unix-socket: add backlog size option to unix_stream_listen()

Update `unix_stream_listen()` to take an options structure to override
default behaviors.  This commit includes the size of the `listen()` backlog.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 19 insertions, 4 deletions

diff --git a/builtin/credential-cache--daemon.c b/builtin/credential-cache--daemon.c
index c61f123a3b..4c6c89ab0d 100644
--- a/builtin/credential-cache--daemon.c
+++ b/builtin/credential-cache--daemon.c
@@ -203,9 +203,10 @@ static int serve_cache_loop(int fd)
 
 static void serve_cache(const char *socket_path, int debug)
 {
+	struct unix_stream_listen_opts opts = UNIX_STREAM_LISTEN_OPTS_INIT;
 	int fd;
 
-	fd = unix_stream_listen(socket_path);
+	fd = unix_stream_listen(socket_path, &opts);
 	if (fd < 0)
 		die_errno("unable to bind to '%s'", socket_path);
 
diff --git a/unix-socket.c b/unix-socket.c
index 69f81d64e9..012becd93d 100644
--- a/unix-socket.c
+++ b/unix-socket.c
@@ -1,6 +1,8 @@
 #include "cache.h"
 #include "unix-socket.h"
 
+#define DEFAULT_UNIX_STREAM_LISTEN_BACKLOG (5)
+
 static int chdir_len(const char *orig, int len)
 {
 	char *path = xmemdupz(orig, len);
@@ -89,9 +91,11 @@ fail:
 	return -1;
 }
 
-int unix_stream_listen(const char *path)
+int unix_stream_listen(const char *path,
+		       const struct unix_stream_listen_opts *opts)
 {
 	int fd = -1, saved_errno;
+	int backlog;
 	struct sockaddr_un sa;
 	struct unix_sockaddr_context ctx;
 
@@ -106,7 +110,10 @@ int unix_stream_listen(const char *path)
 	if (bind(fd, (struct sockaddr *)&sa, sizeof(sa)) < 0)
 		goto fail;
 
-	if (listen(fd, 5) < 0)
+	backlog = opts->listen_backlog_size;
+	if (backlog <= 0)
+		backlog = DEFAULT_UNIX_STREAM_LISTEN_BACKLOG;
+	if (listen(fd, backlog) < 0)
 		goto fail;
 
 	unix_sockaddr_cleanup(&ctx);
diff --git a/unix-socket.h b/unix-socket.h
index e271aeec5a..ec2fb3ea72 100644
--- a/unix-socket.h
+++ b/unix-socket.h
@@ -1,7 +1,14 @@
 #ifndef UNIX_SOCKET_H
 #define UNIX_SOCKET_H
 
+struct unix_stream_listen_opts {
+	int listen_backlog_size;
+};
+
+#define UNIX_STREAM_LISTEN_OPTS_INIT { 0 }
+
 int unix_stream_connect(const char *path);
-int unix_stream_listen(const char *path);
+int unix_stream_listen(const char *path,
+		       const struct unix_stream_listen_opts *opts);
 
 #endif /* UNIX_SOCKET_H */