add the fastindex module

3 files changed, 993 insertions, 0 deletions

diff --git a/libs/fastindex/Makefile b/libs/fastindex/Makefile
new file mode 100644
index 000000000..560a35283
--- /dev/null
+++ b/libs/fastindex/Makefile
@@ -0,0 +1,12 @@
+include ../../build/config.mk
+include ../../build/gccconfig.mk
+
+%.o: %.c
+	$(COMPILE) $(LUA_CFLAGS) $(FPIC) -c -o $@ $< 
+
+compile: src/fastindex.o
+	mkdir -p dist/usr/lib/lua/luci
+	$(LINK) $(SHLIB_FLAGS) -o dist/usr/lib/lua/luci/fastindex.so src/fastindex.o $(LUA_SHLIBS)
+
+clean:
+	rm -f src/*.o
diff --git a/libs/fastindex/src/fastindex.c b/libs/fastindex/src/fastindex.c
new file mode 100644
index 000000000..ab78c0935
--- /dev/null
+++ b/libs/fastindex/src/fastindex.c
@@ -0,0 +1,380 @@
+/*
+ * fastindex - fast lua module indexing plugin
+ * Copyright (C) 2008 Felix Fietkau <nbd@openwrt.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation
+ *
+ * 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 General Public License for more details.
+ */
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/cdefs.h>
+
+#ifndef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE /* XXX: portability hack for timestamp */
+#endif
+
+#include <sys/stat.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <glob.h>
+
+#include <lualib.h>
+#include <lauxlib.h>
+#include "list.h"
+
+#define MODNAME        "fastindex"
+#define PATTERN        "/*.lua"
+#define DEFAULT_BUFLEN 1024
+
+//#define DEBUG 1
+
+#ifdef DEBUG
+#define DPRINTF(...) fprintf(stderr, __VA_ARGS__)
+#else
+#define DPRINTF(...) do {} while (0)
+#endif
+
+/**
+ * list_for_each_offset	-	iterate over a list, start with the provided pointer
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_offset(pos, head, offset) \
+	for (pos = (offset)->next; pos != (offset); \
+	     pos = ((pos->next == (head)) && ((offset) != (head)) ? (head)->next : pos->next))
+
+static char *namespace = NULL;
+
+struct fastindex_entry {
+	struct list_head list;
+	time_t timestamp;
+	int checked;
+	char *name;
+};
+
+struct fastindex_pattern {
+	struct list_head list;
+	char pattern[];
+};
+
+struct fastindex {
+	lua_State *L;
+	int checked;
+	char *func;
+	struct list_head patterns;
+	struct list_head *last;
+	struct list_head entries;
+	int ofs;
+	char *buf;
+	int buflen;
+};
+
+static inline struct fastindex *
+to_fastindex(struct lua_State *L)
+{
+	struct fastindex *f;
+	lua_getfield(L, lua_upvalueindex(1), "__data");
+	f = lua_touserdata(L, -1);
+	lua_pop(L, 1);
+	return f;
+}
+
+static int
+fastindex_module(lua_State *L)
+{
+	const char *s;
+	s = luaL_checkstring(L, 1);
+
+	if (s) {
+		if (namespace)
+			free(namespace);
+		namespace = strdup(s);
+	}
+
+	return 0;
+}
+
+static struct fastindex_entry *
+find_entry(struct fastindex *f, char *name)
+{
+	struct list_head *p;
+
+	if (!f->last)
+		f->last = &f->entries;
+
+	list_for_each_offset(p, &f->entries, f->last) {
+		struct fastindex_entry *e;
+		e = container_of(p, struct fastindex_entry, list);
+		if (!strcmp(e->name, name))
+			return e;
+	}
+	return NULL;
+}
+
+static struct fastindex_entry *
+new_entry(struct fastindex *f, char *name)
+{
+	struct fastindex_entry *e;
+
+	e = malloc(sizeof(struct fastindex_entry));
+	if (!e)
+		goto error;
+
+	memset(e, 0, sizeof(struct fastindex_entry));
+	e->name = strdup(name);
+	if (!e->name) {
+		free(e);
+		goto error;
