[PATCH v4 17/25] trace-cmd library: Read headers from trace file version 7

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

Trace file version 7 has more flexible structure than version 6, headers
are not located at fixed position in the file. A new logic is
implemented to read and parse the headers from this new format.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-input.c | 145 ++++++++++++++++++++++++++++++++----
 1 file changed, 130 insertions(+), 15 deletions(-)

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 7386f407..769bdcc3 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -162,8 +162,7 @@ struct tracecmd_input {
 	struct pid_addr_maps	*pid_maps;
 	/* file information */
 	struct file_section	*sections;
-	size_t			header_files_start;
-	size_t			ftrace_files_start;
+	bool			options_init;
 	unsigned long long	options_start;
 	size_t			total_file_size;
 
@@ -916,19 +915,7 @@ static int read_cpus(struct tracecmd_input *handle)
 	return 0;
 }
 
-/**
- * tracecmd_read_headers - read the header information from trace.dat
- * @handle: input handle for the trace.dat file
- * @state: The state to read up to or zero to read up to options.
- *
- * This reads the trace.dat file for various information. Like the
- * format of the ring buffer, event formats, ftrace formats, kallsyms
- * and printk. This may be called multiple times with different @state
- * values, to read partial data at a time. It will always continue
- * where it left off.
- */
-int tracecmd_read_headers(struct tracecmd_input *handle,
-			  enum tracecmd_file_states state)
+static int read_headers_v6(struct tracecmd_input *handle, enum tracecmd_file_states state)
 {
 	int ret;
 
@@ -994,6 +981,134 @@ int tracecmd_read_headers(struct tracecmd_input *handle,
 	return 0;
 }
 
+static int handle_options(struct tracecmd_input *handle);
+
+static int read_section_header(struct tracecmd_input *handle, unsigned short *id,
+			       unsigned short *flags, unsigned int *size, char **description)
+{
+	unsigned short fl;
+	char *desc = NULL;
+	unsigned short sec_id;
+	unsigned int sz;
+
+	if (read2(handle, &sec_id))
+		return -1;
+	desc = read_string(handle);
+	if (!desc)
+		return -1;
+	if (read2(handle, &fl))
+		goto error;
+	if (read4(handle, &sz))
+		goto error;
+
+	if (id)
+		*id = sec_id;
+	if (flags)
+		*flags = fl;
+	if (size)
+		*size = sz;
+	if (description)
+		*description = desc;
+	else
+		free(desc);
+	return 0;
+
+error:
+	free(desc);
+	return -1;
+}
+
+static int handle_section(struct tracecmd_input *handle, struct file_section *section)
+{
+	unsigned short id, flags;
+	unsigned int size;
+	int ret;
+
+	if (lseek64(handle->fd, section->section_offset, SEEK_SET) == (off_t)-1)
+		return -1;
+	if (read_section_header(handle, &id, &flags, &size, NULL))
+		return -1;
+	section->flags = flags;
+	if (id != section->id)
+		return -1;
+
+	section->data_offset = lseek64(handle->fd, 0, SEEK_CUR);
+
+	switch (section->id) {
+	case TRACECMD_OPTION_HEADER_INFO:
+		ret = read_header_files(handle);
+		break;
+	case TRACECMD_OPTION_FTRACE_EVENTS:
+		ret = read_ftrace_files(handle, NULL);
+		break;
+	case TRACECMD_OPTION_EVENT_FORMATS:
+		ret = read_event_files(handle, NULL);
+		break;
+	case TRACECMD_OPTION_KALLSYMS:
+		ret = read_proc_kallsyms(handle);
+		break;
+	case TRACECMD_OPTION_PRINTK:
+		ret = read_ftrace_printk(handle);
+		break;
+	case TRACECMD_OPTION_CMDLINES:
+		ret = read_and_parse_cmdlines(handle);
+		break;
+	default:
+		ret = 0;
+		break;
+	}
+
+	return ret;
+}
+
+static int read_headers_v7(struct tracecmd_input *handle)
+{
+	struct file_section *section;
+
+	if (handle->options_init)
+		return 0;
+
+	if (!handle->options_start)
+		return -1;
+
+	if (lseek64(handle->fd, handle->options_start, SEEK_SET) == (off64_t)-1) {
+		tracecmd_warning("Filed to goto options offset %lld", handle->options_start);
+		return -1;
+	}
+
+	if (handle_options(handle))
+		return -1;
+
+	section = handle->sections;
+	while (section) {
+		if (handle_section(handle, section))
+			return -1;
+		section = section->next;
+	}
+
+	handle->options_init = true;
+	return 0;
+}
+
+/**
+ * tracecmd_read_headers - read the header information from trace.dat
+ * @handle: input handle for the trace.dat file
+ * @state: The state to read up to or zero to read up to options.
+ *
+ * This reads the trace.dat file for various information. Like the
+ * format of the ring buffer, event formats, ftrace formats, kallsyms
+ * and printk. This may be called multiple times with different @state
+ * values, to read partial data at a time. It will always continue
+ * where it left off.
+ */
+int tracecmd_read_headers(struct tracecmd_input *handle,
+			  enum tracecmd_file_states state)
+{
+	if (!HAS_SECTIONS(handle))
+		return read_headers_v6(handle, state);
+	return read_headers_v7(handle);
+}
+
 static unsigned long long calc_page_offset(struct tracecmd_input *handle,
 					   unsigned long long offset)
 {
-- 
2.31.1