hush: do not reset sighaldlers after fork - instead, prevent them from doing any harm
if they will be called. saves many sigaction calls on every fork. function old new delta hush_main 887 971 +84 sigexit 54 65 +11 run_list 2006 2001 -5 maybe_set_sighandler 76 50 -26 set_fatal_sighandler 186 - -186 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 2/2 up/down: 95/-217) Total: -122 bytes
This commit is contained in:
Denis Vlasenko
parent
d5762932fb
commit
abedaac842
219
shell/hush.c
219
shell/hush.c
@ -493,8 +493,6 @@ struct globals {
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char **traps; /* char *traps[NSIG] */
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/* which signals have non-DFL handler (even with no traps set)? */
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unsigned non_DFL_mask;
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/* which signals are known to be IGNed on entry to shell? */
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unsigned IGN_mask;
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sigset_t blocked_set;
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sigset_t inherited_set;
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};
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@ -895,128 +893,8 @@ static void check_and_run_traps(void)
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}
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}
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/* The stuff below needs to be migrated to "Special action" above */
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/////* Signals are grouped, we handle them in batches */
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////static void set_misc_sighandler(void (*handler)(int))
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////{
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//// bb_signals(0
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//// + (1 << SIGINT)
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//// + (1 << SIGQUIT)
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//// + (1 << SIGTERM)
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//// , handler);
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////}
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#if ENABLE_HUSH_JOB
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/* helper */
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static unsigned maybe_set_sighandler(int sig, void (*handler)(int))
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{
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/* non_DFL_mask'ed signals are, well, masked,
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* no need to set handler for them.
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* IGN_mask'ed signals were found to be IGN on entry,
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* do not change that -> no need to set handler for them either
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*/
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unsigned ign = ((G.IGN_mask|G.non_DFL_mask) >> sig) & 1;
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if (!ign) {
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handler = signal(sig, handler);
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ign = (handler == SIG_IGN);
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if (ign) /* restore back to IGN! */
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signal(sig, handler);
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}
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return ign << sig; /* pass back knowledge about SIG_IGN */
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}
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/* Used only to set handler to restore pgrp on exit, and to reset it to DFL */
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static void set_fatal_sighandler(void (*handler)(int))
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{
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unsigned mask = 0;
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if (HUSH_DEBUG) {
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mask |= maybe_set_sighandler(SIGILL , handler);
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mask |= maybe_set_sighandler(SIGFPE , handler);
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mask |= maybe_set_sighandler(SIGBUS , handler);
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mask |= maybe_set_sighandler(SIGSEGV, handler);
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mask |= maybe_set_sighandler(SIGTRAP, handler);
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} /* else: hush is perfect. what SEGV? */
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mask |= maybe_set_sighandler(SIGABRT, handler);
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/* bash 3.2 seems to handle these just like 'fatal' ones */
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mask |= maybe_set_sighandler(SIGPIPE, handler);
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mask |= maybe_set_sighandler(SIGALRM, handler);
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mask |= maybe_set_sighandler(SIGHUP , handler);
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/* if we aren't interactive... but in this case
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* we never want to restore pgrp on exit, and this fn is not called */
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/*mask |= maybe_set_sighandler(SIGTERM, handler); */
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/*mask |= maybe_set_sighandler(SIGINT , handler); */
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G.IGN_mask = mask;
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}
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/* Used only to suppress ^Z in `cmd` */
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static void IGN_jobctrl_signals(void)
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{
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bb_signals(0
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+ (1 << SIGTSTP)
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+ (1 << SIGTTIN)
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+ (1 << SIGTTOU)
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, SIG_IGN);
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}
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/* SIGCHLD is special and handled separately */
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////static void set_every_sighandler(void (*handler)(int))
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////{
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//// set_fatal_sighandler(handler);
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//// set_jobctrl_sighandler(handler);
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//// set_misc_sighandler(handler);
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//// signal(SIGCHLD, handler);
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////}
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////static void handler_ctrl_c(int sig UNUSED_PARAM)
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////{
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//// debug_printf_jobs("got sig %d\n", sig);
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////// as usual we can have all kinds of nasty problems with leaked malloc data here
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//// siglongjmp(G.toplevel_jb, 1);
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////}
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////static void handler_ctrl_z(int sig UNUSED_PARAM)
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////{
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//// pid_t pid;
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////
