fix: crash on macOS/FreeBSD when running PostgreSQL queries

[renecannao]

Summary

Fixes a crash that occurred immediately when running any PostgreSQL query on macOS and FreeBSD systems.

Problem

ProxySQL crashed with a NULL pointer dereference in CopyCmdMatcher::match() when processing PostgreSQL queries on macOS and FreeBSD.

Backtrace:

* thread #11, stop reason = EXC_BAD_ACCESS (code=1, address=0x5c)
  frame #5: CopyCmdMatcher::match(this=0x0000000000000000, query="SELECT ?;", ...) const at PgSQL_Thread.h:149:10
  frame #6: PgSQL_Session::handler(...) at PgSQL_Session.cpp:2924:27

Root Cause

copy_cmd_matcher was guarded by #ifdef IDLE_THREADS, but IDLE_THREADS is explicitly disabled on macOS (__APPLE__) and FreeBSD in proxy_defines.h:5-8:

#if !defined(__FreeBSD__) && !defined(__APPLE__)
#define IDLE_THREADS
#endif

This created an inconsistent configuration where:

• PgSQL_Thread::copy_cmd_matcher was not defined on macOS/FreeBSD
• PgSQL_Session::copy_cmd_matcher was always defined
• The initialization from thread to session was compiled out
• Usage at PgSQL_Session.cpp:2924 was not guarded → NULL pointer dereference

Solution

Removed #ifdef IDLE_THREADS guards from copy_cmd_matcher since:

1. COPY command detection is a fundamental PostgreSQL feature - it detects COPY ... FROM STDIN/STDOUT commands for fast-forward mode
2. It has no dependency on idle threads - the feature works independently of the threading model
3. This is the correct fix - disabling COPY support on macOS/FreeBSD would be incorrect

Changes

• include/PgSQL_Thread.h - Moved CopyCmdMatcher *copy_cmd_matcher; outside #ifdef IDLE_THREADS
• lib/PgSQL_Thread.cpp - Removed #ifdef IDLE_THREADS guards from initialization/cleanup
• lib/Base_Thread.cpp - Removed #ifdef IDLE_THREADS guard from copy operation

Testing

Tested manually on macOS - PostgreSQL queries now work correctly without crashes.

Affected Systems

• macOS (__APPLE__)
• FreeBSD (__FreeBSD__)

Fixes #5359

Summary by CodeRabbit

• Refactor
  • Internal code reorganization for improved maintainability. Conditional compilation directives were restructured to simplify the codebase without affecting user-facing functionality.

[gemini-code-assist]

Summary of Changes

Hello @renecannao, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a significant stability issue where PostgreSQL queries would cause a crash on macOS and FreeBSD. The problem stemmed from an incorrect conditional compilation directive that prevented the proper initialization of a key component, copy_cmd_matcher, leading to a NULL pointer dereference. By removing these platform-specific compilation guards, the CopyCmdMatcher is now consistently available and correctly initialized, restoring full PostgreSQL functionality on the affected operating systems.

Highlights

• Crash Fix: Addresses a critical crash occurring on macOS and FreeBSD systems when executing PostgreSQL queries, caused by a NULL pointer dereference.
• Root Cause Identified: The crash was traced to copy_cmd_matcher being conditionally compiled under #ifdef IDLE_THREADS, which is explicitly disabled on macOS and FreeBSD. This led to an uninitialized pointer being accessed in PgSQL_Session::handler.
• Conditional Compilation Removal: Removed the #ifdef IDLE_THREADS guards around copy_cmd_matcher declarations and operations, ensuring it is always compiled and properly initialized across all platforms.
• PostgreSQL COPY Command Support: The fix ensures that the essential PostgreSQL COPY command detection, which is independent of idle threads, functions correctly on macOS and FreeBSD.

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Changelog

• include/PgSQL_Thread.h
  • Moved the declaration of CopyCmdMatcher *copy_cmd_matcher; outside of the #ifdef IDLE_THREADS block to ensure it's always included.
• lib/Base_Thread.cpp
  • Removed the #ifdef IDLE_THREADS guard surrounding the assignment of _sess->copy_cmd_matcher, making the assignment unconditional.
• lib/PgSQL_Thread.cpp
  • Removed #ifdef IDLE_THREADS guards from the destructor, init() method, and constructor related to copy_cmd_matcher initialization and cleanup, ensuring these operations are always performed.

Activity

• No review comments or additional activity have been recorded for this pull request yet.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The pull request removes #ifdef IDLE_THREADS conditional compilation guards around the CopyCmdMatcher member across three files. The CopyCmdMatcher pointer is relocated from a conditional block to unconditional declaration in the header, and its initialization and cleanup logic are unconditionally compiled. This ensures consistent compilation behavior across all platforms.

Changes

Cohort / File(s)	Summary
Header Declaration include/PgSQL_Thread.h	Relocated CopyCmdMatcher *copy_cmd_matcher declaration from inside #ifdef IDLE_THREADS conditional block to public member section, ensuring it is always declared regardless of platform or build configuration.
Initialization & Cleanup lib/PgSQL_Thread.cpp	Removed #ifdef IDLE_THREADS guards around CopyCmdMatcher instantiation in init() method and deletion in destructor, making allocation and deallocation unconditional.
Session Registration lib/Base_Thread.cpp	Removed #ifdef IDLE_THREADS guards around the assignment _sess->copy_cmd_matcher in register_session() function, making the copy operation unconditional.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 The copy matcher hops so free,
No longer bound by #ifdef decree,
On every platform it shall thrive,
Keeping PostgreSQL connections alive! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main fix: resolving a crash on macOS/FreeBSD when running PostgreSQL queries due to NULL pointer dereference in CopyCmdMatcher.
Linked Issues check	✅ Passed	All coding requirements from issue #5359 are met: copy_cmd_matcher declaration moved outside #ifdef IDLE_THREADS guards [#5359], initialization/cleanup guards removed [#5359], and register_session() copy guard removed [#5359].
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the NULL pointer dereference issue; no unrelated modifications or feature additions are present.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch v3.0-5359

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[gemini-code-assist]

Code Review

This pull request addresses a crash on macOS and FreeBSD systems when executing PostgreSQL queries. The root cause was a NULL pointer dereference related to copy_cmd_matcher, which was incorrectly defined within an #ifdef IDLE_THREADS block that is disabled on these platforms. The fix involves moving the copy_cmd_matcher declaration and its lifecycle management (initialization, assignment, and cleanup) outside of the conditional compilation block. The changes are correct, well-reasoned, and effectively resolve the bug. The code is clean and the fix is well-contained.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud