trace-cmd: Add new API tracecmd_open_head()

Add an API to create a tracecmd_handle from a file, read and parse only the
trace headers from the file.  This allows for implementing opening a trace file
in stages - reading the trace headers and reading the trace data.

Link: http://lore.kernel.org/linux-trace-devel/20200409132825.79475-3-tz.stoyanov@gmail.com

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
[ Removed double "read" in comment ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2 files changed