From: David Goulet <dgoulet@efficios.com>
Date: Fri, 11 Jan 2013 20:12:12 +0000 (-0500)
Subject: Add pidfile creation for lttng-sessiond
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=35f90c40cf023393851ac47ad526a0e9e1184503

Add pidfile creation for lttng-sessiond

This also adds a pidfile function to common/utils.c so it could be used
by the all binaries needing this feature.

Fixes #276

Signed-off-by: David Goulet <dgoulet@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c
index 237a2cf8d..e5a22460f 100644
--- a/src/bin/lttng-sessiond/main.c
+++ b/src/bin/lttng-sessiond/main.c
@@ -72,6 +72,7 @@ const char default_global_apps_pipe[] = DEFAULT_GLOBAL_APPS_PIPE;
 
 const char *progname;
 const char *opt_tracing_group;
+static const char *opt_pidfile;
 static int opt_sig_parent;
 static int opt_verbose_consumer;
 static int opt_daemon;
@@ -404,6 +405,17 @@ static void cleanup(void)
 	/* First thing first, stop all threads */
 	utils_close_pipe(thread_quit_pipe);
 
+	/*
+	 * If opt_pidfile is undefined, the default file will be wiped when
+	 * removing the rundir.
+	 */
+	if (opt_pidfile) {
+		ret = remove(opt_pidfile);
+		if (ret < 0) {
+			PERROR("remove pidfile %s", opt_pidfile);
+		}
+	}
+
 	DBG("Removing %s directory", rundir);
 	ret = asprintf(&cmd, "rm -rf %s", rundir);
 	if (ret < 0) {
@@ -3406,6 +3418,7 @@ static void usage(void)
 	fprintf(stderr, "  -S, --sig-parent                   Send SIGCHLD to parent pid to notify readiness.\n");
 	fprintf(stderr, "  -q, --quiet                        No output at all.\n");
 	fprintf(stderr, "  -v, --verbose                      Verbose mode. Activate DBG() macro.\n");
+	fprintf(stderr, "  -p, --pidfile FILE                 Write a pid to FILE name overriding the default value.\n");
 	fprintf(stderr, "      --verbose-consumer             Verbose mode for consumer. Activate DBG() macro.\n");
 	fprintf(stderr, "      --no-kernel                    Disable kernel tracer\n");
 }
@@ -3439,12 +3452,13 @@ static int parse_args(int argc, char **argv)
 		{ "verbose", 0, 0, 'v' },
 		{ "verbose-consumer", 0, 0, 'Z' },
 		{ "no-kernel", 0, 0, 'N' },
+		{ "pidfile", 1, 0, 'p' },
 		{ NULL, 0, 0, 0 }
 	};
 
 	while (1) {
 		int option_index = 0;
-		c = getopt_long(argc, argv, "dhqvVSN" "a:c:g:s:C:E:D:F:Z:u:t",
+		c = getopt_long(argc, argv, "dhqvVSN" "a:c:g:s:C:E:D:F:Z:u:t:p:",
 				long_options, &option_index);
 		if (c == -1) {
 			break;
@@ -3521,6 +3535,9 @@ static int parse_args(int argc, char **argv)
 		case 'T':
 			consumerd64_libdir = optarg;
 			break;
+		case 'p':
+			opt_pidfile = optarg;
+			break;
 		default:
 			/* Unknown option or other error.
 			 * Error is printed by getopt, just return */
@@ -3847,6 +3864,38 @@ static void set_ulimit(void)
 	}
 }
 
+/*
+ * Write pidfile using the rundir and opt_pidfile.
+ */
+static void write_pidfile(void)
+{
+	int ret;
+	char pidfile_path[PATH_MAX];
+
+	assert(rundir);
+
+	if (opt_pidfile) {
+		strncpy(pidfile_path, opt_pidfile, sizeof(pidfile_path));
+	} else {
+		/* Build pidfile path from rundir and opt_pidfile. */
+		ret = snprintf(pidfile_path, sizeof(pidfile_path), "%s/"
+				DEFAULT_LTTNG_SESSIOND_PIDFILE, rundir);
+		if (ret < 0) {
+			PERROR("snprintf pidfile path");
+			goto error;
+		}
+	}
+
+	/*
+	 * Create pid file in rundir. Return value is of no importance. The
+	 * execution will continue even though we are not able to write the file.
+	 */
+	(void) utils_create_pid_file(getpid(), pidfile_path);
+
+error:
+	return;
+}
+
 /*
  * main
  */
@@ -4144,6 +4193,8 @@ int main(int argc, char **argv)
 		app_socket_timeout = DEFAULT_APP_SOCKET_RW_TIMEOUT;
 	}
 
+	write_pidfile();
+
 	/* Create thread to manage the client socket */
 	ret = pthread_create(&health_thread, NULL,
 			thread_manage_health, (void *) NULL);
diff --git a/src/common/defaults.h b/src/common/defaults.h
index efcd7924b..0dde57964 100644
--- a/src/common/defaults.h
+++ b/src/common/defaults.h
@@ -72,6 +72,7 @@
 /* Default lttng run directory */
 #define DEFAULT_LTTNG_RUNDIR                    "/var/run/lttng"
 #define DEFAULT_LTTNG_HOME_RUNDIR               "%s/.lttng"
+#define DEFAULT_LTTNG_SESSIOND_PIDFILE          "lttng-sessiond.pid"
 
 /* Default unix socket path */
 #define DEFAULT_GLOBAL_CLIENT_UNIX_SOCK         DEFAULT_LTTNG_RUNDIR "/client-lttng-sessiond"
diff --git a/src/common/utils.c b/src/common/utils.c
index 1a0e47ec4..2f114934f 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -16,6 +16,7 @@
  */
 
 #define _GNU_SOURCE
+#include <assert.h>
 #include <ctype.h>
 #include <fcntl.h>
 #include <limits.h>
@@ -202,3 +203,32 @@ int utils_set_fd_cloexec(int fd)
 end:
 	return ret;
 }
+
+/*
+ * Create pid file to the given path and filename.
+ */
+__attribute__((visibility("hidden")))
+int utils_create_pid_file(pid_t pid, const char *filepath)
+{
+	int ret;
+	FILE *fp;
+
+	assert(filepath);
+
+	fp = fopen(filepath, "w");
+	if (fp == NULL) {
+		PERROR("open pid file %s", filepath);
+		ret = -1;
+		goto error;
+	}
+
+	ret = fprintf(fp, "%d\n", pid);
+	if (ret < 0) {
+		PERROR("fprintf pid file");
+	}
+
+	fclose(fp);
+	DBG("Pid %d written in file %s", pid, filepath);
+error:
+	return ret;
+}
diff --git a/src/common/utils.h b/src/common/utils.h
index c5723aa1d..95e1b6707 100644
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -24,5 +24,6 @@ int utils_create_pipe_cloexec(int *dst);
 void utils_close_pipe(int *src);
 char *utils_strdupdelim(const char *begin, const char *end);
 int utils_set_fd_cloexec(int fd);
+int utils_create_pid_file(pid_t pid, const char *filepath);
 
 #endif /* _COMMON_UTILS_H */