3 * $Id: sig.c,v 1.3 2004/04/08 01:36:13 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 /*----- Header files ------------------------------------------------------*/
46 /*----- Data structures ---------------------------------------------------*/
48 typedef struct sigstate
{
53 /*----- Static variables --------------------------------------------------*/
55 static sel_file sigsel
;
57 static sigstate
*sigs
;
58 static sigset_t ss_all
, ss_caught
;
61 /*----- Main code ---------------------------------------------------------*/
63 /* --- @sig_handler@ --- *
65 * Arguments: @int n@ = signal number
69 * Use: Generic signal handler. Writes a single byte to the
70 * signal pipe. The byte contains the signal number. Also
71 * sets the appropriate bit in @ss_caught@ to indicate which
72 * signals are pending.
75 static void sig_handler(int n
)
78 unsigned char sch
= (unsigned char)n
;
79 sigprocmask(SIG_BLOCK
, &ss_all
, 0);
80 sigaddset(&ss_caught
, n
);
81 write(sigfd
, &sch
, 1);
82 /* The system should reset the signal mask here. */
86 /* --- @sig_read@ --- *
88 * Arguments: @int fd@ = file descriptor to read
89 * @unsigned mode@ = thing to do with descriptor
90 * @void *p@ = uninteresting argument
94 * Use: Dispatches signals to their handlers safely.
97 static void sig_read(int fd
, unsigned mode
, void *p
)
101 /* --- Read the currently caught signals --- *
103 * Block signals while the mask is being copied.
108 unsigned char buf
[256];
110 sigprocmask(SIG_BLOCK
, &ss_all
, &oss
);
112 sigemptyset(&ss_caught
);
113 while (read(fd
, buf
, sizeof(buf
)) > 0)
115 sigprocmask(SIG_SETMASK
, &oss
, 0);
118 /* --- Process the caught signals --- */
122 for (i
= 0; i
< nsig
; i
++) {
124 if (!sigismember(&ss
, i
))
136 /* --- @sig_add@ --- *
138 * Arguments: @sig *s@ = pointer to signal handler block
139 * @int n@ = number of the signal
140 * @void (*proc)(int n, void *p)@ = signal handler function
141 * @void *p@ = argument to pass to handler
145 * Use: Adds a signal handler.
148 void sig_add(sig
*s
, int n
, void (*proc
)(int /*n*/, void */
*p*/
), void *p
)
150 sigstate
*ss
= &sigs
[n
];
152 /* --- Initialize the block --- */
160 /* --- Engage a signal handler, maybe --- */
164 sa
.sa_handler
= sig_handler
;
165 sa
.sa_flags
= SA_NOCLDSTOP
;
167 sa
.sa_flags
|= SA_RESTART
;
169 sigemptyset(&sa
.sa_mask
);
170 sigaddset(&ss_all
, n
);
171 sigaction(n
, &sa
, &ss
->sa
);
174 /* --- Link the block into the list --- */
181 /* --- @sig_remove@ --- *
183 * Arguments: @sig *s@ = pointer to signal handler block
187 * Use: Removes the signal handler from the list.
190 void sig_remove(sig
*s
)
192 sigstate
*ss
= &sigs
[s
->sig
];
194 /* --- Unlink the handler block --- */
197 s
->next
->prev
= s
->prev
;
199 s
->prev
->next
= s
->next
;
203 /* --- Maybe remove the handler --- */
206 sigaction(s
->sig
, &ss
->sa
, 0);
207 sigdelset(&ss_all
, s
->sig
);
211 /* --- @sig_init@ --- *
213 * Arguments: @sel_state *s@ = pointer to select state
217 * Use: Initializes the signal handling system ready for use.
220 void sig_init(sel_state
*s
)
224 /* --- Work out how many signals there are --- */
228 unsigned min
= 0, max
= 0;
232 /* --- Get a good upper bound --- *
234 * Cap the search at 256. I'll be sending signal numbers as bytes.
238 while (sigaddset(&ss
, nsig
) == 0) {
244 /* --- Now binary search until I find the actual limit --- */
249 nsig
= (min
+ max
) >> 1;
252 if (sigaddset(&ss
, nsig
))
260 /* --- Initialize the signal state table --- */
265 sigs
= xmalloc(nsig
* sizeof(*sigs
));
266 for (i
= 0; i
< nsig
; i
++)
270 /* --- Create the signal pipe --- */
273 die(1, "couldn't create pipe for signal handling");
275 /* --- Set both ends to nonblocking and close-on-exec --- */
277 fdflags(fd
[0], O_NONBLOCK
, O_NONBLOCK
, FD_CLOEXEC
, FD_CLOEXEC
);
278 fdflags(fd
[1], O_NONBLOCK
, O_NONBLOCK
, FD_CLOEXEC
, FD_CLOEXEC
);
280 /* --- Set everything up for the future --- */
283 sel_initfile(s
, &sigsel
, fd
[0], SEL_READ
, sig_read
, 0);
284 sel_addfile(&sigsel
);
285 sigemptyset(&ss_all
);
286 sigemptyset(&ss_caught
);
289 /*----- That's all, folks -------------------------------------------------*/