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hush: better signal handling across ctrl-z

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This commit is contained in:
Denis Vlasenko 2007-04-28 16:45:22 +00:00
parent 18e19f2b0d
commit 3ac0e00553
1 changed files with 127 additions and 87 deletions
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208
shell/hush.c
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@ -193,7 +193,7 @@ struct pipe {
int jobid; /* job number */
int num_progs; /* total number of programs in job */
int running_progs; /* number of programs running (not exited) */
char *text; /* name of job */
char *cmdtext; /* name of job */
char *cmdbuf; /* buffer various argv's point into */
pid_t pgrp; /* process group ID for the job */
struct child_prog *progs; /* array of commands in pipe */
@ -441,6 +441,42 @@ static void signal_SA_RESTART(int sig, void (*handler)(int))
sigaction(sig, &sa, NULL);
}
/* Signals are grouped, we handle them in batches */
static void set_fatal_sighandler(void (*handler)(int))
{
signal(SIGILL , handler);
signal(SIGTRAP, handler);
signal(SIGABRT, handler);
signal(SIGFPE , handler);
signal(SIGBUS , handler);
signal(SIGSEGV, handler);
/* bash 3.2 seems to handle these just like 'fatal' ones */
signal(SIGHUP , handler);
signal(SIGPIPE, handler);
signal(SIGALRM, handler);
}
static void set_jobctrl_sighandler(void (*handler)(int))
{
signal(SIGTSTP, handler);
signal(SIGTTIN, handler);
signal(SIGTTOU, handler);
}
static void set_misc_sighandler(void (*handler)(int))
{
signal(SIGINT , handler);
signal(SIGQUIT, handler);
signal(SIGTERM, handler);
}
/* SIGCHLD is special and handled separately */
static void set_every_sighandler(void (*handler)(int))
{
set_fatal_sighandler(handler);
set_jobctrl_sighandler(handler);
set_misc_sighandler(handler);
signal(SIGCHLD, handler);
}
struct nofork_save_area nofork_save;
static sigjmp_buf nofork_jb;
static struct pipe *nofork_pipe;
@ -460,7 +496,7 @@ static void handler_ctrl_z(int sig)
if (!pid) { /* child */
debug_jobs_printf("setting pgrp for child\n");
setpgrp();
signal(SIGTSTP, SIG_DFL); /* make child do default action (stop) */
set_every_sighandler(SIG_DFL);
raise(SIGTSTP); /* resend TSTP so that child will be stopped */
debug_jobs_printf("returning to child\n");
/* return to nofork, it will eventually exit now,
@ -516,35 +552,6 @@ static void hush_exit(int exitcode)
sigexit(- (exitcode & 0xff));
}
/* Signals are grouped, we handle them in batches */
static void set_fatal_sighandler(void (*handler)(int))
{
signal(SIGILL , handler);
signal(SIGTRAP, handler);
signal(SIGABRT, handler);
signal(SIGFPE , handler);
signal(SIGBUS , handler);
signal(SIGSEGV, handler);
/* bash 3.2 seems to handle these just like 'fatal' ones,
* but _without_ printing signal name. TODO: mimic this too? */
signal(SIGHUP , handler);
signal(SIGPIPE, handler);
signal(SIGALRM, handler);
}
static void set_jobctrl_sighandler(void (*handler)(int))
{
signal(SIGTSTP, handler);
signal(SIGTTIN, handler);
signal(SIGTTOU, handler);
}
static void set_misc_sighandler(void (*handler)(int))
{
signal(SIGINT , handler);
signal(SIGQUIT, handler);
signal(SIGTERM, handler);
}
/* SIGCHLD is special and handled separately */
static const char *set_cwd(void)
{
if (cwd == bb_msg_unknown)
@ -719,6 +726,7 @@ static int builtin_fg_bg(char **argv)
if (i < 0) {
if (errno == ESRCH) {
delete_finished_bg_job(pi);
return EXIT_SUCCESS;
} else {
bb_perror_msg("kill (SIGCONT)");
}
@ -759,7 +767,7 @@ static int builtin_jobs(char **argv ATTRIBUTE_UNUSED)
else
status_string = "Running";
printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->text);
printf(JOB_STATUS_FORMAT, job->jobid, status_string, job->cmdtext);
}
return EXIT_SUCCESS;
}
@ -1266,6 +1274,35 @@ static void pseudo_exec(struct child_prog *child)
_exit(EXIT_SUCCESS);
}
static const char *get_cmdtext(struct pipe *pi)
{
char **argv;
char *p;
int len;
/* This is subtle. ->cmdtext is created only on first backgrounding.
