[PATCH 18/25] trace-cmd library: Read extended BUFFER option

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

The BUFFER option is extended in trace file version 7. It holds CPU
metadata related to the recorded CPU traces. Also, there is a new
BUFFER_TEXT option for describing the latency trace data. A new logic
is implemented for these new options.
In trace file version 7, the top buffer is saved as other buffers in the
file, no special treatment. But saving the top buffer in the list of
buffers in the input handler causes problems. It breaks the legacy logic
of trace-cmd library users, which have special logic for trace buffers
processing. That's why "top_buffer" member is added in the input handler
structure, to hold the top buffer.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c | 137 +++++++++++++++++++++++++++++++-----
 1 file changed, 120 insertions(+), 17 deletions(-)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 0aa263ba..3f3b3c75 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -74,9 +74,19 @@ struct cpu_data {
 	int			pipe_fd;
 };
 
+struct cpu_file_data {
+	int			cpu;
+	unsigned long long	offset;
+	unsigned long long	size;
+};
+
 struct input_buffer_instance {
 	char			*name;
 	size_t			offset;
+	char			*clock;
+	bool			latency;
+	int			cpus;
+	struct cpu_file_data	*cpu_data;
 };
 
 struct ts_offset_sample {
@@ -152,6 +162,7 @@ struct tracecmd_input {
 	char *			uname;
 	char *			version;
 	char *			trace_clock;
+	struct input_buffer_instance	top_buffer;
 	struct input_buffer_instance	*buffers;
 	int			parsing_failures;
 	struct guest_trace_info	*guest;
@@ -2860,13 +2871,107 @@ tracecmd_search_task_map(struct tracecmd_input *handle,
 	return lib;
 }
 
+static inline int save_read_number(struct tep_handle *tep, char *data, int *data_size,
+				   int *read_pos, int bytes, unsigned long long *num)
+{
+	if (bytes > *data_size)
+		return -1;
+	*num = tep_read_number(tep, (data + *read_pos), bytes);
+	*read_pos += bytes;
+	*data_size -= bytes;
+	return 0;
+}
+
+static inline char *save_read_string(char *data, int *data_size, int *read_pos)
+{
+	char *str;
+
+	if (*data_size < 1)
+		return NULL;
+	str = strdup(data + *read_pos);
+	if (!str)
+		return NULL;
+	*data_size -= (strlen(str) + 1);
+	if (*data_size < 0) {
+		free(str);
+		return NULL;
+	}
+	*read_pos += (strlen(str) + 1);
+
+	return str;
+}
+
+static int handle_buffer_option(struct tracecmd_input *handle,
+				unsigned short id, char *data, int size)
+{
+	struct input_buffer_instance *buff;
+	unsigned long long tmp;
+	int rsize = 0;
+	char *name;
+	int i;
+
+	if (save_read_number(handle->pevent, data, &size, &rsize, 8, &tmp))
+		return -1;
+	name = save_read_string(data, &size, &rsize);
+	if (!name)
+		return -1;
+
+	if (*name == '\0') {
+		/* top buffer */
+		buff = &handle->top_buffer;
+	} else {
+		buff = realloc(handle->buffers, sizeof(*handle->buffers) * (handle->nr_buffers + 1));
+		if (!buff) {
+			free(name);
+			return -1;
+		}
+		handle->buffers = buff;
+		handle->nr_buffers++;
+
+		buff = &handle->buffers[handle->nr_buffers - 1];
+	}
+	memset(buff, 0, sizeof(struct input_buffer_instance));
+	buff->name = name;
+	buff->offset = tmp;
+	if (handle->file_version < 7)
+		return 0;
+
+	/* file version >= 7 specific data */
+	buff->clock = save_read_string(data, &size, &rsize);
+	if (!buff->clock)
+		return -1;
+	if (id == TRACECMD_OPTION_BUFFER) {
+		if (save_read_number(handle->pevent, data, &size, &rsize, 4, &tmp))
+			return -1;
+		buff->cpus = tmp;
+		if (!buff->cpus)
+			return 0;
+		buff->cpu_data = calloc(buff->cpus, sizeof(struct cpu_file_data));
+		if (!buff->cpu_data)
+			return -1;
+		for (i = 0; i < buff->cpus; i++) {
+			if (save_read_number(handle->pevent, data, &size, &rsize, 4, &tmp))
+				return -1;
+			buff->cpu_data[i].cpu = tmp;
+			if (save_read_number(handle->pevent, data,
+					     &size, &rsize, 8, &buff->cpu_data[i].offset))
+				return -1;
+			if (save_read_number(handle->pevent, data,
+					     &size, &rsize, 8, &buff->cpu_data[i].size))
+				return -1;
+		}
+	} else {
+		buff->latency = true;
+	}
+	return 0;
+}
+
 static int handle_options(struct tracecmd_input *handle)
 {
 	long long offset;
 	unsigned short option;
 	unsigned int size;
 	char *cpustats = NULL;
-	struct input_buffer_instance *buffer;
 	struct hook_list *hook;
 	char *buf;
 	int cpus;
@@ -2955,21 +3060,10 @@ static int handle_options(struct tracecmd_input *handle)
 			handle->cpustats = cpustats;
 			break;
 		case TRACECMD_OPTION_BUFFER:
-			/* A buffer instance is saved at the end of the file */
-			handle->nr_buffers++;
-			handle->buffers = realloc(handle->buffers,
-						  sizeof(*handle->buffers) * handle->nr_buffers);
-			if (!handle->buffers)
-				return -ENOMEM;
-			buffer = &handle->buffers[handle->nr_buffers - 1];
-			buffer->name = strdup(buf + 8);
-			if (!buffer->name) {
-				free(handle->buffers);
-				handle->buffers = NULL;
-				return -ENOMEM;
-			}
-			offset = *(unsigned long long *)buf;
-			buffer->offset = tep_read_number(handle->pevent, &offset, 8);
+		case TRACECMD_OPTION_BUFFER_TEXT:
+			ret = handle_buffer_option(handle, option, buf, size);
+			if (ret < 0)
+				return ret;
 			break;
 		case TRACECMD_OPTION_TRACECLOCK:
 			if (!handle->ts2secs)
@@ -3719,6 +3813,13 @@ void tracecmd_ref(struct tracecmd_input *handle)
 	handle->ref++;
 }
 
+static inline void free_buffer(struct input_buffer_instance *buf)
+{
+	free(buf->name);
+	free(buf->clock);
+	free(buf->cpu_data);
+}
+
 /**
  * tracecmd_close - close and free the trace.dat handle
  * @handle: input handle for the trace.dat file
@@ -3774,8 +3875,9 @@ void tracecmd_close(struct tracecmd_input *handle)
 		free(del_sec);
 	}
 
+	free_buffer(&handle->top_buffer);
 	for (i = 0; i < handle->nr_buffers; i++)
-		free(handle->buffers[i].name);
+		free_buffer(&handle->buffers[i]);
 	free(handle->buffers);
 
 	tracecmd_free_hooks(handle->hooks);
@@ -4219,6 +4321,7 @@ tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx)
 		return NULL;
 
 	*new_handle = *handle;
+	memset(&new_handle->top_buffer, 0, sizeof(new_handle->top_buffer));
 	new_handle->cpu_data = NULL;
 	new_handle->nr_buffers = 0;
 	new_handle->buffers = NULL;
-- 
2.31.1