1 // This is free and unencumbered software released into the public domain.
2 //
3 // Anyone is free to copy, modify, publish, use, compile, sell, or
4 // distribute this software, either in source code form or as a compiled
5 // binary, for any purpose, commercial or non-commercial, and by any
6 // means.
7 //
8 // In jurisdictions that recognize copyright laws, the author or authors
9 // of this software dedicate any and all copyright interest in the
10 // software to the public domain. We make this dedication for the benefit
11 // of the public at large and to the detriment of our heirs and
12 // successors. We intend this dedication to be an overt act of
13 // relinquishment in perpetuity of all present and future rights to this
14 // software under copyright law.
15 //
16 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
19 // IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 // OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 // ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 // OTHER DEALINGS IN THE SOFTWARE.
23 
24 use errors;
25 use io;
26 use rt;
27 use unix::signal;
28 use unix;
29 
30 // In theory we could use TLS to store an event base per-thread and
31 // then we could have a per-thread signal cacher machinery.  In
32 // practice, we only provide signal catching for the global event
33 // loop.
34 
35 fn sigcatch(
36 	sig: signal::sig,
37 	info: *signal::siginfo,
38 	ctx: *opaque
39 ) void = {
40 	// We should be able to write up to PIPE_BUF bytes without
41 	// blocking.
42 	let no = sig: u8;
43 
44 	// read, write
45 	let pipe: (io::file, io::file) = match(global.sigpipe) {
46 	case void =>
47 		// this can't happen
48 		return;
49 	case let pipe: (io::file, io::file) =>
50 		yield pipe;
51 	};
52 
53 	// TODO how to save and restore errno?
54 	match (rt::write(pipe.1, &no, size(u8))) {
55 	case =>
56 		// can't do anything about it.
57 		return;
58 	};
59 };
60 
61 fn sigdispatch(fd: io::file, ev: event, data: nullable *opaque) void = {
62 	let no: u8 = 0;
63 
64 	// read, write
65 	let pipe = global.sigpipe as (io::file, io::file);
66 
67 	match (rt::read(pipe.0, &no, size(u8))) {
68 	case let err: rt::errno =>
69 		// can't do much about.
70 		return;
71 	case => yield;
72 	};
73 
74 	let sigcb = global.sigcb as *fn(signal::sig, nullable *opaque) void;
75 	sigcb(no: signal::sig, global.sigdata);
76 };
77 
78 export fn signal(
79 	sig: signal::sig,
80 	cb: *fn(signal::sig, nullable *opaque) void,
81 	data: nullable *opaque
82 ) (void | errors::error) = {
83 	if (global.sigpipe is void) {
84 		// XXX NOCLOEXEC is O_CLOEXEC or means "do not close-on-exec"?
85 		// read, write
86 		let pipe = unix::pipe(
87 			unix::pipe_flag::NONBLOCK | unix::pipe_flag::NOCLOEXEC
88 		)?;
89 		global.sigpipe = pipe;
90 		add(pipe.0, READ, &sigdispatch, null);
91 	};
92 
93 	global.sigcb = cb;
94 	global.sigdata = data;
95 
96 	signal::handle(sig, &sigcatch);
97 };