iOS: add CodePushBinaryDiffPatcher to apply bsdiff patches

[ofalvai]

_{Stack created with GitHub Stacks CLI • Give Feedback 💬}

[Copilot]

🟡 Changes recommended

The new patcher currently emits misleading hash-mismatch errors when hashing fails (e.g., unreadable/missing files), obscuring the real I/O failure cause.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds an iOS-native binary diff patcher to apply bsdiff patches described by CodePushDiffManifest, aligning iOS with the existing Android diff/patch flow and hardening path handling via resolvePath(_:withinFolder:).

Changes:

• Introduces CodePushBinaryDiffPatcher (Obj-C) to validate hashes, resolve manifest-supplied paths safely, and apply bsdiff patches via bspatch_bridge.
• Adds Swift XCTest coverage for happy-path patching, hash mismatches, unsupported algorithms, path traversal, and symlink-escape attempts.
• Wires the new source + tests into the Xcode project and test bridging header.

File summaries

File	Description
ios/CodePushTests/CodePushTests-Bridging-Header.h	Exposes the new Obj-C patcher to Swift tests.
ios/CodePushTests/CodePushBinaryDiffPatcherTests.swift	Adds test coverage for binary patch application and path/symlink safety.
ios/CodePush/CodePushBinaryDiffPatcher.m	Implements patch application, path resolution, and hash verification.
ios/CodePush/CodePushBinaryDiffPatcher.h	Declares the patcher API and Swift import name.
ios/CodePush.xcodeproj/project.pbxproj	Registers new sources/headers and the new test file in build phases.

Review details

Suppressed comments (1)

ios/CodePush/CodePushBinaryDiffPatcher.m:98

• If hashing the newly patched file fails, newFileHash can be nil and the code reports a confusing "targetHash mismatch ... got (null)" instead of the actual hashing/read error. Handling the nil case separately provides a clearer failure reason.

        NSString *newFileHash = CodePushSha256HexForFile(newFile, &hashError);
        if (!newFileHash || ![newFileHash isEqualToString:entry.targetHash]) {
            if (error) *error = patchApplyError(relativePath, [NSString stringWithFormat:@"targetHash mismatch: expected %@, got %@", entry.targetHash, newFileHash]);
            return NO;

• Files reviewed: 5/5 changed files
• Comments generated: 1
• Review effort level: Lite

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.