[PATCH] trace-cmd record/set: Use write() instead of fwrite() for options

From: "Steven Rostedt (Google)" <[email protected]>

For some reason, using fwrite() to write to trace_options does not return
the error messages. When using -O userstacktrace_delay on a system that did
not have it supported, the  fwrite() succeeds and the user of trace-cmd
things the option is set. This is confusing when looking at the output and
not seeing the delayed stack traces.

Switch fopen()/fwrite() over to open()/write() where there's no dependency
on glibc getting it correct.

Signed-off-by: Steven Rostedt (Google) <[email protected]>
---
 tracecmd/trace-record.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index f36ee6cd..4872d0d7 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -1964,22 +1964,23 @@ static void save_option(struct buffer_instance *instance, const char *option)
 
 static int set_option(struct buffer_instance *instance, const char *option)
 {
-	FILE *fp;
 	char *path;
+	int ret;
+	int fd;
 
 	path = tracefs_instance_get_file(instance->tracefs, "trace_options");
-	fp = fopen(path, "w");
-	if (!fp)
+	fd = open(path, O_WRONLY | O_TRUNC);
+	if (fd < 0)
 		warning("writing to '%s'", path);
 	tracefs_put_tracing_file(path);
 
-	if (!fp)
+	if (fd < 0)
 		return -1;
 
-	fwrite(option, 1, strlen(option), fp);
-	fclose(fp);
+	ret = write(fd, option, strlen(option));
+	close(fd);
 
-	return 0;
+	return ret < 0 ? ret : 0;
 }
 
 static void disable_func_stack_trace_instance(struct buffer_instance *instance)
-- 
2.47.2