libsnapshot: Add decompression check to Inspect_Cow
This adds the -d option to Inspect_Cow, which will cause it to attempt
to decompress all data blocks, reporting any errors it encounters.
Useful for detecting corruption in Cow files.
Bug: 172026020
Test: Inspect_Cow -d [cow_file]
Change-Id: Iebf5f7f485b33b36daab4ab07005ca37e51d692f
diff --git a/fs_mgr/libsnapshot/inspect_cow.cpp b/fs_mgr/libsnapshot/inspect_cow.cpp
index 5ad61f3..453b5c6 100644
--- a/fs_mgr/libsnapshot/inspect_cow.cpp
+++ b/fs_mgr/libsnapshot/inspect_cow.cpp
@@ -36,10 +36,30 @@
}
static void usage(void) {
- LOG(ERROR) << "Usage: inspect_cow [-s] <COW_FILE>";
+ LOG(ERROR) << "Usage: inspect_cow [-sd] <COW_FILE>";
+ LOG(ERROR) << "\t -s Run Silent";
+ LOG(ERROR) << "\t -d Attempt to decompress\n";
}
-static bool Inspect(const std::string& path, bool silent) {
+// Sink that always appends to the end of a string.
+class StringSink : public IByteSink {
+ public:
+ void* GetBuffer(size_t requested, size_t* actual) override {
+ size_t old_size = stream_.size();
+ stream_.resize(old_size + requested, '\0');
+ *actual = requested;
+ return stream_.data() + old_size;
+ }
+ bool ReturnData(void*, size_t) override { return true; }
+ void Reset() { stream_.clear(); }
+
+ std::string& stream() { return stream_; }
+
+ private:
+ std::string stream_;
+};
+
+static bool Inspect(const std::string& path, bool silent, bool decompress) {
android::base::unique_fd fd(open(path.c_str(), O_RDONLY));
if (fd < 0) {
PLOG(ERROR) << "open failed: " << path;
@@ -76,15 +96,25 @@
}
auto iter = reader.GetOpIter();
+ StringSink sink;
+ bool success = true;
while (!iter->Done()) {
const CowOperation& op = iter->Get();
if (!silent) std::cout << op << "\n";
+ if (decompress && op.type == kCowReplaceOp && op.compression != kCowCompressNone) {
+ if (!reader.ReadData(op, &sink)) {
+ std::cerr << "Failed to decompress for :" << op << "\n";
+ success = false;
+ }
+ sink.Reset();
+ }
+
iter->Next();
}
- return true;
+ return success;
}
} // namespace snapshot
@@ -93,11 +123,15 @@
int main(int argc, char** argv) {
int ch;
bool silent = false;
- while ((ch = getopt(argc, argv, "s")) != -1) {
+ bool decompress = false;
+ while ((ch = getopt(argc, argv, "sd")) != -1) {
switch (ch) {
case 's':
silent = true;
break;
+ case 'd':
+ decompress = true;
+ break;
default:
android::snapshot::usage();
}
@@ -109,7 +143,7 @@
return 1;
}
- if (!android::snapshot::Inspect(argv[optind], silent)) {
+ if (!android::snapshot::Inspect(argv[optind], silent, decompress)) {
return 1;
}
return 0;