[12/28] tree structure abstraction for directory hierarchies

diff --git a/Makefile b/Makefile
index 295b7cb..d88b8ff 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@  MANDIR=/usr/share/man/man8
 CFLAGS?=-O1 -g -Wall -Wshadow
 CC?=gcc
 
-OBJS = powerdebug.o sensor.o clocks.o regulator.o display.o
+OBJS = powerdebug.o sensor.o clocks.o regulator.o display.o tree.o
 
 default: powerdebug
 
diff --git a/clocks.c b/clocks.c
index ecc72ea..8a2dc97 100644
--- a/clocks.c
+++ b/clocks.c
@@ -19,6 +19,7 @@ 
 
 #include "powerdebug.h"
 #include "clocks.h"
+#include "tree.h"
 
 #define MAX_LINES 120
 
@@ -41,6 +42,8 @@  struct clock_info {
 	struct clock_info **children;
 } *clocks_info;
 
+static struct tree *clock_tree;
+
 static int locate_debugfs(char *clk_path)
 {
 	const char *mtab = "/proc/mounts";
@@ -73,6 +76,10 @@  int clock_init(void)
 
 	sprintf(clk_dir_path, "%s/clock", clk_dir_path);
 
+	clock_tree = tree_load(clk_dir_path, NULL);
+	if (!clock_tree)
+		return -1;
+
 	return access(clk_dir_path, F_OK);
 }
 
