src/path.c

   1 /* GNU m4 -- A simple macro processor
   2
   3    Copyright (C) 1989, 1990, 1991, 1992, 1993, 2004, 2006, 2007 Free
   4    Software Foundation, Inc.
   5
   6    This file is part of GNU M4.
   7
   8    GNU M4 is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    GNU M4 is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  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   char *env_path;
  55
  56   if (no_gnu_extensions)
  57     return;
  58
  59   env_path = getenv ("M4PATH");
  60   if (env_path == NULL)
  61     return;
  62
  63   env_path = xstrdup (env_path);
  64   path = env_path;
  65
  66   do
  67     {
  68       path_end = strchr (path, ':');
  69       if (path_end)
  70         *path_end = '\0';
  71       add_include_directory (path);
  72       path = path_end + 1;
  73     }
  74   while (path_end);
  75   free (env_path);
  76 }
  77
  78 void
  79 add_include_directory (const char *dir)
  80 {
  81   includes *incl;
  82
  83   if (no_gnu_extensions)
  84     return;
  85
  86   if (*dir == '\0')
  87     dir = ".";
  88
  89   incl = (includes *) xmalloc (sizeof (struct includes));
  90   incl->next = NULL;
  91   incl->len = strlen (dir);
  92   incl->dir = xstrdup (dir);
  93
  94   if (incl->len > dir_max_length) /* remember len of longest directory */
  95     dir_max_length = incl->len;
  96
  97   if (dir_list_end == NULL)
  98     dir_list = incl;
  99   else
 100     dir_list_end->next = incl;
 101   dir_list_end = incl;
 102
 103 #ifdef DEBUG_INCL
 104   fprintf (stderr, "add_include_directory (%s);\n", dir);
 105 #endif
 106 }
 107
 108 /* Search for FILE, first in `.', then according to -I options.  If
 109    successful, return the open file, and if RESULT is not NULL, set
 110    *RESULT to a malloc'd string that represents the file found with
 111    respect to the current working directory.  */
 112
 113 FILE *
 114 m4_path_search (const char *file, char **result)
 115 {
 116   FILE *fp;
 117   includes *incl;
 118   char *name;                   /* buffer for constructed name */
 119   int e;
 120
 121   if (result)
 122     *result = NULL;
 123
 124   /* Reject empty file.  */
 125   if (!*file)
 126     {
 127       errno = ENOENT;
 128       return NULL;
 129     }
 130
 131   /* Look in current working directory first.  */
 132   fp = fopen (file, "r");
 133   if (fp != NULL)
 134     {
 135       if (set_cloexec_flag (fileno (fp), true) != 0)
 136         M4ERROR ((warning_status, errno,
 137                   "Warning: cannot protect input file across forks"));
 138       if (result)
 139         *result = xstrdup (file);
 140       return fp;
 141     }
 142
 143   /* If file not found, and filename absolute, fail.  */
 144   if (*file == '/' || no_gnu_extensions)
 145     return NULL;
 146   e = errno;
 147
 148   name = (char *) xmalloc (dir_max_length + 1 + strlen (file) + 1);
 149
 150   for (incl = dir_list; incl != NULL; incl = incl->next)
 151     {
 152       strncpy (name, incl->dir, incl->len);
 153       name[incl->len] = '/';
 154       strcpy (name + incl->len + 1, file);
 155
 156 #ifdef DEBUG_INCL
 157       fprintf (stderr, "m4_path_search (%s) -- trying %s\n", file, name);
 158 #endif
 159
 160       fp = fopen (name, "r");
 161       if (fp != NULL)
 162         {
 163           if (debug_level & DEBUG_TRACE_PATH)
 164             DEBUG_MESSAGE2 ("path search for `%s' found `%s'", file, name);
 165           if (set_cloexec_flag (fileno (fp), true) != 0)
 166             M4ERROR ((warning_status, errno,
 167                       "Warning: cannot protect input file across forks"));
 168           if (result)
 169             *result = name;
 170           else
 171             free (name);
 172           errno = e;
 173           return fp;
 174         }
 175     }
 176   free (name);
 177   errno = e;
 178   return fp;
 179 }
 180
 181 #ifdef DEBUG_INCL
 182
 183 static void M4_GNUC_UNUSED
 184 include_dump (void)
 185 {
 186   includes *incl;
 187
 188   fprintf (stderr, "include_dump:\n");
 189   for (incl = dir_list; incl != NULL; incl = incl->next)
 190     fprintf (stderr, "\t%s\n", incl->dir);
 191 }
 192
 193 #endif /* DEBUG_INCL */