src/path.c

   1 /* GNU m4 -- A simple macro processor
   2
   3    Copyright (C) 1989, 1990, 1991, 1992, 1993, 2004, 2006 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program 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
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19    02110-1301  USA
  20 */
  21
  22 /* Handling of path search of included files via the builtins "include"
  23    and "sinclude".  */
  24
  25 #include "m4.h"
  26
  27 struct includes
  28 {
  29   struct includes *next;        /* next directory to search */
  30   const char *dir;              /* directory */
  31   int len;
  32 };
  33
  34 typedef struct includes includes;
  35
  36 static includes *dir_list;              /* the list of path directories */
  37 static includes *dir_list_end;          /* the end of same */
  38 static int dir_max_length;              /* length of longest directory name */
  39
  40 \f
  41 void
  42 include_init (void)
  43 {
  44   dir_list = NULL;
  45   dir_list_end = NULL;
  46   dir_max_length = 0;
  47 }
  48
  49 void
  50 include_env_init (void)
  51 {
  52   char *path;
  53   char *path_end;
  54
  55   if (no_gnu_extensions)
  56     return;
  57
  58   path = getenv ("M4PATH");
  59   if (path == NULL)
  60     return;
  61
  62   do
  63     {
  64       path_end = strchr (path, ':');
  65       if (path_end)
  66         *path_end = '\0';
  67       add_include_directory (path);
  68       path = path_end + 1;
  69     }
  70   while (path_end);
  71 }
  72
  73 void
  74 add_include_directory (const char *dir)
  75 {
  76   includes *incl;
  77
  78   if (no_gnu_extensions)
  79     return;
  80
  81   if (*dir == '\0')
  82     dir = ".";
  83
  84   incl = (includes *) xmalloc (sizeof (struct includes));
  85   incl->next = NULL;
  86   incl->len = strlen (dir);
  87   incl->dir = xstrdup (dir);
  88
  89   if (incl->len > dir_max_length) /* remember len of longest directory */
  90     dir_max_length = incl->len;
  91
  92   if (dir_list_end == NULL)
  93     dir_list = incl;
  94   else
  95     dir_list_end->next = incl;
  96   dir_list_end = incl;
  97
  98 #ifdef DEBUG_INCL
  99   fprintf (stderr, "add_include_directory (%s);\n", dir);
 100 #endif
 101 }
 102
 103 /* Search for FILE, first in `.', then according to -I options.  If
 104    successful, return the open file, and if RESULT is not NULL, set
 105    *RESULT to a malloc'd string that represents the file found with
 106    respect to the current working directory.  */
 107
 108 FILE *
 109 path_search (const char *file, const char **result)
 110 {
 111   FILE *fp;
 112   includes *incl;
 113   char *name;                   /* buffer for constructed name */
 114   int e;
 115
 116   if (result)
 117     *result = NULL;
 118
 119   /* Reject empty file.  */
 120   if (!*file)
 121     {
 122       errno = ENOENT;
 123       return NULL;
 124     }
 125
 126   /* Look in current working directory first.  */
 127   fp = fopen (file, "r");
 128   if (fp != NULL)
 129     {
 130       if (set_cloexec_flag (fileno (fp), true) != 0)
 131         M4ERROR ((warning_status, errno,
 132                   "Warning: cannot protect input file across forks"));
 133       if (result)
 134         *result = xstrdup (file);
 135       return fp;
 136     }
 137
 138   /* If file not found, and filename absolute, fail.  */
 139   if (*file == '/' || no_gnu_extensions)
 140     return NULL;
 141   e = errno;
 142
 143   name = (char *) xmalloc (dir_max_length + 1 + strlen (file) + 1);
 144
 145   for (incl = dir_list; incl != NULL; incl = incl->next)
 146     {
 147       strncpy (name, incl->dir, incl->len);
 148       name[incl->len] = '/';
 149       strcpy (name + incl->len + 1, file);
 150
 151 #ifdef DEBUG_INCL
 152       fprintf (stderr, "path_search (%s) -- trying %s\n", file, name);
 153 #endif
 154
 155       fp = fopen (name, "r");
 156       if (fp != NULL)
 157         {
 158           if (debug_level & DEBUG_TRACE_PATH)
 159             DEBUG_MESSAGE2 ("path search for `%s' found `%s'", file, name);
 160           if (set_cloexec_flag (fileno (fp), true) != 0)
 161             M4ERROR ((warning_status, errno,
 162                       "Warning: cannot protect input file across forks"));
 163           if (result)
 164             *result = name;
 165           else
 166             free (name);
 167           errno = e;
 168           return fp;
 169         }
 170     }
 171   free (name);
 172   errno = e;
 173   return fp;
 174 }
 175
 176 #ifdef DEBUG_INCL
 177
 178 static void M4_GNUC_UNUSED
 179 include_dump (void)
 180 {
 181   includes *incl;
 182
 183   fprintf (stderr, "include_dump:\n");
 184   for (incl = dir_list; incl != NULL; incl = incl->next)
 185     fprintf (stderr, "\t%s\n", incl->dir);
 186 }
 187
 188 #endif /* DEBUG_INCL */