ref: ec73849b6936d839410ccb239d14b2f7c7ca3d6f
dir: /sys/src/ape/cmd/pdksh/trap.c/
/*
* signal handling
*/
/* Kludge to avoid bogus re-declaration of sigtraps[] error on AIX 3.2.5 */
#define FROM_TRAP_C
#include "sh.h"
/* Table is indexed by signal number
*
* The script siglist.sh generates siglist.out, which is a sorted, complete
* list of signals
*/
Trap sigtraps[SIGNALS+1] = {
{ SIGEXIT_, "EXIT", "Signal 0" },
{ 1 , "HUP", "Hangup" },
{ 2 , "INT", "Interrupt" },
{ 3 , "QUIT", "Quit" },
{ 4 , "ILL", "Illegal instruction" },
{ 5 , "ABRT", "Abort" },
{ 6 , "FPE", "Floating point exception" },
{ 7 , "KILL", "Killed" },
{ 8 , "SEGV", "Memory fault" },
{ 9 , "PIPE", "Broken pipe" },
{ 10 , "ALRM", "Alarm clock" },
{ 11 , "TERM", "Terminated" },
{ 12 , "USR1", "User defined signal 1" },
{ 13 , "USR2", "User defined signal 2" },
{ 14 , "BUS", "Bus error" },
{ 15 , "CHLD", "Child exited" },
{ 16 , "CONT", "Continued" },
{ 17 , "STOP", "Stopped (signal)" },
{ 18 , "TSTP", "Stopped" },
{ 19 , "TTIN", "Stopped (tty input)" },
{ 20 , "TTOU", "Stopped (tty output)" },
{ SIGERR_, "ERR", "Error handler" },
};
static struct sigaction Sigact_ign, Sigact_trap;
void
inittraps(void)
{
#ifdef HAVE_SYS_SIGLIST
# ifndef SYS_SIGLIST_DECLARED
extern char *sys_siglist[];
# endif
int i;
/* Use system description, if available, for unknown signals... */
for (i = 0; i < NSIG; i++)
if (!sigtraps[i].name && sys_siglist[i] && sys_siglist[i][0])
sigtraps[i].mess = sys_siglist[i];
#endif /* HAVE_SYS_SIGLIST */
sigemptyset(&Sigact_ign.sa_mask);
Sigact_ign.sa_flags = KSH_SA_FLAGS;
Sigact_ign.sa_handler = SIG_IGN;
Sigact_trap = Sigact_ign;
Sigact_trap.sa_handler = trapsig;
sigtraps[SIGINT].flags |= TF_DFL_INTR | TF_TTY_INTR;
sigtraps[SIGQUIT].flags |= TF_DFL_INTR | TF_TTY_INTR;
sigtraps[SIGTERM].flags |= TF_DFL_INTR;/* not fatal for interactive */
sigtraps[SIGHUP].flags |= TF_FATAL;
sigtraps[SIGCHLD].flags |= TF_SHELL_USES;
/* these are always caught so we can clean up any temproary files. */
setsig(&sigtraps[SIGINT], trapsig, SS_RESTORE_ORIG);
setsig(&sigtraps[SIGQUIT], trapsig, SS_RESTORE_ORIG);
setsig(&sigtraps[SIGTERM], trapsig, SS_RESTORE_ORIG);
setsig(&sigtraps[SIGHUP], trapsig, SS_RESTORE_ORIG);
}
#ifdef KSH
static RETSIGTYPE alarm_catcher ARGS((int sig));
void
alarm_init(void)
{
sigtraps[SIGALRM].flags |= TF_SHELL_USES;
setsig(&sigtraps[SIGALRM], alarm_catcher,
SS_RESTORE_ORIG|SS_FORCE|SS_SHTRAP);
}
static RETSIGTYPE
alarm_catcher(int sig)
{
if (ksh_tmout_state == TMOUT_READING) {
int left = alarm(0);
if (left == 0) {
ksh_tmout_state = TMOUT_LEAVING;
intrsig = 1;
} else
alarm(left);
}
return RETSIGVAL;
}
#endif /* KSH */
Trap *
gettrap(const char *name, int igncase)
{
int i;
register Trap *p;
if (digit(*name)) {
int n;
if (getn(name, &n) && 0 <= n && n < SIGNALS)
return &sigtraps[n];
return NULL;
}
for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
if (p->name && (igncase ? strcasecmp(p->name, name) == 0
: strcmp(p->name, name) == 0))
return p;
return NULL;
}
/*
* trap signal handler
*/
RETSIGTYPE
trapsig(int i)
{
Trap *p = &sigtraps[i];
trap = p->set = 1;
if (p->flags & TF_DFL_INTR)
intrsig = 1;
if ((p->flags & TF_FATAL) && !p->trap) {
fatal_trap = 1;
intrsig = 1;
}
if (p->shtrap)
(*p->shtrap)(i);
#ifdef V7_SIGNALS
if (sigtraps[i].cursig == trapsig) /* this for SIGCHLD,SIGALRM */
sigaction(i, &Sigact_trap, (struct sigaction *) 0);
#endif /* V7_SIGNALS */
return RETSIGVAL;
}
/* called when we want to allow the user to ^C out of something - won't
* work if user has trapped SIGINT.
