/[ascend]/trunk/base/generic/utilities/ascSignal.h
ViewVC logotype

Annotation of /trunk/base/generic/utilities/ascSignal.h

Parent Directory Parent Directory | Revision Log Revision Log


Revision 1002 - (hide annotations) (download) (as text)
Sat Dec 30 14:27:47 2006 UTC (16 years, 1 month ago) by johnpye
File MIME type: text/x-chdr
File size: 12515 byte(s)
Some work on fixing error with test_ascSignal.
Breaking down into smaller test cases.
Removed some debug output from detection of ASC_RESETNEEDED.
Changed all calls 'signal' to 'SIGNAL' macro that includes optional debug output.
Removed 'libasctest.so' (made part of libasctestsuite.so FWIW)
Fixed big in test.c wrt CUEA_ABORT.
Added 'print_stack' and 'Asc_SignalPrintStack' and 'Asc_SignalStackLength'.

1 johnpye 526 /* ASCEND modelling environment
2     Copyright (C) 1997 Benjamin Andrew Allan
3     Copyright (C) 2006 Carnegie Mellon University
4 jds 54
5 johnpye 526 This program is free software; you can redistribute it and/or modify
6     it under the terms of the GNU General Public License as published by
7     the Free Software Foundation; either version 2, or (at your option)
8     any later version.
9    
10     This program is distributed in the hope that it will be useful,
11     but WITHOUT ANY WARRANTY; without even the implied warranty of
12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13     GNU General Public License for more details.
14    
15     You should have received a copy of the GNU General Public License
16     along with this program; if not, write to the Free Software
17     Foundation, Inc., 59 Temple Place - Suite 330,
18     Boston, MA 02111-1307, USA.
19     *//**
20     @file
21     Signal handling protocol definitions for ASCEND.
22    
23     This file standardizes the handling of signals because some OS
24     reset signals to SIG_DFL when a trap goes off while others
25     process the signal but leave the trapping function in place.
26     We want the second behavior and this gives it to us.
27    
28     This module implements limited support for managing signal handlers.
29     This includes:
30     - a standard signal handler - Asc_SignalTrap()
31     - global jmp_buf's for use with Asc_SignalTrap()
32     - functions for managing nested signal handlers
33    
34     The following signal types are currently supported:
35     - SIGFPE - floating point exception
36     - SIGINT - CTRL-C interactive attention request
37     - SIGSEGV - segmentation fault
38    
39     A simple use of these facilities to trap floating point exceptions
40     might be as follows:
41     <pre>
42     Asc_SignalInit();
43     Asc_SignalHandlerPush(SIGFPE, Asc_SignalTrap);
44     if (setjmp(g_fpe_env)==0) {
45     y = sqrt(x);
46     } else {
47     y = sqrt(-x);
48     }
49     Asc_SignHandlerPop(SIGFPE,Asc_SignalTrap);
50     Asc_SignalDestroy();
51     </pre>
52 jds 54
53 johnpye 968 This example uses the built-in signal handler Asc_SignalTrap()
54     and the global <code>jmp_buf</code> g_fpe_env. After initializing
55     the signal manager and registering the handler, <code>setjmp</code>
56     is used to select normal and exception paths. The <code>setjmp</code>
57     returns 0 when initially called and the sqrt(x) is calculated. If
58     x is negative, a SIGFPE exception occurs and the handler is called. It
59     uses <code>lngjmp</code> and returns to the if statement, and now
60     'setjmp' returns non-zero and the <code>else</code> clause is executed.
