[PATCH v2 01/10] trace-cmd library: New API for allocating an output handler

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

The API only allocates a handler and performs minimal initialization.
No data is written in the file.
  tracecmd_output_allocate()

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 .../include/private/trace-cmd-private.h       |  4 ++-
 lib/trace-cmd/trace-output.c                  | 36 +++++++++++++++++++
 2 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index f40babef..bed96657 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -102,7 +102,8 @@ static inline int tracecmd_host_bigendian(void)
 /* --- Opening and Reading the trace.dat file --- */
 
 enum tracecmd_file_states {
-	TRACECMD_FILE_INIT = 1,
+	TRACECMD_FILE_ALLOCATED = 0,
+	TRACECMD_FILE_INIT,
 	TRACECMD_FILE_HEADERS,
 	TRACECMD_FILE_FTRACE_EVENTS,
 	TRACECMD_FILE_ALL_EVENTS,
@@ -268,6 +269,7 @@ struct tracecmd_event_list {
 struct tracecmd_option;
 struct tracecmd_msg_handle;
 
+struct tracecmd_output *tracecmd_output_allocate(int fd);
 struct tracecmd_output *tracecmd_create_file_latency(const char *output_file, int cpus);
 struct tracecmd_output *
 tracecmd_create_init_file_glob(const char *output_file,
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index fe1d1aaa..3878b963 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -59,6 +59,7 @@ struct tracecmd_output {
 	unsigned long		file_state;
 	unsigned long		file_version;
 	size_t			options_start;
+	bool			big_endian;
 
 	struct list_head	options;
 	struct tracecmd_msg_handle *msg_handle;
@@ -883,6 +884,41 @@ out_free:
 	return ret;
 }
 
+/**
+ * tracecmd_output_allocate - allocate new output handler to a trace file
+ * @handle: file descriptor to an empty file, it can be -1 if the handler
+ *	    will not write to a file
+ *
+ * This API only allocates a handler and performs minimal initialization.
+ * No data is written in the file.
+ *
+ * Returns pointer to a newly allocated file descriptor, that can be used
+ * with other library APIs. In case of an error, NULL is returned. The returned
+ * handler must be freed with tracecmd_output_close() or tracecmd_output_free()
+ */
+struct tracecmd_output *tracecmd_output_allocate(int fd)
+{
+	struct tracecmd_output *handle;
+
+	handle = calloc(1, sizeof(*handle));
+	if (!handle)
+		return NULL;
+
+	handle->fd = fd;
+
+	handle->file_version = FILE_VERSION;
+
+	handle->page_size = getpagesize();
+	handle->big_endian = tracecmd_host_bigendian();
+
+	list_head_init(&handle->options);
+
+	handle->file_state = TRACECMD_FILE_ALLOCATED;
+
+	return handle;
+}
+
+
 static int select_file_version(struct tracecmd_output *handle,
 				struct tracecmd_input *ihandle)
 {
-- 
2.33.1