fix(rpc): upgradetohd rpc should allow null characters in wallet passphrase

[UdjinM6]

Issue being fixed or feature implemented

A follow-up for 27068 from #6780 to make sure upgradetohd allows null characters in wallet passphrase like encryption RPCs do now. It's a slimmer alternative to #6792 that touches wallet passphrase only with a tiny test adjustment and no refactoring.

What was done?

Fix it, tweak tests

How Has This Been Tested?

Run tests

Breaking Changes

n/a

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone (for repository code-owners and collaborators only)

[github-actions]

⚠️ Potential Merge Conflicts Detected

This PR has potential conflicts with the following open PRs:

• fix(rpc): return correct error codes in upgradetohd rpc #6797 - fix(rpc): return correct error codes in upgradetohd rpc

Please coordinate with the authors of these PRs to avoid merge conflicts.

[coderabbitai]

Walkthrough

The changes update the handling of wallet passphrases in the upgradetohd RPC command by replacing the use of a C-style string pointer with a direct assignment using std::string_view. This adjustment eliminates the need for .c_str() and aligns the assignment with modern C++ practices. In the functional test, the wallet passphrase is modified to include a null character (\0), and a comment is added to indicate that null characters are now permitted in wallet passphrases. No other logic, control flow, or public interfaces are altered.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

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📥 Commits

Reviewing files that changed from the base of the PR and between dc63e25 and 737e85e.

📒 Files selected for processing (2)

• src/wallet/rpc/wallet.cpp (1 hunks)
• test/functional/wallet_upgradetohd.py (1 hunks)

🧰 Additional context used

📓 Path-based instructions (2)

test/functional/**/*.py

📄 CodeRabbit Inference Engine (CLAUDE.md)

Functional tests should be written in Python and placed in test/functional/

Files:

• test/functional/wallet_upgradetohd.py

src/**/*.{cpp,h,cc,cxx,hpp}

📄 CodeRabbit Inference Engine (CLAUDE.md)

src/**/*.{cpp,h,cc,cxx,hpp}: Dash Core C++ codebase must be written in C++20 and require at least Clang 16 or GCC 11.1
Dash uses unordered_lru_cache for efficient caching with LRU eviction

Files:

• src/wallet/rpc/wallet.cpp

🧠 Learnings (3)

📓 Common learnings

Learnt from: kwvg
PR: dashpay/dash#6761
File: src/chainlock/signing.cpp:247-250
Timestamp: 2025-07-29T14:32:48.369Z
Learning: In PR #6761, kwvg acknowledged a null pointer check issue in ChainLockSigner::Cleanup() method but deferred it to follow-up, consistent with the pattern of avoiding scope creep in refactoring PRs.

Learnt from: UdjinM6
PR: dashpay/dash#6786
File: ci/test/04_install.sh:99-101
Timestamp: 2025-08-01T07:46:37.840Z
Learning: In backport PRs like #6786, UdjinM6 prefers to defer non-critical fixes (such as shell command expansion issues) to separate commits/PRs to maintain focus on the primary backport objectives, consistent with the project's pattern of avoiding scope creep.

Learnt from: kwvg
PR: dashpay/dash#6543
File: src/wallet/receive.cpp:240-251
Timestamp: 2025-02-06T14:34:30.466Z
Learning: Pull request #6543 is focused on move-only changes and refactoring, specifically backporting from Bitcoin. Behavior changes should be proposed in separate PRs.

Learnt from: kwvg
PR: dashpay/dash#6718
File: test/functional/test_framework/test_framework.py:2102-2102
Timestamp: 2025-06-09T16:43:20.996Z
Learning: In the test framework consolidation PR (#6718), user kwvg prefers to limit functional changes to those directly related to MasternodeInfo, avoiding scope creep even for minor improvements like error handling consistency.

Learnt from: kwvg
PR: dashpay/dash#6761
File: src/wallet/wallet.cpp:0-0
Timestamp: 2025-07-29T14:33:01.040Z
Learning: In refactoring PRs like #6761, kwvg acknowledges code safety improvements (like null pointer checks and unused parameter warnings) but prefers to defer them to follow-up PRs to maintain focus on the primary refactoring objectives, avoiding scope creep.

Learnt from: kwvg
PR: dashpay/dash#6529
File: src/wallet/rpcwallet.cpp:3002-3003
Timestamp: 2025-02-14T15:19:17.218Z
Learning: The `GetWallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null checks that throw appropriate RPC errors, making additional validation unnecessary.

Learnt from: CR
PR: dashpay/dash#0
File: CLAUDE.md:0-0
Timestamp: 2025-07-20T18:42:49.794Z
Learning: Applies to src/{test,wallet/test,qt/test}/**/*.{cpp,h,cc,cxx,hpp} : Unit tests for C++ code should be placed in src/test/, src/wallet/test/, or src/qt/test/ and use Boost::Test or Qt 5 for GUI tests

📚 Learning: in the test framework consolidation pr (#6718), user kwvg prefers to limit functional changes to tho...

Learnt from: kwvg
PR: dashpay/dash#6718
File: test/functional/test_framework/test_framework.py:2102-2102
Timestamp: 2025-06-09T16:43:20.996Z
Learning: In the test framework consolidation PR (#6718), user kwvg prefers to limit functional changes to those directly related to MasternodeInfo, avoiding scope creep even for minor improvements like error handling consistency.

Applied to files:

• test/functional/wallet_upgradetohd.py

📚 Learning: the `getwallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null chec...

Learnt from: kwvg
PR: dashpay/dash#6529
File: src/wallet/rpcwallet.cpp:3002-3003
Timestamp: 2025-02-14T15:19:17.218Z
Learning: The `GetWallet()` function calls in `src/wallet/rpcwallet.cpp` are properly validated with null checks that throw appropriate RPC errors, making additional validation unnecessary.

Applied to files:

• test/functional/wallet_upgradetohd.py
• src/wallet/rpc/wallet.cpp

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (5)

• GitHub Check: Lint / Run linters
• GitHub Check: x86_64-w64-mingw32 / Build depends
• GitHub Check: x86_64-pc-linux-gnu_multiprocess / Build depends
• GitHub Check: x86_64-apple-darwin / Build depends
• GitHub Check: x86_64-pc-linux-gnu / Build depends

🔇 Additional comments (2)

src/wallet/rpc/wallet.cpp (1)

382-382: LGTM! Correctly enables null characters in wallet passphrases.

The change from .c_str() to std::string_view assignment properly addresses the PR objective. Using .c_str() would truncate the passphrase at the first null character, while std::string_view preserves the full string including embedded null characters.

test/functional/wallet_upgradetohd.py (1)

178-179: Excellent test coverage for null character support.

The test properly validates the new functionality by using a passphrase containing a null character (\0). The added comment clearly documents the new capability, and the test ensures that wallet operations (upgrade, unlock, mnemonic verification, and balance checks) work correctly with null-containing passphrases.

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[UdjinM6]

closing in fav of #6792