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

[Jiri Olsa]

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@xxxxxxxxxx>
---
 tools/perf/builtin-daemon.c | 117 +++++++++++++++++++++++++++++++++++-
 1 file changed, 116 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-daemon.c b/tools/perf/builtin-daemon.c
index ce0373f453d6..495e4ff120ed 100644
--- a/tools/perf/builtin-daemon.c
+++ b/tools/perf/builtin-daemon.c
@@ -1,12 +1,19 @@
 // SPDX-License-Identifier: GPL-2.0
+#include <internal/lib.h>
 #include <subcmd/parse-options.h>
+#include <api/fd/array.h>
 #include <linux/limits.h>
+#include <linux/string.h>
 #include <string.h>
 #include <signal.h>
 #include <stdlib.h>
 #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 +44,92 @@ static void sig_handler(int sig __maybe_unused)
 	done = true;
 }
 
+static int setup_server_socket(struct daemon *daemon)
+{
+	struct sockaddr_un addr;
+	char path[PATH_MAX];
+	int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+
+	if (fd < 0) {
+		fprintf(stderr, "socket: %s\n", strerror(errno));
+		return -1;
+	}
+
+	if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
+		perror("failed: fcntl FD_CLOEXEC");
+		close(fd);
+		return -1;
+	}
+
+	scnprintf(path, sizeof(path), "%s/control", daemon->base);
+
+	if (strlen(path) + 1 >= sizeof(addr.sun_path)) {
+		pr_err("failed: control path too long '%s'\n", path);
+		close(fd);
+		return -1;
+	}
+
+	memset(&addr, 0, sizeof(addr));
+	addr.sun_family = AF_UNIX;
+
+	strlcpy(addr.sun_path, path, sizeof(addr.sun_path) - 1);
+	unlink(path);
+
+	if (bind(fd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
+		perror("failed: bind");
+		close(fd);
+		return -1;
+	}
+
+	if (listen(fd, 1) == -1) {
+		perror("failed: listen");
+		close(fd);
+		return -1;
+	}
+
+	return fd;
+}
+
+union cmd {
+	int cmd;
+};
+
+static int handle_server_socket(struct daemon *daemon __maybe_unused, int sock_fd)
+{
+	int ret = -1, fd;
+	FILE *out = NULL;
+	union cmd cmd;
+
+	fd = accept(sock_fd, NULL, NULL);
+	if (fd < 0) {
+		perror("failed: accept");
+		return -1;
+	}
+
+	if (sizeof(cmd) != readn(fd, &cmd, sizeof(cmd))) {
+		perror("failed: read");
+		goto out;
+	}
+
+	out = fdopen(fd, "w");
+	if (!out) {
+		perror("failed: fdopen");
+		goto out;
+	}
+
+	switch (cmd.cmd) {
+	default:
+		break;
+	}
+
+	fclose(out);
+out:
+	/* If out is defined, then fd is closed via fclose. */
+	if (!out)
+		close(fd);
+	return ret;
+}
+
 static void daemon__exit(struct daemon *daemon)
 {
 	free(daemon->config_real);
@@ -77,6 +170,9 @@ 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);
@@ -93,15 +189,34 @@ 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