61     Finally, the handler is removed and the signal manager cleaned up.<br><br>
62    
63     The stack mechanism also allows nested handlers to be registered. It is
64     important to note that nested handlers for the same signal type cannot
65     both use Asc_SignalTrap() as the handler. This is because different
66     <code>jmp_buf</code> variables must be used and Asc_SignalTrap() uses
67     the same global <code>jmp_buf</code> each time. However, you can use
68     custome <code>jmp_buf</code>'s and handlers:
69    
70     <pre>
71     Asc_SignalInit();
72     Asc_SignalHandlerPush(SIGFPE, Asc_SignalTrap);
73     if (setjmp(g_fpe_env) == 0) {
74     y = sqrt(x);
75     Asc_SignalHandlerPush(SIGFPE, my_handler);
76     if (setjmp(my_jmp_buf) == 0) {
77     y = z/x;
78     } else {
79     Asc_Panic(1, NULL, "Div by zero error.");
80     }
81     Asc_SignHandlerPop(SIGFPE, my_handler);
82     } else {
83     y = sqrt(-x);
84     }
85     Asc_SignHandlerPop(SIGFPE,Asc_SignalTrap);
86     Asc_SignalDestroy();
87     </pre>
88    
89     Here, exceptions in the sqrt(x) calculation are handled by the standard
90     Asc_SignalTrap(), while the division is handled by my_handler.<br><br>
91    
92     Avoid mixing use of the signal manager with direct calls to signal().
93     Once Asc_SignalInit() has been called, use of signal() directly is likely
94     to be lost or to corrupt the managed handlers.<br><br>
95    
96     Another warning: setjmp is expensive if called inside a fast loop.
97    
98 johnpye 526 Requires:
99     #include "utilities/ascConfig.h"
100     *//*
101 johnpye 953 by Benjamin Andrew Allan, May 27, 1997
102     Last in CVS: $Revision: 1.6 $ $Date: 1998/01/10 18:00:05 $ $Author: ballan $
103 johnpye 526 */
104    
105 johnpye 67 #ifndef ASC_ASCSIGNAL_H
106     #define ASC_ASCSIGNAL_H
107 jds 54
108 aw0a 1 #include <signal.h>
109     #include <setjmp.h>
110 johnpye 669 #include "utilities/ascConfig.h"
111    
112 aw0a 1 #ifdef __WIN32__
113 jds 102 # include <process.h>
114 jds 101 #else
115 jds 102 # include <unistd.h>
116 aw0a 1 #endif
117    
118 johnpye 968 #ifdef __WIN32__
119     # define FPRESET _fpreset()
120     #else
121     # define FPRESET (void)0
122     #endif
123    
124 johnpye 953 typedef void SigHandlerFn(int);
125 jds 59 /**< Signature of a signal handling function. */
126 jds 54
127 aw0a 1 #define MAX_TRAP_DEPTH 40L
128 jds 59 /**< The maximum number of traps that can be nested. */
129 aw0a 1
130 johnpye 997 #define ASC_JMP_INFO
131     /**< Whether to store additional information before making a setjmp call */
132 aw0a 1
133 johnpye 997 #ifndef ASC_JMP_INFO
134     # define SETJMP set_jmp
135     # define LONGJMP longjmp
136 johnpye 1002 # define SIGNAL signal
137 johnpye 997 typedef JMP_BUF jmp_buf
138     #else
139 johnpye 1002 # define SETJMP(ENV) (\
140     CONSOLE_DEBUG("SETJMP at %s:%d (%s=%p)",__FILE__,__LINE__,#ENV,ENV.jmp)\
141     ,ENV.filename = __FILE__, ENV.line = __LINE__, ENV.func = __FUNCTION__\
142     ,ENV.varname = #ENV\
143     , setjmp(ENV.jmp)\
144     )
145     # define LONGJMP(ENV,VAL) (\
146     CONSOLE_DEBUG("LONGJMP to %s:%d (%s) (%s=%p)",ENV.filename,ENV.line,ENV.func,ENV.varname,ENV.jmp)\
147     , longjmp(ENV.jmp, VAL)\
148     )
149 johnpye 997 typedef struct{
150     jmp_buf jmp;
151     const char *filename;
152     int line;
153     const char *func;
154 johnpye 1002 const char *varname;
155 johnpye 997 } asc_jmp_buf;
156     #define JMP_BUF asc_jmp_buf
157 johnpye 1002 #define SIGNAL(SIG,HANDLER) (CONSOLE_DEBUG("SIGNAL(%d,%s)",SIG,#HANDLER),signal(SIG,HANDLER))
158 johnpye 997 #endif
159    
160    
161    
162     ASC_DLLSPEC(JMP_BUF) g_fpe_env; /**< Standard signal jmp_buf - floating point error. */
163     ASC_DLLSPEC(JMP_BUF) g_seg_env; /**< Standard signal jmp_buf - segmentation fault. */
164     ASC_DLLSPEC(JMP_BUF) g_int_env; /**< Standard signal jmp_buf - interactive attention (<CTRL>C). */
165    
166     #if 0
167 aw0a 1 extern jmp_buf g_foreign_code_call_env;
168 jds 54 /**<
169 johnpye 953 Not currently in use. Should be when we get to a unified
170     standard for signal handling.