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//// debug_printf_jobs("got tty sig %d in pid %d\n", sig, getpid());
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////
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//// if (!BB_MMU) {
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//// fputs("Sorry, backgrounding (CTRL+Z) of foreground scripts not supported on nommu\n", stderr);
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//// return;
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//// }
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////
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//// pid = fork();
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//// if (pid < 0) /* can't fork. Pretend there was no ctrl-Z */
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//// return;
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//// G.ctrl_z_flag = 1;
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//// if (!pid) { /* child */
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//// if (ENABLE_HUSH_JOB)
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//// die_sleep = 0; /* let nofork's xfuncs die */
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//// bb_setpgrp();
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//// debug_printf_jobs("set pgrp for child %d ok\n", getpid());
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//////// set_every_sighandler(SIG_DFL);
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//// raise(SIGTSTP); /* resend TSTP so that child will be stopped */
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//// debug_printf_jobs("returning in child\n");
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//// /* return to nofork, it will eventually exit now,
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//// * not return back to shell */
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//// return;
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//// }
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//// /* parent */
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//// /* finish filling up pipe info */
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//// G.toplevel_list->pgrp = pid; /* child is in its own pgrp */
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//// G.toplevel_list->cmds[0].pid = pid;
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//// /* parent needs to longjmp out of running nofork.
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//// * we will "return" exitcode 0, with child put in background */
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////// as usual we can have all kinds of nasty problems with leaked malloc data here
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//// debug_printf_jobs("siglongjmp in parent\n");
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//// siglongjmp(G.toplevel_jb, 1);
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////}
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/* Restores tty foreground process group, and exits.
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* May be called as signal handler for fatal signal
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* (will faithfully resend signal to itself, producing correct exit state)
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@ -1029,7 +907,9 @@ static void sigexit(int sig)
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sigprocmask_allsigs(SIG_BLOCK);
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#if ENABLE_HUSH_INTERACTIVE
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if (G.interactive_fd)
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/* Careful: we can end up here after [v]fork. Do not restore
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* tty pgrp, only top-level shell process does that */
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if (G.interactive_fd && getpid() == G.root_pid)
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tcsetpgrp(G.interactive_fd, G.saved_tty_pgrp);
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#endif
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@ -1040,10 +920,56 @@ static void sigexit(int sig)
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kill_myself_with_sig(sig); /* does not return */
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}
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/* helper */
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static void maybe_set_sighandler(int sig)
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{
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void (*handler)(int);
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/* non_DFL_mask'ed signals are, well, masked,
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* no need to set handler for them.
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*/
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if (!((G.non_DFL_mask >> sig) & 1)) {
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handler = signal(sig, sigexit);
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if (handler == SIG_IGN) /* restore back to IGN! */
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signal(sig, handler);
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}
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}
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/* Used only to set handler to restore pgrp on exit, and to reset it to DFL */
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static void set_fatal_signals_to_sigexit(void)
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{
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if (HUSH_DEBUG) {
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maybe_set_sighandler(SIGILL );
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maybe_set_sighandler(SIGFPE );
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maybe_set_sighandler(SIGBUS );
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maybe_set_sighandler(SIGSEGV);
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maybe_set_sighandler(SIGTRAP);
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} /* else: hush is perfect. what SEGV? */
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maybe_set_sighandler(SIGABRT);
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/* bash 3.2 seems to handle these just like 'fatal' ones */
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maybe_set_sighandler(SIGPIPE);
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maybe_set_sighandler(SIGALRM);
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maybe_set_sighandler(SIGHUP );
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/* if we aren't interactive... but in this case
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* we never want to restore pgrp on exit, and this fn is not called */
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/*maybe_set_sighandler(SIGTERM);*/
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/*maybe_set_sighandler(SIGINT );*/
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}
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/* Used only to suppress ^Z in `cmd` */
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static void set_jobctrl_signals_to_IGN(void)
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{
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bb_signals(0
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+ (1 << SIGTSTP)
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+ (1 << SIGTTIN)
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+ (1 << SIGTTOU)
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, SIG_IGN);
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}
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#else /* !JOB */
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#define set_fatal_sighandler(handler) ((void)0)
