3 * $Id: sig.c,v 1.1 1999/07/26 23:16:26 mdw Exp $
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of the mLib utilities library.
14 * mLib is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU Library General Public License as
16 * published by the Free Software Foundation; either version 2 of the
17 * License, or (at your option) any later version.
19 * mLib is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU Library General Public License for more details.
24 * You should have received a copy of the GNU Library General Public
25 * License along with mLib; if not, write to the Free
26 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.1 1999/07/26 23:16:26 mdw
34 * Signal handling integrated into I/O system.
38 /*----- Header files ------------------------------------------------------*/
54 /*----- Data structures ---------------------------------------------------*/
56 typedef struct sigstate
{
61 /*----- Static variables --------------------------------------------------*/
63 static sel_file sigsel
;
65 static sigstate
*sigs
;
67 /*----- Main code ---------------------------------------------------------*/
69 /* --- @sig_handler@ --- *
71 * Arguments: @int n@ = signal number
75 * Use: Generic signal handler. Just writes a single byte to the
76 * signal pipe. The byte contains the signal number.
79 static void sig_handler(int n
)
81 unsigned char sch
= (unsigned char)n
;
82 write(sigfd
, &sch
, 1);
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
)
99 unsigned char buf
[256];
103 while ((r
= read(fd
, buf
, sizeof(buf
))) > 0) {
104 unsigned char *p
, *q
;
105 for (p
= buf
, q
= buf
+ r
; p
< q
; p
++) {
108 if (sigismember(&ss
, n
))
121 /* --- @sig_add@ --- *
123 * Arguments: @sig *s@ = pointer to signal handler block
124 * @int n@ = number of the signal
125 * @void (*proc)(int n, void *p)@ = signal handler function
126 * @void *p@ = argument to pass to handler
130 * Use: Adds a signal handler.
133 void sig_add(sig
*s
, int n
, void (*proc
)(int /*n*/, void */
*p*/
), void *p
)
135 sigstate
*ss
= &sigs
[n
];
137 /* --- Initialize the block --- */
145 /* --- Engage a signal handler, maybe --- */
149 sa
.sa_handler
= sig_handler
;
150 sa
.sa_flags
= SA_NOCLDSTOP
;
152 sa
.sa_flags
|= SA_RESTART
;
154 sigemptyset(&sa
.sa_mask
);
155 sigaction(n
, &sa
, &ss
->sa
);
158 /* --- Link the block into the list --- */
165 /* --- @sig_remove@ --- *
167 * Arguments: @sig *s@ = pointer to signal handler block
171 * Use: Removes the signal handler from the list.
174 void sig_remove(sig
*s
)
176 sigstate
*ss
= &sigs
[s
->sig
];
178 /* --- Unlink the handler block --- */
181 s
->next
->prev
= s
->prev
;
183 s
->prev
->next
= s
->next
;
187 /* --- Maybe remove the handler --- */
190 sigaction(s
->sig
, &ss
->sa
, 0);
193 /* --- @sig_init@ --- *
195 * Arguments: @sel_state *s@ = pointer to select state
199 * Use: Initializes the signal handling system ready for use.
202 void sig_init(sel_state
*s
)
207 /* --- Work out how many signals there are --- */
211 unsigned min
= 0, max
= 0;
215 /* --- Get a good upper bound --- *
217 * Cap the search at 256. I'll be sending signal numbers as bytes.
221 while (sigaddset(&ss
, nsig
) == 0) {
227 /* --- Now binary search until I find the actual limit --- */
232 nsig
= (min
+ max
) >> 1;
235 if (sigaddset(&ss
, nsig
))
243 /* --- Initialize the signal state table --- */
248 sigs
= xmalloc(nsig
* sizeof(*sigs
));
249 for (i
= 0; i
< nsig
; i
++)
253 /* --- Create the signal pipe --- */
256 die(1, "couldn't create pipe for signal handling");
258 /* --- Set both ends to nonblocking and close-on-exec --- */
260 fdflags(fd
[0], O_NONBLOCK
, O_NONBLOCK
, FD_CLOEXEC
, FD_CLOEXEC
);
261 fdflags(fd
[1], O_NONBLOCK
, O_NONBLOCK
, FD_CLOEXEC
, FD_CLOEXEC
);
263 /* --- Set everything up for the future --- */
266 sel_initfile(s
, &sigsel
, fd
[0], SEL_READ
, sig_read
, 0);
267 sel_addfile(&sigsel
);
270 /*----- That's all, folks -------------------------------------------------*/