3 files changed, 123 insertions, 29 deletions

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 6a9c041134bb..76c0b2c49eb8 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -2218,15 +2218,29 @@ int perf_event__synthesize_tracing_data(int fd, struct perf_evlist *evlist,
 				   struct perf_session *session __unused)
 {
 	union perf_event ev;
+	struct tracing_data *tdata;
 	ssize_t size = 0, aligned_size = 0, padding;
 	int err __used = 0;
 
+	/*
+	 * We are going to store the size of the data followed
+	 * by the data contents. Since the fd descriptor is a pipe,
+	 * we cannot seek back to store the size of the data once
+	 * we know it. Instead we:
+	 *
+	 * - write the tracing data to the temp file
+	 * - get/write the data size to pipe
+	 * - write the tracing data from the temp file
+	 *   to the pipe
+	 */
+	tdata = tracing_data_get(&evlist->entries, fd, true);
+	if (!tdata)
+		return -1;
+
 	memset(&ev, 0, sizeof(ev));
 
 	ev.tracing_data.header.type = PERF_RECORD_HEADER_TRACING_DATA;
-	size = read_tracing_data_size(fd, &evlist->entries);
-	if (size <= 0)
-		return size;
+	size = tdata->size;
 	aligned_size = ALIGN(size, sizeof(u64));
 	padding = aligned_size - size;
 	ev.tracing_data.header.size = sizeof(ev.tracing_data);
@@ -2234,7 +2248,12 @@ int perf_event__synthesize_tracing_data(int fd, struct perf_evlist *evlist,
 
 	process(&ev, NULL, session);
 
-	err = read_tracing_data(fd, &evlist->entries);
+	/*
+	 * The put function will copy all the tracing data
+	 * stored in temp file to the pipe.
+	 */
+	tracing_data_put(tdata);
+
 	write_padded(fd, NULL, 0, padding);
 
 	return aligned_size;
diff --git a/tools/perf/util/trace-event-info.c b/tools/perf/util/trace-event-info.c
index 3403f814ad72..2d530cf74f43 100644
--- a/tools/perf/util/trace-event-info.c
+++ b/tools/perf/util/trace-event-info.c
@@ -196,7 +196,8 @@ static void record_file(const char *file, size_t hdr_sz)
 		die("Can't read '%s'", file);
 
 	/* put in zeros for file size, then fill true size later */
-	write_or_die(&size, hdr_sz);
+	if (hdr_sz)
+		write_or_die(&size, hdr_sz);
 
 	do {
 		r = read(fd, buf, BUFSIZ);
@@ -212,7 +213,7 @@ static void record_file(const char *file, size_t hdr_sz)
 	if (bigendian())
 		sizep += sizeof(u64) - hdr_sz;
 
-	if (pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0)
+	if (hdr_sz && pwrite(output_fd, sizep, hdr_sz, hdr_pos) < 0)
 		die("writing to %s", output_file);
 }
 
@@ -428,6 +429,19 @@ get_tracepoints_path(struct list_head *pattrs)
 	return nr_tracepoints > 0 ? path.next : NULL;
 }
 
+static void
+put_tracepoints_path(struct tracepoint_path *tps)
+{
+	while (tps) {
+		struct tracepoint_path *t = tps;
+
+		tps = tps->next;
+		free(t->name);
+		free(t->system);
+		free(t);
+	}
+}
+
 bool have_tracepoints(struct list_head *pattrs)
 {
 	struct perf_evsel *pos;
@@ -439,19 +453,11 @@ bool have_tracepoints(struct list_head *pattrs)
 	return false;
 }
 
-int read_tracing_data(int fd, struct list_head *pattrs)
+static void tracing_data_header(void)
 {
-	char buf[BUFSIZ];
-	struct tracepoint_path *tps = get_tracepoints_path(pattrs);
-
-	/*
-	 * What? No tracepoints? No sense writing anything here, bail out.
-	 */
-	if (tps == NULL)
-		return -1;
-
-	output_fd = fd;
+	char buf[20];
 
