perf tools: Add perf_data_file__write function

Adding perf_data_file__write function to provide single file write
operation.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Changbin Du <changbin.du@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-c3f9p4xzykr845ktqcek6p4t@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/data.c

@@ -144,10 +144,16 @@ void perf_data__close(struct perf_data *data)
 	close(data->file.fd);
 }
 
+ssize_t perf_data_file__write(struct perf_data_file *file,
+			      void *buf, size_t size)
+{
+	return writen(file->fd, buf, size);
+}
+
 ssize_t perf_data__write(struct perf_data *data,
 			      void *buf, size_t size)
 {
-	return writen(data->file.fd, buf, size);
+	return perf_data_file__write(&data->file, buf, size);
 }
 
 int perf_data__switch(struct perf_data *data,

tools/perf/util/data.h

@@ -50,6 +50,8 @@ int perf_data__open(struct perf_data *data);
 void perf_data__close(struct perf_data *data);
 ssize_t perf_data__write(struct perf_data *data,
 			      void *buf, size_t size);
+ssize_t perf_data_file__write(struct perf_data_file *file,
+			      void *buf, size_t size);
 /*
  * If at_exit is set, only rename current perf.data to
  * perf.data.<postfix>, continue write on original data.