The World of Computer Software/World_Of_Computer_Software-02-385-Vol-1of3.iso/k/ksh48.zip/sh/trap.c

C/C++ Source or Header | 1992-08-25 | 4KB | 204 lines

/*
 * signal handling
 */

#ifndef lint
static char *RCSid = "$Id: trap.c,v 1.3 1992/08/10 12:03:15 sjg Exp $";
#endif

#include "stdh.h"
#include <errno.h>
#include <signal.h>
#include <setjmp.h>
#include "sh.h"

Trap sigtraps [SIGNALS] = {
    {0,    "EXIT", "Signal 0"}, /* todo: belongs in e.loc->exit */
    {SIGINT, "INT", "Interrupt"},
    {SIGILL, "ILL", "Illegal instruction"},
    {SIGFPE, "FPE", "Floating exception"},
    {SIGSEGV, "SEGV", "Memory fault"},
    {SIGTERM, "TERM", "Terminated"},
#ifdef OS2
    {SIGBREAK, "BREAK", "Ctrl-Break"},
#endif
    {SIGHUP, "HUP", "Hangup"},
    {SIGQUIT, "QUIT", "Quit"},
    {SIGTRAP, "TRAP", "Trace trap"},
#ifdef    SIGABRT
    {SIGABRT, "ABRT", "Abort"},
#else
    {SIGIOT, "IOT", "IOT instruction"},
#endif
    {SIGEMT, "EMT", "EMT trap"},
    {SIGKILL, "KILL", "Killed"},
#ifdef _MINIX
    {SIGUSR1, "USR1", "User defined signal 1"},
    {SIGUSR2, "USR2", "User defined signal 2"},
    {SIGSTKFLT, "STKFLT", "Stack fault"},
#else
    {SIGBUS, "BUS", "Bus error"},
    {SIGSYS, "SYS", "Bad system call"},
#endif
    {SIGPIPE, "PIPE", "Broken pipe"},
    {SIGALRM, "ALRM", "Alarm clock"},
#ifdef _SYSV
#ifndef OS2
    {SIGUSR1, "USR1", "User defined signal 1"},
    {SIGUSR2, "USR2", "User defined signal 2"},
    {SIGPWR, "PWR", "Power-fail restart"},
#endif
    {SIGCLD, "CLD", "Death of a child"},
#ifdef JOBS            /* todo: need to be more portable */
    {SIGTSTP, "TSTP", "Stop"},
    {SIGTTIN, "TTIN", "Stop (tty input)"},
#ifdef SIGPOLL
    {SIGPOLL, "POLL", "Pollable event occured"},
#endif
    {SIGSTOP, "STOP", "Stop (signal)"},
    {SIGTTOU, "TTOU", "Stop (tty output)"},
    {SIGCONT, "CONT", "Continue"},
#endif
#else
#ifdef JOBS            /* todo: need to be more portable */
    {SIGURG, "URG", "Urgent condition"}, /* BSDism */
    {SIGSTOP, "STOP", "Stop (signal)"},
    {SIGTSTP, "TSTP", "Stop"},
    {SIGCONT, "CONT", "Continue"},
    {SIGCHLD, "CHLD", "Waiting children"},
    {SIGTTIN, "TTIN", "Stop (tty input)"},
    {SIGTTOU, "TTOU", "Stop (tty output)"},
#endif
#endif
};

Trap *
gettrap(name)
    char *name;
{
    int i;
    register Trap *p;

    if (digit(*name)) {
        i = getn(name);
        return (0 <= i && i < SIGNALS) ? &sigtraps[getn(name)] : NULL;
    }
#if 0
    if (strcmp("ERR", name) == 0)
        return &e.loc->err;
    if (strcmp("EXIT", name) == 0)
        return &e.loc->exit;
#endif
    for (p = sigtraps, i = SIGNALS; --i >= 0; p++)
        if (p->name != NULL && strcmp(p->name, name) == 0)
            return p;
    return NULL;
}

/*
 * trap signal handler
 */
void
trapsig(i)
    int i;
{
    trap = sigtraps[i].set = 1;
    if (i == SIGINT && (e.type == E_PARSE || e.type == E_LOOP))
        /* dangerous but necessary to deal with BSD silly signals */
        longjmp(e.jbuf, 1);
#ifdef USE_SIGACT
    sigaction(i, &Sigact_trap, NULL);
#else
    (void) signal(i, trapsig);
#endif
}

/*
 * run any pending traps
 */
runtraps()
{
    int i;
    register Trap *p;

    for (p = sigtraps, i = SIGNALS; --i >= 0; p++)
        if (p->set)
            runtrap(p);
    trap = 0;
}

runtrap(p)
    Trap *p;
{
    char *trapstr;

    p->set = 0;
    if ((trapstr = p->trap) == NULL)
        if (p->signal == SIGINT)
            unwind();    /* return to shell() */
        else
            return 0;
    if (p->signal == 0)    /* ??? */
        p->trap = 0;
    command(trapstr);
}

/* restore signals for children */
cleartraps()
{
    int i;
    register Trap *p;

    if ((p = sigtraps)->trap != NULL) {    /* Maybe put in exchild() */
        afree((void *)p->trap,APERM);    /* Necessary? */
        p->trap = NULL;
    }
    for (i = SIGNALS, p = sigtraps; --i >= 0; p++) {
        p->set = 0;
#ifdef USE_SIGACT
        if (p->ourtrap)
        {
          sigaction(p->signal, &Sigact_ign, &Sigact);
          if (Sigact.sa_handler != SIG_IGN)
            sigaction(p->signal, &Sigact_dfl, NULL);
        }
#else
        if (p->ourtrap && signal(p->signal, SIG_IGN) != SIG_IGN)
            (void) signal(p->signal, SIG_DFL);
#endif
    }
}

ignoresig(i)
    int i;
{
#ifdef USE_SIGACT
  sigaction(i, &Sigact_ign, &Sigact);
  sigemptyset(&Sigact.sa_mask);
  Sigact.sa_flags = 0;

  if (Sigact.sa_handler != SIG_IGN)
    sigtraps[i].sig_dfl = 1;
#else
  if (signal(i, SIG_IGN) != SIG_IGN)
    sigtraps[i].sig_dfl = 1;
#endif
}

restoresigs()
{
    int i;
    register Trap *p;

    for (p = sigtraps, i = SIGNALS; --i >= 0; p++)
        if (p->sig_dfl) {
            p->sig_dfl = 0;
#ifdef USE_SIGACT
            sigaction(p->signal, &Sigact_dfl, NULL);
#else
            (void) signal(p->signal, SIG_DFL);
#endif
        }
}