+	/* just guessing this is someone's birthday.. ;) */
 	buf[0] = 23;
 	buf[1] = 8;
 	buf[2] = 68;
@@ -476,28 +482,86 @@ int read_tracing_data(int fd, struct list_head *pattrs)
 	/* save page_size */
 	page_size = sysconf(_SC_PAGESIZE);
 	write_or_die(&page_size, 4);
+}
+
+struct tracing_data *tracing_data_get(struct list_head *pattrs,
+				      int fd, bool temp)
+{
+	struct tracepoint_path *tps;
+	struct tracing_data *tdata;
+
+	output_fd = fd;
+
+	tps = get_tracepoints_path(pattrs);
+	if (!tps)
+		return NULL;
 
+	tdata = malloc_or_die(sizeof(*tdata));
+	tdata->temp = temp;
+	tdata->size = 0;
+
+	if (temp) {
+		int temp_fd;
+
+		snprintf(tdata->temp_file, sizeof(tdata->temp_file),
+			 "/tmp/perf-XXXXXX");
+		if (!mkstemp(tdata->temp_file))
+			die("Can't make temp file");
+
+		temp_fd = open(tdata->temp_file, O_RDWR);
+		if (temp_fd < 0)
+			die("Can't read '%s'", tdata->temp_file);
+
+		/*
+		 * Set the temp file the default output, so all the
+		 * tracing data are stored into it.
+		 */
+		output_fd = temp_fd;
+	}
+
+	tracing_data_header();
 	read_header_files();
 	read_ftrace_files(tps);
 	read_event_files(tps);
 	read_proc_kallsyms();
 	read_ftrace_printk();
 
-	return 0;
+	/*
+	 * All tracing data are stored by now, we can restore
+	 * the default output file in case we used temp file.
+	 */
+	if (temp) {
+		tdata->size = lseek(output_fd, 0, SEEK_CUR);
+		close(output_fd);
+		output_fd = fd;
+	}
+
+	put_tracepoints_path(tps);
+	return tdata;
 }
 
-ssize_t read_tracing_data_size(int fd, struct list_head *pattrs)
+void tracing_data_put(struct tracing_data *tdata)
 {
-	ssize_t size;
-	int err = 0;
+	if (tdata->temp) {
+		record_file(tdata->temp_file, 0);
+		unlink(tdata->temp_file);
+	}
 
-	calc_data_size = 1;
-	err = read_tracing_data(fd, pattrs);
-	size = calc_data_size - 1;
-	calc_data_size = 0;
+	free(tdata);
+}
 
-	if (err < 0)
-		return err;
+int read_tracing_data(int fd, struct list_head *pattrs)
+{
+	struct tracing_data *tdata;
 
-	return size;
+	/*
+	 * We work over the real file, so we can write data
+	 * directly, no temp file is needed.
+	 */
+	tdata = tracing_data_get(pattrs, fd, false);
+	if (!tdata)
+		return -ENOMEM;
+
+	tracing_data_put(tdata);
+	return 0;
 }
diff --git a/tools/perf/util/trace-event.h b/tools/perf/util/trace-event.h
index f674dda3363b..a84100817649 100644
--- a/tools/perf/util/trace-event.h
+++ b/tools/perf/util/trace-event.h
@@ -263,7 +263,18 @@ void *raw_field_ptr(struct event *event, const char *name, void *data);
 unsigned long long eval_flag(const char *flag);
 
 int read_tracing_data(int fd, struct list_head *pattrs);
-ssize_t read_tracing_data_size(int fd, struct list_head *pattrs);
+
+struct tracing_data {
+	/* size is only valid if temp is 'true' */
+	ssize_t size;
+	bool temp;
+	char temp_file[50];
+};
+
+struct tracing_data *tracing_data_get(struct list_head *pattrs,
+				      int fd, bool temp);
+void tracing_data_put(struct tracing_data *tdata);
+
 
 /* taken from kernel/trace/trace.h */
 enum trace_flag_type {