hush: implement proper SIGHUP handling
function old new delta check_and_run_traps 164 229 +65 insert_bg_job 376 366 -10 hush_main 937 927 -10
This commit is contained in:
Denis Vlasenko
parent
7b9e5c57ae
commit
6b9e05392b
199
shell/hush.c
199
shell/hush.c
@ -52,11 +52,10 @@
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* grep for "TODO" and fix (some of them are easy)
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* change { and } from special chars to reserved words
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* $var refs in function do not pick up values set by "var=val func"
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* builtins: return, ulimit
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* builtins: ulimit
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* follow IFS rules more precisely, including update semantics
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* figure out what to do with backslash-newline
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* continuation lines, both explicit and implicit - done?
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* SIGHUP handling
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* separate job control from interactiveness
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* (testcase: booting with init=/bin/hush does not show prompt (2009-04))
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*
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@ -1070,8 +1069,9 @@ static void restore_G_args(save_arg_t *sv, char **argv)
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* "trap 'cmd' SIGxxx":
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* set bit in blocked_set (even if 'cmd' is '')
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* after [v]fork, if we plan to be a shell:
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* nothing for {} child shell (say, "true | { true; true; } | true")
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* unset all traps if () shell.
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* unblock signals with special interactive handling
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* (child shell is not interactive),
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* unset all traps (note: regardless of child shell's type - {}, (), etc)
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* after [v]fork, if we plan to exec:
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* POSIX says pending signal mask is cleared in child - no need to clear it.
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* Restore blocked signal set to one inherited by shell just prior to exec.
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@ -1084,9 +1084,9 @@ enum {
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SPECIAL_INTERACTIVE_SIGS = 0
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#if ENABLE_HUSH_JOB
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| (1 << SIGTTIN) | (1 << SIGTTOU) | (1 << SIGTSTP)
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| (1 << SIGHUP)
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#endif
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| (1 << SIGTERM)
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//TODO | (1 << SIGHUP)
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| (1 << SIGINT)
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};
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@ -1095,53 +1095,6 @@ enum {
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// G.count_SIGCHLD++;
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//}
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static int check_and_run_traps(int sig)
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{
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static const struct timespec zero_timespec = { 0, 0 };
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smalluint save_rcode;
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int last_sig = 0;
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if (sig)
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goto jump_in;
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while (1) {
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sig = sigtimedwait(&G.blocked_set, NULL, &zero_timespec);
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if (sig <= 0)
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break;
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jump_in:
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last_sig = sig;
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if (G.traps && G.traps[sig]) {
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if (G.traps[sig][0]) {
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/* We have user-defined handler */
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char *argv[] = { NULL, xstrdup(G.traps[sig]), NULL };
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save_rcode = G.last_exitcode;
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builtin_eval(argv);
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free(argv[1]);
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G.last_exitcode = save_rcode;
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} /* else: "" trap, ignoring signal */
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continue;
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}
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/* not a trap: special action */
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switch (sig) {
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// case SIGCHLD:
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// G.count_SIGCHLD++;
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// break;
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case SIGINT:
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//TODO: add putchar('\n') also when we detect that child was killed (sleep 5 + ^C)
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/* Builtin was ^C'ed, make it look prettier: */
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bb_putchar('\n');
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G.flag_SIGINT = 1;
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break;
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//TODO
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// case SIGHUP: ...
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// break;
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default: /* ignored: */
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/* SIGTERM, SIGQUIT, SIGTTIN, SIGTTOU, SIGTSTP */
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break;
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}
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}
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return last_sig;
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}
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#if ENABLE_HUSH_JOB
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/* After [v]fork, in child: do not restore tty pgrp on xfunc death */
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@ -1151,7 +1104,7 @@ static int check_and_run_traps(int sig)
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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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* (will resend signal to itself, producing correct exit state)
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* or called directly with -EXITCODE.
