Fix bash OSC 7 reporting $HOSTNAME instead of gethostname(2)#277
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Bash inherits $HOSTNAME from the environment. Toolbox/container
runtimes export it with a value that disagrees with the kernel
hostname, so emacs' (system-name) — which reads gethostname(2) —
sees a mismatch, ghostel--update-directory classifies the buffer
as remote, and TRAMP fires on every cd. zsh ($HOST) and fish
($(hostname)) read gethostname(2) directly and aren't affected.
Capture the real kernel hostname via ${var@P} on \H (bash 4.4+),
which expands the same value bash uses internally for the \H
prompt escape — sourced from gethostname(2) at startup and not
overridable from the environment. On bash <4.4 the @p transform
is unavailable, so fall back to $HOSTNAME (pre-fix behavior).
Fixes #276.
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Summary
etc/shell/ghostel.bash) emitted$HOSTNAMEin the OSC 7 directory-tracking sequence.$HOSTNAMEis inherited from the parent environment — toolbox/container runtimes export it with a value that disagrees withgethostname(2). Emacs'system-namereadsgethostname(2)directly, so the host strings didn't match,ghostel--update-directorymisclassified the buffer as remote, and TRAMP fired on everycd. zsh ($HOST) and fish ((hostname)) readgethostname(2)directly and aren't affected.${var@P}on\H(bash 4.4+) — same value bash uses internally for the\HPS1 escape, sourced fromgethostname(2)at startup and not overridable from the environment. Zero forks, no external binary dependency.@Ptransform is unavailable (it produces abad substitutionerror and leaves the variable as the literal\H, which would actually break OSC 7 worse than the original bug). Guard withBASH_VERSINFOand fall back to$HOSTNAME— pre-tramp getting triggered inside local fedora-toolbox container #276 behavior for those users, no regression.bash --noprofile --norcsubprocess with a poisonedHOSTNAME=…, calls__ghostel_osc7, and asserts the emitted host passesghostel--local-host-p— the same predicate the production code applies inghostel--update-directory.Fixes #276.
Test plan
make -j4 allpasses (382 tests).ghostel-test-bash-osc7-ignores-env-hostnamepasses against the patched bash integration.main's bash integration (confirms it exercises the bug, not just any assertion).bash -n etc/shell/ghostel.bashclean on both modern bash (5.x) and/bin/bash3.2.HOSTNAME:HOSTNAME=lying-fake bash -c 'source etc/shell/ghostel.bash; echo $__ghostel_host'reports the real kernel hostname on bash 4.4+.