hush: better signal handling across ctrl-z
This commit is contained in:
Denis Vlasenko
parent
18e19f2b0d
commit
3ac0e00553
214
shell/hush.c
214
shell/hush.c
@ -193,7 +193,7 @@ struct pipe {
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int jobid; /* job number */
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int num_progs; /* total number of programs in job */
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int running_progs; /* number of programs running (not exited) */
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char *text; /* name of job */
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char *cmdtext; /* name of job */
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char *cmdbuf; /* buffer various argv's point into */
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pid_t pgrp; /* process group ID for the job */
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struct child_prog *progs; /* array of commands in pipe */
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@ -441,6 +441,42 @@ static void signal_SA_RESTART(int sig, void (*handler)(int))
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sigaction(sig, &sa, NULL);
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}
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/* Signals are grouped, we handle them in batches */
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static void set_fatal_sighandler(void (*handler)(int))
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{
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signal(SIGILL , handler);
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signal(SIGTRAP, handler);
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signal(SIGABRT, handler);
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signal(SIGFPE , handler);
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signal(SIGBUS , handler);
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signal(SIGSEGV, handler);
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/* bash 3.2 seems to handle these just like 'fatal' ones */
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signal(SIGHUP , handler);
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signal(SIGPIPE, handler);
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signal(SIGALRM, handler);
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}
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static void set_jobctrl_sighandler(void (*handler)(int))
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{
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signal(SIGTSTP, handler);
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signal(SIGTTIN, handler);
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signal(SIGTTOU, handler);
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}
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static void set_misc_sighandler(void (*handler)(int))
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{
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signal(SIGINT , handler);
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signal(SIGQUIT, handler);
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signal(SIGTERM, handler);
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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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struct nofork_save_area nofork_save;
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static sigjmp_buf nofork_jb;
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static struct pipe *nofork_pipe;
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@ -460,7 +496,7 @@ static void handler_ctrl_z(int sig)
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if (!pid) { /* child */
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debug_jobs_printf("setting pgrp for child\n");
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setpgrp();
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signal(SIGTSTP, SIG_DFL); /* make child do default action (stop) */
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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_jobs_printf("returning to child\n");
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/* return to nofork, it will eventually exit now,
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@ -516,35 +552,6 @@ static void hush_exit(int exitcode)
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sigexit(- (exitcode & 0xff));
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}
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/* Signals are grouped, we handle them in batches */
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static void set_fatal_sighandler(void (*handler)(int))
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{
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signal(SIGILL , handler);
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signal(SIGTRAP, handler);
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signal(SIGABRT, handler);
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signal(SIGFPE , handler);
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signal(SIGBUS , handler);
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signal(SIGSEGV, handler);
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/* bash 3.2 seems to handle these just like 'fatal' ones,
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* but _without_ printing signal name. TODO: mimic this too? */
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signal(SIGHUP , handler);
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signal(SIGPIPE, handler);
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signal(SIGALRM, handler);
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}
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static void set_jobctrl_sighandler(void (*handler)(int))
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{
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signal(SIGTSTP, handler);
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signal(SIGTTIN, handler);
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signal(SIGTTOU, handler);
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}
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static void set_misc_sighandler(void (*handler)(int))
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{
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signal(SIGINT , handler);
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signal(SIGQUIT, handler);
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signal(SIGTERM, handler);
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}
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/* SIGCHLD is special and handled separately */
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static const char *set_cwd(void)
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{
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if (cwd == bb_msg_unknown)
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@ -719,6 +726,7 @@ static int builtin_fg_bg(char **argv)
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if (i < 0) {
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if (errno == ESRCH) {
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delete_finished_bg_job(pi);
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return EXIT_SUCCESS;
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} else {
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bb_perror_msg("kill (SIGCONT)");
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}
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@ -759,7 +767,7 @@ static int builtin_jobs(char **argv ATTRIBUTE_UNUSED)
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else
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status_string = "Running";
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printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
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printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->cmdtext);
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}
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return EXIT_SUCCESS;
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}
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@ -1266,6 +1274,35 @@ static void pseudo_exec(struct child_prog *child)
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_exit(EXIT_SUCCESS);
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}
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static const char *get_cmdtext(struct pipe *pi)
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{
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char **argv;
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char *p;
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int len;
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/* This is subtle. ->cmdtext is created only on first backgrounding.
