[WIP] main: oneshot mode, reading source file contents from stdin

[masatake]

$ echo 'int v; int main(void) {return 0;}'  | ./ctags --oneshot=a.c -x --sort=yes -o -
main             function      1 a.c              int v; int main(void) {return 0;}
v                variable      1 a.c              int v; int main(void) {return 0;}
$ echo 'int v; int main(void) {return 0;}'  | ./ctags --oneshot=a.c -x --sort=no  -o -
v                variable      1 a.c              int v; int main(void) {return 0;}
main             function      1 a.c              int v; int main(void) {return 0;}
$ echo 'int v; int main(void) {return 0;}'  | ./ctags --oneshot=a.c -x --sort=no --output-format=json -o -
{"_type": "tag", "name": "v", "path": "a.c", "pattern": "/^int v; int main(void) {return 0;}$/", "typeref": "typename:int", "kind": "variable"}
{"_type": "tag", "name": "main", "path": "a.c", "pattern": "/^int v; int main(void) {return 0;}$/", "typeref": "typename:int", "kind": "function"}
$ echo 'int v; int main(void) {return 0;}'  | ./ctags --oneshot-limit=6  --oneshot=a.c -x --sort=no --output-format=xref
ctags: Warning: input read from stdin exceeds the limit: name: a.c, size: 6
v                variable      1 a.c              int v;

TODO:

• merge V: enable stack usage guard #4387 first
• write about --oneshot-limit to ctags.1
• add more test cases
• implement JSON based error report
• update --help message for --_interactive

[masatake]

I must merge #4387.

[Copilot]

Pull request overview

Adds a new “oneshot” execution mode so ctags can read a single source file’s contents from stdin while still treating it as a named file for language detection and output paths (optionally with a size limit), and wires this into interactive/sandbox behavior and Windows build files.

Changes:

• Add --oneshot=<filename> and --oneshot-limit=<bytes> to read source contents from stdin and emit tags to stdout.
• Introduce interactiveOneshot() main loop and adjust sorting/sandbox interactions (including forcing internal sort in sandbox oneshot).
• Add a writer init hook (used by the JSON writer) and update Windows project generation inputs/outputs plus documentation and a basic regression test.

Reviewed changes

Copilot reviewed 21 out of 22 changed files in this pull request and generated 13 comments.

Show a summary per file

File	Description
win32/ctags_vs2013.vcxproj.filters	Includes main/seccomp.c and main/interactive_p.h in the VS filters list.
win32/ctags_vs2013.vcxproj	Adds main/seccomp.c and main/interactive_p.h to the VS project build inputs.
win32/GNUmakefile	Stops excluding main/seccomp.c and main/interactive_p.h from generated VS project lists.
man/ctags.1.rst.in	Documents --oneshot=<filename> (template man page).
main/writer_p.h	Adds a tagWriter.init callback hook.
main/writer.c	Calls writer->init() from setTagWriter() when provided.
main/writer-json.c	Adds JSON writer init to pre-seed hashing before seccomp sandboxing.
main/sort_p.h	Adjusts header guards so internal sort API is always declared.
main/sort.c	Makes internal sort code always compiled; improves safety around mio_file_get_fp().
main/parse.c	Updates filter-vs-interactive checks to use the new interactive bitmask flags and adjusts closeTagFile() call.
main/options_p.h	Changes Option.interactive from enum states to a bitmask of interactive flags.
main/options.h	Removes inSandbox() declaration from the public header.
main/options.c	Implements oneshot option parsing, oneshot input limit, updated interactive parsing, and sandbox/sort checks.
main/main.c	Adds interactiveOneshot() loop to read stdin into a memory MIO and parse it as a named file; refactors sandbox prep.
main/interactive_p.h	Extends interactive args with fname and limit; declares interactiveOneshot().
main/entry_p.h	Updates closeTagFile() signature to accept a “force internal sort” flag.
main/entry.c	Updates sandbox detection and adds forceUseInternalSort plumbing into tag sorting/closing.
docs/news/HEAD.rst	Announces the new --oneshot=<filename> option.
docs/man/ctags.1.rst	Documents --oneshot=<filename> (generated man page).
Tmain/oneshot.d/stdout-expected.txt	Expected output for the new oneshot regression test.
Tmain/oneshot.d/stderr-expected.txt	Placeholder expected stderr for oneshot tests.
Tmain/oneshot.d/run.sh	New test script covering oneshot sorting and -x output.

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[Copilot]

The man page documents --oneshot, but the newly introduced --oneshot-limit=<bytes> option is not described here. Consider adding a short paragraph in this section explaining the limit behavior (including that 0 disables the limit and the default is 32MB).

[Copilot]

Reading stdin one byte at a time via getchar() + mio_putc() adds avoidable overhead, especially with the default 32MB limit. Consider buffered reads (e.g., fread() into a stack buffer and mio_write()), while still enforcing iargs->limit.

[Copilot]

The template man page documents --oneshot, but the newly added --oneshot-limit=<bytes> option isn’t described in this section. Please add a short description here so generated man pages include it.