linux-kernel - [PATCH 11/13] perf tools: Add lzma_is

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Date:   Fri, 17 Aug 2018 11:48:11 +0200
From:   Jiri Olsa <jolsa@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>
Subject: [PATCH 11/13] perf tools: Add lzma_is_compressed function

Add implementation of the is_compressed callback for lzma.

Link: http://lkml.kernel.org/n/tip-tdgpdhdfk7sm5hsyjvfs2skh@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@...nel.org>
---
 tools/perf/util/lzma.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/lzma.c b/tools/perf/util/lzma.c
index 7032caaf75eb..b1dd29a9d915 100644
--- a/tools/perf/util/lzma.c
+++ b/tools/perf/util/lzma.c
@@ -3,9 +3,13 @@
 #include <lzma.h>
 #include <stdio.h>
 #include <linux/compiler.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include "compress.h"
 #include "util.h"
 #include "debug.h"
+#include <unistd.h>
 
 #define BUFSIZE 8192
 
@@ -100,7 +104,18 @@ int lzma_decompress_to_file(const char *input, int output_fd)
 	return err;
 }
 
-bool lzma_is_compressed(const char *input __maybe_unused)
+bool lzma_is_compressed(const char *input)
 {
-	return true;
+	int fd = open(input, O_RDONLY);
+	const uint8_t magic[6] = { 0xFD, '7', 'z', 'X', 'Z', 0x00 };
+	char buf[6] = { 0 };
+	ssize_t rc;
+
+	if (fd < 0)
+		return -1;
+
+	rc = read(fd, buf, sizeof(buf));
+	close(fd);
+	return rc == sizeof(buf) ?
+	       memcmp(buf, magic, sizeof(buf)) == 0 : false;
 }
-- 
2.17.1