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* (Think "cat, <ctrl-z>, fg, <ctrl-z>, fg, <ctrl-z>...." here...)
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* On subsequent bg argv can be trashed, but we won't use it */
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if (pi->cmdtext)
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return pi->cmdtext;
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argv = pi->progs[0].argv;
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if (!argv || !argv[0])
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return (pi->cmdtext = xzalloc(1));
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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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argv = pi->progs[0].argv;
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do {
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len = strlen(*argv);
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memcpy(p, *argv, len);
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p += len;
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*p++ = ' ';
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} while (*++argv);
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p[-1] = '\0';
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return pi->cmdtext;
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}
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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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@ -1288,27 +1325,17 @@ static void insert_bg_job(struct pipe *pi)
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/* physically copy the struct job */
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memcpy(thejob, pi, sizeof(struct pipe));
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// (pi->num_progs+1) is one-too-many I think?
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thejob->progs = xmalloc(sizeof(pi->progs[0]) * (pi->num_progs+1));
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memcpy(thejob->progs, pi->progs, sizeof(pi->progs[0]) * (pi->num_progs+1));
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thejob->progs = xmalloc(sizeof(pi->progs[0]) * pi->num_progs);
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memcpy(thejob->progs, pi->progs, sizeof(pi->progs[0]) * pi->num_progs);
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thejob->next = NULL;
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/*seems to be wrong:*/
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/*thejob->running_progs = thejob->num_progs;*/
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/*thejob->stopped_progs = 0;*/
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thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */
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//if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0])
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{
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// FIXME: overflow check? and also trim the size, BUFSIZ can be 4K!
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char *bar = thejob->text;
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char **foo = pi->progs[0].argv;
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if (foo)
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while (*foo)
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bar += sprintf(bar, "%s ", *foo++);
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}
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thejob->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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printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid);
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printf("[%d] %d %s\n", thejob->jobid, thejob->progs[0].pid, thejob->cmdtext);
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last_bg_pid = thejob->progs[0].pid;
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last_jobid = thejob->jobid;
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}
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@ -1433,7 +1460,7 @@ static int checkjobs(struct pipe* fg_pipe)
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pi->running_progs--;
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if (!pi->running_progs) {
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printf(JOB_STATUS_FORMAT, pi->jobid,
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"Done", pi->text);
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"Done", pi->cmdtext);
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delete_finished_bg_job(pi);
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}
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} else {
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@ -1466,6 +1493,32 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
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return rcode;
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}
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/* run_pipe_real's helper */
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static int run_single_fg_nofork(struct pipe *pi, const struct bb_applet *a,
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char **argv)
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{
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int rcode;
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/* TSTP handler will store pid etc in pi */
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nofork_pipe = pi;
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save_nofork_data(&nofork_save);
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if (sigsetjmp(nofork_jb, 1) == 0) {
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signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
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rcode = run_nofork_applet_prime(&nofork_save, a, argv);
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if (--nofork_save.saved != 0) {
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/* Ctrl-Z forked, we are child */
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exit(rcode);
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}
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return rcode;
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}
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/* Ctrl-Z forked, we are parent.
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* Sighandler has longjmped us here */
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signal(SIGTSTP, SIG_IGN);
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debug_jobs_printf("Exiting nofork early\n");
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restore_nofork_data(&nofork_save);
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insert_bg_job(pi);
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return 0;
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}
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/* run_pipe_real() starts all the jobs, but doesn't wait for anything
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* to finish. See checkjobs().
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*
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@ -1575,6 +1628,7 @@ static int run_pipe_real(struct pipe *pi)
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* This is perfect for work that comes after exec().
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* Is it really safe for inline use? Experimentally,
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* things seem to work with glibc. */
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// TODO: fflush(NULL)?
