crypto: ignore directory paths in OPENSSL_CONF

[haramj]

Summary

This PR improves the robustness of Node.js startup when the OPENSSL_CONF environment variable points to a directory instead of a file. Currently, such cases cause a fatal OpenSSL configuration error, preventing Node.js from starting. This change detects directory paths early, emits a descriptive warning, and allows Node.js to continue booting using default settings.

Root Cause Analysis

In src/node.cc, the InitializeOncePerProcessInternal function attempts to load the OpenSSL configuration. If OPENSSL_CONF is set to a directory (e.g., /tmp or C:), OpenSSL's internal fopen() fails, raising a fatal error that triggers an early return and process exit.

Changes

• Pre-check with stat(): Detects if conf_file is a directory before passing it to OpenSSL.
• Cross-platform Compatibility: Implemented directory detection using S_ISDIR and bitwise masks for environments where the macro is unavailable.
• Warning Instead of Exit: Replaced the fatal error exit with a fprintf(stderr, ...) warning to inform the user that the directory path is being ignored.
• Error Queue Management: Ensured the OpenSSL error queue is cleared using ERR_clear_error() to prevent side effects for subsequent operations.

Validation & Testing

1. Manual Verification (macOS Apple Silicon)
   I performed a clean build after running make distclean and verified the fix:
   $ export OPENSSL_CONF=/tmp
   $ ./node --use-system-ca -e "console.log('Final Validation: I am alive!')"

Actual Output:

Warning: OPENSSL_CONF path is a directory; ignoring: /tmp
Final Validation: I am alive!

2. Automated Test Suite
   I ran the full test suite using python3 tools/test.py:
   • Passed: 5284 tests.
   • Failed: 7 tests (All verified as missing FFI test fixtures, unrelated to this change).
   • All parallel/test-crypto-* tests passed successfully.
3. Linting
   • Passed make lint-cpp (Ensured all lines are 80 characters or less).

Fixes: #63256

[nodejs-github-bot]

Review requested:

• @nodejs/startup

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.37%. Comparing base (30c5a65) to head (032c6d1).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #63273      +/-   ##
==========================================
+ Coverage   90.35%   90.37%   +0.01%     
==========================================
  Files         790      790              
  Lines      273773   273783      +10     
  Branches    52368    52371       +3     
==========================================
+ Hits       247374   247432      +58     
+ Misses      16908    16845      -63     
- Partials     9491     9506      +15     

Files with missing lines	Coverage Δ
src/node.cc	79.46% <100.00%> (+2.09%)	⬆️

... and 28 files with indirect coverage changes

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[haramj]

@nodejs/startup please take a look at this PR when you have some time?