+	}
+	INIT_LIST_HEAD(&e->list);
+
+	return e;
+
+error:
+	return NULL;
+}
+
+static void free_entry(struct fastindex_entry *e)
+{
+	list_del(&e->list);
+	free(e->name);
+	free(e);
+}
+
+int bufferwriter(lua_State *L, const void *p, size_t sz, void *ud)
+{
+	struct fastindex *f = ud;
+
+	while (f->ofs + sz > f->buflen) {
+		char *b = f->buf;
+		f->buflen *= 2;
+		f->buf = realloc(f->buf, f->buflen);
+		if (!f->buf) {
+			free(b);
+			return 1;
+		}
+	}
+	memcpy(f->buf + f->ofs, p, sz);
+	f->ofs += sz;
+	return 0;
+}
+
+static void
+load_index(struct fastindex *f, struct fastindex_entry *e)
+{
+	lua_State *L;
+
+	DPRINTF("Loading module: %s\n", e->name);
+
+	if (!f->buf)
+		f->buf = malloc(f->buflen);
+
+	if (!f->buf)
+		luaL_error(f->L, "Out of memory!\n");
+
+	f->ofs = 0;
+	L = luaL_newstate();
+	if (!L)
+		return;
+
+	namespace = NULL;
+	luaL_openlibs(L);
+	lua_pushcfunction(L, fastindex_module);
+	lua_setfield(L, LUA_GLOBALSINDEX, "module");
+
+	do {
+		if (luaL_dofile(L, e->name)) {
+			DPRINTF("Warning: unable to open module '%s'\n", e->name);
+			break;
+		}
+
+		lua_getglobal(L, f->func);
+		lua_dump(L, bufferwriter, f);
+		DPRINTF("Got %d bytes\n", f->ofs);
+		if (f->ofs == 0)
+			break;
+		lua_createtable(f->L, (namespace ? 2 : 1), 0);
+		luaL_loadbuffer(f->L, f->buf, f->ofs, "tmp");
+		lua_rawseti(f->L, -2, 1);
+		if (namespace) {
+			DPRINTF("Module has namespace '%s'\n", namespace);
+			lua_pushstring(f->L, namespace);
+			lua_rawseti(f->L, -2, 2);
+			free(namespace);
+			namespace = NULL;
+		}
+		lua_setfield(f->L, -2, e->name);
+	} while (0);
+
+	lua_close(L);
+}
+
+
+static int
+fastindex_scan(lua_State *L)
+{
+	struct list_head *tmp, *p;
+	struct fastindex *f;
+	glob_t gl;
+	int i;
+	int gl_flags = GLOB_NOESCAPE | GLOB_NOSORT | GLOB_MARK;
+
+	f = to_fastindex(L);
+	f->checked++;
+
+
+	if (list_empty(&f->patterns))
+		return 0;
+
+	lua_getfield(L, lua_upvalueindex(1), "indexes");
+	list_for_each(p, &f->patterns) {
+		struct fastindex_pattern *pt = container_of(p, struct fastindex_pattern, list);
+		glob(pt->pattern, gl_flags, NULL, &gl);
+		gl_flags |= GLOB_APPEND;
+	}
+	for (i = 0; i < gl.gl_pathc; i++) {
+		struct fastindex_entry *e;
+		struct stat st;
+
+		if (stat(gl.gl_pathv[i], &st))
+			continue;
+
+		if ((st.st_mode & S_IFMT) != S_IFREG)
+			continue;
+
+		e = find_entry(f, gl.gl_pathv[i]);
+		if (!e) {
+			e = new_entry(f, gl.gl_pathv[i]);
+			list_add_tail(&e->list, &f->entries);
+		}
+
+		e->checked = f->checked;
+		if ((e->timestamp < st.st_mtime)) {
+			load_index(f, e);
+			e->timestamp = st.st_mtime;
+		}
+	}
+	globfree(&gl);
+	list_for_each_safe(p, tmp, &f->entries) {
+		struct fastindex_entry *e = container_of(p, struct fastindex_entry, list);
+		if (e->checked < f->checked) {
+			lua_pushnil(f->L);
+			lua_setfield(f->L, -2, e->name);
+			free_entry(e);
+		}
+	}
+	lua_pop(L, 1);
+
+	return 0;
+}
+
+static int
+fastindex_free(lua_State *L)
+{
+	struct fastindex *f;
+	struct list_head *p, *tmp;
+
+	f = lua_touserdata(L, -1);
+	list_for_each_safe(p, tmp, &f->patterns) {
+		struct fastindex_pattern *pt;
+		pt = container_of(p, struct fastindex_pattern, list);
+		list_del(p);
+		free(pt);
+	}
+	list_for_each_safe(p, tmp, &f->entries) {
+		struct fastindex_entry *e;
+		e = container_of(p, struct fastindex_entry, list);
+		free_entry(e);
+	}
+	return 0;
+}
+
