67f718640
Denys Vlasenko
2009-09-25
Subject
hush: do not reset to default "" traps in subshell
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shell/hush.c +23 -18shell/hush_test/hush-trap/subshell.right +6 -0shell/hush_test/hush-trap/subshell.tests +20 -0
shell/hush.c+23 -18
| @@ -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) |
| - | sigdelset(&G.blocked_set, sig); |
| + | 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); | |
shell/hush_test/hush-trap/subshell.right+6 -0
| @@ -0,0 +1,6 @@ | |
| + | Ok |
| + | Ok |
| + | Ok |
| + | Ok |
| + | TERM |
| + | Done |
shell/hush_test/hush-trap/subshell.tests+20 -0
| @@ -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 |