[PATCH v2] trace-cmd: Check if file version is supported

[PATCH v2] trace-cmd: Check if file version is supported

[Tzvetomir Stoyanov (VMware)]

When reading a trace file, version of the file is ignored. This could
case problems when bumping the version number because of changes in
in the structure of the file. The old code should detect unsupported
file version and should not try to read it.
A new trace-cmd library API is added to check if version is supported:
 tracecmd_is_version_supported()
Checks are added in the code to ensure not trying to read trace file
with unsupported version.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
v2 changes:
 - Fix the comparison of the version, to include the current version number.
 - Make the version variable unsigned.
 - Coding style fixes.

 lib/trace-cmd/include/private/trace-cmd-private.h |  2 ++
 lib/trace-cmd/trace-input.c                       | 10 ++++++++++
 lib/trace-cmd/trace-util.c                        |  7 +++++++
 tracecmd/trace-dump.c                             |  7 +++++++
 4 files changed, 26 insertions(+)

diff --git a/lib/trace-cmd/include/private/trace-cmd-private.h b/lib/trace-cmd/include/private/trace-cmd-private.h
index 56f82244..f7c1fa10 100644
--- a/lib/trace-cmd/include/private/trace-cmd-private.h
+++ b/lib/trace-cmd/include/private/trace-cmd-private.h
@@ -42,6 +42,8 @@ void tracecmd_record_ref(struct tep_record *record);
 void tracecmd_set_debug(bool set_debug);
 bool tracecmd_get_debug(void);
 
+bool tracecmd_is_version_supported(unsigned int version);
+
 struct tracecmd_output;
 struct tracecmd_recorder;
 struct hook_list;
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 991abd5f..0de651a2 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -117,6 +117,7 @@ struct tracecmd_input {
 	bool			use_trace_clock;
 	bool			read_page;
 	bool			use_pipe;
+	int			file_version;
 	struct cpu_data 	*cpu_data;
 	long long		ts_offset;
 	struct tsc2nsec		tsc_calc;
@@ -3175,6 +3176,7 @@ struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 	unsigned int page_size;
 	char *version;
 	char buf[BUFSIZ];
+	unsigned long ver;
 
 	handle = malloc(sizeof(*handle));
 	if (!handle)
@@ -3199,6 +3201,14 @@ struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 	if (!version)
 		goto failed_read;
 	pr_stat("version = %s\n", version);
+	ver = strtol(version, NULL, 10);
+	if (!ver && errno)
+		goto failed_read;
+	if (!tracecmd_is_version_supported(ver)) {
+		tracecmd_warning("Unsupported file version %lu", ver);
+		goto failed_read;
+	}
+	handle->file_version = ver;
 	free(version);
 
 	if (do_read_check(handle, buf, 1))
diff --git a/lib/trace-cmd/trace-util.c b/lib/trace-cmd/trace-util.c
index 2d3bc741..a6fc64c8 100644
--- a/lib/trace-cmd/trace-util.c
+++ b/lib/trace-cmd/trace-util.c
@@ -582,3 +582,10 @@ unsigned long long tracecmd_generate_traceid(void)
 	free(str);
 	return hash;
 }
+
+bool tracecmd_is_version_supported(unsigned int version)
+{
+	if (version <= FILE_VERSION)
+		return true;
+	return false;
+}
diff --git a/tracecmd/trace-dump.c b/tracecmd/trace-dump.c
index 3f56f65a..aa48eaad 100644
--- a/tracecmd/trace-dump.c
+++ b/tracecmd/trace-dump.c
@@ -10,6 +10,7 @@
 #include <getopt.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <errno.h>
 
 #include "trace-local.h"
 
@@ -145,6 +146,7 @@ static void dump_initial_format(int fd)
 	char magic[] = TRACECMD_MAGIC;
 	char buf[DUMP_SIZE];
 	int val4;
+	unsigned long ver;
 
 	do_print(SUMMARY, "\t[Initial format]\n");
 
@@ -166,6 +168,11 @@ static void dump_initial_format(int fd)
 		die("no version string");
 
 	do_print(SUMMARY, "\t\t%s\t[Version]\n", buf);
+	ver = strtol(buf, NULL, 10);
+	if (!ver && errno)
+		die("Invalid file version string %s", buf);
+	if (!tracecmd_is_version_supported(ver))
+		die("Unsupported file version %lu", ver);
 
 	/* get file endianness*/
 	if (read_file_bytes(fd, buf, 1))
-- 
2.30.2