From: Paul Chaignon <paul.chaignon@gmail.com>
Date: Mon, 1 Apr 2019 20:26:00 +0000 (+0200)
Subject: Add -Z option to print only failing syscalls
X-Git-Tag: v5.2~8
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=092e4968460c1efd61ee9e3bba2ede0ec1e983c4;p=strace

Add -Z option to print only failing syscalls

Existing -z option prints only successful syscalls.
This change adds a -Z option to print only failing syscalls.

Both options will start to behave properly with the subsequent commit.

* strace.c (init): Handle new -Z option.
* defs.h (failing_only): New prototype.
* syscall.c (failing_only): New variable.
(syscall_exiting_trace): Ignore failed syscalls if failing_only is set.

References: https://github.com/strace/strace/issues/50
Co-Authored-by: Burkhard Kohl <burkhard.kohl@intel.com>
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
---

diff --git a/defs.h b/defs.h
index a9c36d15..ca458d40 100644
--- a/defs.h
+++ b/defs.h
@@ -417,6 +417,7 @@ extern bool iflag;
 extern bool count_wallclock;
 extern unsigned int qflag;
 extern bool not_failing_only;
+extern bool failing_only;
 extern unsigned int show_fd_path;
 /* are we filtering traces based on paths? */
 extern struct path_set {
diff --git a/strace.c b/strace.c
index 74c44253..27027a30 100644
--- a/strace.c
+++ b/strace.c
@@ -109,8 +109,9 @@ static bool daemonized_tracer;
 static int post_attach_sigstop = TCB_IGNORE_ONE_SIGSTOP;
 #define use_seize (post_attach_sigstop == 0)
 
-/* Sometimes we want to print only succeeding syscalls. */
+/* Sometimes we want to print succeeding/failing syscalls only. */
 bool not_failing_only;
+bool failing_only;
 
 /* Show path associated with fd arguments */
 unsigned int show_fd_path;
@@ -304,6 +305,7 @@ Miscellaneous:\n\
  */
 /* this is broken, so don't document it
 -z -- print only succeeding syscalls\n\
+-Z -- print only failing syscalls\n\
  */
 , DEFAULT_ACOLUMN, DEFAULT_STRLEN, DEFAULT_SORTBY);
 	exit(0);
@@ -1579,7 +1581,7 @@ init(int argc, char *argv[])
 #ifdef ENABLE_STACKTRACE
 	    "k"
 #endif
-	    "a:Ab:cCdDe:E:fFhiI:o:O:p:P:qrs:S:tTu:vVwxX:yz")) != EOF) {
+	    "a:Ab:cCdDe:E:fFhiI:o:O:p:P:qrs:S:tTu:vVwxX:yzZ")) != EOF) {
 		switch (c) {
 		case 'a':
 			acolumn = string_to_uint(optarg);
@@ -1710,6 +1712,9 @@ init(int argc, char *argv[])
 		case 'z':
 			not_failing_only = 1;
 			break;
+		case 'Z':
+			failing_only = 1;
+			break;
 		default:
 			error_msg_and_help(NULL);
 			break;
diff --git a/syscall.c b/syscall.c
index 9d4800fd..e73e4274 100644
--- a/syscall.c
+++ b/syscall.c
@@ -759,8 +759,10 @@ syscall_exiting_trace(struct tcb *tcp, struct timespec *ts, int res)
 	 * whereas the intended result is that open(...) line
 	 * is not shown at all.
 	 */
-		if (not_failing_only && tcp->u_error)
-			return 0;	/* ignore failed syscalls */
+		if ((not_failing_only && syserror(tcp)) ||
+		    (failing_only && !syserror(tcp)))
+			return 0;	/* ignore failed/successful
+					 * syscalls */
 		if (tcp->sys_func_rval & RVAL_DECODED)
 			sys_res = tcp->sys_func_rval;
 		else