PR6930: staprun: supports error message to syslog

Add an interface (eprintf) to output error messages to syslogd,
because staprun has no stderr after detaching from console.

3 files changed, 33 insertions, 8 deletions

diff --git a/runtime/staprun/common.c b/runtime/staprun/common.c
index fd16b4b8..b8860248 100644
--- a/runtime/staprun/common.c
+++ b/runtime/staprun/common.c
@@ -344,3 +344,24 @@ int send_request(int type, void *data, int len)
         if (rc < 0) return rc;
         return (rc != len+4);
 }
+
+#include <stdarg.h>
+
+static int use_syslog = 0;
+
+void eprintf(const char *fmt, ...)
+{
+	va_list va;
+	va_start(va, fmt);
+	if (use_syslog)
+		vsyslog(LOG_ERR, fmt, va);
+	else
+		vfprintf(stderr, fmt, va);
+	va_end(va);
+}
+
+void switch_syslog(const char *name)
+{
+	openlog(name, LOG_PID, LOG_DAEMON);
+	use_syslog = 1;
+}
diff --git a/runtime/staprun/mainloop.c b/runtime/staprun/mainloop.c
index db6ef6b7..e91e6302 100644
--- a/runtime/staprun/mainloop.c
+++ b/runtime/staprun/mainloop.c
@@ -468,7 +468,7 @@ int stp_main_loop(void)
       }
 #endif
     case STP_OOB_DATA:
-      fputs((char *)data, stderr);
+      eprintf("%s", (char *)data);
       break;
     case STP_EXIT:
       {
diff --git a/runtime/staprun/staprun.h b/runtime/staprun/staprun.h
index 84cf63fc..4c43e3ee 100644
--- a/runtime/staprun/staprun.h
+++ b/runtime/staprun/staprun.h
@@ -33,31 +33,35 @@
 #include <sys/wait.h>
 #include <sys/statfs.h>
 #include <linux/version.h>
+#include <syslog.h>
 
 /* Include config.h to pick up dependency for --prefix usage. */
 #include "config.h"
 
-#define dbug(level, args...) {if (verbose>=level) {fprintf(stderr,"%s:%s:%d ",__name__,__FUNCTION__, __LINE__); fprintf(stderr,args);}}
+extern void eprintf(const char *fmt, ...);
+extern void switch_syslog(const char *name);
+
+#define dbug(level, args...) do {if (verbose>=level) {eprintf("%s:%s:%d ",__name__,__FUNCTION__, __LINE__); eprintf(args);}} while (0)
 
 extern char *__name__;
 
 /* print to stderr */
-#define err(args...) fprintf(stderr,args)
+#define err(args...) eprintf(args)
 
 /* better perror() */
 #define perr(args...) do {					\
 		int _errno = errno;				\
-		fputs("ERROR: ", stderr);			\
-		fprintf(stderr, args);				\
-		fprintf(stderr, ": %s\n", strerror(_errno));	\
+		eprintf("ERROR: ");				\
+		eprintf(args);					\
+		eprintf(": %s\n", strerror(_errno));		\
 	} while (0)
 
 /* Error messages. Use these for serious errors, not informational messages to stderr. */
-#define _err(args...) do {fprintf(stderr,"%s:%s:%d: ERROR: ",__name__, __FUNCTION__, __LINE__); fprintf(stderr,args);} while(0)
+#define _err(args...) do {eprintf("%s:%s:%d: ERROR: ",__name__, __FUNCTION__, __LINE__); eprintf(args);} while(0)
 #define _perr(args...) do {					\
 		int _errno = errno;				\
 		_err(args);					\
-		fprintf(stderr, ": %s\n", strerror(_errno));	\
+		eprintf(": %s\n", strerror(_errno));	\
 	} while (0)
 #define overflow_error() _err("Internal buffer overflow. Please file a bug report.\n")