commit 8a28163d33d85b9742900f173ed765145a449a56
author David Anderson <dvander@google.com> Tue Oct 03 15:55:09 2023 -0700
committer David Anderson <dvander@google.com> Tue Oct 03 16:02:26 2023 -0700
tree 248cf47f956536babab6adca1a4f5872017b5ec8
parent e877885533696352a67707b4ed61643351160a6d

inspect_cow: Add an --extract-to argument.

This adds an --extract-to argument to inspect_cow to verify that full
OTA snapshots contain correct data. It does not yet work for ordered
ops.

Test: inspect_cow
Bug: N/A
Change-Id: I9014da3e83fd4fb5ea54ac1d36e527b3e3e6c9d5

Change-Id: I7e256e8ddec626980cdcf8680bbeac3c2e9d8de1

fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp

diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
index a6dee4f..83b5a12 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/inspect_cow.cpp
@@ -22,6 +22,7 @@
 #include <string>
 #include <vector>
 
+#include <android-base/file.h>
 #include <android-base/logging.h>
 #include <android-base/unique_fd.h>
 #include <gflags/gflags.h>
@@ -38,11 +39,13 @@
 DEFINE_bool(verify_merge_sequence, false, "Verify merge order sequencing");
 DEFINE_bool(show_merge_sequence, false, "Show merge order sequence");
 DEFINE_bool(show_raw_ops, false, "Show raw ops directly from the underlying parser");
+DEFINE_string(extract_to, "", "Extract the COW contents to the given file");
 
 namespace android {
 namespace snapshot {
 
 using android::base::borrowed_fd;
+using android::base::unique_fd;
 
 void MyLogger(android::base::LogId, android::base::LogSeverity severity, const char*, const char*,
               unsigned int, const char* message) {
@@ -53,7 +56,7 @@
     }
 }
 
-static void ShowBad(CowReader& reader, const struct CowOperation* op) {
+static void ShowBad(CowReader& reader, const CowOperation* op) {
     size_t count;
     auto buffer = std::make_unique<uint8_t[]>(op->data_length);
 
@@ -104,12 +107,21 @@
 }
 
 static bool Inspect(const std::string& path) {
-    android::base::unique_fd fd(open(path.c_str(), O_RDONLY));
+    unique_fd fd(open(path.c_str(), O_RDONLY));
     if (fd < 0) {
         PLOG(ERROR) << "open failed: " << path;
         return false;
     }
 
+    unique_fd extract_to;
+    if (!FLAGS_extract_to.empty()) {
+        extract_to.reset(open(FLAGS_extract_to.c_str(), O_RDWR | O_CREAT | O_TRUNC, 0664));
+        if (extract_to < 0) {
+            PLOG(ERROR) << "could not open " << FLAGS_extract_to << " for writing";
+            return false;
+        }
+    }
+
     CowReader reader;
 
     auto start_time = std::chrono::steady_clock::now();
@@ -186,12 +198,23 @@
 
         if (!FLAGS_silent && FLAGS_show_ops) std::cout << *op << "\n";
 
-        if (FLAGS_decompress && op->type == kCowReplaceOp && op->compression != kCowCompressNone) {
+        if ((FLAGS_decompress || extract_to >= 0) && op->type == kCowReplaceOp) {
             if (reader.ReadData(op, buffer.data(), buffer.size()) < 0) {
                 std::cerr << "Failed to decompress for :" << *op << "\n";
                 success = false;
                 if (FLAGS_show_bad_data) ShowBad(reader, op);
             }
+            if (extract_to >= 0) {
+                off_t offset = uint64_t(op->new_block) * header.block_size;
+                if (!android::base::WriteFullyAtOffset(extract_to, buffer.data(), buffer.size(),
+                                                       offset)) {
+                    PLOG(ERROR) << "failed to write block " << op->new_block;
+                    return false;
+                }
+            }
+        } else if (extract_to >= 0 && !IsMetadataOp(*op) && op->type != kCowZeroOp) {
+            PLOG(ERROR) << "Cannot extract op yet: " << *op;
+            return false;
         }
 
         if (op->type == kCowSequenceOp && FLAGS_show_merge_sequence) {