[PATCH 04/24] perf daemon: Add server socket support

[Jiri Olsa <jolsa@kernel.org>]

Add support to create server socket that listens for client
commands and process them.

This patch adds only the core support, all commands using
this functionality are coming in following patches.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/builtin-daemon.c | 101 +++++++++++++++++++++++++++++++++++-
 1 file changed, 100 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index 8d0ac44ec808..756d60616d7d 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <subcmd/parse-options.h>
+#include <api/fd/array.h>
 #include <linux/limits.h>
 #include <string.h>
 #include <signal.h>
@@ -7,6 +8,10 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <errno.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <poll.h>
 #include "builtin.h"
 #include "perf.h"
 #include "debug.h"
@@ -37,6 +42,78 @@ static void sig_handler(int sig __maybe_unused)
 	done = true;
 }
 
+static int setup_server_socket(struct daemon *daemon)
+{
+	struct sockaddr_un addr;
+	char path[100];
+	int fd;
+
+	fd = socket(AF_UNIX, SOCK_STREAM, 0);
+	if (fd < 0) {
+		fprintf(stderr, "socket: %s\n", strerror(errno));
+		return -1;
+	}
+
+	fcntl(fd, F_SETFD, FD_CLOEXEC);
+
+	scnprintf(path, PATH_MAX, "%s/control", daemon->base);
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_UNIX;
+
+	strncpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
+	unlink(path);
+
+	if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+		perror("failed: bind");
+		return -1;
+	}
+
+	if (listen(fd, 1) == -1) {
+		perror("failed: listen");
+		return -1;
+	}
+
+	return fd;
+}
+
+union cmd {
+	int cmd;
+};
+
+static int handle_server_socket(struct daemon *daemon __maybe_unused, int sock_fd)
+{
+	int ret = -EINVAL, fd;
+	union cmd cmd;
+	FILE *out;
+
+	fd = accept(sock_fd, NULL, NULL);
+	if (fd < 0) {
+		fprintf(stderr, "accept: %s\n", strerror(errno));
+		return -1;
+	}
+
+	if (sizeof(cmd) != read(fd, &cmd, sizeof(cmd))) {
+		fprintf(stderr, "read: %s\n", strerror(errno));
+		return -1;
+	}
+
+	out = fdopen(fd, "w");
+	if (!out) {
+		perror("failed: fdopen");
+		return -1;
+	}
+
+	switch (cmd.cmd) {
+	default:
+		break;
+	}
+
+	fclose(out);
+	close(fd);
+	return ret;
+}
+
 static void daemon__free(struct daemon *daemon)
 {
 	free(daemon->config_real);
@@ -82,6 +159,9 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 		OPT_PARENT(parent_options),
 		OPT_END()
 	};
+	int sock_fd = -1;
+	int sock_pos;
+	struct fdarray fda;
 	int err = 0;
 
 	argc = parse_options(argc, argv, start_options, daemon_usage, 0);
@@ -98,15 +178,34 @@ static int __cmd_start(struct daemon *daemon, struct option parent_options[],
 
 	pr_info("daemon started (pid %d)\n", getpid());
 
+	fdarray__init(&fda, 1);
+
+	sock_fd = setup_server_socket(daemon);
+	if (sock_fd < 0)
+		goto out;
+
+	sock_pos = fdarray__add(&fda, sock_fd, POLLIN|POLLERR|POLLHUP, 0);
+	if (sock_pos < 0)
+		goto out;
+
 	signal(SIGINT, sig_handler);
 	signal(SIGTERM, sig_handler);
 
 	while (!done && !err) {
-		sleep(1);
+		if (fdarray__poll(&fda, -1)) {
+			if (fda.entries[sock_pos].revents & POLLIN)
+				err = handle_server_socket(daemon, sock_fd);
+		}
 	}
 
+out:
+	fdarray__exit(&fda);
+
 	daemon__exit(daemon);
 
+	if (sock_fd != -1)
+		close(sock_fd);
+
 	pr_info("daemon exited\n");
 	fclose(daemon->out);
 	return err;
-- 
2.29.2