[PATCH v2 19/21] trace-cmd: Move buffers description outside of options

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

When a new buffer data are written in the trace file, the file offset is
stored in the buffer description. As the buffer description is part of
the trace options, which are already written in the file, the offset field
in this option is updated with the new value. This causes a serious
problem when option section of the file is compressed. Updating a value
in already compressed section may change the size of this section, which
can make the calculated offset of the buffer trace data invalid. To
solve that problem and to enable the compression of the option section
of the file, the structure of the trace file is changed:
 - In trace file v7, the description of the buffers is moved to a
   separate section in the trace file medatata. It is stored after the
   CPU count section and before the option section. The format of this
   new buffers description is:
    4 bytes - count of the buffers, stored in the file. The top buffer
      is not counted.
    For each buffer:
     8 bytes, offset of the trace data for this buffer in the file.
     null-terminated string, name of the buffer.
   The new section is mandatory, in case of no buffers - the count 0 is
   stored in the first 4 bytes.
 - In trace file v6, the description of the buffers is not changed.

These changes are needed for compression of the options sections from
the trace file.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 .../include/private/trace-cmd-private.h       |  1 +
 lib/trace-cmd/trace-input.c                   | 40 ++++++++++
 lib/trace-cmd/trace-output.c                  | 78 ++++++++++++++++++-
 tracecmd/trace-dump.c                         | 24 ++++++
 tracecmd/trace-listen.c                       |  3 +
 tracecmd/trace-record.c                       |  4 +
 6 files changed, 146 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 7d34f27b..d7488346 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -112,6 +112,7 @@ enum tracecmd_file_states {
 	TRACECMD_FILE_PRINTK,
 	TRACECMD_FILE_CMD_LINES,
 	TRACECMD_FILE_CPU_COUNT,
+	TRACECMD_FILE_BUFERS,
 	TRACECMD_FILE_OPTIONS,
 	TRACECMD_FILE_CPU_LATENCY,
 	TRACECMD_FILE_CPU_FLYRECORD,
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index f3b01db3..8ec9173b 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -881,6 +881,39 @@ static int read_cpus(struct tracecmd_input *handle)
 	return 0;
 }
 
+static int read_buffers(struct tracecmd_input *handle)
+{
+	struct input_buffer_instance *buffer;
+	unsigned long long offset;
+	unsigned int count;
+	int i;
+
+	if (handle->file_version < 7 || handle->file_state >= TRACECMD_FILE_BUFERS)
+		return 0;
+
+	if (read4(handle, &count) < 0)
+		return -1;
+	i = handle->nr_buffers;
+	handle->nr_buffers += count;
+	handle->buffers = realloc(handle->buffers,
+				  sizeof(*handle->buffers) * handle->nr_buffers);
+	if (!handle->buffers)
+		return -1;
+
+	for (; i < handle->nr_buffers; i++) {
+		buffer = &handle->buffers[i];
+		if (read8(handle, &offset) < 0)
+			return -1;
+		buffer->offset = offset;
+		buffer->name = read_string(handle);
+		if (!buffer->name)
+			return -1;
+	}
+
+	handle->file_state = TRACECMD_FILE_BUFERS;
+	return 0;
+}
+
 /**
  * tracecmd_read_headers - read the header information from trace.dat
  * @handle: input handle for the trace.dat file
@@ -955,6 +988,13 @@ int tracecmd_read_headers(struct tracecmd_input *handle,
 	if (state <= handle->file_state)
 		return 0;
 
+	if (read_buffers(handle) < 0)
+		return -1;
+
+	if (state <= handle->file_state)
+		return 0;
+
+
 	if (read_options_type(handle) < 0)
 		return -1;
 
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index aa55a089..57b11493 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -376,6 +376,17 @@ static int check_out_state(struct tracecmd_output *handle, int new_state)
 	if (!handle)
 		return -1;
 
+	if (handle->file_version < 7) {
+		switch (new_state) {
+		case TRACECMD_FILE_BUFERS:
+			tracecmd_warning("State %d is not supported in trace file version %d",
+					 new_state, handle->file_version);
+			return -1;
+		default:
+			break;
+		}
+	}
+
 	switch (new_state) {
 	case TRACECMD_FILE_HEADERS:
 	case TRACECMD_FILE_FTRACE_EVENTS:
@@ -384,10 +395,16 @@ static int check_out_state(struct tracecmd_output *handle, int new_state)
 	case TRACECMD_FILE_PRINTK:
 	case TRACECMD_FILE_CMD_LINES:
 	case TRACECMD_FILE_CPU_COUNT:
-	case TRACECMD_FILE_OPTIONS:
+	case TRACECMD_FILE_BUFERS:
 		if (handle->file_state == (new_state - 1))
 			return 0;
 		break;
+	case TRACECMD_FILE_OPTIONS:
+		if (handle->file_version < 7 && handle->file_state == TRACECMD_FILE_CPU_COUNT)
+			return 0;
+		if (handle->file_version >= 7 && handle->file_state == TRACECMD_FILE_BUFERS)
+			return 0;
+		break;
 	case TRACECMD_FILE_CPU_LATENCY:
 	case TRACECMD_FILE_CPU_FLYRECORD:
 		if (handle->file_state == TRACECMD_FILE_OPTIONS)
@@ -1436,7 +1453,7 @@ int tracecmd_add_buffer_description(struct tracecmd_output *handle, const char *
 	return 0;
 }
 
-int tracecmd_write_buffers_description(struct tracecmd_output *handle)
+static int write_buffers_description_v6(struct tracecmd_output *handle)
 {
 	struct tracecmd_option *option;
 	struct tracecmd_buffer *buf;
@@ -1450,6 +1467,56 @@ int tracecmd_write_buffers_description(struct tracecmd_output *handle)
 	return 0;
 }
 