171     @todo Implement use of g_foreign_code_call_env?
172     */
173 johnpye 997 #endif
174 aw0a 1
175 johnpye 522 ASC_DLLSPEC(void ) Asc_SignalTrap(int sigval);
176 jds 54 /**<
177 jds 59 * Standard signal handler.
178 jds 54 * This is the trap that should be used for most applications in
179 jds 59 * ASCEND. It prints a message then calls longjmp(GLOBAL, sigval)
180     * where GLOBAL is one of g_fpe_env, g_seg_env, or g_int_env.
181     * Because the jmp_buf is global, so you can't nest calls to
182     * setjmp where both use this trap function.<br><br>
183 aw0a 1 *
184 jds 54 * Trivial Example:
185     * <pre>
186     * Asc_SignalHandlerPush(SIGFPE,Asc_SignalTrap);
187     * if (setjmp(g_fpe_env)==0) {
188     * y = sqrt(x);
189     * } else {
190     * y = sqrt(-x);
191     * }
192     * Asc_SignHandlerPop(SIGFPE,Asc_SignalTrap);
193 jds 59 *
194 aw0a 1 * For x < 0 the else is called because setjmp returns nonzero
195     * when the body of the 'if' signals range error.
196 jds 54 * </pre>
197 johnpye 485 * Remember always to use Asc_SignalHandlerPush() and
198     * Asc_SignalHandlerPop(). You can write an alternate function
199 jds 59 * to use instead of AscSignalTrap() if need be. The signals
200 jds 54 * SIGFPE, SIGINT, SIGSEGV are understood.<br><br>
201 aw0a 1 *
202 jds 59 * Note - this handler does not reinstall itself. After an exception,
203     * you need to reinstall the handler (if desired) using
204     * Asc_SignalRecover().
205     *
206     * @todo Should utilities/ascSignal.c:Asc_SignalTrap() reinstall itself
207     * after it catches an expection using Asc_SignalRecover()?
208     * @param sigval Holds the signal type code when called during
209     * an exception.
210 aw0a 1 */
211    
212 johnpye 593 ASC_DLLSPEC(int ) Asc_SignalInit(void);
213 johnpye 485 /**<
214 jds 59 * Initializes the signal manager.
215 johnpye 485 * This should be called before using any of the signal handling
216 jds 59 * functions in this module. It initializes the internal stacks
217     * for mangaging signal handlers. This function does not install
218     * any signal handlers (although any existing handlers are left
219     * in place). Calling this function more than once will have no
220     * effect and an error code will be returned.<br><br>
221     *
222     * @return Returns 0 if successful, 1 if memory could not be
223     * allocated, and 2 if an error occurred.
224 aw0a 1 */
225    
226 johnpye 593 ASC_DLLSPEC(void ) Asc_SignalDestroy(void);
227 jds 59 /**<
228     * Cleans up and destroys the stacks of signal handlers.
229     * It does not change the status of any registered signal handlers
230     * That is, any handlers registered when this function is called
231     * will still be registered. It is important to call
232     * Asc_SignalHandlerPop() for each occurrence of Asc_SignalHandlerPush()
233     * before calling this function. Otherwise, any signal handlers
234     * that were installed before Asc_SignalInit() was called will be lost.
235 aw0a 1 */
236    
237 johnpye 522 ASC_DLLSPEC(void ) Asc_SignalRecover(int force);
238 jds 59 /**<
239     * Reinstalls the most recently pushed handler that has been
240     * installed for each supported signal type. This should be called
241     * after every trapped exception and at any other time when the
242     * status of exception handlers may have become not well-defined.
