ash: fix "orwell bug" 1984. Testcase:
trap_handler() {
echo trap
}
trap trap_handler USR1
sleep 3600 &
while true; do wait; done
This commit is contained in:
Denis Vlasenko
parent
0ef240d979
commit
991a1da148
101
shell/ash.c
101
shell/ash.c
@ -164,7 +164,16 @@ struct globals_misc {
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char *arg0; /* value of $0 */
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struct jmploc *exception_handler;
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int exception;
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// disabled by vda: cannot understand how it was supposed to work -
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// cannot fix bugs. That's why you have to explain your non-trivial designs!
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// /* do we generate EXSIG events */
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// int exsig; /* counter */
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volatile int suppressint; /* counter */
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volatile /*sig_atomic_t*/ smallint intpending; /* 1 = got SIGINT */
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/* last pending signal */
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volatile /*sig_atomic_t*/ smallint pendingsig;
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smallint exception; /* kind of exception (0..5) */
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/* exceptions */
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#define EXINT 0 /* SIGINT received */
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#define EXERROR 1 /* a generic error */
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@ -172,12 +181,6 @@ struct globals_misc {
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#define EXEXEC 3 /* command execution failed */
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#define EXEXIT 4 /* exit the shell */
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#define EXSIG 5 /* trapped signal in wait(1) */
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volatile int suppressint;
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volatile sig_atomic_t intpending;
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/* do we generate EXSIG events */
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int exsig;
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/* last pending signal */
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volatile sig_atomic_t pendingsig;
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/* trap handler commands */
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char *trap[NSIG];
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@ -211,7 +214,7 @@ static struct globals_misc *const ptr_to_globals_misc __attribute__ ((section ("
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#define exception (G_misc.exception )
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#define suppressint (G_misc.suppressint )
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#define intpending (G_misc.intpending )
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#define exsig (G_misc.exsig )
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//#define exsig (G_misc.exsig )
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#define pendingsig (G_misc.pendingsig )
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#define trap (G_misc.trap )
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#define isloginsh (G_misc.isloginsh)
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@ -281,6 +284,7 @@ raise_interrupt(void)
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i = EXSIG;
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if (gotsig[SIGINT - 1] && !trap[SIGINT]) {
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if (!(rootshell && iflag)) {
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/* Kill ourself with SIGINT */
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signal(SIGINT, SIG_DFL);
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raise(SIGINT);
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}
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@ -333,15 +337,6 @@ force_int_on(void)
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raise_interrupt(); \
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} while (0)
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#define EXSIGON \
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do { \
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exsig++; \
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xbarrier(); \
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if (pendingsig) \
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raise_exception(EXSIG); \
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} while (0)
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/* EXSIG is turned off by evalbltin(). */
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/*
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* Ignore a signal. Only one usage site - in forkchild()
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*/
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@ -363,10 +358,10 @@ onsig(int signo)
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gotsig[signo - 1] = 1;
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pendingsig = signo;
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if (exsig || (signo == SIGINT && !trap[SIGINT])) {
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if ( /* exsig || */ (signo == SIGINT && !trap[SIGINT])) {
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if (!suppressint) {
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pendingsig = 0;
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raise_interrupt();
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raise_interrupt(); /* does not return */
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}
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intpending = 1;
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}
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@ -3256,12 +3251,11 @@ setsignal(int signo)
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struct sigaction act;
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t = trap[signo];
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action = S_IGN;
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if (t == NULL)
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action = S_DFL;
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else if (*t != '\0')
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action = S_CATCH;
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else
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action = S_IGN;
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if (rootshell && action == S_DFL) {
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switch (signo) {
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case SIGINT:
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@ -3294,7 +3288,7 @@ setsignal(int signo)
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/*
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* current setting unknown
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*/
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if (sigaction(signo, 0, &act) == -1) {
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if (sigaction(signo, NULL, &act) == -1) {
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/*
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* Pretend it worked; maybe we should give a warning
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* here, but other shells don't. We don't alter
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@ -3302,19 +3296,19 @@ setsignal(int signo)
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*/
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return;
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}
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tsig = S_RESET; /* force to be set */
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if (act.sa_handler == SIG_IGN) {
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tsig = S_HARD_IGN;
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if (mflag
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&& (signo == SIGTSTP || signo == SIGTTIN || signo == SIGTTOU)
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) {
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tsig = S_IGN; /* don't hard ignore these */
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} else
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tsig = S_HARD_IGN;
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} else {
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tsig = S_RESET; /* force to be set */
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}
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}
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}
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if (tsig == S_HARD_IGN || tsig == action)
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return;
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act.sa_handler = SIG_DFL;
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switch (action) {
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case S_CATCH:
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act.sa_handler = onsig;
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@ -3322,13 +3316,11 @@ setsignal(int signo)
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case S_IGN:
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act.sa_handler = SIG_IGN;
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break;
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default:
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act.sa_handler = SIG_DFL;
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}
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*t = action;
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act.sa_flags = 0;
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sigfillset(&act.sa_mask);
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sigaction(signo, &act, 0);
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sigaction(signo, &act, NULL);
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}
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/* mode flags for set_curjob */
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@ -3763,7 +3755,8 @@ waitproc(int wait_flags, int *status)
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if (jobctl)
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wait_flags |= WUNTRACED;
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#endif
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return waitpid(-1, status, wait_flags); // safe_waitpid?
