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Do not share terminal state between concurrent terminals in one process - #44
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alexey-milovidov merged 1 commit intoOct 12, 2026
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Several terminals can work concurrently in one process, e.g. client sessions embedded into a server, each attached to its own pseudo-terminal. - Only a terminal that installed the `SIGWINCH` handler registers itself as the receiver of window size notifications, the registration is atomic, and a terminal unregisters only itself. - The partially read UTF-8 sequence in `read_unicode_character`, the modifiers of the escape sequence being parsed, and the buffer of `ansi_color` are per thread. Previously concurrent multi-byte input could corrupt each other, and a race allowed a one-byte out-of-bounds write. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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`master` of `replxx` now contains the fix of the shared terminal state. The new commit merges it with the history recall changes used by ClickHouse and fixes Ctrl-V blocking after the esc delay support from `master`. Related: ClickHouse/replxx#44 Related: ClickHouse/replxx#46 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
azat
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| thread_local char8_t utf8String[5]; | ||
| thread_local size_t utf8Count = 0; |
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This is not enough, multiple terminals may work over different fds, and this states should be per-fd, we need to move this state into the Terminal object
I've fixed it here - #47
alexey-milovidov
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`master` got a simpler version of the same fix (#44) and the esc delay support. The conflicts are resolved in favor of this branch: the UTF-8 decoder state is kept in `Terminal`, the escape sequence routines take the `Terminal`, and the `SIGWINCH` disposition is restored. The esc delay parameter from `master` is passed through, `Terminal::read_unicode_character` waits with `poll` as on `master`, and `read_verbatim` still does not wait after the first character. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Several terminals can work concurrently in one process. ClickHouse does this with client sessions embedded into the server (the web terminal and SSH), each attached to its own pseudo-terminal. Some replxx state was process-wide, so these sessions could affect each other:
SIGWINCHreceiver (_terminal_): every terminal that entered raw mode stored itself in a non-atomic global, and leaving raw mode cleared it even if another terminal had registered. Now only a terminal that installed the window change handler registers itself, the registration is atomic (so the signal handler can read it safely), and a terminal unregisters only itself.read_unicode_character: concurrent multi-byte input could corrupt each other. Also, a race between the bounds check and the write allowed a one-byte out-of-bounds write. The state is nowthread_local.thisKeyMetaCtrl): concurrent terminals could get each other's Ctrl/Alt bits. Nowthread_local.ansi_colorbuffer: nowthread_local. The result is consumed right away by the calling thread.The remaining mutable-looking globals are set only during static initialization.
ClickHouse PR: ClickHouse/ClickHouse#125510
ClickHouse currently uses this change on top of the
clickhouse/history-recalled-hints-fixbranch (commit e8e3d2f). This PR has the same change cherry-picked ontomaster.🤖 Generated with Claude Code