243     * If no handler has been pushed for a given signal type, SIG_DFL is
244 johnpye 485 * installed. Note that the standard handler function Asc_SignalTrap()
245     * does not call this function. If you use the standard handler and
246     * you want it reinstalled after an exception, be sure to call this
247     * function after the longjmp return. This call is not particularly
248 jds 59 * cheap if it does the reinstallation.<br><br>
249 aw0a 1 *
250 jds 59 * This module tests on startup for whether the OS reverts to
251     * SIG_DFL when a trap function is called. If it does NOT then
252     * this function will simply return unless force != 0. You don't
253     * want to call this function with force == 1 normally after a
254     * caught exception. However, if you're not sure of the handler
255 johnpye 485 * installation status and want to make sure the handlers are
256 jds 59 * installed, call with force == 1. Also, gdb or other
257     * debuggers which intercept and screw up signals may require
258     * applying force (manually) to ensure that the signals get
259     * reinstalled.
260     *
261 johnpye 485 * @param force If non-zero, the most recent handlers are
262 jds 59 * reinstalled even if not required by the
263     * compiler/platform.
264 aw0a 1 */
265    
266 johnpye 968 ASC_DLLSPEC(int ) Asc_SignalHandlerPushDefault(int signum);
267 johnpye 953 ASC_DLLSPEC(int ) Asc_SignalHandlerPush(int signum, SigHandlerFn *func);
268 jds 54 /**<
269 aw0a 1 * Adds a handler to the stack of signal handlers for the given signal.
270     * There is a maximum stack limit, so returns 1 if limit exceeded.
271     * Returns -1 if stack of signal requested does not exist.
272 jds 54 * Pushing a NULL handler func does NOT change anything at all.
273 aw0a 1 * On a successful return, the handler has been installed and will
274 jds 59 * remain installed until a Asc_SignalHandlerPop() or another push.
275     * The handler will remain installed as long as Asc_SignalRecover()
276     * is used properly after every exception.
277     *
278     * @param signum The signal type that func should handle.
279     * @param func The signal handler to register for signum signal types.
280     * @return Returns 1 if the stack limit is exceeded, -1 if managing
281     * of signals for the specified signum is not supported or
282     * initialized, or 0 if the function completes successfully.
283     * @todo Shouldn't utilities/ascSignal.c:Asc_SignalHandlerPush() return
284     * an error code on a NULL func? It seems too easy for someone to
285 johnpye 485 * accidentally push a NULL without realizing it, and then later
286 jds 59 * popping an unintended handler.
287 aw0a 1 */
288    
289 johnpye 968 ASC_DLLSPEC(int ) Asc_SignalHandlerPopDefault(int signum);
290 johnpye 953 ASC_DLLSPEC(int ) Asc_SignalHandlerPop(int signum, SigHandlerFn *func);
291 jds 54 /**<
292 jds 59 * Removes the last-pushed handler from the stack for signum signal types.
293 johnpye 485 * If the removed handler is the same as func, it is uninstalled and
294 jds 59 * replaced with the handler now at the top of the stack. If not, non-zero
295     * is returned and you need to call Asc_SignalRecover() to uninstall the
296 johnpye 485 * current handler if desired. Note that the top handler is popped off
297     * the stack whether it matches func or not. Non-zero is also returned if
298     * the stack is empty. A side effect is that all managed signal types will
299 jds 59 * have the registered handlers reinstalled.
300     *
301     * @param signum The signal type whose top-most handler should be replaced.
302     * @param func The handler function that should be at the top of the
303     * stack (and currently installed) for signals of type signum.
304     * @return Returns non-zero if func is not the replaced handler or if
305     * the stack is empty, 0 if the function completed successfully.
306     * @todo Does it make more sense for utilities/ascSignal.c:Asc_SignalHanderPop()
307 johnpye 485 * to fail completely if func is not the top-most handler? It is not
308     * clear why the function should pop the top handler no matter what, but
309 jds 59 * only call Asc_SignalRecover() if it matches func.
310 aw0a 1 */
311    
312 johnpye 1002 ASC_DLLSPEC(void) Asc_SignalPrintStack(int signum);
313    
314     ASC_DLLSPEC(int) Asc_SignalStackLength(int signum);
315    
316 johnpye 67 #endif /* ASC_ASCSIGNAL_H */
317 jds 54

john.pye@anu.edu.au
ViewVC Help
Powered by ViewVC 1.1.22