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 ------------------------------------------------------*/
44 /*----- Data structures ---------------------------------------------------*/
46 typedef struct sigstate {
51 /*----- Static variables --------------------------------------------------*/
53 static sel_file sigsel;
55 static sigstate *sigs;
56 static sigset_t ss_all, ss_caught;
59 /*----- Main code ---------------------------------------------------------*/
61 /* --- @sig_handler@ --- *
63 * Arguments: @int n@ = signal number
67 * Use: Generic signal handler. Writes a single byte to the
68 * signal pipe. The byte contains the signal number. Also
69 * sets the appropriate bit in @ss_caught@ to indicate which
70 * signals are pending.
73 static void sig_handler(int n)
76 unsigned char sch = (unsigned char)n;
77 sigprocmask(SIG_BLOCK, &ss_all, 0);
78 sigaddset(&ss_caught, n);
79 write(sigfd, &sch, 1);
80 /* The system should reset the signal mask here. */
84 /* --- @sig_read@ --- *
86 * Arguments: @int fd@ = file descriptor to read
87 * @unsigned mode@ = thing to do with descriptor
88 * @void *p@ = uninteresting argument
92 * Use: Dispatches signals to their handlers safely.
95 static void sig_read(int fd, unsigned mode, void *p)
99 /* --- Read the currently caught signals --- *
101 * Block signals while the mask is being copied.
106 unsigned char buf[256];
108 sigprocmask(SIG_BLOCK, &ss_all, &oss);
110 sigemptyset(&ss_caught);
111 while (read(fd, buf, sizeof(buf)) > 0)
113 sigprocmask(SIG_SETMASK, &oss, 0);
116 /* --- Process the caught signals --- */
120 for (i = 0; i < nsig; i++) {
122 if (!sigismember(&ss, i))
134 /* --- @sig_add@ --- *
136 * Arguments: @sig *s@ = pointer to signal handler block
137 * @int n@ = number of the signal
138 * @void (*proc)(int n, void *p)@ = signal handler function
139 * @void *p@ = argument to pass to handler
143 * Use: Adds a signal handler.
146 void sig_add(sig *s, int n, void (*proc)(int /*n*/, void */*p*/), void *p)
148 sigstate *ss = &sigs[n];
150 /* --- Initialize the block --- */
158 /* --- Engage a signal handler, maybe --- */
162 sa.sa_handler = sig_handler;
163 sa.sa_flags = SA_NOCLDSTOP;
165 sa.sa_flags |= SA_RESTART;
167 sigemptyset(&sa.sa_mask);
168 sigaddset(&ss_all, n);
169 sigaction(n, &sa, &ss->sa);
172 /* --- Link the block into the list --- */
179 /* --- @sig_remove@ --- *
181 * Arguments: @sig *s@ = pointer to signal handler block
185 * Use: Removes the signal handler from the list.
188 void sig_remove(sig *s)
190 sigstate *ss = &sigs[s->sig];
192 /* --- Unlink the handler block --- */
195 s->next->prev = s->prev;
197 s->prev->next = s->next;
201 /* --- Maybe remove the handler --- */
204 sigaction(s->sig, &ss->sa, 0);
205 sigdelset(&ss_all, s->sig);
209 /* --- @sig_init@ --- *
211 * Arguments: @sel_state *s@ = pointer to select state
215 * Use: Initializes the signal handling system ready for use.
218 void sig_init(sel_state *s)
222 /* --- Work out how many signals there are --- */
226 unsigned min = 0, max = 0;
230 /* --- Get a good upper bound --- *
232 * Cap the search at 256. I'll be sending signal numbers as bytes.
236 while (sigaddset(&ss, nsig) == 0) {
242 /* --- Now binary search until I find the actual limit --- */
247 nsig = (min + max) >> 1;
250 if (sigaddset(&ss, nsig))
258 /* --- Initialize the signal state table --- */
263 sigs = xmalloc(nsig * sizeof(*sigs));
264 for (i = 0; i < nsig; i++)
268 /* --- Create the signal pipe --- */
271 die(1, "couldn't create pipe for signal handling");
273 /* --- Set both ends to nonblocking and close-on-exec --- */
275 fdflags(fd[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
276 fdflags(fd[1], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC);
278 /* --- Set everything up for the future --- */
281 sel_initfile(s, &sigsel, fd[0], SEL_READ, sig_read, 0);
282 sel_addfile(&sigsel);
283 sigemptyset(&ss_all);
284 sigemptyset(&ss_caught);
287 /*----- That's all, folks -------------------------------------------------*/