[RFC] make unibi_out output never cross buffer boundaries #7676
Only got to looking into this again today, sorry.
This is a new approach: The patches now introduce a "cork" state which prevents the buffer from being flushed (in cases where it ordinarily would be flushed, an overflow flag is raised and no further output is done). This reduces the code duplication somewhat.
When looking at the other users of
e838452 fixed an issue where long (true color) escape sequences got interrupted by the cursor visibility toggling caused by buffer flushes. cdfaecb introduces a new issue which causes similar problems: While the old buffer flushing code appended the cursor visibility escapes to the buffer before/after flushing, the new code effectively prepends the sequences. Assume the following sequence of events occurs: - A long escape code is issued using unibi_out when the buffer is almost full - out() gets called for a prefix of that escape code, causing the buffer to fill up - flush_buf(ui, false) is called and (correctly) does not insert any cursor toggling escapes - The rest of the escape code is written into the now empty buffer - At some later point, some other part of nvim calls flush_buf(ui, true), which then toggles the cursor, corrupting the escape code This could possibly also be fixed by tracking the state of the buffer (i.e. does it contain a partially output escape code?), but this seems fragile in the same way e838452 turned out to be. The root cause for all these problems is the mismatch between nvim's (implicit) assumption that the buffer is flushable at any point in time and the non-atomicity of unibilium's character based callback interface. The proper fix (without modifying unibilium) is to ensure nvim's assumption about the buffer state holds at all times. To that end, add a "cork" flag which ensures one unibi_out-call never splits its output across a buffer flush; if an escape code does not fit into the current buffer, flush it without any part of the escape code in it and insert the whole escape code in the emptied buffer. This is a little more complex because it modifies the buffer in place rather than printing into another buffer, checking the remaining space in the terminal buffer and then memcpy'ing it.
The previous commit ensures that we can never flush the buffer in a state where toggling cursor visibility can corrupt other escape codes. Thus, we can remove the workaround added as part of e838452, simplyfing the code and hiding the cursor on more occasions.
FEATURES: 3cc7ebf #7234 built-in VimL expression parser 6a7c904 #4419 implement <Cmd> key to invoke command in any mode b836328 #7679 'startup: treat stdin as text instead of commands' 58b210e :digraphs : highlight with hl-SpecialKey #2690 7a13611 #8276 'startup: Let `-s -` read from stdin' 1e71978 events: VimSuspend, VimResume #8280 1e7d5e8 #6272 'stdpath()' f96d99a #8247 server: introduce --listen e8c39f7 #8226 insert-mode: interpret unmapped META as ESC 98e7112 msg: do not scroll entire screen (#8088) f72630b #8055 let negative 'writedelay' show all redraws 5d2dd2e win: has("wsl") on Windows Subsystem for Linux #7330 a4f6cec cmdline: CmdlineEnter and CmdlineLeave autocommands (#7422) 207b7ca #6844 channels: support buffered output and bytes sockets/stdio API: f85cbea #7917 API: buffer updates 418abfc #6743 API: list information about all channels/jobs. 36b2e3f #8375 API: nvim_get_commands 273d2cd #8329 API: Make nvim_set_option() update `:verbose set …` 8d40b36 #8371 API: more reliable/descriptive VimL errors ebb1acb #8353 API: nvim_call_dict_function 9f994bb #8004 API: nvim_list_uis 3405704 #7520 API/UI: forward option updates to UIs 911b1e4 #7821 API: improve nvim_command_output WINDOWS OS: 9cefd83 #8084, #8516 build/win: support MSVC ee4e1fd win: Fix reading content from stdin (#8267) TUI: ffb8904 #8309 TUI: add support for mouse release events in urxvt 8d5a46e #8081 TUI: implement "standout" attribute 6071637 TUI: support TERM=konsole-256color 67848c0 #7653 TUI: report TUI info with -V3 ('verbose' >= 3) 3d0ee17 TUI/rxvt: enable focus-reporting d109f56 #7640 TUI: 'term' option: reflect effective terminal behavior FIXES: ed6a113 #8273 'job-control: avoid kill-timer race' 4e02f1a #8107 'jobs: separate process-group' 451c48a terminal: flush vterm output buffer on pty output #8486 5d6732f :checkhealth fixes #8335 53f11dc #8218 'Fix errors reported by PVS' d05712f inccommand: pause :terminal redraws (#8307) 51af911 inccommand: do not execute trailing commands #8256 84359a4 terminal: resize to the max dimensions (#8249) d49c1dd #8228 Make vim_fgets() return the same values as in Vim 60e96a4 screen: winhl=Normal:Background should not override syntax (#8093) 0c59ac1 #5908 'shada: Also save numbered marks' ba87a2c cscope: ignore EINTR while reading the prompt (#8079) b1412dc #7971 ':terminal Enter/Leave should not increment jumplist' 3a5721e TUI: libtermkey: force CSI driver for mouse input #7948 6ff13d7 #7720 TUI: faster startup 1c6e956 #7862 TUI: fix resize-related segfaults a58c909 #7676 TUI: always hide cursor when flushing, never flush buffers during unibilium output 303e1df #7624 TUI: disable BCE almost always 249bdb0 #7761 mark: Make sure that jumplist item will not have zero lnum 6f41ce0 #7704 macOS: Set $LANG based on the system locale a043899 #7633 'Retry fgets on EINTR' CHANGES: ad60927 #8304 default to 'nofsync' f3f1970 #8035 defaults: 'fillchars' a6052c7 #7984 defaults: sidescroll=1 b69fa86 #7888 defaults: enable cscopeverbose 7c4bb23 defaults: do :filetype stuff unless explicitly "off" 2aa308c #5658 'Apply :lmap in macros' 8ce6393 terminal: Leave 'relativenumber' alone (#8360) e46534b #4486 refactor: Remove maxmem, maxmemtot options 131aad9 win: defaults: 'shellcmdflag', 'shellxquote' #7343 c57d315 #8031 jobwait(): return -2 on interrupt also with timeout 6452831 clipboard: macOS: fallback to tmux if pbcopy is broken #7940 300d365 #7919 Make 'langnoremap' apply directly after a map ada1956 #7880 'lua/executor: Remove lightuserdata' INTERNAL: de0a954 #7806 internal statistics for list impl dee78a4 #7708 rewrite internal list impl