5 * (c) 1999 Straylight/Edgeware
8 /*----- Licensing notice --------------------------------------------------*
10 * This file is part of the mLib utilities library.
12 * mLib is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
17 * mLib is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
22 * You should have received a copy of the GNU Library General Public
23 * License along with mLib; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
28 /*----- Header files ------------------------------------------------------*/
45 /*----- Data structures ---------------------------------------------------*/
47 typedef struct sigstate {
52 /*----- Static variables --------------------------------------------------*/
54 static sel_file sigsel;
56 static sigstate *sigs;
57 static sigset_t ss_all, ss_caught;
60 /*----- Main code ---------------------------------------------------------*/
62 /* --- @sig_handler@ --- *
64 * Arguments: @int n@ = signal number
68 * Use: Generic signal handler. Writes a single byte to the
69 * signal pipe. The byte contains the signal number. Also
70 * sets the appropriate bit in @ss_caught@ to indicate which
71 * signals are pending.
74 static void sig_handler(int n)
77 unsigned char sch = (unsigned char)n;
78 sigprocmask(SIG_BLOCK, &ss_all, 0);
79 sigaddset(&ss_caught, n);
80 DISCARD(write(sigfd, &sch, 1));
81 /* The system should reset the signal mask here. */
85 /* --- @sig_read@ --- *
87 * Arguments: @int fd@ = file descriptor to read
88 * @unsigned mode@ = thing to do with descriptor
89 * @void *p@ = uninteresting argument
93 * Use: Dispatches signals to their handlers safely.
96 static void sig_read(int fd, unsigned mode, void *p)
100 /* --- Read the currently caught signals --- *
102 * Block signals while the mask is being copied.
107 unsigned char buf[256];
109 sigprocmask(SIG_BLOCK, &ss_all, &oss);
111 sigemptyset(&ss_caught);
112 while (read(fd, buf, sizeof(buf)) > 0)
114 sigprocmask(SIG_SETMASK, &oss, 0);
117 /* --- Process the caught signals --- */
121 for (i = 0; i < nsig; i++) {
123 if (!sigismember(&ss, i))
135 /* --- @sig_add@ --- *
137 * Arguments: @sig *s@ = pointer to signal handler block
138 * @int n@ = number of the signal
139 * @void (*proc)(int n, void *p)@ = signal handler function
140 * @void *p@ = argument to pass to handler
144 * Use: Adds a signal handler.
147 void sig_add(sig *s, int n, void (*proc)(int /*n*/, void */*p*/), void *p)
149 sigstate *ss = &sigs[n];
151 /* --- Initialize the block --- */
159 /* --- Engage a signal handler, maybe --- */
163 sa.sa_handler = sig_handler;
164 sa.sa_flags = SA_NOCLDSTOP;
166 sa.sa_flags |= SA_RESTART;
168 sigemptyset(&sa.sa_mask);
169 sigaddset(&ss_all, n);
170 sigaction(n, &sa, &ss->sa);
173 /* --- Link the block into the list --- */
180 /* --- @sig_remove@ --- *
182 * Arguments: @sig *s@ = pointer to signal handler block
186 * Use: Removes the signal handler from the list.
189 void sig_remove(sig *s)
191 sigstate *ss = &sigs[s->sig];
193 /* --- Unlink the handler block --- */
196 s->next->prev = s->prev;
198 s->prev->next = s->next;
202 /* --- Maybe remove the handler --- */
205 sigaction(s->sig, &ss->sa, 0);
206 sigdelset(&ss_all, s->sig);
210 /* --- @sig_init@ --- *
212 * Arguments: @sel_state *s@ = pointer to select state
216 * Use: Initializes the signal handling system ready for use.
219 void sig_init(sel_state *s)
223 /* --- Work out how many signals there are --- */
227 unsigned min = 0, max = 0;
231 /* --- Get a good upper bound --- *
233 * Cap the search at 256. I'll be sending signal numbers as bytes.
237 while (sigaddset(&ss, nsig) == 0) {
243 /* --- Now binary search until I find the actual limit --- */
248 nsig = (min + max) >> 1;
251 if (sigaddset(&ss, nsig))
259 /* --- Initialize the signal state table --- */
264 sigs = xmalloc(nsig * sizeof(*sigs));
265 for (i = 0; i < nsig; i++)
269 /* --- Create the signal pipe --- */
272 die(1, "couldn't create pipe for signal handling");
274 /* --- Set both ends to nonblocking and close-on-exec --- */
276 fdflags(fd[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
277 fdflags(fd[1], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
279 /* --- Set everything up for the future --- */
282 sel_initfile(s, &sigsel, fd[0], SEL_READ, sig_read, 0);
283 sel_addfile(&sigsel);
284 sigemptyset(&ss_all);
285 sigemptyset(&ss_caught);
288 /*----- That's all, folks -------------------------------------------------*/