[PATCH 5/5] perf test: Mute test cases if verbose == 0

[Wang Nan]

Sometimes error messages in breaks the pretty output of 'perf test'.
For example:

 # mv /lib/modules/4.3.0-rc4+/build/vmlinux{,.bak}
 # ./perf test LLVM BPF
 35: Test LLVM searching and compiling                        :
 35.1: Basic BPF llvm compiling test                          : Ok
 35.2: Test kbuild searching                                  : Ok
 35.3: Compile source for BPF prologue generation test        : Ok
 37: Test BPF filter                                          :
 37.1: Test basic BPF filtering                               : Ok
 37.2: Test BPF prologue generation                           :Failed to find the path for kernel: No such file or directory
  FAILED!

This patch mute test cases thoroughly by redirect their stdout and
stderr to /dev/null when verbose == 0. After applying this patch:

 # ./perf test LLVM BPF
 35: Test LLVM searching and compiling                        :
 35.1: Basic BPF llvm compiling test                          : Ok
 35.2: Test kbuild searching                                  : Ok
 35.3: Compile source for BPF prologue generation test        : Ok
 37: Test BPF filter                                          :
 37.1: Test basic BPF filtering                               : Ok
 37.2: Test BPF prologue generation                           : FAILED!

 # ./perf test -v LLVM BPF
 35: Test LLVM searching and compiling                        :
 35.1: Basic BPF llvm compiling test                          :
 --- start ---
 test child forked, pid 13183
 Kernel build dir is set to /lib/modules/4.3.0-rc4+/build
 set env: KBUILD_DIR=/lib/modules/4.3.0-rc4+/build
 ...
 bpf: config 'func=null_lseek file->f_mode offset orig' is ok
 Looking at the vmlinux_path (7 entries long)
 Failed to find the path for kernel: No such file or directory
 bpf_probe: failed to convert perf probe eventsFailed to add events selected by BPF
 test child finished with -1
 ---- end ----
 Test BPF filter subtest 1: FAILED!

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/tests/builtin-test.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 9914412..799edad 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -227,7 +227,22 @@ static int run_test(struct test *test, int subtest)
 	}
 
 	if (!child) {
+		int nullfd;
+
 		pr_debug("test child forked, pid %d\n", getpid());
+
+		if (!verbose) {
+			nullfd = open("/dev/null", O_WRONLY);
+			if (nullfd >= 0) {
+				close(STDERR_FILENO);
+				close(STDOUT_FILENO);
+
+				dup2(nullfd, STDOUT_FILENO);
+				dup2(STDOUT_FILENO, STDERR_FILENO);
+				close(nullfd);
+			}
+		}
+
 		if (!test->need_subtests)
 			err = test->func();
 		else
-- 
1.8.3.4

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