[PATCH/RFC 09/11] daemon: use run-command api for async serving

[Erik Faye-Lund <kusmabite@googlemail.com>]

fork() is only available on POSIX, so to support git-daemon
on Windows we have to use something else. Conveniently
enough, we have an API for async operation already.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
---
 daemon.c |   79 ++++++++++++++++++++++++++++---------------------------------
 1 files changed, 36 insertions(+), 43 deletions(-)

diff --git a/daemon.c b/daemon.c
index a0aead5..1b0e290 100644
--- a/daemon.c
+++ b/daemon.c
@@ -372,7 +372,8 @@ static int run_service_command(int fd, const char **argv)
 	cld.argv = argv;
 	cld.git_cmd = 1;
 	cld.err = -1;
-	cld.in = cld.out = fd;
+	cld.in = dup(fd);
+	cld.out = fd;
 	if (start_command(&cld))
 		return -1;
 
@@ -609,11 +610,11 @@ static unsigned int live_children;
 
 static struct child {
 	struct child *next;
-	pid_t pid;
+	struct async async;
 	struct sockaddr_storage address;
 } *firstborn;
 
-static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
+static void add_child(struct async *async, struct sockaddr *addr, int addrlen)
 {
 	struct child *newborn, **cradle;
 
@@ -623,7 +624,7 @@ static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 	 */
 	newborn = xcalloc(1, sizeof(*newborn));
 	live_children++;
-	newborn->pid = pid;
+	memcpy(&newborn->async, async, sizeof(struct async));
 	memcpy(&newborn->address, addr, addrlen);
 	for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 		if (!memcmp(&(*cradle)->address, &newborn->address,
@@ -633,19 +634,6 @@ static void add_child(pid_t pid, struct sockaddr *addr, int addrlen)
 	*cradle = newborn;
 }
 
-static void remove_child(pid_t pid)
-{
-	struct child **cradle, *blanket;
-
-	for (cradle = &firstborn; (blanket = *cradle); cradle = &blanket->next)
-		if (blanket->pid == pid) {
-			*cradle = blanket->next;
-			live_children--;
-			free(blanket);
-			break;
-		}
-}
-
 /*
  * This gets called if the number of connections grows
  * past "max_connections".
@@ -654,7 +642,7 @@ static void remove_child(pid_t pid)
  */
 static void kill_some_child(void)
 {
-	const struct child *blanket, *next;
+	struct child *blanket, *next;
 
 	if (!(blanket = firstborn))
 		return;
@@ -662,28 +650,37 @@ static void kill_some_child(void)
 	for (; (next = blanket->next); blanket = next)
 		if (!memcmp(&blanket->address, &next->address,
 			    sizeof(next->address))) {
-			kill(blanket->pid, SIGTERM);
+			kill_async(&blanket->async);
 			break;
 		}
 }
 
 static void check_dead_children(void)
 {
-	int status;
-	pid_t pid;
-
-	while ((pid = waitpid(-1, &status, WNOHANG)) > 0) {
-		const char *dead = "";
-		remove_child(pid);
-		if (!WIFEXITED(status) || (WEXITSTATUS(status) > 0))
-			dead = " (with error)";
-		loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
-	}
+	struct child **cradle, *blanket;
+	for (cradle = &firstborn; (blanket = *cradle);)
+		if (!is_async_alive(&blanket->async)) {
+			*cradle = blanket->next;
+			loginfo("Disconnected\n");
+			live_children--;
+			close(blanket->async.out);
+			free(blanket);
+		} else
+			cradle = &blanket->next;
+}
+
+int async_execute(int fd, void *data)
+{
+	int ret = execute(fd, data);
+	close(fd);
+	free(data);
+	return ret;
 }
 
 static void handle(int incoming, struct sockaddr *addr, int addrlen)
 {
-	pid_t pid;
+	struct sockaddr_storage *ss;
+	struct async async = { 0 };
 
 	if (max_connections && live_children >= max_connections) {
 		kill_some_child();
@@ -696,22 +693,18 @@ static void handle(int incoming, struct sockaddr *addr, int addrlen)
 		}
 	}
 
-	if ((pid = fork())) {
-		close(incoming);
-		if (pid < 0) {
-			logerror("Couldn't fork %s", strerror(errno));
-			return;
-		}
+	ss = xmalloc(sizeof(*ss));
+	memcpy(ss, addr, addrlen);
 
-		add_child(pid, addr, addrlen);
-		return;
-	}
+	async.proc = async_execute;
+	async.data = ss;
+	async.out = incoming;
 
-	dup2(incoming, 0);
-	dup2(incoming, 1);
+	if (start_async(&async))
+		logerror("unable to fork");
+	else
+		add_child(&async, addr, addrlen);
 	close(incoming);
-
-	exit(execute(0, addr));
 }
 
 static void child_handler(int signo)
-- 
1.6.5.rc2.7.g4f8d3