[PATCH v3 1/2] libtracecmd: Support querying position within a new compressed block

tracecmd_compress_lseek() refuses to return position within a new
block, because handle->buffer is NULL. Add support for this; do not
implement actually seeking within a new block, because this is not
required at the moment.

Signed-off-by: Ilya Leoshkevich <[email protected]>
---
 lib/trace-cmd/trace-compress.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/trace-cmd/trace-compress.c b/lib/trace-cmd/trace-compress.c
index 2a7a3e24..3e10cf5b 100644
--- a/lib/trace-cmd/trace-compress.c
+++ b/lib/trace-cmd/trace-compress.c
@@ -132,9 +132,12 @@ off_t tracecmd_compress_lseek(struct tracecmd_compression *handle, off_t offset,
 {
 	unsigned long p;
 
-	if (!handle || !handle->buffer)
+	if (!handle)
 		return (off_t)-1;
 
+	if (!handle->buffer)
+		return (whence == SEEK_CUR && offset == 0) ? 0 : (off_t)-1;
+
 	switch (whence) {
 	case SEEK_CUR:
 		p = handle->pointer + offset;
-- 
2.50.1