Fix NULL pointer access error in SynthDriverAudioStream

[gexgd0419]

Link to issue number:

None

Summary of the issue:

This is a fix for the NULL pointer access error introduced by #17592 and reported in this comment.

According to Microsoft's documentation, the pcbWritten parameter in ISequentialStream::Write and the plibNewPosition parameter in IStream::Seek can be NULL, in which case the function should ignore the output parameter and succeed.

Description of user facing changes

None

Description of development approach

ISequentialStream_RemoteWrite and IStream_RemoteSeek are changed to use the low level implementation. This makes checking the output parameter easier. Then, check if the output pointer is NULL before assigning the output value.

Testing strategy:

Known issues with pull request:

None

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

@coderabbitai summary

[burmancomp]

Thanks @gexgd0419, works for me.