MSW: make interrupting Maxima more robust (#2289) - #2402
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The interrupt sets a bit in a shared-memory segment named after the Lisp's pid. That pid is only known if Maxima's first prompt reported it; otherwise the name was built from the pid of maxima.bat and the segment wasn't found. Now every process below the one wxMaxima started is tried as well (DescendantPids(), a pure function with a unit test). The fallback sent a Ctrl+C to wxMaxima's own console, which wxmaxima.exe, a GUI-subsystem program, does not have. It now attaches to Maxima's hidden console for that. FormatMessage() was handed the buffer pointer instead of its address, so the reason Windows gave for a failure was always lost; it is reported now, together with the segment names that were tried. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BUfW6XqBP4WxRKwDCu4dBS
It never worked: wxmaxima.exe has no console to send a Ctrl+C from, and Maxima leads a new process group, which ignores Ctrl+C. A failed interrupt now says so instead of trying it. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BUfW6XqBP4WxRKwDCu4dBS
gunterkoenigsmann
marked this pull request as ready for review
September 29, 2026 17:01
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Requested by Gunter · project thread
Before: On some Windows systems Ctrl+G only showed "Could not send an interrupt signal to maxima.", and the user had to restart Maxima and lost the session (#2289). The message never said why.
After: wxMaxima now finds the Lisp's shared-memory segment even when Maxima didn't report its pid. When interrupting fails, the log says which segments were tried and what Windows reported. The console Ctrl+C fallback is gone, because it never worked.
How:
gcl-<pid>ormaxima-<pid>, named after the Lisp's pid. We only know that pid if Maxima's first prompt reported it; otherwise the name was built frommaxima.bat's pid and never matched. Now every process below the one we started is tried as well. The process-tree walk is a pure, portable function,DescendantPids()insrc/ProcessTree.{h,cpp}, with a unit test that covers reused pids and cycles.wxmaxima.exeis a GUI-subsystem program without one, and Maxima leads a new process group, which ignores Ctrl+C.FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER …)was passed the buffer pointer instead of its address, so Windows' error text was always lost. It is now passed correctly.The real fix for threaded Lisps, a channel of wxMaxima's own, is #2405, which is stacked on this PR.
Testing: the Linux build is clean and all unit tests pass, including the new
ProcessTreetest. The Windows-only code compiles with MinGW-w64 against stubbed wx types; the minGW CI job does the real build. Not tested on real Windows.🤖 Generated with Claude Code
https://claude.ai/code/session_01BUfW6XqBP4WxRKwDCu4dBS