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setup_redirects(child, squirrel);
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rcode = x->function(argv + i);
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restore_redirects(squirrel);
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@ -1586,32 +1640,16 @@ static int run_pipe_real(struct pipe *pi)
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const struct bb_applet *a = find_applet_by_name(argv[i]);
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if (a && a->nofork) {
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setup_redirects(child, squirrel);
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/* TSTP handler will store pid etc in pi */
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nofork_pipe = pi;
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save_nofork_data(&nofork_save);
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if (sigsetjmp(nofork_jb, 1) == 0) {
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signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
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rcode = run_nofork_applet_prime(&nofork_save, a, argv + i);
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if (--nofork_save.saved != 0)
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/* Ctrl-Z! forked, we are child */
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exit(rcode);
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restore_redirects(squirrel);
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return rcode;
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} else {
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/* Ctrl-Z, forked, we are parent.
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* Sighandler has longjmped us here */
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signal(SIGTSTP, SIG_IGN);
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debug_jobs_printf("Exiting nofork early\n");
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restore_nofork_data(&nofork_save);
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restore_redirects(squirrel);
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insert_bg_job(pi);
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return 0;
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}
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rcode = run_single_fg_nofork(pi, a, argv + i);
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restore_redirects(squirrel);
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return rcode;
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}
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}
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#endif
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}
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/* Going to fork a child per each pipe member */
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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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@ -1639,6 +1677,8 @@ static int run_pipe_real(struct pipe *pi)
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/* Every child adds itself to new process group
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* with pgid == pid of first child in pipe */
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if (interactive_fd) {
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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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if (pi->pgrp < 0) /* true for 1st process only */
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pi->pgrp = getpid();
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if (setpgid(0, pi->pgrp) == 0 && pi->followup != PIPE_BG) {
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@ -1646,8 +1686,6 @@ static int run_pipe_real(struct pipe *pi)
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* to avoid races */
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tcsetpgrp(interactive_fd, pi->pgrp);
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}
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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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}
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// in non-interactive case fatal sigs are already SIG_DFL
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close_all();
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@ -1878,6 +1916,8 @@ static int free_pipe(struct pipe *pi, int indent)
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}
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free(pi->progs); /* children are an array, they get freed all at once */
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pi->progs = NULL;
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free(pi->cmdtext);
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pi->cmdtext = NULL;
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return ret_code;
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}
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@ -2252,12 +2292,13 @@ static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
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static struct pipe *new_pipe(void)
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{
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struct pipe *pi;
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pi = xmalloc(sizeof(struct pipe));
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pi->num_progs = 0;
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pi->progs = NULL;
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pi->next = NULL;
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pi->followup = 0; /* invalid */
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pi->r_mode = RES_NONE;
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pi = xzalloc(sizeof(struct pipe));
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/*pi->num_progs = 0;*/
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/*pi->progs = NULL;*/
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/*pi->next = NULL;*/
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/*pi->followup = 0; invalid */
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if (RES_NONE)
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pi->r_mode = RES_NONE;
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return pi;
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}
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@ -2424,13 +2465,14 @@ static int done_command(struct p_context *ctx)
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pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
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prog = pi->progs + pi->num_progs;
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prog->redirects = NULL;
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prog->argv = NULL;
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prog->is_stopped = 0;
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prog->group = NULL;
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prog->glob_result.gl_pathv = NULL;
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memset(prog, 0, sizeof(*prog));
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/*prog->redirects = NULL;*/
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/*prog->argv = NULL;
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/*prog->is_stopped = 0;*/
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/*prog->group = NULL;*/
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/*prog->glob_result.gl_pathv = NULL;*/
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prog->family = pi;
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prog->sp = 0;
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/*prog->sp = 0;*/
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ctx->child = prog;
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prog->type = ctx->type;
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@ -3008,15 +3050,13 @@ static void setup_job_control(void)
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set_misc_sighandler(SIG_IGN);
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//huh? signal(SIGCHLD, SIG_IGN);
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/* We _must_ do cleanup on fatal signals */
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/* We _must_ restore tty pgrp fatal signals */
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set_fatal_sighandler(sigexit);
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/* Put ourselves in our own process group. */
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shell_pgrp = getpid();
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setpgrp(); /* is the same as setpgid(shell_pgrp, shell_pgrp); */
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setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
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/* Grab control of the terminal. */
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tcsetpgrp(interactive_fd, shell_pgrp);
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tcsetpgrp(interactive_fd, getpid());
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}
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int hush_main(int argc, char **argv);
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