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/* NB: _not_ safe_waitpid, we need to detect EINTR */
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return waitpid(-1, status, wait_flags);
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}
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/*
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@ -3781,8 +3774,14 @@ dowait(int wait_flags, struct job *job)
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TRACE(("dowait(%d) called\n", wait_flags));
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pid = waitproc(wait_flags, &status);
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TRACE(("wait returns pid=%d, status=%d\n", pid, status));
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if (pid <= 0)
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if (pid <= 0) {
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/* If we were doing blocking wait and (probably) got EINTR,
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* check for pending sigs received while waiting.
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* (NB: can be moved into callers if needed) */
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if (wait_flags == DOWAIT_BLOCK && pendingsig)
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raise_exception(EXSIG);
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return pid;
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}
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INT_OFF;
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thisjob = NULL;
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for (jp = curjob; jp; jp = jp->prev_job) {
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@ -4004,7 +4003,10 @@ waitcmd(int argc, char **argv)
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int retval;
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struct job *jp;
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EXSIGON;
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// exsig++;
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// xbarrier();
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if (pendingsig)
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raise_exception(EXSIG);
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nextopt(nullstr);
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retval = 0;
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@ -4015,10 +4017,8 @@ waitcmd(int argc, char **argv)
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for (;;) {
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jp = curjob;
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while (1) {
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if (!jp) {
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/* no running procs */
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goto out;
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}
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if (!jp) /* no running procs */
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goto ret;
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if (jp->state == JOBRUNNING)
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break;
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jp->waited = 1;
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@ -4051,7 +4051,7 @@ waitcmd(int argc, char **argv)
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;
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} while (*++argv);
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out:
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ret:
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return retval;
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}
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@ -4450,7 +4450,7 @@ clear_traps(void)
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char **tp;
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for (tp = trap; tp < &trap[NSIG]; tp++) {
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if (*tp && **tp) { /* trap not NULL or SIG_IGN */
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if (*tp && **tp) { /* trap not NULL or "" (SIG_IGN) */
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INT_OFF;
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free(*tp);
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*tp = NULL;
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@ -4613,8 +4613,8 @@ waitforjob(struct job *jp)
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* intuit from the subprocess exit status whether a SIGINT
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* occurred, and if so interrupt ourselves. Yuck. - mycroft
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*/
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if (jp->sigint)
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raise(SIGINT);
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if (jp->sigint) /* TODO: do the same with all signals */
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raise(SIGINT); /* ... by raise(jp->sig) instead? */
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}
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if (jp->state == JOBDONE)
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#endif
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@ -7437,7 +7437,7 @@ dotrap(void)
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char *q;
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int i;
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int savestatus;
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int skip = 0;
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int skip;
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savestatus = exitstatus;
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pendingsig = 0;
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@ -7454,10 +7454,10 @@ dotrap(void)
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skip = evalstring(p, SKIPEVAL);
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exitstatus = savestatus;
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if (skip)
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break;
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return skip;
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}
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return skip;
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return 0;
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}
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/* forward declarations - evaluation is fairly recursive business... */
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@ -8434,22 +8434,15 @@ evalcommand(union node *cmd, int flags)
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}
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if (evalbltin(cmdentry.u.cmd, argc, argv)) {
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int exit_status;
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int i, j;
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i = exception;
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int i = exception;
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if (i == EXEXIT)
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goto raise;
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exit_status = 2;
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j = 0;
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if (i == EXINT)
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j = SIGINT;
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exit_status = 128 + SIGINT;
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if (i == EXSIG)
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j = pendingsig;
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if (j)
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exit_status = j + 128;
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exit_status = 128 + pendingsig;
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exitstatus = exit_status;
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if (i == EXINT || spclbltin > 0) {
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raise:
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longjmp(exception_handler->loc, 1);
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@ -8499,7 +8492,7 @@ evalbltin(const struct builtincmd *cmd, int argc, char **argv)
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exitstatus |= ferror(stdout);
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clearerr(stdout);
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commandname = savecmdname;
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exsig = 0;
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// exsig = 0;
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exception_handler = savehandler;
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return i;
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31
shell/ash_doc.txt
Normal file
31
shell/ash_doc.txt
Normal file
@ -0,0 +1,31 @@
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Wait + signals
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We had some bugs here which are hard to test in testsuite.
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Bug 1280 (http://busybox.net/bugs/view.php?id=1280):
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was misbehaving in interactive ash. Correct behavior:
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$ sleep 20 &
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$ wait
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^C
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$ wait
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^C
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$ wait
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^C
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...
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Bug 1984 (http://busybox.net/bugs/view.php?id=1984):
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traps were not triggering:
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trap_handler_usr () {
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echo trap usr
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}
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trap_handler_int () {
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echo trap int
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}
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trap trap_handler_usr USR1
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trap trap_handler_int INT
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sleep 3600 &
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echo "Please do: kill -USR1 $$"
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echo "or: kill -INT $$"
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while true; do wait; echo wait interrupted; done
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