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#define IGN_jobctrl_signals(handler) ((void)0)
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#define set_fatal_signals_to_sigexit(handler) ((void)0)
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#define set_jobctrl_signals_to_IGN(handler) ((void)0)
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#endif /* JOB */
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@ -1057,11 +983,12 @@ static void hush_exit(int exitcode)
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free(argv[1]);
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}
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if (ENABLE_HUSH_JOB) {
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fflush(NULL); /* flush all streams */
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sigexit(- (exitcode & 0xff));
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} else
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exit(exitcode);
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#if ENABLE_HUSH_JOB
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fflush(NULL); /* flush all streams */
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sigexit(- (exitcode & 0xff));
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#else
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exit(exitcode);
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#endif
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}
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@ -2641,10 +2568,6 @@ static int run_pipe(struct pipe *pi)
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* might include `cmd` runs! Do not rerun it! We *must*
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* use argv_expanded if it's non-NULL */
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/* Disable job control signals for shell (parent) and
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* for initial child code after fork */
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//// set_jobctrl_sighandler(SIG_IGN);
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/* Going to fork a child per each pipe member */
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pi->alive_cmds = 0;
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nextin = 0;
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@ -2677,8 +2600,6 @@ static int run_pipe(struct pipe *pi)
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* with pgid == pid_of_first_child_in_pipe */
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if (G.run_list_level == 1 && G.interactive_fd) {
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pid_t pgrp;
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/* Don't do pgrp restore anymore on fatal signals */
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set_fatal_sighandler(SIG_DFL);
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pgrp = pi->pgrp;
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if (pgrp < 0) /* true for 1st process only */
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pgrp = getpid();
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@ -2698,9 +2619,8 @@ static int run_pipe(struct pipe *pi)
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setup_redirects(command, NULL);
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/* Restore default handlers just prior to exec */
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//// set_jobctrl_sighandler(SIG_DFL);
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//// set_misc_sighandler(SIG_DFL);
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//// signal(SIGCHLD, SIG_DFL);
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/*signal(SIGCHLD, SIG_DFL); - so far we don't have any handlers */
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/* Stores to nommu_save list of env vars putenv'ed
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* (NOMMU, on MMU we don't need that) */
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/* cast away volatility... */
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@ -2877,7 +2797,7 @@ static int run_list(struct pipe *pi)
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* in order to return, no direct "return" statements please.
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* This helps to ensure that no memory is leaked. */
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//TODO: needs re-thinking
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////TODO: ctrl-Z handling needs re-thinking and re-testing
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#if ENABLE_HUSH_JOB
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/* Example of nested list: "while true; do { sleep 1 | exit 2; } done".
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@ -3674,12 +3594,11 @@ static FILE *generate_stream_from_list(struct pipe *head)
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#endif
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/* Process substitution is not considered to be usual
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* 'command execution'.
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* SUSv3 says ctrl-Z should be ignored, ctrl-C should not. */
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//// /* Not needed, we are relying on it being disabled
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//// * everywhere outside actual command execution. */
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IGN_jobctrl_signals();
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//// set_misc_sighandler(SIG_DFL);
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/* Freeing 'head' here would break NOMMU. */
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* SUSv3 says ctrl-Z should be ignored, ctrl-C should not.
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*/
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set_jobctrl_signals_to_IGN();
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/* Note: freeing 'head' here would break NOMMU. */
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_exit(run_list(head));
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}
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close(channel[1]);
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@ -4493,13 +4412,8 @@ static void setup_job_control(void)
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shell_pgrp = getpgrp();
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}
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/* Ignore job-control and misc signals. */
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//// set_jobctrl_sighandler(SIG_IGN);
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//// set_misc_sighandler(SIG_IGN);
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//huh? signal(SIGCHLD, SIG_IGN);
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/* We _must_ restore tty pgrp on fatal signals */
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set_fatal_sighandler(sigexit);
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set_fatal_signals_to_sigexit();
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/* Put ourselves in our own process group. */
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bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
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@ -4682,7 +4596,6 @@ int hush_main(int argc, char **argv)
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}
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if (G.interactive_fd) {
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fcntl(G.interactive_fd, F_SETFD, FD_CLOEXEC);
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//// set_misc_sighandler(SIG_IGN);
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}
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}
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init_signal_mask();
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