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Diffstat (limited to 'builtins/trap.def')
| -rw-r--r-- | builtins/trap.def | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/builtins/trap.def b/builtins/trap.def new file mode 100644 index 0000000..0984698 --- /dev/null +++ b/builtins/trap.def @@ -0,0 +1,306 @@ +This file is trap.def, from which is created trap.c. +It implements the builtin "trap" in Bash. + +Copyright (C) 1987-2015 Free Software Foundation, Inc. + +This file is part of GNU Bash, the Bourne Again SHell. + +Bash is free software: you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation, either version 3 of the License, or +(at your option) any later version. + +Bash is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with Bash. If not, see <http://www.gnu.org/licenses/>. + +$PRODUCES trap.c + +$BUILTIN trap +$FUNCTION trap_builtin +$SHORT_DOC trap [-lp] [[arg] signal_spec ...] +Trap signals and other events. + +Defines and activates handlers to be run when the shell receives signals +or other conditions. + +ARG is a command to be read and executed when the shell receives the +signal(s) SIGNAL_SPEC. If ARG is absent (and a single SIGNAL_SPEC +is supplied) or `-', each specified signal is reset to its original +value. If ARG is the null string each SIGNAL_SPEC is ignored by the +shell and by the commands it invokes. + +If a SIGNAL_SPEC is EXIT (0) ARG is executed on exit from the shell. If +a SIGNAL_SPEC is DEBUG, ARG is executed before every simple command. If +a SIGNAL_SPEC is RETURN, ARG is executed each time a shell function or a +script run by the . or source builtins finishes executing. A SIGNAL_SPEC +of ERR means to execute ARG each time a command's failure would cause the +shell to exit when the -e option is enabled. + +If no arguments are supplied, trap prints the list of commands associated +with each signal. + +Options: + -l print a list of signal names and their corresponding numbers + -p display the trap commands associated with each SIGNAL_SPEC + +Each SIGNAL_SPEC is either a signal name in <signal.h> or a signal number. +Signal names are case insensitive and the SIG prefix is optional. A +signal may be sent to the shell with "kill -signal $$". + +Exit Status: +Returns success unless a SIGSPEC is invalid or an invalid option is given. +$END + +#include <config.h> + +#if defined (HAVE_UNISTD_H) +# ifdef _MINIX +# include <sys/types.h> +# endif +# include <unistd.h> +#endif + +#include "../bashtypes.h" +#include <signal.h> +#include <stdio.h> +#include "../bashansi.h" + +#include "../shell.h" +#include "../trap.h" +#include "common.h" +#include "bashgetopt.h" + +static void showtrap __P((int)); +static int display_traps __P((WORD_LIST *)); + +/* The trap command: + + trap <arg> <signal ...> + trap <signal ...> + trap -l + trap -p [sigspec ...] + trap [--] + + Set things up so that ARG is executed when SIGNAL(s) N is received. + If ARG is the empty string, then ignore the SIGNAL(s). If there is + no ARG, then set the trap for SIGNAL(s) to its original value. Just + plain "trap" means to print out the list of commands associated with + each signal number. Single arg of "-l" means list the signal names. */ + +/* Possible operations to perform on the list of signals.*/ +#define SET 0 /* Set this signal to first_arg. */ +#define REVERT 1 /* Revert to this signals original value. */ +#define IGNORE 2 /* Ignore this signal. */ + +int +trap_builtin (list) + WORD_LIST *list; +{ + int list_signal_names, display, result, opt; + + list_signal_names = display = 0; + result = EXECUTION_SUCCESS; + + reset_internal_getopt (); + while ((opt = internal_getopt (list, "lp")) != -1) + { + switch (opt) + { + case 'l': + list_signal_names++; + break; + case 'p': + display++; + break; + CASE_HELPOPT; + default: + builtin_usage (); + return (EX_USAGE); + } + } + list = loptend; + + opt = DSIG_NOCASE|DSIG_SIGPREFIX; /* flags for decode_signal */ + + if (list_signal_names) + return (sh_chkwrite (display_signal_list ((WORD_LIST *)NULL, 1))); + else