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[RFC] cscope: ignore EINTR while reading the prompt #8079

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merged 1 commit into from
Feb 28, 2018
Merged

[RFC] cscope: ignore EINTR while reading the prompt #8079

merged 1 commit into from
Feb 28, 2018

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mhinz
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@mhinz mhinz commented Feb 27, 2018

The following code..

au VimEnter,DirChanged * if filereadable('.git/cscope.out') |
    \ exe 'cs add .git/cscope.out' | endif

..would lead to this issue:

Error detected while processing VimEnter Auto commands for "*":
cs_read_prompt EOF: Interrupted system call
Error detected while processing VimEnter Auto commands for "*":
E262: error reading cscope connection 0

Once again a SIGCHLD could interfere with the old cscope code.

This is merely a workaround for the time being. We don't block SIGCHLD signals,
since they're needed by libuv. The proper fix would be to rewrite if_cscope.c to
use libuv for handling processes.

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mhinz commented Feb 27, 2018

Could be a fix for #6229 as well.

@marvim marvim added the RFC label Feb 28, 2018
justinmk
justinmk reviewed Feb 28, 2018
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src/nvim/if_cscope.c Outdated
for (size_t n = 0; n < strlen(CSCOPE_PROMPT); ++n) {
if (n > 0)
for (size_t n = 0; n < strlen(CSCOPE_PROMPT); n++) {
if (ferror(csinfo[i].fr_fp) && errno == EINTR) {
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manpage for ferror() mentions that it does not modify errno, but I don't like having to check this. Specially if the code is changed later on.

Actually, it isn't clear what function this errno check is associated with. It should be saved immediately after the function call.

int e = errno;
...
if (ferror(csinfo[i].fr_fp) && e == EINTR) {

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The commit title/description is confusing. EINTR is not only associated with SIGCHLD. "Ignore SIGCHLD" makes me think a sigmask is being set up, but we aren't doing that.

@mhinz mhinz changed the title [RFC] cscope: ignore SIGCHLD while reading the prompt [RFC] cscope: ignore EINTR while reading the prompt Feb 28, 2018
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mhinz commented Feb 28, 2018

Okay, I think the intention of the code is a bit clearer now.

jamessan
jamessan reviewed Feb 28, 2018
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Is there any reason to not add the same error handling to the later getc call?

src/nvim/if_cscope.c Outdated
while (1) {
do {
errno = 0;
ch = getc(csinfo[i].fr_fp);
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For general hygiene, I'd suggest using fgetc instead of getc.

src/nvim/if_cscope.c Outdated
do {
errno = 0;
ch = getc(csinfo[i].fr_fp);
} while (errno == EINTR);
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I still think it's best to check ch == EOF && ferror(csinfo[i].fr_fp) && errno == EINTR since there's nothing guaranteeing that errno remains unchanged on a successful call to getc.

@mhinz mhinz force-pushed the cscope-fix branch 3 times, most recently from 9e8f623 to f48015f Compare February 28, 2018 12:51
@mhinz
cscope: ignore EINTR while reading the prompt
2913584 
The following code..

    au VimEnter,DirChanged * if filereadable('.git/cscope.out') |
        \ exe 'cs add .git/cscope.out' | endif

..would lead to this issue:

    Error detected while processing VimEnter Auto commands for "*":
    cs_read_prompt EOF: Interrupted system call
    Error detected while processing VimEnter Auto commands for "*":
    E262: error reading cscope connection 0

A signal, in this case SIGCHLD, during a system call leads to errno being set
to EINTR. Ignore it.

This is merely a workaround for the time being. We don't block SIGCHLD signals,
since they're needed by libuv. The proper fix would be to rewrite if_cscope.c to
use libuv for handling processes.
@mhinz
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mhinz commented Feb 28, 2018

I slightly changed the order again and check errno before ferror() now. Now everyone should be happy. :->

@mhinz mhinz merged commit ba87a2c into neovim:master Feb 28, 2018
@mhinz mhinz deleted the cscope-fix branch February 28, 2018 22:37
@jszakmeister jszakmeister removed the RFC label Feb 28, 2018
@justinmk justinmk mentioned this pull request Feb 28, 2018
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@justinmk justinmk mentioned this pull request Mar 12, 2018
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justinmk added a commit that referenced this pull request Jun 11, 2018
@justinmk
NVIM v0.3.0
44c6deb 
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
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@jamessan jamessan jamessan approved these changes

@justinmk justinmk justinmk approved these changes

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@mhinz @justinmk @jamessan @jszakmeister @marvim