diff --git a/tree.c b/tree.c
new file mode 100644
index 0000000..e681f4f
--- /dev/null
+++ b/tree.c
@@ -0,0 +1,225 @@ 
+/*******************************************************************************
+ * Copyright (C) 2010, Linaro Limited.
+ *
+ * This file is part of PowerDebug.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Author:
+ *     Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ *******************************************************************************/
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#undef _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "tree.h"
+
+/*
+ * Allocate a tree structure and initialize the different fields.
+ *
+ * @path  : the absolute path to the directory
+ * @depth : the depth in the tree
+ * Returns a tree structure on success, NULL otherwise
+ */
+static inline struct tree *tree_alloc(const char *path, int depth)
+{
+	struct tree *t;
+
+	t = malloc(sizeof(*t));
+	if (!t)
+		return NULL;
+
+	/* Full pathname */
+	t->path = strdup(path);
+	if (!t->path) {
+		free(t);
+		return NULL;
+	}
+
+	/* Basename pointer on the full path name */
+	t->name = strrchr(t->path, '/') + 1;
+
+	t->depth = depth;
+	t->tail = t;
+	t->child = NULL;
+	t->parent = NULL;
+	t->next = NULL;
+	t->prev = NULL;
+	t->private = NULL;
+
+	return t;
+}
+
+/*
+ * Free a tree structure and the fields we allocated in the
+ * tree_alloc function.
+ *
+ * @t : the tree structure to be freed
+ */
+static inline void tree_free(struct tree *t)
+{
+	free(t->path);
+	free(t);
+}
+
+/*
+ * Add at the end of the list the new list element.
+ *
+ * @head : the list to be appened
+ * @new  : the new element to be added at the end of the list
+ */
+static inline void tree_add_tail(struct tree *head, struct tree *new)
+{
+	new->prev = head->tail;
+	head->tail->next = new;
+	head->tail = new;
+}
+
+/*
+ * Add a child in to a parent list, at the end of this list.
+ *
+ * @parent : the parent list to add the child
+ * @child  : the child to be added
+ */
+static inline void tree_add_child(struct tree *parent, struct tree *child)
+{
+	child->parent = parent;
+
+	if (parent->child)
+		return tree_add_tail(parent->child, child);
+
+	parent->child = child;
+}
+
+/*
+ * This function will browse the directory structure and build a
+ * tree reflecting the content of the directory tree.
+ *
+ * @tree   : the root node of the tree
+ * @filter : a callback to filter out the directories
+ * Returns 0 on success, -1 otherwise
+ */
+static int tree_scan(struct tree *tree, tree_filter_t filter)
+{
+	DIR *dir;
+	char *basedir, *newpath;
+	struct dirent dirent, *direntp;
+	struct stat s;
+	int ret = 0;
+
+	dir = opendir(tree->path);
+	if (!dir)
+		return -1;
+
+	while (!readdir_r(dir, &dirent, &direntp)) {
+
+		struct tree *child;
+
+                if (!direntp)
+                        break;
+
+                if (direntp->d_name[0] == '.')
+                        continue;
+
+		if (filter && filter(direntp->d_name))
+			continue;
+
+		ret = asprintf(&basedir, "%s", tree->path);
+		if (ret < 0)
+			return -1;
+
+		ret = basename(basedir) ? 0 : -1;
+		if (ret < 0)
+			goto out_free_basedir;
+
+		ret = asprintf(&newpath, "%s/%s", basedir, direntp->d_name);
+		if (ret < 0)
+			goto out_free_basedir;
+
+		ret = stat(newpath, &s);
+		if (ret)
+			goto out_free_newpath;
+
+		if (S_ISDIR(s.st_mode)) {
+
+			ret = -1;
+
+			child = tree_alloc(newpath, tree->depth + 1);
+			if (!child)
+				goto out_free_newpath;
+
+			tree_add_child(tree, child);
+
+			ret = tree_scan(child, filter);
+		}
+
+	out_free_newpath:
+		free(newpath);
+
+	out_free_basedir:
+		free(basedir);
+
+		if (ret)
+			break;
+	}
+
+	closedir(dir);
+
+	return ret;
+}
+
+/*
+ * This function takes the topmost directory path and populate the
+ * directory tree structures.
+ *
+ * @tree : a path to the topmost directory path
+ * Returns a tree structure corresponding to the root node of the
+ * directory tree representation on success, NULL otherwise
+ */
+struct tree *tree_load(const char *path, tree_filter_t filter)
+{
+	struct tree *tree;
+
+	tree = tree_alloc(path, 0);
+	if (!tree)
+		return NULL;
+
+	if (tree_scan(tree, filter)) {
+		tree_free(tree);
+		return NULL;
+	}
+
+	return tree;
+}
+
+/*
+ * This function will go over the tree passed as parameter and
+ * will call the callback passed as parameter for each node.
+ *
+ * @tree : the topmost node where we begin to browse the tree
+ * Returns 0 on success, < 0 otherwise
+ */
+int tree_for_each(struct tree *tree, tree_cb_t cb, void *data)
+{
+	if (!tree)
+		return 0;
+
+	if (cb(tree, data))
+		return -1;
+
+	if (tree_for_each(tree->child, cb, data))
+		return -1;
+
+	return tree_for_each(tree->next, cb, data);
+}
diff --git a/tree.h b/tree.h
new file mode 100644
index 0000000..57c70f8
--- /dev/null
+++ b/tree.h
@@ -0,0 +1,45 @@ 
+/*******************************************************************************
+ * Copyright (C) 2010, Linaro Limited.
+ *
+ * This file is part of PowerDebug.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Author:
+ *     Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ *******************************************************************************/
+
+/*
+ * Structure describing a node of the clock tree
+ *
+ * tail  : points to the last element in the list
+ * next  : points to the next element in the list
+ * child  : points to the child node
+ * parent : points to the parent node
+ * depth  : the recursive level of the node
+ * path   : absolute pathname of the directory
+ * name   : basename of the directory
+ */
+struct tree {
+	struct tree *tail;
+	struct tree *next;
+	struct tree *prev;
+	struct tree *child;
+	struct tree *parent;
+	char *path;
+	char *name;
+	void *private;
+	unsigned char depth;
+};
+
+typedef int (*tree_cb_t)(struct tree *t, void *data);
+
+typedef int (*tree_filter_t)(const char *name);
+
+extern struct tree *tree_load(const char *path, tree_filter_t filter);
+
+extern int tree_for_each(struct tree *tree, tree_cb_t cb, void *data);