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/*
File: walk_tree.c
Copyright (C) 2007 Andreas Gruenbacher <a.gruenbacher@computer.org>
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at
your option) any later version.
This program 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <dirent.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include "walk_tree.h"
struct entry_handle {
struct entry_handle *prev, *next;
dev_t dev;
ino_t ino;
DIR *stream;
off_t pos;
};
struct entry_handle head = {
.next = &head,
.prev = &head,
/* The other fields are unused. */
};
struct entry_handle *closed = &head;
unsigned int num_dir_handles;
static int walk_tree_visited(dev_t dev, ino_t ino)
{
struct entry_handle *i;
for (i = head.next; i != &head; i = i->next)
if (i->dev == dev && i->ino == ino)
return 1;
return 0;
}
static int walk_tree_rec(const char *path, int walk_flags,
int (*func)(const char *, const struct stat *, int,
void *), void *arg, int depth)
{
int follow_symlinks = (walk_flags & WALK_TREE_LOGICAL) ||
(!(walk_flags & WALK_TREE_PHYSICAL) &&
depth == 0);
int have_dir_stat = 0, flags = walk_flags, err;
struct entry_handle dir;
struct stat st;
/*
* If (walk_flags & WALK_TREE_PHYSICAL), do not traverse symlinks.
* If (walk_flags & WALK_TREE_LOGICAL), traverse all symlinks.
* Otherwise, traverse only top-level symlinks.
*/
if (depth == 0)
flags |= WALK_TREE_TOPLEVEL;
if (lstat(path, &st) != 0)
return func(path, NULL, flags | WALK_TREE_FAILED, arg);
if (S_ISLNK(st.st_mode)) {
flags |= WALK_TREE_SYMLINK;
if ((flags & WALK_TREE_DEREFERENCE) ||
((flags & WALK_TREE_TOPLEVEL) &&
(flags & WALK_TREE_DEREFERENCE_TOPLEVEL))) {
if (stat(path, &st) != 0)
return func(path, NULL,
flags | WALK_TREE_FAILED, arg);
dir.dev = st.st_dev;
dir.ino = st.st_ino;
have_dir_stat = 1;
}
} else if (S_ISDIR(st.st_mode)) {
dir.dev = st.st_dev;
dir.ino = st.st_ino;
have_dir_stat = 1;
}
err = func(path, &st, flags, arg);
/*
* Recurse if WALK_TREE_RECURSIVE and the path is:
* a dir not from a symlink
* a link and follow_symlinks
*/
if ((flags & WALK_TREE_RECURSIVE) &&
(!(flags & WALK_TREE_SYMLINK) && S_ISDIR(st.st_mode)) ||
((flags & WALK_TREE_SYMLINK) && follow_symlinks)) {
struct dirent *entry;
/*
* Check if we have already visited this directory to break
* endless loops.
*
* If we haven't stat()ed the file yet, do an opendir() for
* figuring out whether we have a directory, and check whether
* the directory has been visited afterwards. This saves a
* system call for each non-directory found.
*/
if (have_dir_stat && walk_tree_visited(dir.dev, dir.ino))
return err;
if (num_dir_handles == 0 && closed->prev != &head) {
close_another_dir:
/* Close the topmost directory handle still open. */
closed = closed->prev;
closed->pos = telldir(closed->stream);
closedir(closed->stream);
closed->stream = NULL;
num_dir_handles++;
}
dir.stream = opendir(path);
if (!dir.stream) {
if (errno == ENFILE && closed->prev != &head) {
/* Ran out of file descriptors. */
num_dir_handles = 0;
goto close_another_dir;
}
/*
* PATH may be a symlink to a regular file, or a dead
* symlink which we didn't follow above.
*/
if (errno != ENOTDIR && errno != ENOENT)
err += func(path, NULL, flags |
WALK_TREE_FAILED, arg);
return err;
}
/* See walk_tree_visited() comment above... */
if (!have_dir_stat) {
if (stat(path, &st) != 0)
goto skip_dir;
dir.dev = st.st_dev;
dir.ino = st.st_ino;
if (walk_tree_visited(dir.dev, dir.ino))
goto skip_dir;
}
/* Insert into the list of handles. */
dir.next = head.next;
dir.prev = &head;
dir.prev->next = &dir;
dir.next->prev = &dir;
num_dir_handles--;
while ((entry = readdir(dir.stream)) != NULL) {
char *path_end;
if (!strcmp(entry->d_name, ".") ||
!strcmp(entry->d_name, ".."))
continue;
path_end = strchr(path, 0);
if ((path_end - path) + strlen(entry->d_name) + 1 >=
FILENAME_MAX) {
errno = ENAMETOOLONG;
err += func(path, NULL,
flags | WALK_TREE_FAILED, arg);
continue;
}
*path_end++ = '/';
strcpy(path_end, entry->d_name);
err += walk_tree_rec(path, walk_flags, func, arg,
depth + 1);
*--path_end = 0;
if (!dir.stream) {
/* Reopen the directory handle. */
dir.stream = opendir(path);
if (!dir.stream)
return err + func(path, NULL, flags |
WALK_TREE_FAILED, arg);
seekdir(dir.stream, dir.pos);
closed = closed->next;
num_dir_handles--;
}
}
/* Remove from the list of handles. */
dir.prev->next = dir.next;
dir.next->prev = dir.prev;
num_dir_handles++;
skip_dir:
if (closedir(dir.stream) != 0)
err += func(path, NULL, flags | WALK_TREE_FAILED, arg);
}
return err;
}
int walk_tree(const char *path, int walk_flags, unsigned int num,
int (*func)(const char *, const struct stat *, int, void *),
void *arg)
{
char path_copy[FILENAME_MAX];
num_dir_handles = num;
if (num_dir_handles < 1) {
struct rlimit rlimit;
num_dir_handles = 1;
if (getrlimit(RLIMIT_NOFILE, &rlimit) == 0 &&
rlimit.rlim_cur >= 2)
num_dir_handles = rlimit.rlim_cur / 2;
}
if (strlen(path) >= FILENAME_MAX) {
errno = ENAMETOOLONG;
return func(path, NULL, WALK_TREE_FAILED, arg);
}
strcpy(path_copy, path);
return walk_tree_rec(path_copy, walk_flags, func, arg, 0);
}
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