perf record: auto detect when stdout is a pipe
This patch gives the ability to 'perf record' to detect when its stdout
has been redirected to a pipe. There's now no more need to add '-o -'
switch in this case.
However '-o <path>' option has always precedence, that is if specified
and stdout has been connected via a pipe then the output will go into
the specified output.
LKML-Reference: <m3ipxo966i.fsf@gmail.com>
Signed-off-by: Franck Bui-Huu <fbuihuu@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 45a3689..1346d42 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -48,7 +48,7 @@
static int freq = 1000;
static int output;
static int pipe_output = 0;
-static const char *output_name = "perf.data";
+static const char *output_name = NULL;
static int group = 0;
static int realtime_prio = 0;
static bool nodelay = false;
@@ -497,18 +497,26 @@
exit(-1);
}
- if (!strcmp(output_name, "-"))
- pipe_output = 1;
- else if (!stat(output_name, &st) && st.st_size) {
- if (write_mode == WRITE_FORCE) {
- char oldname[PATH_MAX];
- snprintf(oldname, sizeof(oldname), "%s.old",
- output_name);
- unlink(oldname);
- rename(output_name, oldname);
+ if (!output_name) {
+ if (!fstat(STDOUT_FILENO, &st) && S_ISFIFO(st.st_mode))
+ pipe_output = 1;
+ else
+ output_name = "perf.data";
+ }
+ if (output_name) {
+ if (!strcmp(output_name, "-"))
+ pipe_output = 1;
+ else if (!stat(output_name, &st) && st.st_size) {
+ if (write_mode == WRITE_FORCE) {
+ char oldname[PATH_MAX];
+ snprintf(oldname, sizeof(oldname), "%s.old",
+ output_name);
+ unlink(oldname);
+ rename(output_name, oldname);
+ }
+ } else if (write_mode == WRITE_APPEND) {
+ write_mode = WRITE_FORCE;
}
- } else if (write_mode == WRITE_APPEND) {
- write_mode = WRITE_FORCE;
}
flags = O_CREAT|O_RDWR;