91836baf8
Denys Vlasenko
2009-09-23
Subject
hush: fix `trap`
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shell/hush.c +43 -1shell/hush_test/hush-trap/savetrap.right +3 -0shell/hush_test/hush-trap/savetrap.tests +6 -0
shell/hush.c+43 -1
| @@ -5180,6 +5180,47 @@ static FILE *generate_stream_from_string(const char *s) | |
| xmove_fd(channel[1], 1); | |
| /* Prevent it from trying to handle ctrl-z etc */ | |
| IF_HUSH_JOB(G.run_list_level = 1;) | |
| + | /* Awful hack for `trap` or $(trap). |
| + | * |
| + | * http://www.opengroup.org/onlinepubs/009695399/utilities/trap.html |
| + | * contains an example where "trap" is executed in a subshell: |
| + | * |
| + | * save_traps=$(trap) |
| + | * ... |
| + | * eval "$save_traps" |
| + | * |
| + | * Standard does not say that "trap" in subshell shall print |
| + | * parent shell's traps. It only says that its output |
| + | * must have suitable form, but then, in the above example |
| + | * (which is not supposed to be normative), it implies that. |
| + | * |
| + | * bash (and probably other shell) does implement it |
| + | * (traps are reset to defaults, but "trap" still shows them), |
| + | * but as a result, "trap" logic is hopelessly messed up: |
| + | * |
| + | * # trap |
| + | * trap -- 'echo Ho' SIGWINCH <--- we have a handler |
| + | * # (trap) <--- trap is in subshell - no output (correct, traps are reset) |
| + | * # true | trap <--- trap is in subshell - no output (ditto) |
| + | * # echo `true | trap` <--- in subshell - output (but traps are reset!) |
| + | * trap -- 'echo Ho' SIGWINCH |
| + | * # echo `(trap)` <--- in subshell in subshell - output |
| + | * trap -- 'echo Ho' SIGWINCH |
| + | * # echo `true | (trap)` <--- in subshell in subshell in subshell - output! |
| + | * trap -- 'echo Ho' SIGWINCH |
| + | * |
| + | * The rules when to forget and when to not forget traps |
| + | * get really complex and nonsensical. |
| + | * |
| + | * Our solution: ONLY bare $(trap) or `trap` is special. |
| + | */ |
| + | s = skip_whitespace(s); |
| + | if (strncmp(s, "trap", 4) == 0 && (*skip_whitespace(s + 4) == '\0')) |
| + | { |
| + | static const char *const argv[] = { NULL, NULL }; |
| + | builtin_trap((char**)argv); |
| + | exit(0); /* not _exit() - we need to fflush */ |
| + | } |
| #if BB_MMU | |
| reset_traps_to_defaults(); | |
| parse_and_run_string(s); | |
| @@ -7057,7 +7098,8 @@ static int FAST_FUNC builtin_trap(char **argv) | |
| if (G.traps[i]) { | |
| printf("trap -- "); | |
| print_escaped(G.traps[i]); | |
| - | printf(" %s\n", get_signame(i)); |
| + | /* bash compat: it says SIGxxx, not just xxx */ |
| + | printf(" SIG%s\n", get_signame(i)); |
| } | |
| } | |
| /*fflush(stdout); - done after each builtin anyway */ | |
shell/hush_test/hush-trap/savetrap.right+3 -0
| @@ -0,0 +1,3 @@ | |
| + | trap -- 'echo WINCH!' SIGWINCH |
| + | trap -- 'echo WINCH!' SIGWINCH |
| + | Done |
shell/hush_test/hush-trap/savetrap.tests+6 -0
| @@ -0,0 +1,6 @@ | |
| + | trap 'echo WINCH!' SIGWINCH |
| + | v=` trap ` |
| + | echo $v |
| + | v=`trap` |
| + | echo $v |
| + | echo Done |