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* We also call it if xfunc is exiting. */
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static void sigexit(int sig) NORETURN;
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@ -1201,6 +1154,65 @@ static void hush_exit(int exitcode)
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#endif
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}
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static int check_and_run_traps(int sig)
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{
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static const struct timespec zero_timespec = { 0, 0 };
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smalluint save_rcode;
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int last_sig = 0;
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if (sig)
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goto jump_in;
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while (1) {
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sig = sigtimedwait(&G.blocked_set, NULL, &zero_timespec);
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if (sig <= 0)
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break;
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jump_in:
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last_sig = sig;
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if (G.traps && G.traps[sig]) {
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if (G.traps[sig][0]) {
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/* We have user-defined handler */
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char *argv[] = { NULL, xstrdup(G.traps[sig]), NULL };
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save_rcode = G.last_exitcode;
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builtin_eval(argv);
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free(argv[1]);
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G.last_exitcode = save_rcode;
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} /* else: "" trap, ignoring signal */
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continue;
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}
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/* not a trap: special action */
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switch (sig) {
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// case SIGCHLD:
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// G.count_SIGCHLD++;
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// break;
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case SIGINT:
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//TODO: add putchar('\n') also when we detect that child was killed (sleep 5 + ^C)
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/* Builtin was ^C'ed, make it look prettier: */
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bb_putchar('\n');
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G.flag_SIGINT = 1;
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break;
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#if ENABLE_HUSH_JOB
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case SIGHUP: {
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struct pipe *job;
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/* bash is observed to signal whole process groups,
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* not individual processes */
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for (job = G.job_list; job; job = job->next) {
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if (job->pgrp <= 0)
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continue;
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debug_printf_exec("HUPing pgrp %d\n", job->pgrp);
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if (kill(- job->pgrp, SIGHUP) == 0)
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kill(- job->pgrp, SIGCONT);
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}
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sigexit(SIGHUP);
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}
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#endif
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default: /* ignored: */
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/* SIGTERM, SIGQUIT, SIGTTIN, SIGTTOU, SIGTSTP */
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break;
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}
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}
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return last_sig;
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}
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static const char *set_cwd(void)
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{
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@ -2061,7 +2073,9 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
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case '`': /* <SPECIAL_VAR_SYMBOL>`cmd<SPECIAL_VAR_SYMBOL> */
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*p = '\0';
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arg++;
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//TODO: can we just stuff it into "output" directly?
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/* Can't just stuff it into output o_string,
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* expanded result may need to be globbed
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* and $IFS-splitted */
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debug_printf_subst("SUBST '%s' first_ch %x\n", arg, first_ch);
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process_command_subs(&subst_result, arg);
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debug_printf_subst("SUBST RES '%s'\n", subst_result.data);
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@ -2777,7 +2791,8 @@ static const struct function *find_function(const char *name)
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}
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funcp = funcp->next;
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}
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debug_printf_exec("found function '%s'\n", name);
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if (funcp)
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debug_printf_exec("found function '%s'\n", name);
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return funcp;
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}
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@ -2819,7 +2834,7 @@ static struct function *new_function(char *name)
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}
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goto skip;
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}
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debug_printf_exec("remembering new function '%s'\n", command->argv[0]);
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debug_printf_exec("remembering new function '%s'\n", name);
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funcp = *funcpp = xzalloc(sizeof(*funcp));
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/*funcp->next = NULL;*/
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skip:
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@ -3059,8 +3074,11 @@ static const char *get_cmdtext(struct pipe *pi)
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}
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len = 0;
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do len += strlen(*argv) + 1; while (*++argv);
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pi->cmdtext = p = xmalloc(len);
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do {
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len += strlen(*argv) + 1;
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} while (*++argv);
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p = xmalloc(len);
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pi->cmdtext = p;// = xmalloc(len);
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argv = pi->cmds[0].argv;
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do {
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len = strlen(*argv);
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@ -3074,44 +3092,36 @@ static const char *get_cmdtext(struct pipe *pi)
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static void insert_bg_job(struct pipe *pi)
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{
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struct pipe *thejob;
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struct pipe *job, **jobp;
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int i;
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/* Linear search for the ID of the job to use */
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pi->jobid = 1;
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for (thejob = G.job_list; thejob; thejob = thejob->next)
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if (thejob->jobid >= pi->jobid)
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pi->jobid = thejob->jobid + 1;
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for (job = G.job_list; job; job = job->next)
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if (job->jobid >= pi->jobid)
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pi->jobid = job->jobid + 1;
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/* Add thejob to the list of running jobs */
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if (!G.job_list) {
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thejob = G.job_list = xmalloc(sizeof(*thejob));
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} else {
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for (thejob = G.job_list; thejob->next; thejob = thejob->next)
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continue;
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thejob->next = xmalloc(sizeof(*thejob));
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thejob = thejob->next;
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}
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/* Add job to the list of running jobs */
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jobp = &G.job_list;
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while ((job = *jobp) != NULL)
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jobp = &job->next;
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job = *jobp = xmalloc(sizeof(*job));
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/* Physically copy the struct job */
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memcpy(thejob, pi, sizeof(struct pipe));
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thejob->cmds = xzalloc(sizeof(pi->cmds[0]) * pi->num_cmds);
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/* We cannot copy entire pi->cmds[] vector! Double free()s will happen */
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*job = *pi; /* physical copy */
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job->next = NULL;
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job->cmds = xzalloc(sizeof(pi->cmds[0]) * pi->num_cmds);
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/* Cannot copy entire pi->cmds[] vector! This causes double frees */
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for (i = 0; i < pi->num_cmds; i++) {
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// TODO: do we really need to have so many fields which are just dead weight
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// at execution stage?
