v4.19.13 snapshot.
diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
new file mode 100644
index 0000000..d8cfc19
--- /dev/null
+++ b/tools/perf/util/data.c
@@ -0,0 +1,189 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+#include "data.h"
+#include "util.h"
+#include "debug.h"
+
+static bool check_pipe(struct perf_data *data)
+{
+ struct stat st;
+ bool is_pipe = false;
+ int fd = perf_data__is_read(data) ?
+ STDIN_FILENO : STDOUT_FILENO;
+
+ if (!data->file.path) {
+ if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
+ is_pipe = true;
+ } else {
+ if (!strcmp(data->file.path, "-"))
+ is_pipe = true;
+ }
+
+ if (is_pipe)
+ data->file.fd = fd;
+
+ return data->is_pipe = is_pipe;
+}
+
+static int check_backup(struct perf_data *data)
+{
+ struct stat st;
+
+ if (!stat(data->file.path, &st) && st.st_size) {
+ /* TODO check errors properly */
+ char oldname[PATH_MAX];
+ snprintf(oldname, sizeof(oldname), "%s.old",
+ data->file.path);
+ unlink(oldname);
+ rename(data->file.path, oldname);
+ }
+
+ return 0;
+}
+
+static int open_file_read(struct perf_data *data)
+{
+ struct stat st;
+ int fd;
+ char sbuf[STRERR_BUFSIZE];
+
+ fd = open(data->file.path, O_RDONLY);
+ if (fd < 0) {
+ int err = errno;
+
+ pr_err("failed to open %s: %s", data->file.path,
+ str_error_r(err, sbuf, sizeof(sbuf)));
+ if (err == ENOENT && !strcmp(data->file.path, "perf.data"))
+ pr_err(" (try 'perf record' first)");
+ pr_err("\n");
+ return -err;
+ }
+
+ if (fstat(fd, &st) < 0)
+ goto out_close;
+
+ if (!data->force && st.st_uid && (st.st_uid != geteuid())) {
+ pr_err("File %s not owned by current user or root (use -f to override)\n",
+ data->file.path);
+ goto out_close;
+ }
+
+ if (!st.st_size) {
+ pr_info("zero-sized data (%s), nothing to do!\n",
+ data->file.path);
+ goto out_close;
+ }
+
+ data->size = st.st_size;
+ return fd;
+
+ out_close:
+ close(fd);
+ return -1;
+}
+
+static int open_file_write(struct perf_data *data)
+{
+ int fd;
+ char sbuf[STRERR_BUFSIZE];
+
+ if (check_backup(data))
+ return -1;
+
+ fd = open(data->file.path, O_CREAT|O_RDWR|O_TRUNC|O_CLOEXEC,
+ S_IRUSR|S_IWUSR);
+
+ if (fd < 0)
+ pr_err("failed to open %s : %s\n", data->file.path,
+ str_error_r(errno, sbuf, sizeof(sbuf)));
+
+ return fd;
+}
+
+static int open_file(struct perf_data *data)
+{
+ int fd;
+
+ fd = perf_data__is_read(data) ?
+ open_file_read(data) : open_file_write(data);
+
+ data->file.fd = fd;
+ return fd < 0 ? -1 : 0;
+}
+
+int perf_data__open(struct perf_data *data)
+{
+ if (check_pipe(data))
+ return 0;
+
+ if (!data->file.path)
+ data->file.path = "perf.data";
+
+ return open_file(data);
+}
+
+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 perf_data_file__write(&data->file, buf, size);
+}
+
+int perf_data__switch(struct perf_data *data,
+ const char *postfix,
+ size_t pos, bool at_exit)
+{
+ char *new_filepath;
+ int ret;
+
+ if (check_pipe(data))
+ return -EINVAL;
+ if (perf_data__is_read(data))
+ return -EINVAL;
+
+ if (asprintf(&new_filepath, "%s.%s", data->file.path, postfix) < 0)
+ return -ENOMEM;
+
+ /*
+ * Only fire a warning, don't return error, continue fill
+ * original file.
+ */
+ if (rename(data->file.path, new_filepath))
+ pr_warning("Failed to rename %s to %s\n", data->file.path, new_filepath);
+
+ if (!at_exit) {
+ close(data->file.fd);
+ ret = perf_data__open(data);
+ if (ret < 0)
+ goto out;
+
+ if (lseek(data->file.fd, pos, SEEK_SET) == (off_t)-1) {
+ ret = -errno;
+ pr_debug("Failed to lseek to %zu: %s",
+ pos, strerror(errno));
+ goto out;
+ }
+ }
+ ret = data->file.fd;
+out:
+ free(new_filepath);
+ return ret;
+}