remote debugger

lualib-src/lua-debugchannel.c

@@ -0,0 +1,195 @@
+// only for debug use
+#include <lua.h>
+#include <lauxlib.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define METANAME "debugchannel"
+#define LOCK(q) while (__sync_lock_test_and_set(&(q)->lock,1)) {}
+#define UNLOCK(q) __sync_lock_release(&(q)->lock);
+
+struct command {
+	struct command * next;
+	size_t sz;
+};
+
+struct channel {
+	int lock;
+	int ref;
+	struct command * head;
+	struct command * tail;
+};
+
+static struct channel *
+channel_new() {
+	struct channel * c = malloc(sizeof(*c));
+	memset(c, 0 , sizeof(*c));
+	c->ref = 1;
+
+	return c;
+}
+
+static struct channel *
+channel_connect(struct channel *c) {
+	struct channel * ret = NULL;
+	LOCK(c)
+	if (c->ref == 1) {
+		++c->ref;
+		ret = c;
+	}
+	UNLOCK(c)
+	return ret;
+}
+
+static struct channel *
+channel_release(struct channel *c) {
+	LOCK(c)
+	--c->ref;
+	if (c->ref > 0) {
+		UNLOCK(c)
+		return c;
+	}
+	// never unlock while reference is 0
+	struct command * p = c->head;
+	c->head = NULL;
+	c->tail = NULL;
+	while(p) {
+		struct command *next = p->next;
+		free(p);
+		p = next;
+	}
+	return NULL;
+}
+
+// call free after channel_read
+static struct command *
+channel_read(struct channel *c, double timeout) {
+	struct command * ret = NULL;
+	LOCK(c)
+	if (c->head == NULL) {
+		UNLOCK(c)
+		int ti = (int)(timeout * 100000);
+		usleep(ti);
+		return NULL;
+	}
+	ret = c->head;
+	c->head = ret->next;
+	if (c->head == NULL) {
+		c->tail = NULL;
+	}
+	UNLOCK(c)
+	
+	return ret;
+}
+
+static void
+channel_write(struct channel *c, const char * s, size_t sz) {
+	struct command * cmd = malloc(sizeof(*cmd)+ sz);
+	cmd->sz = sz;
+	cmd->next = NULL;
+	memcpy(cmd+1, s, sz);
+	LOCK(c)
+	if (c->tail == NULL) {
+		c->head = c->tail = cmd;
+	} else {
+		c->tail->next = cmd;
+		c->tail = cmd;
+	}
+	UNLOCK(c)
+}
+
+struct channel_box {
+	struct channel *c;
+};
+
+static int
+lread(lua_State *L) {
+	struct channel_box *cb = luaL_checkudata(L,1, METANAME);
+	double ti = luaL_optnumber(L, 2, 0);
+	struct command * c = channel_read(cb->c, ti);
+	if (c == NULL)
+		return 0;
+	lua_pushlstring(L, (const char *)(c+1), c->sz);
+	free(c);
+	return 1;
+}
+
+static int
+lwrite(lua_State *L) {
+	struct channel_box *cb = luaL_checkudata(L,1, METANAME);
+	size_t sz;
+	const char * str = luaL_checklstring(L, 2, &sz);
+	channel_write(cb->c, str, sz);
+	return 0;
+}
+
+static int
+lrelease(lua_State *L) {
+	struct channel_box *cb = lua_touserdata(L, 1);
+	if (cb) {
+		if (channel_release(cb->c) == NULL) {
+			cb->c = NULL;
+		}
+	}
+
+	return 0;
+}
+
+static struct channel *
+new_channel(lua_State *L, struct channel *c) {
+	if (c == NULL) {
+		c = channel_new();
+	} else {
+		c = channel_connect(c);
+	}
+	if (c == NULL) {
+		luaL_error(L, "new channel failed");
+		// never go here
+	}
+	struct channel_box * cb = lua_newuserdata(L, sizeof(*cb));
+	cb->c = c;
+	if (luaL_newmetatable(L, METANAME)) {
+		luaL_Reg l[]={
+			{ "read", lread },
+			{ "write", lwrite },
+			{ NULL, NULL },
+		};
+		luaL_newlib(L,l);
+		lua_setfield(L, -2, "__index");
+		lua_pushcfunction(L, lrelease);
+		lua_setfield(L, -2, "__gc");
+	}
+	lua_setmetatable(L, -2);
+	return c;
+}
+
+static int
+lcreate(lua_State *L) {
+	struct channel *c = new_channel(L, NULL);
+	lua_pushlightuserdata(L, c);
+	return 2;
+}
+
+static int
+lconnect(lua_State *L) {
+	struct channel *c = lua_touserdata(L, 1);
+	if (c == NULL)
+		return luaL_error(L, "Invalid channel pointer");
+	new_channel(L, c);
+
+	return 1;
+}
+
+int
+luaopen_debugchannel(lua_State *L) {
+	luaL_Reg l[] = {
+		{ "create", lcreate },	// for write
+		{ "connect", lconnect },	// for read
+		{ "release", lrelease },
+		{ NULL, NULL },
+	};
+	luaL_checkversion(L);
+	luaL_newlib(L,l);
+	return 1;
+}