+static int
+fastindex_add(lua_State *L)
+{
+	struct fastindex_pattern *pt;
+	struct fastindex *f;
+	const char *str;
+
+	f = to_fastindex(L);
+	str = luaL_checkstring(L, 1);
+	if (!str)
+		luaL_error(L, "Invalid argument");
+
+	pt = malloc(sizeof(struct fastindex_pattern) + strlen(str) + 1);
+	if (!pt)
+		luaL_error(L, "Out of memory");
+
+	INIT_LIST_HEAD(&pt->list);
+	strcpy(pt->pattern, str);
+	list_add(&pt->list, &f->patterns);
+
+	return 0;
+}
+
+static const luaL_Reg fastindex_m[] = {
+	{ "add", fastindex_add },
+	{ "scan", fastindex_scan },
+	{ NULL, NULL }
+};
+
+static int
+fastindex_new(lua_State *L)
+{
+	struct fastindex *f;
+	const char *func;
+
+	func = luaL_checkstring(L, 1);
+
+	f = lua_newuserdata(L, sizeof(struct fastindex));
+	lua_createtable(L, 0, 2);
+	lua_pushvalue(L, -1);
+	lua_setfield(L, -2, "__index");
+	lua_pushcfunction(L, fastindex_free);
+	lua_setfield(L, -2, "__gc");
+	lua_pushvalue(L, -1);
+	lua_setmetatable(L, -3);
+	lua_pushvalue(L, -2);
+	lua_setfield(L, -2, "__data");
+	lua_createtable(L, 0, 1);
+	lua_setfield(L, -2, "indexes");
+	lua_pushvalue(L, -2);
+	luaI_openlib(L, NULL, fastindex_m, 1);
+
+	memset(f, 0, sizeof(struct fastindex));
+	f->L = L;
+	f->buflen = DEFAULT_BUFLEN;
+	INIT_LIST_HEAD(&f->entries);
+	INIT_LIST_HEAD(&f->patterns);
+
+	f->func = strdup(func);
+	if (!f->func) {
+		if (f->func)
+			free(f->func);
+		luaL_error(L, "Out of memory\n");
+	}
+
+	return 1;
+}
+
+static const luaL_Reg fastindex[] = {
+	{ "new", fastindex_new },
+	{ NULL, NULL },
+};
+
+int
+luaopen_fastindex(lua_State *L)
+{
+	luaL_register(L, MODNAME, fastindex);
+	return 0;
+}
diff --git a/libs/fastindex/src/list.h b/libs/fastindex/src/list.h
new file mode 100644
index 000000000..2959a061d
--- /dev/null
+++ b/libs/fastindex/src/list.h
@@ -0,0 +1,601 @@
+#ifndef _LINUX_LIST_H
+#define _LINUX_LIST_H
+
+#include <stddef.h>
+/**
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:	the pointer to the member.
+ * @type:	the type of the container struct this is embedded in.
+ * @member:	the name of the member within the struct.
+ *
+ */
+#ifndef container_of
+#define container_of(ptr, type, member) (			\
+	(type *)( (char *)ptr - offsetof(type,member) ))
+#endif
+
+
+/*
+ * Simple doubly linked list implementation.
+ *
+ * Some of the internal functions ("__xxx") are useful when
+ * manipulating whole lists rather than single entries, as
+ * sometimes we already know the next/prev entries and we can
+ * generate better code by using them directly rather than
+ * using the generic single-entry routines.
+ */
+
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define LIST_HEAD(name) \
+	struct list_head name = LIST_HEAD_INIT(name)
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+	list->next = list;
+	list->prev = list;
+}
+
+/*
+ * Insert a new entry between two known consecutive entries.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_add(struct list_head *new,
+			      struct list_head *prev,
+			      struct list_head *next)
+{
+	next->prev = new;
+	new->next = next;
+	new->prev = prev;
+	prev->next = new;
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head, head->next);
+}
+
+
+/**
+ * list_add_tail - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it before
+ *
+ * Insert a new entry before the specified head.
+ * This is useful for implementing queues.