+static int write_buffers_description_v7(struct tracecmd_output *handle)
+{
+	struct tracecmd_buffer *buf;
+	char *data = NULL;
+	int count = 0;
+	int size;
+	int ret;
+
+	ret = check_out_state(handle, TRACECMD_FILE_BUFERS);
+	if (ret < 0) {
+		tracecmd_warning("Cannot write buffers descriptions");
+		return ret;
+	}
+
+	list_for_each_entry(buf, &handle->buffers, list) {
+		count++;
+	}
+
+	count = convert_endian_4(handle, count);
+	ret = do_write_check(handle, &count, 4);
+	if (ret < 0)
+		return ret;
+
+	list_for_each_entry(buf, &handle->buffers, list) {
+		size = 8 + strlen(buf->name) + 1;
+		data = malloc(size);
+		if (!data)
+			goto error;
+		*(tsize_t *)data = 0;
+		strcpy(data + 8, buf->name);
+		/* Save the data location in case it needs to be updated */
+		buf->offset = do_lseek(handle, 0, SEEK_CUR);
+		if (do_write_check(handle, data, size))
+			goto error;
+	}
+
+	handle->file_state = TRACECMD_FILE_BUFERS;
+	return 0;
+error:
+	return -1;
+}
+
+int tracecmd_write_buffers_description(struct tracecmd_output *handle)
+{
+	if (handle->file_version >= 7)
+		return write_buffers_description_v7(handle);
+
+	return write_buffers_description_v6(handle);
+}
+
 static tsize_t get_buffer_file_offset(struct tracecmd_output *handle, const char *name)
 {
 	struct tracecmd_buffer *buf;
@@ -1508,7 +1575,8 @@ struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, in
 
 	if (tracecmd_write_cpus(handle, cpus) < 0)
 		goto out_free;
-
+	if (tracecmd_write_buffers_description(handle) < 0)
+		goto out_free;
 	if (tracecmd_write_options(handle) < 0)
 		goto out_free;
 
@@ -1701,7 +1769,9 @@ int tracecmd_append_cpu_data(struct tracecmd_output *handle,
 	ret = tracecmd_write_cpus(handle, cpus);
 	if (ret)
 		return ret;
-
+	ret = tracecmd_write_buffers_description(handle);
+	if (ret)
+		return ret;
 	ret = tracecmd_write_options(handle);
 	if (ret)
 		return ret;
diff --git a/tracecmd/trace-dump.c b/tracecmd/trace-dump.c
index ed82104b..d6136360 100644
--- a/tracecmd/trace-dump.c
+++ b/tracecmd/trace-dump.c
@@ -420,6 +420,29 @@ static void dump_cpus_count(int fd)
 	do_print(SUMMARY, "\t%d [CPUs with tracing data]\n", trace_cpus);
 }
 
+static void dump_buffers(int fd)
+{
+	unsigned long long offset;
+	char name[DUMP_SIZE];
+	int count;
+
+	if (file_version < 7)
+		return;
+
+	if (read_file_number(fd, &count, 4))
+		die("cannot read the buffers count");
+	do_print(SUMMARY, "\t%d [buffers with tracing data]\n", count);
+
+	while (count) {
+		if (read_file_number(fd, &offset, 8))
+			die("cannot read the buffer offset");
+		if (read_file_string(fd, name, DUMP_SIZE))
+			die("cannot read the buffer name");
+		do_print(SUMMARY, "\t\t %llu %s[data offset, buffer name]\n", offset, name);
+		count--;
+	}
+}
+
 static void dump_option_string(int fd, int size, char *desc)
 {
 	do_print(OPTIONS, "\t\t[Option %s, %d bytes]\n", desc, size);
@@ -762,6 +785,7 @@ static void dump_file(const char *file)
 	dump_printk(fd);
 	dump_cmdlines(fd);
 	dump_cpus_count(fd);
+	dump_buffers(fd);
 	dump_therest(fd);
 
 	tep_free(tep);
diff --git a/tracecmd/trace-listen.c b/tracecmd/trace-listen.c
index 0ae1c948..62debdb6 100644
--- a/tracecmd/trace-listen.c
+++ b/tracecmd/trace-listen.c
@@ -604,6 +604,9 @@ static int put_together_file(int cpus, int ofd, const char *node,
 
 	if (write_options) {
 		ret = tracecmd_write_cpus(handle, cpus);
+		if (ret)
+			goto out;
+		ret = tracecmd_write_buffers_description(handle);
 		if (ret)
 			goto out;
 		ret = tracecmd_write_options(handle);
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index e12d77cc..5516fe3a 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -3653,6 +3653,9 @@ setup_connection(struct buffer_instance *instance, struct common_record_context
 		if (ret)
 			goto error;
 		ret = tracecmd_write_cpus(network_handle, instance->cpu_count);
+		if (ret)
+			goto error;
+		ret = tracecmd_write_buffers_description(network_handle);
 		if (ret)
 			goto error;
 		ret = tracecmd_write_options(network_handle);
@@ -3856,6 +3859,7 @@ static void setup_agent(struct buffer_instance *instance,
 	add_options(network_handle, ctx);
 	tracecmd_write_cmdlines(network_handle);
 	tracecmd_write_cpus(network_handle, instance->cpu_count);
+	tracecmd_write_buffers_description(network_handle);
 	tracecmd_write_options(network_handle);
 	tracecmd_msg_finish_sending_data(instance->msg_handle);
 	instance->network_handle = network_handle;
-- 
2.31.1