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hush: do not reset to default "" traps in subshell

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function                                             old     new   delta
reset_traps_to_defaults                              164     211     +47
builtin_umask                                        123     121      -2

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2009-09-25 14:21:06 +02:00
parent 4ea0ca8193
commit 67f7186403
3 changed files with 49 additions and 18 deletions
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39
shell/hush.c
View File

@ -1112,13 +1112,10 @@ static void restore_G_args(save_arg_t *sv, char **argv)
* are to count SIGCHLDs
* and to restore tty pgrp on signal-induced exit.
*
* TODO compat:
* Note 2 (compat):
* Standard says "When a subshell is entered, traps that are not being ignored
* are set to the default actions". bash interprets it so that traps which
* are set to "" (ignore) are NOT reset to defaults. We reset them to default.
* bash example:
* # trap '' SYS; (bash -c 'kill -SYS $PPID'; echo YES)
* YES <-- subshell was not killed by SIGSYS
* are set to "" (ignore) are NOT reset to defaults. We do the same.
*/
enum {
SPECIAL_INTERACTIVE_SIGS = 0
@ -2605,43 +2602,51 @@ static void reset_traps_to_defaults(void)
{
/* This function is always called in a child shell
* after fork (not vfork, NOMMU doesn't use this function).
* Child shells are not interactive.
* SIGTTIN/SIGTTOU/SIGTSTP should not have special handling.
* Testcase: (while :; do :; done) + ^Z should background.
* Same goes for SIGTERM, SIGHUP, SIGINT.
*/
unsigned sig;
unsigned mask;
/* Child shells are not interactive.
* SIGTTIN/SIGTTOU/SIGTSTP should not have special handling.
* Testcase: (while :; do :; done) + ^Z should background.
* Same goes for SIGTERM, SIGHUP, SIGINT.
*/
if (!G.traps && !(G.non_DFL_mask & SPECIAL_INTERACTIVE_SIGS))
return;
return; /* already no traps and no SPECIAL_INTERACTIVE_SIGS */
/* Stupid. It can be done with *single* &= op, but we can't use
* the fact that G.blocked_set is implemented as a bitmask... */
/* Switching off SPECIAL_INTERACTIVE_SIGS.
* Stupid. It can be done with *single* &= op, but we can't use
* the fact that G.blocked_set is implemented as a bitmask
* in libc... */
mask = (SPECIAL_INTERACTIVE_SIGS >> 1);
sig = 1;
while (1) {
if (mask & 1)
if (mask & 1) {
/* Careful. Only if no trap or trap is not "" */
if (!G.traps || !G.traps[sig] || G.traps[sig][0])
sigdelset(&G.blocked_set, sig);
}
mask >>= 1;
if (!mask)
break;
sig++;
}
/* Our homegrown sig mask is saner to work with :) */
G.non_DFL_mask &= ~SPECIAL_INTERACTIVE_SIGS;
/* Resetting all traps to default except empty ones */
mask = G.non_DFL_mask;
if (G.traps) for (sig = 0; sig < NSIG; sig++, mask >>= 1) {
if (!G.traps[sig])
if (!G.traps[sig] || !G.traps[sig][0])
continue;
free(G.traps[sig]);
G.traps[sig] = NULL;
/* There is no signal for 0 (EXIT) */
if (sig == 0)
continue;
/* There was a trap handler, we are removing it.
/* There was a trap handler, we just removed it.
* But if sig still has non-DFL handling,
* we should not unblock it. */
* we should not unblock the sig. */
if (mask & 1)
continue;
sigdelset(&G.blocked_set, sig);

6
shell/hush_test/hush-trap/subshell.right Normal file
View File

@ -0,0 +1,6 @@
Ok
Ok
Ok
Ok
TERM
Done

20
shell/hush_test/hush-trap/subshell.tests Executable file
View File

@ -0,0 +1,20 @@
# Non-empty traps should be reset in subshell
# HUP is special in interactive shells
trap '' HUP
# QUIT is always special
trap '' QUIT
# SYS is not special
trap '' SYS
# WINCH is harmless
trap 'bad: caught WINCH' WINCH
# With TERM we'll check whether it is reset
trap 'bad: caught TERM' TERM
# using bash, becuase we don't have $PPID (yet)
(bash -c 'kill -HUP $PPID'; echo Ok)
(bash -c 'kill -QUIT $PPID'; echo Ok)
(bash -c 'kill -SYS $PPID'; echo Ok)
(bash -c 'kill -WINCH $PPID'; echo Ok)
(bash -c 'kill -TERM $PPID'; echo Bad: TERM is not reset)
echo Done