[PATCH v2] sysklogd/logread: implement dumpfollow mode of operation

[Phil Sutter]

This is basically a combination of the default (dump mode) and -f
(follow mode). Specifying -F makes logread first dump the log buffer and
then immediately start following it.
---
Changes since v1:
- help text extended to cover new flag
---
 sysklogd/logread.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index bea73d9..634dc69 100644
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -10,10 +10,11 @@
  */
 
 //usage:#define logread_trivial_usage
-//usage:       "[-f]"
+//usage:       "[-fF]"
 //usage:#define logread_full_usage "\n\n"
 //usage:       "Show messages in syslogd's circular buffer\n"
 //usage:     "\n	-f	Output data as log grows"
+//usage:     "\n	-F	Same as -f, but dump buffer first"
 
 #include "libbb.h"
 #include <sys/ipc.h>
@@ -83,7 +84,10 @@ int logread_main(int argc UNUSED_PARAM, char **argv)
 	unsigned cur;
 	int log_semid; /* ipc semaphore id */
 	int log_shmid; /* ipc shared memory id */
-	smallint follow = getopt32(argv, "f");
+	smallint follow, dumpfollow, args = getopt32(argv, "Ff");
+
+	dumpfollow = args & 0x1;
+	follow = args & 0x2;
 
 	INIT_G();
 
@@ -129,7 +133,11 @@ int logread_main(int argc UNUSED_PARAM, char **argv)
 			printf("cur:%u tail:%u size:%u\n",
 					cur, shbuf_tail, shbuf_size);
 
-		if (!follow) {
+		if (!follow || dumpfollow) {
+			if (dumpfollow) {
+				follow = 1;
+				dumpfollow = 0;
+			}
 			/* advance to oldest complete message */
 			/* find NUL */
 			cur += strlen(shbuf_data + cur);
-- 
1.8.5.5