if (display || list == 0) + { + initialize_terminating_signals (); + get_all_original_signals (); + return (sh_chkwrite (display_traps (list))); + } + else + { + char *first_arg; + int operation, sig, first_signal; + + operation = SET; + first_arg = list->word->word; + first_signal = first_arg && *first_arg && all_digits (first_arg) && signal_object_p (first_arg, opt); + + /* Backwards compatibility. XXX - question about whether or not we + should throw an error if an all-digit argument doesn't correspond + to a valid signal number (e.g., if it's `50' on a system with only + 32 signals). */ + if (first_signal) + operation = REVERT; + /* When in posix mode, the historical behavior of looking for a + missing first argument is disabled. To revert to the original + signal handling disposition, use `-' as the first argument. */ + else if (posixly_correct == 0 && first_arg && *first_arg && + (*first_arg != '-' || first_arg[1]) && + signal_object_p (first_arg, opt) && list->next == 0) + operation = REVERT; + else + { + list = list->next; + if (list == 0) + { + builtin_usage (); + return (EX_USAGE); + } + else if (*first_arg == '\0') + operation = IGNORE; + else if (first_arg[0] == '-' && !first_arg[1]) + operation = REVERT; + } + + /* If we're in a command substitution, we haven't freed the trap strings + (though we reset the signal handlers). If we're setting a trap to + handle a signal here, free the rest of the trap strings since they + don't apply any more. */ + if (subshell_environment & SUBSHELL_RESETTRAP) + { + free_trap_strings (); + subshell_environment &= ~SUBSHELL_RESETTRAP; + } + + while (list) + { + sig = decode_signal (list->word->word, opt); + + if (sig == NO_SIG) + { + sh_invalidsig (list->word->word); + result = EXECUTION_FAILURE; + } + else + { + switch (operation) + { + case SET: + set_signal (sig, first_arg); + break; + + case REVERT: + restore_default_signal (sig); + + /* Signals that the shell treats specially need special + handling. */ + switch (sig) + { + case SIGINT: + /* XXX - should we do this if original disposition + was SIG_IGN? */ + if (interactive) + set_signal_handler (SIGINT, sigint_sighandler); + /* special cases for interactive == 0 */ + else if (interactive_shell && (sourcelevel||running_trap)) + set_signal_handler (SIGINT, sigint_sighandler); + else + set_signal_handler (SIGINT, termsig_sighandler); + break; + + case SIGQUIT: + /* Always ignore SIGQUIT. */ + set_signal_handler (SIGQUIT, SIG_IGN); + break; + case SIGTERM: +#if defined (JOB_CONTROL) + case SIGTTIN: + case SIGTTOU: + case SIGTSTP: +#endif /* JOB_CONTROL */ + if (interactive) + set_signal_handler (sig, SIG_IGN); + break; + } + break; + + case IGNORE: + ignore_signal (sig); + break; + } + } + list = list->next; + } + } + + return (result); +} + +static void +showtrap (i) + int i; +{ + char *t, *p, *sn; + + p = trap_list[i]; + if (p == (char *)DEFAULT_SIG && signal_is_hard_ignored (i) == 0) + return; + else if (signal_is_hard_ignored (i)) + t = (char *)NULL; + else + t = (p == (char *)IGNORE_SIG) ? (char *)NULL : sh_single_quote (p); + + sn = signal_name (i); + /* Make sure that signals whose names are unknown (for whatever reason) + are printed as signal numbers. */ + if (STREQN (sn, "SIGJUNK", 7) || STREQN (sn, "unknown", 7)) + printf ("trap -- %s %d\n", t ? t : "''", i); + else if (posixly_correct) + { + if (STREQN (sn, "SIG", 3)) + printf ("trap -- %s %s\n", t ? t : "''", sn+3); + else + printf ("trap -- %s %s\n", t ? t : "''", sn); + } + else + printf ("trap -- %s %s\n", t ? t : "''", sn); + + FREE (t); +} + +static int +display_traps (list) + WORD_LIST *list; +{ + int result, i; + + if (list == 0) + { + for (i = 0; i < BASH_NSIG; i++) + showtrap (i); + return (EXECUTION_SUCCESS); + } + + for (result = EXECUTION_SUCCESS; list; list = list->next) + { + i = decode_signal (list->word->word, DSIG_NOCASE|DSIG_SIGPREFIX); + if (i == NO_SIG) + { + sh_invalidsig (list->word->word); + result = EXECUTION_FAILURE; + } + else + showtrap (i); + } + + return (result); +} |