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/* GNU m4 -- A simple macro processor
Copyright (C) 1989-1993, 2004, 2006-2014, 2016 Free Software
Foundation, Inc.
This file is part of GNU M4.
GNU M4 is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
GNU M4 is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* Handling of path search of included files via the builtins "include"
and "sinclude". */
#include "m4.h"
#include "sys/stat.h"
struct includes
{
struct includes *next; /* next directory to search */
const char *dir; /* directory */
int len;
};
typedef struct includes includes;
static includes *dir_list; /* the list of path directories */
static includes *dir_list_end; /* the end of same */
static int dir_max_length; /* length of longest directory name */
void
include_init (void)
{
dir_list = NULL;
dir_list_end = NULL;
dir_max_length = 0;
}
void
include_env_init (void)
{
char *path;
char *path_end;
char *env_path;
if (no_gnu_extensions)
return;
env_path = getenv ("M4PATH");
if (env_path == NULL)
return;
env_path = xstrdup (env_path);
path = env_path;
do
{
path_end = strchr (path, ':');
if (path_end)
*path_end = '\0';
add_include_directory (path);
path = path_end + 1;
}
while (path_end);
free (env_path);
}
void
add_include_directory (const char *dir)
{
includes *incl;
if (no_gnu_extensions)
return;
if (*dir == '\0')
dir = ".";
incl = (includes *) xmalloc (sizeof (struct includes));
incl->next = NULL;
incl->len = strlen (dir);
incl->dir = xstrdup (dir);
if (incl->len > dir_max_length) /* remember len of longest directory */
dir_max_length = incl->len;
if (dir_list_end == NULL)
dir_list = incl;
else
dir_list_end->next = incl;
dir_list_end = incl;
#ifdef DEBUG_INCL
xfprintf (stderr, "add_include_directory (%s);\n", dir);
#endif
}
/* Attempt to open FILE; if it opens, verify that it is not a
directory, and ensure it does not leak across execs. */
static FILE *
m4_fopen (const char *file)
{
FILE *fp = fopen (file, "r");
if (fp)
{
struct stat st;
int fd = fileno (fp);
if (fstat (fd, &st) == 0 && S_ISDIR (st.st_mode))
{
fclose (fp);
errno = EISDIR;
return NULL;
}
if (set_cloexec_flag (fd, true) != 0)
M4ERROR ((warning_status, errno,
"Warning: cannot protect input file across forks"));
}
return fp;
}
/* Search for FILE, first in `.', then according to -I options. If
successful, return the open file, and if RESULT is not NULL, set
*RESULT to a malloc'd string that represents the file found with
respect to the current working directory. */
FILE *
m4_path_search (const char *file, char **result)
{
FILE *fp;
includes *incl;
char *name; /* buffer for constructed name */
int e;
if (result)
*result = NULL;
/* Reject empty file. */
if (!*file)
{
errno = ENOENT;
return NULL;
}
/* Look in current working directory first. */
fp = m4_fopen (file);
if (fp != NULL)
{
if (result)
*result = xstrdup (file);
return fp;
}
/* If file not found, and filename absolute, fail. */
if (IS_ABSOLUTE_FILE_NAME (file) || no_gnu_extensions)
return NULL;
e = errno;
for (incl = dir_list; incl != NULL; incl = incl->next)
{
name = file_name_concat (incl->dir, file, NULL);
#ifdef DEBUG_INCL
xfprintf (stderr, "m4_path_search (%s) -- trying %s\n", file, name);
#endif
fp = m4_fopen (name);
if (fp != NULL)
{
if (debug_level & DEBUG_TRACE_PATH)
DEBUG_MESSAGE2 ("path search for `%s' found `%s'", file, name);
if (result)
*result = name;
else
free (name);
return fp;
}
free (name);
}
errno = e;
return fp;
}
#ifdef DEBUG_INCL
static void M4_GNUC_UNUSED
include_dump (void)
{
includes *incl;
xfprintf (stderr, "include_dump:\n");
for (incl = dir_list; incl != NULL; incl = incl->next)
xfprintf (stderr, "\t%s\n", incl->dir);
}
#endif /* DEBUG_INCL */
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