+ */
+static inline void list_add_tail(struct list_head *new, struct list_head *head)
+{
+	__list_add(new, head->prev, head);
+}
+
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head * prev, struct list_head * next)
+{
+	next->prev = prev;
+	prev->next = next;
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void list_del(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	entry->next = NULL;
+	entry->prev = NULL;
+}
+
+/**
+ * list_replace - replace old entry by new one
+ * @old : the element to be replaced
+ * @new : the new element to insert
+ *
+ * If @old was empty, it will be overwritten.
+ */
+static inline void list_replace(struct list_head *old,
+				struct list_head *new)
+{
+	new->next = old->next;
+	new->next->prev = new;
+	new->prev = old->prev;
+	new->prev->next = new;
+}
+
+static inline void list_replace_init(struct list_head *old,
+					struct list_head *new)
+{
+	list_replace(old, new);
+	INIT_LIST_HEAD(old);
+}
+
+/**
+ * list_del_init - deletes entry from list and reinitialize it.
+ * @entry: the element to delete from the list.
+ */
+static inline void list_del_init(struct list_head *entry)
+{
+	__list_del(entry->prev, entry->next);
+	INIT_LIST_HEAD(entry);
+}
+
+/**
+ * list_move - delete from one list and add as another's head
+ * @list: the entry to move
+ * @head: the head that will precede our entry
+ */
+static inline void list_move(struct list_head *list, struct list_head *head)
+{
+	__list_del(list->prev, list->next);
+	list_add(list, head);
+}
+
+/**
+ * list_move_tail - delete from one list and add as another's tail
+ * @list: the entry to move
+ * @head: the head that will follow our entry
+ */
+static inline void list_move_tail(struct list_head *list,
+				  struct list_head *head)
+{
+	__list_del(list->prev, list->next);
+	list_add_tail(list, head);
+}
+
+/**
+ * list_is_last - tests whether @list is the last entry in list @head
+ * @list: the entry to test
+ * @head: the head of the list
+ */
+static inline int list_is_last(const struct list_head *list,
+				const struct list_head *head)
+{
+	return list->next == head;
+}
+
+/**
+ * list_empty - tests whether a list is empty
+ * @head: the list to test.
+ */
+static inline int list_empty(const struct list_head *head)
+{
+	return head->next == head;
+}
+
+/**
+ * list_empty_careful - tests whether a list is empty and not being modified
+ * @head: the list to test
+ *
+ * Description:
+ * tests whether a list is empty _and_ checks that no other CPU might be
+ * in the process of modifying either member (next or prev)
+ *
+ * NOTE: using list_empty_careful() without synchronization
+ * can only be safe if the only activity that can happen
+ * to the list entry is list_del_init(). Eg. it cannot be used
+ * if another CPU could re-list_add() it.
+ */
+static inline int list_empty_careful(const struct list_head *head)
+{
+	struct list_head *next = head->next;
+	return (next == head) && (next == head->prev);
+}
+
+static inline void __list_splice(struct list_head *list,
+				 struct list_head *head)
+{
+	struct list_head *first = list->next;
+	struct list_head *last = list->prev;
+	struct list_head *at = head->next;
+
+	first->prev = head;
+	head->next = first;
+
+	last->next = at;
+	at->prev = last;
+}
+
+/**
+ * list_splice - join two lists
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ */
+static inline void list_splice(struct list_head *list, struct list_head *head)
+{
+	if (!list_empty(list))
+		__list_splice(list, head);
+}
+
+/**
+ * list_splice_init - join two lists and reinitialise the emptied list.
+ * @list: the new list to add.
+ * @head: the place to add it in the first list.
+ *
+ * The list at @list is reinitialised
+ */
+static inline void list_splice_init(struct list_head *list,
+				    struct list_head *head)
+{
+	if (!list_empty(list)) {
+		__list_splice(list, head);
+		INIT_LIST_HEAD(list);
+	}
+}
+
+/**
+ * list_entry - get the struct for this entry
+ * @ptr:	the &struct list_head pointer.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_entry(ptr, type, member) \
+	container_of(ptr, type, member)
+
+/**
+ * list_first_entry - get the first element from a list
+ * @ptr:	the list head to take the element from.
+ * @type:	the type of the struct this is embedded in.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Note, that list is expected to be not empty.
+ */
+#define list_first_entry(ptr, type, member) \
+	list_entry((ptr)->next, type, member)
+
+/**
+ * list_for_each	-	iterate over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each(pos, head) \
+	for (pos = (head)->next; pos != (head); \
+        	pos = pos->next)
+
+/**
+ * __list_for_each	-	iterate over a list
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ *
+ * This variant differs from list_for_each() in that it's the
+ * simplest possible list iteration code, no prefetching is done.
