term: clamp zero window size from Docker PTY#964
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tomholford wants to merge 1 commit intourbit:developfrom
Open
term: clamp zero window size from Docker PTY#964tomholford wants to merge 1 commit intourbit:developfrom
tomholford wants to merge 1 commit intourbit:developfrom
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When Docker allocates a PTY (tty: true + stdin_open: true) but nobody is attached, TIOCGWINSZ succeeds but reports 0x0. This causes a decrement-underflow crash in drum when it receives %blew [0 0]. Clamp to 80x24 defaults when ioctl returns zero dimensions, matching the existing fallback when ioctl fails entirely. Unlike the prior attempt (urbit#959), this does not change the initial row_l from 0 — that value serves as a sentinel throughout term.c to skip cursor positioning during early boot (checked by hija/loja and the spinner). Changing it to 24 caused blank lines in terminal output on macOS. Resolves urbit#159.
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Summary
tty: true+stdin_open: true) but nobody is attached,TIOCGWINSZsucceeds but reports 0x0decrement-underflowcrash in drum when it receives%blew [0 0]This is a v2 of #959, which was merged then reverted due to a regression. The prior version also changed the initial
row_lfrom 0 to 24, which broke terminal output on macOS —row_l = 0is a sentinel used byhija/lojaand the spinner to skip cursor positioning during early boot. Setting it to 24 caused everyu3l_log()call before the first%blewevent to reposition the cursor, producing blank lines. This version keepsrow_l = 0and only adds the clamping inu3_term_get_blew.Resolves #159.
See also urbit/urbit#4750
Test results
Docker on x86_64 Linux VPS (Ubuntu,
tty: true+stdin_open: true, no attach):x86_64-linux-musl, built Docker image, transferred to VPSmacOS aarch64 (native build, PTY via
script):row_l = 0sentinel works correctly