From 13755d946d034eb7395a818db7ace2c9cb60b4cb Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Mon, 10 Oct 2011 19:51:26 +0200
Subject: [PATCH] server: improve pidfile and log handling

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 log.c    | 20 ++++++++++++++++++--
 log.h    |  1 +
 server.c | 54 +++++++++++++++++++++++++++++++++++++++++++++---------
 server.h |  2 +-
 4 files changed, 65 insertions(+), 12 deletions(-)

diff --git a/log.c b/log.c
index a16baafc..af974f85 100644
--- a/log.c
+++ b/log.c
@@ -21,6 +21,16 @@ int log_valist(const char *str, va_list args)
 	return len;
 }
 
+int log_local_buf(const char *buf, size_t len)
+{
+	if (log_syslog)
+		syslog(LOG_INFO, "%s", buf);
+	else
+		len = fwrite(buf, len, 1, f_out);
+
+	return len;
+}
+
 int log_local(const char *format, ...)
 {
 	char buffer[1024];
@@ -51,7 +61,10 @@ int log_info(const char *format, ...)
 
 	if (is_backend)
 		return fio_server_text_output(buffer, len);
-	else
+	else if (log_syslog) {
+		syslog(LOG_INFO, "%s", buffer);
+		return len;
+	} else
 		return fwrite(buffer, len, 1, f_out);
 }
 
@@ -67,7 +80,10 @@ int log_err(const char *format, ...)
 
 	if (is_backend)
 		return fio_server_text_output(buffer, len);
-	else {
+	else if (log_syslog) {
+		syslog(LOG_INFO, "%s", buffer);
+		return len;
+	} else {
 		if (f_err != stderr) {
 			int fio_unused ret;
 
diff --git a/log.h b/log.h
index a69846ef..fdf3d7b1 100644
--- a/log.h
+++ b/log.h
@@ -11,5 +11,6 @@ extern int log_err(const char *format, ...);
 extern int log_info(const char *format, ...);
 extern int log_local(const char *format, ...);
 extern int log_valist(const char *str, va_list);
+extern int log_local_buf(const char *buf, size_t);
 
 #endif
diff --git a/server.c b/server.c
index 2de65ad2..4f9c0231 100644
--- a/server.c
+++ b/server.c
@@ -525,12 +525,12 @@ out:
 	return exitval;
 }
 
-int fio_server_text_output(const char *buf, unsigned int len)
+int fio_server_text_output(const char *buf, size_t len)
 {
 	if (server_fd != -1)
 		return fio_net_send_cmd(server_fd, FIO_NET_CMD_TEXT, buf, len, 0);
 
-	return fwrite(buf, len, 1, f_err);
+	return log_local_buf(buf, len);
 }
 
 static void convert_io_stat(struct io_stat *dst, struct io_stat *src)
@@ -924,17 +924,46 @@ static void server_signal_handler(void)
 	sigaction(SIGTERM, &act, NULL);
 }
 
-static void write_pid(pid_t pid, const char *pidfile)
+static int check_existing_pidfile(const char *pidfile)
+{
+	struct stat sb;
+	char buf[16];
+	pid_t pid;
+	FILE *f;
+
+	if (stat(pidfile, &sb))
+		return 0;
+
+	f = fopen(pidfile, "r");
+	if (!f)
+		return 0;
+
+	if (fread(buf, sb.st_size, 1, f) < 0) {
+		fclose(f);
+		return 1;
+	}
+	fclose(f);
+
+	pid = atoi(buf);
+	if (kill(pid, SIGCONT) < 0)
+		return 0;
+
+	return 1;
+}
+
+static int write_pid(pid_t pid, const char *pidfile)
 {
 	FILE *fpid;
 
 	fpid = fopen(pidfile, "w");
 	if (!fpid) {
 		log_err("fio: failed opening pid file %s\n", pidfile);
-		return;
+		return 1;
 	}
 
 	fprintf(fpid, "%u\n", (unsigned int) pid);
+	fclose(fpid);
+	return 0;
 }
 
 /*
@@ -950,24 +979,31 @@ int fio_start_server(char *pidfile)
 	if (!pidfile)
 		return fio_server();
 
-	openlog("fio", LOG_NDELAY|LOG_NOWAIT|LOG_PID, LOG_USER);
+	if (check_existing_pidfile(pidfile)) {
+		log_err("fio: pidfile %s exists and server appears alive\n",
+								pidfile);
+		return -1;
+	}
+
 	pid = fork();
 	if (pid < 0) {
-		syslog(LOG_ERR, "failed server fork");
+		log_err("fio: failed server fork: %s", strerror(errno));
 		free(pidfile);
 		return -1;
 	} else if (pid) {
-		write_pid(pid, pidfile);
-		exit(0);
+		int ret = write_pid(pid, pidfile);
+
+		exit(ret);
 	}
 
 	setsid();
+	openlog("fio", LOG_NDELAY|LOG_NOWAIT|LOG_PID, LOG_USER);
+	log_syslog = 1;
 	close(STDIN_FILENO);
 	close(STDOUT_FILENO);
 	close(STDERR_FILENO);
 	f_out = NULL;
 	f_err = NULL;
-	log_syslog = 1;
 
 	ret = fio_server();
 
diff --git a/server.h b/server.h
index 72e4cc88..ea888af4 100644
--- a/server.h
+++ b/server.h
@@ -76,7 +76,7 @@ struct cmd_line_pdu {
 };
 
 extern int fio_start_server(char *);
-extern int fio_server_text_output(const char *, unsigned int len);
+extern int fio_server_text_output(const char *, size_t);
 extern int fio_server_log(const char *format, ...);
 extern int fio_net_send_cmd(int, uint16_t, const void *, off_t, uint64_t);
 extern int fio_net_send_simple_cmd(int sk, uint16_t opcode, uint64_t tag);
-- 
2.25.1