+ * Use this for code that knows the list to be very short (empty
+ * or 1 entry) most of the time.
+ */
+#define __list_for_each(pos, head) \
+	for (pos = (head)->next; pos != (head); pos = pos->next)
+
+/**
+ * list_for_each_prev	-	iterate over a list backwards
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev(pos, head) \
+	for (pos = (head)->prev; pos != (head); \
+        	pos = pos->prev)
+
+/**
+ * list_for_each_safe - iterate over a list safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_safe(pos, n, head) \
+	for (pos = (head)->next, n = pos->next; pos != (head); \
+		pos = n, n = pos->next)
+
+/**
+ * list_for_each_prev_safe - iterate over a list backwards safe against removal of list entry
+ * @pos:	the &struct list_head to use as a loop cursor.
+ * @n:		another &struct list_head to use as temporary storage
+ * @head:	the head for your list.
+ */
+#define list_for_each_prev_safe(pos, n, head) \
+	for (pos = (head)->prev, n = pos->prev; \
+	     pos != (head); \
+	     pos = n, n = pos->prev)
+
+/**
+ * list_for_each_entry	-	iterate over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry(pos, head, member)				\
+	for (pos = list_entry((head)->next, typeof(*pos), member);	\
+	     &pos->member != (head); 	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_reverse - iterate backwards over list of given type.
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_reverse(pos, head, member)			\
+	for (pos = list_entry((head)->prev, typeof(*pos), member);	\
+	     &pos->member != (head); 	\
+	     pos = list_entry(pos->member.prev, typeof(*pos), member))
+
+/**
+ * list_prepare_entry - prepare a pos entry for use in list_for_each_entry_continue()
+ * @pos:	the type * to use as a start point
+ * @head:	the head of the list
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Prepares a pos entry for use as a start point in list_for_each_entry_continue().
+ */
+#define list_prepare_entry(pos, head, member) \
+	((pos) ? : list_entry(head, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue - continue iteration over list of given type
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Continue to iterate over list of given type, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue(pos, head, member) 		\
+	for (pos = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_continue_reverse - iterate backwards from the given point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Start to iterate over list of given type backwards, continuing after
+ * the current position.
+ */
+#define list_for_each_entry_continue_reverse(pos, head, member)		\
+	for (pos = list_entry(pos->member.prev, typeof(*pos), member);	\
+	     &pos->member != (head);	\
+	     pos = list_entry(pos->member.prev, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_from - iterate over list of given type from the current point
+ * @pos:	the type * to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing from current position.
+ */
+#define list_for_each_entry_from(pos, head, member) 			\
+	for (; &pos->member != (head);	\
+	     pos = list_entry(pos->member.next, typeof(*pos), member))
+
+/**
+ * list_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ */
+#define list_for_each_entry_safe(pos, n, head, member)			\
+	for (pos = list_entry((head)->next, typeof(*pos), member),	\
+		n = list_entry(pos->member.next, typeof(*pos), member);	\
+	     &pos->member != (head); 					\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_continue
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type, continuing after current point,
+ * safe against removal of list entry.
+ */
+#define list_for_each_entry_safe_continue(pos, n, head, member) 		\
+	for (pos = list_entry(pos->member.next, typeof(*pos), member), 		\
+		n = list_entry(pos->member.next, typeof(*pos), member);		\
+	     &pos->member != (head);						\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_from
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate over list of given type from current point, safe against
+ * removal of list entry.
+ */
+#define list_for_each_entry_safe_from(pos, n, head, member) 			\
+	for (n = list_entry(pos->member.next, typeof(*pos), member);		\
+	     &pos->member != (head);						\
+	     pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+/**
+ * list_for_each_entry_safe_reverse
+ * @pos:	the type * to use as a loop cursor.
+ * @n:		another type * to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the list_struct within the struct.
+ *
+ * Iterate backwards over list of given type, safe against removal
+ * of list entry.
+ */
+#define list_for_each_entry_safe_reverse(pos, n, head, member)		\
+	for (pos = list_entry((head)->prev, typeof(*pos), member),	\
+		n = list_entry(pos->member.prev, typeof(*pos), member);	\
+	     &pos->member != (head); 					\
+	     pos = n, n = list_entry(n->member.prev, typeof(*n), member))
+
+/*
+ * Double linked lists with a single pointer list head.
+ * Mostly useful for hash tables where the two pointer list head is
+ * too wasteful.
