Put libmisc on its own branch

1 files changed, 228 insertions, 0 deletions

diff --git a/libmisc/walk_tree.c b/libmisc/walk_tree.c
new file mode 100644
index 0000000..2777145
--- /dev/null
+++ b/libmisc/walk_tree.c
@@ -0,0 +1,228 @@
+/*
+  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) {
+			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);
+}