[PATCH v2 04/20] trace-cmd library: Inherit compression algorithm from input file

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

When a new trace file output handler is allocated, based on given trace
file input handler - use the same compression algorithm.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 .../include/private/trace-cmd-private.h       |  2 ++
 lib/trace-cmd/trace-input.c                   | 16 ++++++++++++++++
 lib/trace-cmd/trace-output.c                  | 19 +++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index 04b3cb41..30315c00 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -255,6 +255,8 @@ tracecmd_get_cursor(struct tracecmd_input *handle, int cpu);
 
 unsigned long tracecmd_get_in_file_version(struct tracecmd_input *handle);
 size_t tracecmd_get_options_offset(struct tracecmd_input *handle);
+int tracecmd_get_file_compress_proto(struct tracecmd_input *handle,
+				     const char **name, const char **version);
 
 int tracecmd_ftrace_overrides(struct tracecmd_input *handle, struct tracecmd_ftrace *finfo);
 bool tracecmd_get_use_trace_clock(struct tracecmd_input *handle);
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 3eef539f..11ee6470 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -4608,6 +4608,22 @@ unsigned long tracecmd_get_in_file_version(struct tracecmd_input *handle)
 	return handle->file_version;
 }
 
+/**
+ * tracecmd_get_file_compress_proto - get name and version of compression algorithm,
+ *				      used to compress the trace file
+ * @handle: input handle for the trace.dat file
+ * @name: return, name of the compression algorithm.
+ * @version: return, version of the compression algorithm.
+ *
+ * Returns 0 on success, or -1 in case of an error. If 0 is returned, the name and version of the
+ * algorithm are stored in @name and @version. The returned strings must *not* be freed.
+ */
+int tracecmd_get_file_compress_proto(struct tracecmd_input *handle,
+				     const char **name, const char **version)
+{
+	return tracecmd_compress_proto_get_name(handle->compress, name, version);
+}
+
 /**
  * tracecmd_get_use_trace_clock - return use_trace_clock
  * @handle: input handle for the trace.dat file
diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index d9502023..edf05cfe 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -1213,6 +1213,9 @@ int tracecmd_output_set_kallsyms(struct tracecmd_output *handler, const char *ka
  */
 int tracecmd_output_set_from_input(struct tracecmd_output *handler, struct tracecmd_input *ihandle)
 {
+	const char *cname = NULL;
+	const char *cver = NULL;
+
 	if (!handler || !ihandle || handler->file_state != TRACECMD_FILE_ALLOCATED)
 		return -1;
 
@@ -1227,6 +1230,14 @@ int tracecmd_output_set_from_input(struct tracecmd_output *handler, struct trace
 	else
 		handler->big_endian = false;
 
+	if (!tracecmd_get_file_compress_proto(ihandle, &cname, &cver)) {
+		handler->compress = tracecmd_compress_alloc(cname, cver, handler->fd,
+							    handler->pevent, handler->msg_handle);
+		if (!handler->compress)
+			return -1;
+		if (handler->file_version < FILE_VERSION_COMPRESSION)
+			handler->file_version = FILE_VERSION_COMPRESSION;
+	}
 
 	return 0;
 }
@@ -2166,6 +2177,8 @@ struct tracecmd_output *tracecmd_get_output_handle_fd(int fd)
 {
 	struct tracecmd_output *handle = NULL;
 	struct tracecmd_input *ihandle;
+	const char *cname = NULL;
+	const char *cver = NULL;
 	int fd2;
 
 	/* Move the file descriptor to the beginning */
@@ -2205,6 +2218,12 @@ struct tracecmd_output *tracecmd_get_output_handle_fd(int fd)
 	list_head_init(&handle->options);
 	list_head_init(&handle->buffers);
 
+	if (!tracecmd_get_file_compress_proto(ihandle, &cname, &cver)) {
+		handle->compress = tracecmd_compress_alloc(cname, cver, handle->fd,
+							   handle->pevent, handle->msg_handle);
+		if (!handle->compress)
+			goto out_free;
+	}
 	tracecmd_close(ihandle);
 
 	return handle;
-- 
2.31.1