+ * You lose the ability to access the tail in O(1).
+ */
+
+struct hlist_head {
+	struct hlist_node *first;
+};
+
+struct hlist_node {
+	struct hlist_node *next, **pprev;
+};
+
+#define HLIST_HEAD_INIT { .first = NULL }
+#define HLIST_HEAD(name) struct hlist_head name = {  .first = NULL }
+#define INIT_HLIST_HEAD(ptr) ((ptr)->first = NULL)
+static inline void INIT_HLIST_NODE(struct hlist_node *h)
+{
+	h->next = NULL;
+	h->pprev = NULL;
+}
+
+static inline int hlist_unhashed(const struct hlist_node *h)
+{
+	return !h->pprev;
+}
+
+static inline int hlist_empty(const struct hlist_head *h)
+{
+	return !h->first;
+}
+
+static inline void __hlist_del(struct hlist_node *n)
+{
+	struct hlist_node *next = n->next;
+	struct hlist_node **pprev = n->pprev;
+	*pprev = next;
+	if (next)
+		next->pprev = pprev;
+}
+
+static inline void hlist_del(struct hlist_node *n)
+{
+	__hlist_del(n);
+	n->next = NULL;
+	n->pprev = NULL;
+}
+
+static inline void hlist_del_init(struct hlist_node *n)
+{
+	if (!hlist_unhashed(n)) {
+		__hlist_del(n);
+		INIT_HLIST_NODE(n);
+	}
+}
+
+
+static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
+{
+	struct hlist_node *first = h->first;
+	n->next = first;
+	if (first)
+		first->pprev = &n->next;
+	h->first = n;
+	n->pprev = &h->first;
+}
+
+
+/* next must be != NULL */
+static inline void hlist_add_before(struct hlist_node *n,
+					struct hlist_node *next)
+{
+	n->pprev = next->pprev;
+	n->next = next;
+	next->pprev = &n->next;
+	*(n->pprev) = n;
+}
+
+static inline void hlist_add_after(struct hlist_node *n,
+					struct hlist_node *next)
+{
+	next->next = n->next;
+	n->next = next;
+	next->pprev = &n->next;
+
+	if(next->next)
+		next->next->pprev  = &next->next;
+}
+
+#define hlist_entry(ptr, type, member) container_of(ptr,type,member)
+
+#define hlist_for_each(pos, head) \
+	for (pos = (head)->first; pos; pos = pos->next)
+
+#define hlist_for_each_safe(pos, n, head) \
+	for (pos = (head)->first; pos; pos = n)
+
+/**
+ * hlist_for_each_entry	- iterate over list of given type
+ * @tpos:	the type * to use as a loop cursor.
+ * @pos:	the &struct hlist_node to use as a loop cursor.
+ * @head:	the head for your list.
+ * @member:	the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry(tpos, pos, head, member)			 \
+	for (pos = (head)->first; pos &&				 \
+		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+	     pos = pos->next)
+
+/**
+ * hlist_for_each_entry_continue - iterate over a hlist continuing after current point
+ * @tpos:	the type * to use as a loop cursor.
+ * @pos:	the &struct hlist_node to use as a loop cursor.
+ * @member:	the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_continue(tpos, pos, member)		\
+	for (pos = (pos)->next; pos &&					\
+	     ({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;});   \
+	     pos = pos->next)
+
+/**
+ * hlist_for_each_entry_from - iterate over a hlist continuing from current point
+ * @tpos:	the type * to use as a loop cursor.
+ * @pos:	the &struct hlist_node to use as a loop cursor.
+ * @member:	the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_from(tpos, pos, member)			 \
+	for (; pos &&			 \
+		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+	     pos = pos->next)
+
+/**
+ * hlist_for_each_entry_safe - iterate over list of given type safe against removal of list entry
+ * @tpos:	the type * to use as a loop cursor.
+ * @pos:	the &struct hlist_node to use as a loop cursor.
+ * @n:		another &struct hlist_node to use as temporary storage
+ * @head:	the head for your list.
+ * @member:	the name of the hlist_node within the struct.
+ */
+#define hlist_for_each_entry_safe(tpos, pos, n, head, member) 		 \
+	for (pos = (head)->first;					 \
+	     pos && ({ n = pos->next; 1; }) && 				 \
+		({ tpos = hlist_entry(pos, typeof(*tpos), member); 1;}); \
+	     pos = n)
+
+#endif