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thejob->cmds[i].pid = pi->cmds[i].pid;
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job->cmds[i].pid = pi->cmds[i].pid;
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/* all other fields are not used and stay zero */
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}
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thejob->next = NULL;
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thejob->cmdtext = xstrdup(get_cmdtext(pi));
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job->cmdtext = xstrdup(get_cmdtext(pi));
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/* We don't wait for background thejobs to return -- append it
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to the list of backgrounded thejobs and leave it alone */
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if (G_interactive_fd)
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printf("[%d] %d %s\n", thejob->jobid, thejob->cmds[0].pid, thejob->cmdtext);
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G.last_bg_pid = thejob->cmds[0].pid;
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G.last_jobid = thejob->jobid;
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printf("[%d] %d %s\n", job->jobid, job->cmds[0].pid, job->cmdtext);
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/* Last command's pid goes to $! */
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G.last_bg_pid = job->cmds[job->num_cmds - 1].pid;
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G.last_jobid = job->jobid;
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}
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static void remove_bg_job(struct pipe *pi)
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@ -3306,7 +3316,7 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
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* cmd || ... { list } || ...
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* If it is, then we can run cmd as a builtin, NOFORK [do we do this?],
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* or (if SH_STANDALONE) an applet, and we can run the { list }
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* with run_list(). If it isn't one of these, we fork and exec cmd.
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* with run_list. If it isn't one of these, we fork and exec cmd.
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*
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* Cases when we must fork:
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* non-single: cmd | cmd
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@ -3942,7 +3952,11 @@ static int run_list(struct pipe *pi)
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check_and_run_traps(0);
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#if ENABLE_HUSH_JOB
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if (G.run_list_level == 1)
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{
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debug_printf_exec("insert_bg_job1\n");
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insert_bg_job(pi);
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debug_printf_exec("insert_bg_job2\n");
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}
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#endif
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G.last_exitcode = rcode = EXIT_SUCCESS;
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debug_printf_exec(": cmd&: exitcode EXIT_SUCCESS\n");
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@ -5853,11 +5867,10 @@ static void set_fatal_handlers(void)
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/* bash 3.2 seems to handle these just like 'fatal' ones */
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maybe_set_to_sigexit(SIGPIPE);
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maybe_set_to_sigexit(SIGALRM);
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//TODO: disable and move down when proper SIGHUP handling is added
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maybe_set_to_sigexit(SIGHUP );
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/* if we are interactive, [SIGHUP,] SIGTERM and SIGINT are masked.
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/* if we are interactive, SIGHUP, SIGTERM and SIGINT are masked.
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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_to_sigexit(SIGHUP );*/
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/*maybe_set_to_sigexit(SIGTERM);*/
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/*maybe_set_to_sigexit(SIGINT );*/
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}
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@ -6350,7 +6363,7 @@ static int builtin_exec(char **argv)
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#if !BB_MMU
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nommu_save_t dummy;
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#endif
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// TODO: if exec fails, bash does NOT exit! We do...
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/* TODO: if exec fails, bash does NOT exit! We do... */
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pseudo_exec_argv(&dummy, argv, 0, NULL);
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/* never returns */
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}
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@ -6472,8 +6485,8 @@ static int builtin_fg_bg(char **argv)
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bb_error_msg("%s: %d: no such job", argv[0], jobnum);
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return EXIT_FAILURE;
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found:
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// TODO: bash prints a string representation
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// of job being foregrounded (like "sleep 1 | cat")
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/* TODO: bash prints a string representation
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* of job being foregrounded (like "sleep 1 | cat") */
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if (argv[0][0] == 'f') {
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/* Put the job into the foreground. */
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tcsetpgrp(G_interactive_fd, pi->pgrp);
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@ -6705,7 +6718,7 @@ static int builtin_source(char **argv)
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if (*++argv == NULL)
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return EXIT_FAILURE;
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/* TODO: search through $PATH is missing */
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// TODO: search through $PATH is missing
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input = fopen_or_warn(*argv, "r");
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if (!input) {
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/* bb_perror_msg("%s", *argv); - done by fopen_or_warn */
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