[PATCH] perf buildid-list: Initialize zstd_data

[Milian Wolff]

Fixes segmentation fault when trying to obtain buildid list (e.g. via
perf-archive) from a zstd-compressed `perf.data` file:

```
    $ perf record -z ls
    ...
    [ perf record: Captured and wrote 0,010 MB perf.data, compressed (original 0,001 MB, ratio is 2,190) ]
    $ memcheck perf buildid-list
    ...
    ==57268== Invalid read of size 4
    ==57268==    at 0x5260D88: ZSTD_decompressStream (in /usr/lib/libzstd.so.1.4.9)
    ==57268==    by 0x4BB51B: zstd_decompress_stream (zstd.c:100)
    ==57268==    by 0x425C6C: perf_session__process_compressed_event (session.c:73)
    ==57268==    by 0x427450: perf_session__process_user_event (session.c:1631)
    ==57268==    by 0x42A609: reader__process_events (session.c:2207)
    ==57268==    by 0x42A609: __perf_session__process_events (session.c:2264)
    ==57268==    by 0x42A609: perf_session__process_events (session.c:2297)
    ==57268==    by 0x343A62: perf_session__list_build_ids (builtin-buildid-list.c:88)
    ==57268==    by 0x343A62: cmd_buildid_list (builtin-buildid-list.c:120)
    ==57268==    by 0x3C7732: run_builtin (perf.c:313)
    ==57268==    by 0x331157: handle_internal_command (perf.c:365)
    ==57268==    by 0x331157: run_argv (perf.c:409)
    ==57268==    by 0x331157: main (perf.c:539)
    ==57268==  Address 0x7470 is not stack'd, malloc'd or (recently) free'd
```

Signed-off-by: Milian Wolff <milian.wolff@xxxxxxxx>
---
 tools/perf/builtin-buildid-list.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/builtin-buildid-list.c b/tools/perf/builtin-buildid-list.c
index 87f5b1a4a7fa..833405c27dae 100644
--- a/tools/perf/builtin-buildid-list.c
+++ b/tools/perf/builtin-buildid-list.c
@@ -80,6 +80,9 @@ static int perf_session__list_build_ids(bool force, bool with_hits)
 	if (!perf_header__has_feat(&session->header, HEADER_BUILD_ID))
 		with_hits = true;
 
+	if (zstd_init(&(session->zstd_data), 0) < 0)
+		pr_warning("Decompression initialization failed. Reported data may be incomplete.\n");
+
 	/*
 	 * in pipe-mode, the only way to get the buildids is to parse
 	 * the record stream. Buildids are stored as RECORD_HEADER_BUILD_ID
-- 
2.31.1