perf_data_file__switch() closes current output file, renames it, then
open a new one to continue recording. It will be used by perf record
to split output into multiple perf.data files.

Signed-off-by: Wang Nan <wangn...@huawei.com>
Signed-off-by: He Kuang <heku...@huawei.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu...@hitachi.com>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Zefan Li <lize...@huawei.com>
Cc: pi3or...@163.com
---
 tools/perf/util/data.c | 41 +++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/data.h | 11 ++++++++++-
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index 1921942..be835161 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -136,3 +136,44 @@ ssize_t perf_data_file__write(struct perf_data_file *file,
 {
        return writen(file->fd, buf, size);
 }
+
+int perf_data_file__switch(struct perf_data_file *file,
+                          const char *postfix,
+                          size_t pos, bool at_exit)
+{
+       char *new_filepath;
+       int ret;
+
+       if (check_pipe(file))
+               return -EINVAL;
+       if (perf_data_file__is_read(file))
+               return -EINVAL;
+
+       if (asprintf(&new_filepath, "%s.%s", file->path, postfix) < 0)
+               return -ENOMEM;
+
+       /*
+        * Only fire a warning, don't return error, continue fill
+        * original file.
+        */
+       if (rename(file->path, new_filepath))
+               pr_warning("Failed to rename %s to %s\n", file->path, 
new_filepath);
+
+       if (!at_exit) {
+               close(file->fd);
+               ret = perf_data_file__open(file);
+               if (ret < 0)
+                       goto out;
+
+               if (lseek(file->fd, pos, SEEK_SET) == (off_t)-1) {
+                       ret = -errno;
+                       pr_debug("Failed to lseek to %zu: %s",
+                                pos, strerror(errno));
+                       goto out;
+               }
+       }
+       ret = file->fd;
+out:
+       free(new_filepath);
+       return ret;
+}
diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
index 2b15d0c..ae510ce 100644
--- a/tools/perf/util/data.h
+++ b/tools/perf/util/data.h
@@ -46,5 +46,14 @@ int perf_data_file__open(struct perf_data_file *file);
 void perf_data_file__close(struct perf_data_file *file);
 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 file.
+ * Set at_exit when flushing the last output.
+ *
+ * Return value is fd of new output.
+ */
+int perf_data_file__switch(struct perf_data_file *file,
+                          const char *postfix,
+                          size_t pos, bool at_exit);
 #endif /* __PERF_DATA_H */
-- 
1.8.3.4

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