*/
void
intrcheck(void)
{
if (intrsig)
runtraps(TF_DFL_INTR|TF_FATAL);
}
/* called after EINTR to check if a signal with normally causes process
* termination has been received.
*/
int
fatal_trap_check(void)
{
int i;
Trap *p;
/* todo: should check if signal is fatal, not the TF_DFL_INTR flag */
for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
if (p->set && (p->flags & (TF_DFL_INTR|TF_FATAL)))
/* return value is used as an exit code */
return 128 + p->signal;
return 0;
}
/* Returns the signal number of any pending traps: ie, a signal which has
* occured for which a trap has been set or for which the TF_DFL_INTR flag
* is set.
*/
int
trap_pending(void)
{
int i;
Trap *p;
for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
if (p->set && ((p->trap && p->trap[0])
|| ((p->flags & (TF_DFL_INTR|TF_FATAL))
&& !p->trap)))
return p->signal;
return 0;
}
/*
* run any pending traps. If intr is set, only run traps that
* can interrupt commands.
*/
void
runtraps(int flag)
{
int i;
register Trap *p;
#ifdef KSH
if (ksh_tmout_state == TMOUT_LEAVING) {
ksh_tmout_state = TMOUT_EXECUTING;
warningf(FALSE, "timed out waiting for input");
unwind(LEXIT);
} else
/* XXX: this means the alarm will have no effect if a trap
* is caught after the alarm() was started...not good.
*/
ksh_tmout_state = TMOUT_EXECUTING;
#endif /* KSH */
if (!flag)
trap = 0;
if (flag & TF_DFL_INTR)
intrsig = 0;
if (flag & TF_FATAL)
fatal_trap = 0;
for (p = sigtraps, i = SIGNALS+1; --i >= 0; p++)
if (p->set && (!flag
|| ((p->flags & flag) && p->trap == (char *) 0)))
runtrap(p);
}
void
runtrap(Trap *p)
{
int i = p->signal;
char *trapstr = p->trap;
int oexstat;
int UNINITIALIZED(old_changed);
p->set = 0;
if (trapstr == (char *) 0) { /* SIG_DFL */
if (p->flags & TF_FATAL) {
/* eg, SIGHUP */
exstat = 128 + i;
unwind(LLEAVE);
}
if (p->flags & TF_DFL_INTR) {
/* eg, SIGINT, SIGQUIT, SIGTERM, etc. */
exstat = 128 + i;
unwind(LINTR);
}
return;
}
if (trapstr[0] == '\0') /* SIG_IGN */
return;
if (i == SIGEXIT_ || i == SIGERR_) { /* avoid recursion on these */
old_changed = p->flags & TF_CHANGED;
p->flags &= ~TF_CHANGED;
p->trap = (char *) 0;
}
oexstat = exstat;
/* Note: trapstr is fully parsed before anything is executed, thus
* no problem with afree(p->trap) in settrap() while still in use.
