9f8886c7 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: sig.c,v 1.1 1999/07/26 23:16:26 mdw Exp $ |
4 | * |
5 | * Signal handling |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of the mLib utilities library. |
13 | * |
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. |
18 | * |
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. |
23 | * |
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, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: sig.c,v $ |
33 | * Revision 1.1 1999/07/26 23:16:26 mdw |
34 | * Signal handling integrated into I/O system. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <errno.h> |
41 | #include <signal.h> |
42 | #include <stdio.h> |
43 | #include <stdlib.h> |
44 | #include <string.h> |
45 | |
46 | #include <fcntl.h> |
47 | |
48 | #include "alloc.h" |
49 | #include "fdflags.h" |
50 | #include "report.h" |
51 | #include "sel.h" |
52 | #include "sig.h" |
53 | |
54 | /*----- Data structures ---------------------------------------------------*/ |
55 | |
56 | typedef struct sigstate { |
57 | struct sigaction sa; |
58 | sig *list; |
59 | } sigstate; |
60 | |
61 | /*----- Static variables --------------------------------------------------*/ |
62 | |
63 | static sel_file sigsel; |
64 | static int sigfd; |
65 | static sigstate *sigs; |
66 | |
67 | /*----- Main code ---------------------------------------------------------*/ |
68 | |
69 | /* --- @sig_handler@ --- * |
70 | * |
71 | * Arguments: @int n@ = signal number |
72 | * |
73 | * Returns: --- |
74 | * |
75 | * Use: Generic signal handler. Just writes a single byte to the |
76 | * signal pipe. The byte contains the signal number. |
77 | */ |
78 | |
79 | static void sig_handler(int n) |
80 | { |
81 | unsigned char sch = (unsigned char)n; |
82 | write(sigfd, &sch, 1); |
83 | } |
84 | |
85 | /* --- @sig_read@ --- * |
86 | * |
87 | * Arguments: @int fd@ = file descriptor to read |
88 | * @unsigned mode@ = thing to do with descriptor |
89 | * @void *p@ = uninteresting argument |
90 | * |
91 | * Returns: --- |
92 | * |
93 | * Use: Dispatches signals to their handlers safely. |
94 | */ |
95 | |
96 | static void sig_read(int fd, unsigned mode, void *p) |
97 | { |
98 | sigset_t ss; |
99 | unsigned char buf[256]; |
100 | int r; |
101 | |
102 | sigemptyset(&ss); |
103 | while ((r = read(fd, buf, sizeof(buf))) > 0) { |
104 | unsigned char *p, *q; |
105 | for (p = buf, q = buf + r; p < q; p++) { |
106 | sig *s; |
107 | int n = *p; |
108 | if (sigismember(&ss, n)) |
109 | continue; |
110 | sigaddset(&ss, n); |
111 | s = sigs[n].list; |
112 | while (s) { |
113 | sig *ss = s; |
114 | s = s->next; |
115 | ss->proc(n, ss->p); |
116 | } |
117 | } |
118 | } |
119 | } |
120 | |
121 | /* --- @sig_add@ --- * |
122 | * |
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 |
127 | * |
128 | * Returns: --- |
129 | * |
130 | * Use: Adds a signal handler. |
131 | */ |
132 | |
133 | void sig_add(sig *s, int n, void (*proc)(int /*n*/, void */*p*/), void *p) |
134 | { |
135 | sigstate *ss = &sigs[n]; |
136 | |
137 | /* --- Initialize the block --- */ |
138 | |
139 | s->proc = proc; |
140 | s->p = p; |
141 | s->sig = n; |
142 | s->next = ss->list; |
143 | s->prev = 0; |
