exceptions.c

/*******************************************************************************
 * Copyright (c) 2007 Wind River Systems, Inc. and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Eclipse Public License v1.0 
 * which accompanies this distribution, and is available at 
 * http://www.eclipse.org/legal/epl-v10.html 
 *  
 * Contributors:
 *     Wind River Systems - initial API and implementation
 *******************************************************************************/

/*
 * Exception handling. Functionality is similar to C++ try/catch.
 * Usage example:
    Trap trap;
    if (set_trap(&trap)) {
        // Some code that can throw an exception by calling exception()
        ...

        clear_trap(&trap);
    }
    else {
        // Exception handling code
        if (trap.error == ...
        ...
    }
 * Only main thread is allowed to use exceptions.
 */

#if _WRS_KERNEL
#  include <vxWorks.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "exceptions.h"
#include "events.h"
#include "trace.h"

static Trap * chain = NULL;

int set_trap_a(Trap * trap) {
    assert(is_dispatch_thread());
    memset(trap, 0, sizeof(Trap));
    trap->next = chain;
    chain = trap;
    return 0;
}

int set_trap_b(Trap * trap) {
    if (trap->error == 0) return 1;
    assert(trap == chain);
    chain = trap->next;
    return 0;
}

void clear_trap(Trap * trap) {
    assert(is_dispatch_thread());
    assert(trap == chain);
    chain = trap->next;
}

void exception(int error) {
    assert(is_dispatch_thread());
    assert(error != 0);
    if (chain == NULL) {
        trace(LOG_ALWAYS, "Unhandled exception %d: %s", error, errno_to_str(error));
        exit(error);
    }
    longjmp(chain->env, error);
}

void str_exception(int error, char * msg) {
    assert(is_dispatch_thread());
    assert(error != 0);
    if (chain == NULL) {
        trace(LOG_ALWAYS, "Unhandled exception %d: %s", error, errno_to_str(error));
        exit(error);
    }
    strncpy(chain->msg, msg, sizeof(chain->msg));
    longjmp(chain->env, error);
}