path: root/tools
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authorStephane Eranian <eranian@google.com>2012-05-15 13:11:11 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2012-06-11 11:20:21 -0300
commitfc3e4d077d5c7a7bc1ad5bc143895b4e070e5a8b (patch)
tree47c8345fbc1615a4118183d0eb1355ab2399651c /tools
parentperf tools: Fix endianity swapping for adds_features bitmask (diff)
perf stat: Fix default output file
The following commit: commit 56f3bae70638b33477a6015fd362ccfe354fd3ee Author: Jim Cromie <jim.cromie@gmail.com> Date: Wed Sep 7 17:14:00 2011 -0600 perf stat: Add --log-fd <N> option to redirect stderr elsewhere introduced a bug in the way perf stat outputs the results by default, i.e., without the --log-fd or --output option. It would default to writing to file descriptor 0, i.e., stdin. Writing to stdin is allowed and is equivalent to writing to stdout. However, there is a major difference for any script that was already capturing the output of perf stat via redirection: perf stat >/tmp/log .... or perf stat 2>/tmp/log .... They would not capture anything anymore. They would have to do: perf stat 0>/tmp/log ... This breaks compatibility with existing scripts and does not look very natural. This patch fixes the problem by looking at output_fd only when it was modified by user (> 0). It also checks that the value if positive. Passing --log-fd 0 is ignored. I would also argue that defaulting to stderr for the results is not the right thing to do, though this patch does not address this specific issue. Signed-off-by: Stephane Eranian <eranian@google.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Jim Cromie <jim.cromie@gmail.com> Link: http://lkml.kernel.org/r/20120515111111.GA9870@quad Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
1 files changed, 7 insertions, 1 deletions
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 262589991ea4..07b5c7703dd1 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1179,6 +1179,12 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
fprintf(stderr, "cannot use both --output and --log-fd\n");
usage_with_options(stat_usage, options);
+ if (output_fd < 0) {
+ fprintf(stderr, "argument to --log-fd must be a > 0\n");
+ usage_with_options(stat_usage, options);
+ }
if (!output) {
struct timespec tm;
mode = append_file ? "a" : "w";
@@ -1190,7 +1196,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
clock_gettime(CLOCK_REALTIME, &tm);
fprintf(output, "# started on %s\n", ctime(&tm.tv_sec));
- } else if (output_fd != 2) {
+ } else if (output_fd > 0) {
mode = append_file ? "a" : "w";
output = fdopen(output_fd, mode);
if (!output) {