diff options
| -rw-r--r-- | extension/ChangeLog | 10 | ||||
| -rw-r--r-- | extension/select.c | 89 |
2 files changed, 84 insertions, 15 deletions
diff --git a/extension/ChangeLog b/extension/ChangeLog index 68ba6fe2..4bfc64d4 100644 --- a/extension/ChangeLog +++ b/extension/ChangeLog @@ -1,5 +1,15 @@ 2013-07-05 Andrew J. Schorr <aschorr@telemetry-investments.com> + * select.c (signal_result): New function to set result string from + signal function and detect when we need to roll back. + (do_signal): Now takes an optional 3rd override argument. Instead + of returning -1 or 0, we now return information about the previously + installed signal handler: default, ignore, trap, or unknown. An + empty string is returned on error. If it is an unknown handler, + and override is not non-zero, we roll back the handler and return "". + +2013-07-05 Andrew J. Schorr <aschorr@telemetry-investments.com> + * select.c (set_non_blocking): Do not attempt F_SETFL if F_GETFL fails. (do_set_non_blocking): Add support for case when called with a single "" argument. diff --git a/extension/select.c b/extension/select.c index 4d28457d..3bcef166 100644 --- a/extension/select.c +++ b/extension/select.c @@ -147,6 +147,25 @@ get_signal_number(awk_value_t signame) } } +static awk_value_t * +signal_result(awk_value_t *result, void (*func)(int)) +{ + awk_value_t override; + + if (func == SIG_DFL) + return make_const_string("default", 7, result); + if (func == SIG_IGN) + return make_const_string("ignore", 6, result); + if (func == signal_handler) + return make_const_string("trap", 4, result); + if (get_argument(2, AWK_NUMBER, & override) && override.num_value) + return make_const_string("unknown", 7, result); + /* need to roll it back! */ + update_ERRNO_string(_("select_signal: override not requested for unknown signal handler")); + make_null_string(result); + return NULL; +} + /* do_signal --- trap signals */ static awk_value_t * @@ -156,17 +175,17 @@ do_signal(int nargs, awk_value_t *result) int signum; void (*func)(int); - if (do_lint && nargs > 2) + if (do_lint && nargs > 3) lintwarn(ext_id, _("select_signal: called with too many arguments")); if (! get_argument(0, AWK_UNDEFINED, & signame)) { update_ERRNO_string(_("select_signal: missing required signal name argument")); - return make_number(-1, result); + return make_null_string(result); } if ((signum = get_signal_number(signame)) < 0) - return make_number(-1, result); + return make_null_string(result); if (! get_argument(1, AWK_STRING, & disposition)) { update_ERRNO_string(_("select_signal: missing required signal disposition argument")); - return make_number(-1, result); + return make_null_string(result); } if (strcasecmp(disposition.str_value.str, "default") == 0) func = SIG_DFL; @@ -176,29 +195,69 @@ do_signal(int nargs, awk_value_t *result) func = signal_handler; else { update_ERRNO_string(_("select_signal: invalid disposition argument")); - return make_number(-1, result); + return make_null_string(result); } + +#ifdef HAVE_SIGPROCMASK +/* Temporarily block this signal in case we need to roll back the handler! */ +#define PROTECT \ + sigset_t set, oldset; \ + sigemptyset(& set); \ + sigaddset(& set, signum); \ + sigprocmask(SIG_BLOCK, &set, &oldset); +#define RELEASE sigprocmask(SIG_SETMASK, &oldset, NULL); +#else +/* Brain-damaged platform, so we will have to live with the race condition. */ +#define PROTECT +#define RELEASE +#endif + #ifdef HAVE_SIGACTION { - int rc; - struct sigaction sa; + awk_value_t override; + struct sigaction sa, prev; sa.sa_handler = func; sigfillset(& sa.sa_mask); /* block all signals in handler */ sa.sa_flags = SA_RESTART; - if ((rc = sigaction(signum, &sa, NULL)) < 0) - update_ERRNO_int(errno); - return make_number(rc, result); + { + PROTECT + if (sigaction(signum, &sa, &prev) < 0) { + update_ERRNO_int(errno); + RELEASE + return make_null_string(result); + } + if (signal_result(result, prev.sa_handler)) { + RELEASE + return result; + } + /* roll it back! */ + sigaction(signum, &prev, NULL); + RELEASE + return result; + } } #else /* * Fall back to signal; this is available on all platforms. We can * only hope that it does the right thing. */ - if (signal(signum, func) == SIG_ERR) { - update_ERRNO_int(errno); - return make_number(-1, result); + { + void (*prev)(int); + PROTECT + if ((prev = signal(signum, func)) == SIG_ERR) { + update_ERRNO_int(errno); + RELEASE + return make_null_string(result); + } + if (signal_result(result, prev)) { + RELEASE + return result; + } + /* roll it back! */ + signal(signum, prev); + RELEASE + return result; } - return make_number(0, result); #endif } @@ -461,7 +520,7 @@ do_set_non_blocking(int nargs, awk_value_t *result) static awk_ext_func_t func_table[] = { { "select", do_select, 5 }, - { "select_signal", do_signal, 2 }, + { "select_signal", do_signal, 3 }, { "set_non_blocking", do_set_non_blocking, 2 }, { "kill", do_kill, 2 }, }; |