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 a9c36d152e27d53919ed95de4bfef8d0f0bae6e7..ca458d40faf68b2bd19f0e9afd02d202a826b4a3 100644 (file)
--- 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 74c44253c178c45d2c952d7e4b988e8e6af10fb7..27027a305b362b6911f87eab02f420f9b440a7e7 100644 (file)
--- 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 9d4800fd504a1c87f313f5ef842cc62da367be9c..e73e427495057311671c49717a2b429549e52743 100644 (file)
--- 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