[PATCH v6 27/45] trace-cmd: Read compressed latency trace data

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

When reading trace file version 7 with latency trace data, uncompress the
data. A new trace-cmd API is introduced to handle that case:
  tracecmd_latency_data_read()

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 .../include/private/trace-cmd-private.h       |  2 +
 lib/trace-cmd/trace-input.c                   | 42 ++++++++++++++++++-
 tracecmd/trace-read.c                         |  6 +--
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index 067ba34d..4a3eb1bc 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -208,6 +208,8 @@ tracecmd_peek_data_ref(struct tracecmd_input *handle, int cpu)
 	return rec;
 }
 
+int tracecmd_latency_data_read(struct tracecmd_input *handle, void *buf, size_t size);
+
 struct tep_record *
 tracecmd_read_prev(struct tracecmd_input *handle, struct tep_record *record);
 
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 327082a2..12876838 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -137,6 +137,9 @@ struct tracecmd_input {
 	bool			read_page;
 	bool			use_pipe;
 	int			file_version;
+	/* temporary file for uncompressed latency data */
+	int			lat_cfd;
+	char			lat_cfile[26]; /* strlen(COMPR_TEMP_FILE) */
 	struct cpu_data 	*cpu_data;
 	long long		ts_offset;
 	struct tsc2nsec		tsc_calc;
@@ -2995,6 +2998,35 @@ static int read_options_type(struct tracecmd_input *handle)
 	return 0;
 }
 
+int tracecmd_latency_data_read(struct tracecmd_input *handle, void *buf, size_t size)
+{
+	int fd, r;
+
+	if (handle->file_state != TRACECMD_FILE_CPU_LATENCY)
+		return -1;
+	if (handle->lat_cfd >= 0)
+		fd = handle->lat_cfd;
+	else
+		fd = handle->fd;
+	r = read(fd, buf, size);
+
+	return r;
+}
+
+static int latency_data_uncompress(struct tracecmd_input *handle)
+{
+	int ret;
+
+	strcpy(handle->lat_cfile, COMPR_TEMP_FILE);
+	handle->lat_cfd = mkstemp(handle->lat_cfile);
+	if (handle->lat_cfd < 0)
+		return -1;
+	ret = tracecmd_uncompress_copy_to(handle->compress, handle->lat_cfd, NULL, NULL);
+	if (!ret)
+		lseek64(handle->lat_cfd, 0, SEEK_SET);
+	return ret;
+}
+
 static int read_cpu_data(struct tracecmd_input *handle)
 {
 	struct tep_handle *pevent = handle->pevent;
@@ -3009,8 +3041,11 @@ static int read_cpu_data(struct tracecmd_input *handle)
 	/*
 	 * Check if this is a latency report or not.
 	 */
-	if (handle->file_state == TRACECMD_FILE_CPU_LATENCY)
+	if (handle->file_state == TRACECMD_FILE_CPU_LATENCY) {
+		if (handle->file_version >= 7 && latency_data_uncompress(handle))
+			return -1;
 		return 1;
+	}
 
 	/* We expect this to be flyrecord */
 	if (handle->file_state != TRACECMD_FILE_CPU_FLYRECORD)
@@ -3448,6 +3483,7 @@ struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 
 	handle->fd = fd;
 	handle->ref = 1;
+	handle->lat_cfd = -1;
 
 	if (do_read_check(handle, buf, 3))
 		goto failed_read;
@@ -3698,6 +3734,10 @@ void tracecmd_close(struct tracecmd_input *handle)
 	free(handle->uname);
 	free(handle->trace_clock);
 	close(handle->fd);
+	if (handle->lat_cfd >= 0) {
+		close(handle->lat_cfd);
+		unlink(handle->lat_cfile);
+	}
 
 	tracecmd_free_hooks(handle->hooks);
 	handle->hooks = NULL;
diff --git a/tracecmd/trace-read.c b/tracecmd/trace-read.c
index d605d05a..dfb814b7 100644
--- a/tracecmd/trace-read.c
+++ b/tracecmd/trace-read.c
@@ -948,13 +948,13 @@ void trace_show_data(struct tracecmd_input *handle, struct tep_record *record)
 	printf("\n");
 }
 
-static void read_rest(void)
+static void read_latency(struct tracecmd_input *handle)
 {
 	char buf[BUFSIZ + 1];
 	int r;
 
 	do {
-		r = read(input_fd, buf, BUFSIZ);
+		r = tracecmd_latency_data_read(handle, buf, BUFSIZ);
 		if (r > 0) {
 			buf[r] = 0;
 			printf("%s", buf);
@@ -1241,7 +1241,7 @@ static void read_data_info(struct list_head *handle_list, enum output_type otype
 		if (ret > 0) {
 			if (multi_inputs)
 				die("latency traces do not work with multiple inputs");
-			read_rest();
+			read_latency(handles->handle);
 			return;
 		}
 
-- 
2.31.1