[PATCH 17/33] Daemonizing the Process

[Janani Venkataraman <jananive@linux.vnet.ibm.com>]

For the purpose of a self dump, we start a daemon which accepts requests and
acts like a server. This method was adapted from the CRIU self dump
application.

Checks if the process is running as root, if yes daemonizes it through the
daemon library call and opens a log file to log in the events of the daemon.

Signed-off-by: Janani Venkataraman <jananive@linux.vnet.ibm.com>
---
 src/coredump.c |   35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/src/coredump.c b/src/coredump.c
index a6bcaae..09fb8da 100644
--- a/src/coredump.c
+++ b/src/coredump.c
@@ -29,6 +29,9 @@
 #include <dirent.h>
 #include <errno.h>
 #include <elf.h>
+#include <errno.h>
+#include <syslog.h>
+#include <signal.h>
 #include <sys/ptrace.h>
 #include <coredump.h>
 
@@ -50,6 +53,13 @@ void gencore_log(char *fmt, ...)
 /* Core process object */
 struct core_proc cp;
 
+#ifndef GENCORE_DAEMON_LOGFILE
+#define GENCORE_DAEMON_LOGFILE "/var/log/gencored.log"
+#endif
+
+/* PID of Daemon */
+int pid_log;
+
 /* Initialised core process members */
 void init_core(void)
 {
@@ -248,6 +258,31 @@ cleanup:
 /* Daemon for self dump */
 int daemon_dump(void)
 {
+	/* Check if daemon is running as root */
+	if (geteuid()) {
+		fprintf(stderr, "Run the daemon as root.\n");
+		return -1;
+	}
+
+	/* Daemonizing it */
+	if (daemon(0, 0)) {
+		fprintf(stderr, "Daemon not up %s.", strerror(errno));
+		return -1;
+	}
+
+	/* Get the PID of the daemon */
+	pid_log = getpid();
+
+	fp_log = fopen(GENCORE_DAEMON_LOGFILE, "w+");
+	if (fp_log == NULL) {
+		openlog("gencore_daemon_log", LOG_PID|LOG_CONS, LOG_USER);
+		syslog(LOG_DAEMON, "Could not open: %s.\n",
+					GENCORE_DAEMON_LOGFILE);
+		closelog();
+		return -1;
+	}
+
+	fclose(fp_log);
 	return 0;
 }