144 | |
145 | /* --- Engage a signal handler, maybe --- */ |
146 | |
147 | if (!ss->list) { |
148 | struct sigaction sa; |
149 | sa.sa_handler = sig_handler; |
150 | sa.sa_flags = SA_NOCLDSTOP; |
151 | #ifdef SA_RESTART |
152 | sa.sa_flags |= SA_RESTART; |
153 | #endif |
154 | sigemptyset(&sa.sa_mask); |
155 | sigaction(n, &sa, &ss->sa); |
156 | } |
157 | |
158 | /* --- Link the block into the list --- */ |
159 | |
160 | if (ss->list) |
161 | ss->list->prev = s; |
162 | ss->list = s; |
163 | } |
164 | |
165 | /* --- @sig_remove@ --- * |
166 | * |
167 | * Arguments: @sig *s@ = pointer to signal handler block |
168 | * |
169 | * Returns: --- |
170 | * |
171 | * Use: Removes the signal handler from the list. |
172 | */ |
173 | |
174 | void sig_remove(sig *s) |
175 | { |
176 | sigstate *ss = &sigs[s->sig]; |
177 | |
178 | /* --- Unlink the handler block --- */ |
179 | |
180 | if (s->next) |
181 | s->next->prev = s->prev; |
182 | if (s->prev) |
183 | s->prev->next = s->next; |
184 | else |
185 | ss->list = s->next; |
186 | |
187 | /* --- Maybe remove the handler --- */ |
188 | |
189 | if (!ss->list) |
190 | sigaction(s->sig, &ss->sa, 0); |
191 | } |
192 | |
193 | /* --- @sig_init@ --- * |
194 | * |
195 | * Arguments: @sel_state *s@ = pointer to select state |
196 | * |
197 | * Returns: --- |
198 | * |
199 | * Use: Initializes the signal handling system ready for use. |
200 | */ |
201 | |
202 | void sig_init(sel_state *s) |
203 | { |
204 | int fd[2]; |
205 | unsigned nsig; |
206 | |
207 | /* --- Work out how many signals there are --- */ |
208 | |
209 | { |
210 | sigset_t ss; |
211 | unsigned min = 0, max = 0; |
212 | |
213 | sigemptyset(&ss); |
214 | |
215 | /* --- Get a good upper bound --- * |
216 | * |
217 | * Cap the search at 256. I'll be sending signal numbers as bytes. |
218 | */ |
219 | |
220 | nsig = 1; |
221 | while (sigaddset(&ss, nsig) == 0) { |
222 | if (nsig == 256) |
223 | goto counted; |
224 | nsig <<= 1; |
225 | } |
226 | |
227 | /* --- Now binary search until I find the actual limit --- */ |
228 | |
229 | min = nsig >> 1; |
230 | max = nsig; |
231 | for (;;) { |
232 | nsig = (min + max) >> 1; |
233 | if (nsig == min) |
234 | break; |
235 | if (sigaddset(&ss, nsig)) |
236 | max = nsig; |
237 | else |
238 | min = nsig; |
239 | } |
240 | counted:; |
241 | } |
242 | |
243 | /* --- Initialize the signal state table --- */ |
244 | |
245 | { |
246 | unsigned i; |
247 | |
248 | sigs = xmalloc(nsig * sizeof(*sigs)); |
249 | for (i = 0; i < nsig; i++) |
250 | sigs[i].list = 0; |
251 | } |
252 | |
253 | /* --- Create the signal pipe --- */ |
254 | |
255 | if (pipe(fd)) |
256 | die(1, "couldn't create pipe for signal handling"); |
257 | |
258 | /* --- Set both ends to nonblocking and close-on-exec --- */ |
259 | |
260 | fdflags(fd[0], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
261 | fdflags(fd[1], O_NONBLOCK, O_NONBLOCK, FD_CLOEXEC, FD_CLOEXEC); |
262 | |
263 | /* --- Set everything up for the future --- */ |
264 | |
265 | sigfd = fd[1]; |
266 | sel_initfile(s, &sigsel, fd[0], SEL_READ, sig_read, 0); |
267 | sel_addfile(&sigsel); |
268 | } |
269 | |
270 | /*----- That's all, folks -------------------------------------------------*/ |