*/
command(trapstr);
exstat = oexstat;
if (i == SIGEXIT_ || i == SIGERR_) {
if (p->flags & TF_CHANGED)
/* don't clear TF_CHANGED */
afree(trapstr, APERM);
else
p->trap = trapstr;
p->flags |= old_changed;
}
}
/* clear pending traps and reset user's trap handlers; used after fork(2) */
void
cleartraps(void)
{
int i;
Trap *p;
trap = 0;
intrsig = 0;
fatal_trap = 0;
for (i = SIGNALS+1, p = sigtraps; --i >= 0; p++) {
p->set = 0;
if ((p->flags & TF_USER_SET) && (p->trap && p->trap[0]))
settrap(p, (char *) 0);
}
}
/* restore signals just before an exec(2) */
void
restoresigs(void)
{
int i;
Trap *p;
for (i = SIGNALS+1, p = sigtraps; --i >= 0; p++)
if (p->flags & (TF_EXEC_IGN|TF_EXEC_DFL))
setsig(p, (p->flags & TF_EXEC_IGN) ? SIG_IGN : SIG_DFL,
SS_RESTORE_CURR|SS_FORCE);
}
void
settrap(Trap *p, char *s)
{
handler_t f;
if (p->trap)
afree(p->trap, APERM);
p->trap = str_save(s, APERM); /* handles s == 0 */
p->flags |= TF_CHANGED;
f = !s ? SIG_DFL : s[0] ? trapsig : SIG_IGN;
p->flags |= TF_USER_SET;
if ((p->flags & (TF_DFL_INTR|TF_FATAL)) && f == SIG_DFL)
f = trapsig;
else if (p->flags & TF_SHELL_USES) {
if (!(p->flags & TF_ORIG_IGN) || Flag(FTALKING)) {
/* do what user wants at exec time */
p->flags &= ~(TF_EXEC_IGN|TF_EXEC_DFL);
if (f == SIG_IGN)
p->flags |= TF_EXEC_IGN;
else
p->flags |= TF_EXEC_DFL;
}
/* assumes handler already set to what shell wants it
* (normally trapsig, but could be j_sigchld() or SIG_IGN)
*/
return;
}
/* todo: should we let user know signal is ignored? how? */
setsig(p, f, SS_RESTORE_CURR|SS_USER);
}
/* Called by c_print() when writing to a co-process to ensure SIGPIPE won't
* kill shell (unless user catches it and exits)
*/
int
block_pipe(void)
{
int restore_dfl = 0;
Trap *p = &sigtraps[SIGPIPE];
if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL))) {
setsig(p, SIG_IGN, SS_RESTORE_CURR);
if (p->flags & TF_ORIG_DFL)
restore_dfl = 1;
} else if (p->cursig == SIG_DFL) {
setsig(p, SIG_IGN, SS_RESTORE_CURR);
restore_dfl = 1; /* restore to SIG_DFL */
}
return restore_dfl;
}
/* Called by c_print() to undo whatever block_pipe() did */
void
restore_pipe(int restore_dfl)
{
if (restore_dfl)
setsig(&sigtraps[SIGPIPE], SIG_DFL, SS_RESTORE_CURR);
}
/* Set action for a signal. Action may not be set if original
* action was SIG_IGN, depending on the value of flags and
* FTALKING.
*/
int
setsig(Trap *p, handler_t f, int flags)
{
struct sigaction sigact;
if (p->signal == SIGEXIT_ || p->signal == SIGERR_)
return 1;
/* First time setting this signal? If so, get and note the current
* setting.
*/
if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL))) {
sigaction(p->signal, &Sigact_ign, &sigact);
p->flags |= sigact.sa_handler == SIG_IGN ?
TF_ORIG_IGN : TF_ORIG_DFL;
p->cursig = SIG_IGN;
}
/* Generally, an ignored signal stays ignored, except if
* - the user of an interactive shell wants to change it
* - the shell wants for force a change
*/
if ((p->flags & TF_ORIG_IGN) && !(flags & SS_FORCE)
&& (!(flags & SS_USER) || !Flag(FTALKING)))
return 0;
setexecsig(p, flags & SS_RESTORE_MASK);
/* This is here 'cause there should be a way of clearing shtraps, but
* don't know if this is a sane way of doing it. At the moment,
* all users of shtrap are lifetime users (SIGCHLD, SIGALRM, SIGWINCH).
*/
if (!(flags & SS_USER))
p->shtrap = (handler_t) 0;
if (flags & SS_SHTRAP) {
p->shtrap = f;
f = trapsig;
}
if (p->cursig != f) {
p->cursig = f;
sigemptyset(&sigact.sa_mask);
sigact.sa_flags = KSH_SA_FLAGS;
sigact.sa_handler = f;
sigaction(p->signal, &sigact, (struct sigaction *) 0);
}
return 1;
}
/* control what signal is set to before an exec() */
void
setexecsig(Trap *p, int restore)
{
/* XXX debugging */
if (!(p->flags & (TF_ORIG_IGN|TF_ORIG_DFL)))
internal_errorf(1, "setexecsig: unset signal %d(%s)",
p->signal, p->name);
/* restore original value for exec'd kids */
p->flags &= ~(TF_EXEC_IGN|TF_EXEC_DFL);
switch (restore & SS_RESTORE_MASK) {
case SS_RESTORE_CURR: /* leave things as they currently are */
break;
case SS_RESTORE_ORIG:
p->flags |= p->flags & TF_ORIG_IGN ? TF_EXEC_IGN : TF_EXEC_DFL;
break;
case SS_RESTORE_DFL:
p->flags |= TF_EXEC_DFL;
break;
case SS_RESTORE_IGN:
p->flags |= TF_EXEC_IGN;
break;
}
}