From 2ae13b1b501e945274fa27f2b61a77f4e2be4697 Mon Sep 17 00:00:00 2001
From: Eugene Syromyatnikov <evgsyr@gmail.com>
Date: Thu, 27 Sep 2018 00:42:27 +0200
Subject: [PATCH] syslog: do not print bufp and len for commands that ignore
 them

* syslog.c (SYS_FUNC(syslog)): Defer printing of comma after the first
argument to the specific command handlers, return RVAL_DECODED without
additional printing for SYSLOG_ACTION_CLOSE, SYSLOG_ACTION_OPEN,
SYSLOG_ACTION_CLEAR, SYSLOG_ACTION_CONSOLE_OFF,
SYSLOG_ACTION_CONSOLE_ON, SYSLOG_ACTION_SIZE_UNREAD,
SYSLOG_ACTION_SIZE_BUFFER.
* tests/syslog.c: Add checks.
---
 syslog.c           | 18 ++++++++++++++++--
 tests/gen_tests.in |  2 +-
 tests/syslog.c     | 28 ++++++++++++++++++++++------
 3 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/syslog.c b/syslog.c
index 626663ee..92d68f2a 100644
--- a/syslog.c
+++ b/syslog.c
@@ -18,22 +18,36 @@ SYS_FUNC(syslog)
 		/* type */
 		printxval_ex(syslog_action_type, type, "SYSLOG_ACTION_???",
 			     XLAT_STYLE_VERBOSE | XLAT_STYLE_FMT_D);
-		tprints(", ");
 	}
 
 	switch (type) {
+	/* Those commands have bufp and len ignored */
+	case SYSLOG_ACTION_CLOSE:
+	case SYSLOG_ACTION_OPEN:
+	case SYSLOG_ACTION_CLEAR:
+	case SYSLOG_ACTION_CONSOLE_OFF:
+	case SYSLOG_ACTION_CONSOLE_ON:
+	case SYSLOG_ACTION_SIZE_UNREAD:
+	case SYSLOG_ACTION_SIZE_BUFFER:
+		return RVAL_DECODED;
+
 	case SYSLOG_ACTION_READ:
 	case SYSLOG_ACTION_READ_ALL:
 	case SYSLOG_ACTION_READ_CLEAR:
-		if (entering(tcp))
+		if (entering(tcp)) {
+			tprints(", ");
 			return 0;
+		}
 		break;
 	default:
+		tprints(", ");
 		printaddr(tcp->u_arg[1]);
 		tprintf(", %" PRI_klu, tcp->u_arg[2]);
 		return RVAL_DECODED;
 	}
 
+	/* syscall exit handler for SYSLOG_ACTION_READ* */
+
 	/* bufp */
 	if (syserror(tcp))
 		printaddr(tcp->u_arg[1]);
diff --git a/tests/gen_tests.in b/tests/gen_tests.in
index 4fdf4722..8ad044a8 100644
--- a/tests/gen_tests.in
+++ b/tests/gen_tests.in
@@ -500,7 +500,7 @@ sync	-a7
 sync_file_range
 sync_file_range2
 sysinfo	-a14
-syslog	-a36
+syslog	-a35
 tee
 time	-a10
 timer_create
diff --git a/tests/syslog.c b/tests/syslog.c
index 028514b3..151880d1 100644
--- a/tests/syslog.c
+++ b/tests/syslog.c
@@ -19,16 +19,32 @@
 int
 main(void)
 {
+	static const struct cmd_str {
+		unsigned int cmd;
+		const char *str;
+	} no_args[] = {
+		{ 0,  "0 /* SYSLOG_ACTION_CLOSE */" },
+		{ 1,  "1 /* SYSLOG_ACTION_OPEN */" },
+		{ 5,  "5 /* SYSLOG_ACTION_CLEAR */" },
+		{ 6,  "6 /* SYSLOG_ACTION_CONSOLE_OFF */" },
+		{ 7,  "7 /* SYSLOG_ACTION_CONSOLE_ON */" },
+		{ 9,  "9 /* SYSLOG_ACTION_SIZE_UNREAD */" },
+		{ 10, "10 /* SYSLOG_ACTION_SIZE_BUFFER */" },
+	};
+	static const kernel_ulong_t high =
+		(kernel_ulong_t) 0xbadc0ded00000000ULL;
 	const long addr = (long) 0xfacefeeddeadbeefULL;
-
-	int rc = syscall(__NR_syslog, SYSLOG_ACTION_READ, addr, -1);
+	int rc;
+	for (size_t i = 0; i < ARRAY_SIZE(no_args); i++) {
+		rc = syscall(__NR_syslog, high | no_args[i].cmd, addr, -1);
+		printf("syslog(%s) = %s\n",
+		no_args[i].str, sprintrc(rc));
+	}
+
+	rc = syscall(__NR_syslog, SYSLOG_ACTION_READ, addr, -1);
 	printf("syslog(2 /* SYSLOG_ACTION_READ */, %#lx, -1) = %s\n",
 	       addr, sprintrc(rc));
 
-	rc = syscall(__NR_syslog, SYSLOG_ACTION_SIZE_BUFFER, NULL, 10);
-	printf("syslog(10 /* SYSLOG_ACTION_SIZE_BUFFER */, NULL, 10) = %s\n",
-	       sprintrc(rc));
-
 	puts("+++ exited with 0 +++");
 	return 0;
 }
-- 
2.40.0