drivers/syslog: Prepend Process ID to syslog message

Change-Id: I999045034a29acb06f39710436c06b427c543b00
Signed-off-by: chao.an <anchao@xiaomi.com>

drivers/syslog/Kconfig

@@ -111,6 +111,12 @@ config SYSLOG_TIMESTAMP_REALTIME
 		CLOCK_MONOTONIC, if enabled, will be used or the system timer
 		is not.
 
+config SYSLOG_PROCESSID
+	bool "Prepend Process ID to syslog message"
+	default n
+	---help---
+		Prepend Process ID to syslog message.
+
 config SYSLOG_PREFIX
 	bool "Prepend prefix to syslog message"
 	default n

drivers/syslog/vsyslog.c

@@ -138,6 +138,12 @@ int nx_vsyslog(int priority, FAR const IPTR char *fmt, FAR va_list *ap)
   ret = 0;
 #endif
 
+#if defined(CONFIG_SYSLOG_PROCESSID)
+  /* Pre-pend the Process ID */
+
+  ret += lib_sprintf(&stream.public, "[%2d] ", (int)getpid());
+#endif
+
 #if defined(CONFIG_SYSLOG_PREFIX)
   /* Pre-pend the prefix, if available */