* (Think "cat, <ctrl-z>, fg, <ctrl-z>, fg, <ctrl-z>...." here...)
* On subsequent bg argv can be trashed, but we won't use it */
if (pi->cmdtext)
return pi->cmdtext;
argv = pi->progs[0].argv;
if (!argv || !argv[0])
return (pi->cmdtext = xzalloc(1));
len = 0;
do len += strlen(*argv) + 1; while (*++argv);
pi->cmdtext = p = xmalloc(len);
argv = pi->progs[0].argv;
do {
len = strlen(*argv);
memcpy(p, *argv, len);
p += len;
*p++ = ' ';
} while (*++argv);
p[-1] = '\0';
return pi->cmdtext;
}
static void insert_bg_job(struct pipe *pi)
{
struct pipe *thejob;
@ -1288,27 +1325,17 @@ static void insert_bg_job(struct pipe *pi)
/* physically copy the struct job */
memcpy(thejob, pi, sizeof(struct pipe));
// (pi->num_progs+1) is one-too-many I think?
thejob->progs = xmalloc(sizeof(pi->progs[0]) * (pi->num_progs+1));
memcpy(thejob->progs, pi->progs, sizeof(pi->progs[0]) * (pi->num_progs+1));
thejob->progs = xmalloc(sizeof(pi->progs[0]) * pi->num_progs);
memcpy(thejob->progs, pi->progs, sizeof(pi->progs[0]) * pi->num_progs);
thejob->next = NULL;
/*seems to be wrong:*/
/*thejob->running_progs = thejob->num_progs;*/
/*thejob->stopped_progs = 0;*/
thejob->text = xmalloc(BUFSIZ); /* cmdedit buffer size */
//if (pi->progs[0] && pi->progs[0].argv && pi->progs[0].argv[0])
{
// FIXME: overflow check? and also trim the size, BUFSIZ can be 4K!
char *bar = thejob->text;
char **foo = pi->progs[0].argv;
if (foo)
while (*foo)
bar += sprintf(bar, "%s ", *foo++);
}
thejob->cmdtext = xstrdup(get_cmdtext(pi));
/* we don't wait for background thejobs to return -- append it
to the list of backgrounded thejobs and leave it alone */
printf("[%d] %d\n", thejob->jobid, thejob->progs[0].pid);
printf("[%d] %d %s\n", thejob->jobid, thejob->progs[0].pid, thejob->cmdtext);
last_bg_pid = thejob->progs[0].pid;
last_jobid = thejob->jobid;
}
@ -1433,7 +1460,7 @@ static int checkjobs(struct pipe* fg_pipe)
pi->running_progs--;
if (!pi->running_progs) {
printf(JOB_STATUS_FORMAT, pi->jobid,
"Done", pi->text);
"Done", pi->cmdtext);
delete_finished_bg_job(pi);
}
} else {
@ -1466,6 +1493,32 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
return rcode;
}
/* run_pipe_real's helper */
static int run_single_fg_nofork(struct pipe *pi, const struct bb_applet *a,
char **argv)
{
int rcode;
/* TSTP handler will store pid etc in pi */
nofork_pipe = pi;
save_nofork_data(&nofork_save);
if (sigsetjmp(nofork_jb, 1) == 0) {
signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
rcode = run_nofork_applet_prime(&nofork_save, a, argv);
if (--nofork_save.saved != 0) {
/* Ctrl-Z forked, we are child */
exit(rcode);
}
return rcode;
}
/* Ctrl-Z forked, we are parent.
* Sighandler has longjmped us here */
signal(SIGTSTP, SIG_IGN);
debug_jobs_printf("Exiting nofork early\n");
restore_nofork_data(&nofork_save);
insert_bg_job(pi);
return 0;
}
/* run_pipe_real() starts all the jobs, but doesn't wait for anything
* to finish. See checkjobs().
*
@ -1575,6 +1628,7 @@ static int run_pipe_real(struct pipe *pi)
* This is perfect for work that comes after exec().
