.h"
  31
  32 // If this is set, create temporary files there
  33 #define GROFF_TMPDIR_ENVVAR "GROFF_TMPDIR"
  34 // otherwise if this is set, create temporary files there
  35 #define TMPDIR_ENVVAR "TMPDIR"
  36 // otherwise, on MS-DOS or MS-Windows ...
  37 #if defined(__MSDOS__) || defined(_WIN32)
  38 // if either of these is set, create temporary files there
  39 // (giving priority to WIN32_TMPDIR_ENVVAR)
  40 #define WIN32_TMPDIR_ENVVAR "TMP"
  41 #define MSDOS_TMPDIR_ENVVAR "TEMP"
  42 #endif
  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_SHORT ""
  52 #define TMPFILE_PREFIX_LONG "groff"
  53
  54 char *tmpfile_prefix;
  55 size_t tmpfile_prefix_len;
  56 int use_short_postfix = 0;
  57
  58 struct temp_init {
  59   temp_init();
  60   ~temp_init();
  61 } _temp_init;
  62
  63 temp_init::temp_init()
  64 {
  65   // First, choose a location for creating temporary files...
  66   const char *tem;
  67   // using the first match for any of the environment specs in listed order.
  68   if (
  69       (tem = getenv(GROFF_TMPDIR_ENVVAR)) == NULL
  70       && (tem = getenv(TMPDIR_ENVVAR)) == NULL
  71 #if defined(__MSDOS__) || defined(_WIN32)
  72       // If we didn't find a match for either of the above
  73       // (which are preferred, regardless of the host operating system),
  74       // and we are hosted on either MS-Windows or MS-DOS,
  75       // then try the Microsoft conventions.
  76       && (tem = getenv(WIN32_TMPDIR_ENVVAR)) == NULL
  77       && (tem = getenv(MSDOS_TMPDIR_ENVVAR)) == NULL
  78 #endif
  79      )
  80     // If we didn't find an environment spec fall back to this default.
  81     tem = DEFAULT_TMPDIR;
  82   size_t tem_len = strlen(tem);
  83   const char *tem_end = tem + tem_len - 1;
  84   int need_slash = strchr(DIR_SEPS, *tem_end) == NULL ? 1 : 0;
  85   char *tem2 = new char[tem_len + need_slash + 1];
  86   strcpy(tem2, tem);
  87   if (need_slash)
  88     strcat(tem2, "/");
  89   const char *tem3 = TMPFILE_PREFIX_LONG;
  90   if (file_name_max(tem2) <= 14) {
  91     tem3 = TMPFILE_PREFIX_SHORT;
  92     use_short_postfix = 1;
  93   }
  94   tmpfile_prefix_len = tem_len + need_slash + strlen(tem3);
  95   tmpfile_prefix = new char[tmpfile_prefix_len + 1];
  96   strcpy(tmpfile_prefix, tem2);
  97   strcat(tmpfile_prefix, tem3);
  98   a_delete tem2;
  99 }
 100
 101 temp_init::~temp_init()
 102 {
 103   a_delete tmpfile_prefix;
 104 }
 105
 106 /*
 107  *  Generate a temporary name template with a postfix
 108  *  immediately after the TMPFILE_PREFIX.
 109  *  It uses the groff preferences for a temporary directory.
 110  *  Note that no file name is either created or opened,
 111  *  only the *template* is returned.
 112  */
 113
 114 char *xtmptemplate(const char *postfix_long, const char *postfix_short)
 115 {
 116   const char *postfix = use_short_postfix ? postfix_short : postfix_long;
 117   int postlen = 0;
 118   if (postfix)
 119     postlen = strlen(postfix);
 120   char *templ = new char[tmpfile_prefix_len + postlen + 6 + 1];
 121   strcpy(templ, tmpfile_prefix);
 122   if (postlen > 0)
 123     strcat(templ, postfix);
 124   strcat(templ, "XXXXXX");
 125   return templ;
 126 }
 127
 128 // The trick with unlinking the temporary file while it is still in
 129 // use is not portable, it will fail on MS-DOS and most MS-Windows
 130 // filesystems.  So it cannot be used on non-Posix systems.
 131 // Instead, we maintain a list of files to be deleted on exit.
 132 // This should be portable to all platforms.
 133
 134 struct xtmpfile_list {
 135   char *fname;
 136   xtmpfile_list *next;
 137   xtmpfile_list(char *fn) : fname(fn), next(0) {}
 138 };
 139
 140 xtmpfile_list *xtmpfiles_to_delete = 0;
 141
 142 struct xtmpfile_list_init {
 143   ~xtmpfile_list_init();
 144 } _xtmpfile_list_init;
 145
 146 xtmpfile_list_init::~xtmpfile_list_init()
 147 {
 148   xtmpfile_list *x = xtmpfiles_to_delete;
 149   while (x != 0) {
 150     if (unlink(x->fname) < 0)
 151       error("cannot unlink `%1': %2", x->fname, strerror(errno));
 152     xtmpfile_list *tmp = x;
 153     x = x->next;
 154     a_delete tmp->fname;
 155     delete tmp;
 156   }
 157 }
 158
 159 static void add_tmp_file(const char *name)
 160 {
 161   char *s = new char[strlen(name)+1];
 162   strcpy(s, name);
 163   xtmpfile_list *x = new xtmpfile_list(s);
 164   x->next = xtmpfiles_to_delete;
 165   xtmpfiles_to_delete = x;
 166 }
 167
 168 // Open a temporary file and with fatal error on failure.
 169
 170 FILE *xtmpfile(char **namep,
 171                const char *postfix_long, const char *postfix_short,
 172                int do_unlink)
 173 {
 174   char *templ = xtmptemplate(postfix_long, postfix_short);
 175   errno = 0;
 176   int fd = mkstemp(templ);
 177   if (fd < 0)
 178     fatal("cannot create temporary file: %1", strerror(errno));
 179   errno = 0;
 180   FILE *fp = fdopen(fd, FOPEN_RWB); // many callers of xtmpfile use binary I/O
 181   if (!fp)
 182     fatal("fdopen: %1", strerror(errno));
 183   if (do_unlink)
 184     add_tmp_file(templ);
 185   if (namep)
 186     *namep = templ;
 187   else
 188     a_delete templ;
 189   return fp;
 190 }