* Is it really safe for inline use? Experimentally,
* things seem to work with glibc. */
// TODO: fflush(NULL)?
setup_redirects(child, squirrel);
rcode = x->function(argv + i);
restore_redirects(squirrel);
@ -1586,32 +1640,16 @@ static int run_pipe_real(struct pipe *pi)
const struct bb_applet *a = find_applet_by_name(argv[i]);
if (a && a->nofork) {
setup_redirects(child, squirrel);
/* TSTP handler will store pid etc in pi */
nofork_pipe = pi;
save_nofork_data(&nofork_save);
if (sigsetjmp(nofork_jb, 1) == 0) {
signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
rcode = run_nofork_applet_prime(&nofork_save, a, argv + i);
if (--nofork_save.saved != 0)
/* Ctrl-Z! forked, we are child */
exit(rcode);
rcode = run_single_fg_nofork(pi, a, argv + i);
restore_redirects(squirrel);
return rcode;
} else {
/* Ctrl-Z, forked, we are parent.
* Sighandler has longjmped us here */
signal(SIGTSTP, SIG_IGN);
debug_jobs_printf("Exiting nofork early\n");
restore_nofork_data(&nofork_save);
restore_redirects(squirrel);
insert_bg_job(pi);
return 0;
}
}
}
#endif
}
/* Going to fork a child per each pipe member */
/* Disable job control signals for shell (parent) and
* for initial child code after fork */
set_jobctrl_sighandler(SIG_IGN);
@ -1639,6 +1677,8 @@ static int run_pipe_real(struct pipe *pi)
/* Every child adds itself to new process group
* with pgid == pid of first child in pipe */
if (interactive_fd) {
/* Don't do pgrp restore anymore on fatal signals */
set_fatal_sighandler(SIG_DFL);
if (pi->pgrp < 0) /* true for 1st process only */
pi->pgrp = getpid();
if (setpgid(0, pi->pgrp) == 0 && pi->followup != PIPE_BG) {
@ -1646,8 +1686,6 @@ static int run_pipe_real(struct pipe *pi)
* to avoid races */
tcsetpgrp(interactive_fd, pi->pgrp);
}
/* Don't do pgrp restore anymore on fatal signals */
set_fatal_sighandler(SIG_DFL);
}
// in non-interactive case fatal sigs are already SIG_DFL
close_all();
@ -1878,6 +1916,8 @@ static int free_pipe(struct pipe *pi, int indent)
}
free(pi->progs); /* children are an array, they get freed all at once */
pi->progs = NULL;
free(pi->cmdtext);
pi->cmdtext = NULL;
return ret_code;
}
@ -2252,11 +2292,12 @@ static int setup_redirect(struct p_context *ctx, int fd, redir_type style,
static struct pipe *new_pipe(void)
{
struct pipe *pi;
pi = xmalloc(sizeof(struct pipe));
pi->num_progs = 0;
pi->progs = NULL;
pi->next = NULL;
pi->followup = 0; /* invalid */
pi = xzalloc(sizeof(struct pipe));
/*pi->num_progs = 0;*/
/*pi->progs = NULL;*/
/*pi->next = NULL;*/
/*pi->followup = 0; invalid */
if (RES_NONE)
pi->r_mode = RES_NONE;
return pi;
}
@ -2424,13 +2465,14 @@ static int done_command(struct p_context *ctx)
pi->progs = xrealloc(pi->progs, sizeof(*pi->progs) * (pi->num_progs+1));
prog = pi->progs + pi->num_progs;
prog->redirects = NULL;
prog->argv = NULL;
prog->is_stopped = 0;
prog->group = NULL;
prog->glob_result.gl_pathv = NULL;
memset(prog, 0, sizeof(*prog));
/*prog->redirects = NULL;*/
/*prog->argv = NULL;
/*prog->is_stopped = 0;*/
/*prog->group = NULL;*/
/*prog->glob_result.gl_pathv = NULL;*/
prog->family = pi;
prog->sp = 0;
/*prog->sp = 0;*/
ctx->child = prog;
prog->type = ctx->type;
@ -3008,15 +3050,13 @@ static void setup_job_control(void)
set_misc_sighandler(SIG_IGN);
//huh? signal(SIGCHLD, SIG_IGN);
/* We _must_ do cleanup on fatal signals */
/* We _must_ restore tty pgrp fatal signals */
set_fatal_sighandler(sigexit);
/* Put ourselves in our own process group. */
shell_pgrp = getpid();
setpgrp(); /* is the same as setpgid(shell_pgrp, shell_pgrp); */
setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
/* Grab control of the terminal. */
tcsetpgrp(interactive_fd, shell_pgrp);
tcsetpgrp(interactive_fd, getpid());
}
int hush_main(int argc, char **argv);