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hush: fix "while true; do true; done" + ctrl-z

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This commit is contained in:
Denis Vlasenko 2007-05-04 21:37:27 +00:00
parent 3349fc4da9
commit ac0e5ab96a
2 changed files with 123 additions and 92 deletions
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3
shell/README
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@ -1,5 +1,8 @@
Various bits of what is known about busybox shells, in no particular order. Various bits of what is known about busybox shells, in no particular order.
2007-05-04
hush: make ctrl-Z/C work correctly for "while true; do true; done"
2007-05-03 2007-05-03
hush: new bug spotted: Ctrl-C on "while true; do true; done" doesn't hush: new bug spotted: Ctrl-C on "while true; do true; done" doesn't
work right: work right:

212
shell/hush.c
View File

@ -468,7 +468,6 @@ static const struct built_in_command bltins[] = {
#if ENABLE_HUSH_JOB #if ENABLE_HUSH_JOB
#if ENABLE_FEATURE_SH_STANDALONE
/* move to libbb? */ /* move to libbb? */
static void signal_SA_RESTART(int sig, void (*handler)(int)) static void signal_SA_RESTART(int sig, void (*handler)(int))
{ {
@ -478,7 +477,6 @@ static void signal_SA_RESTART(int sig, void (*handler)(int))
sigemptyset(&sa.sa_mask); sigemptyset(&sa.sa_mask);
sigaction(sig, &sa, NULL); sigaction(sig, &sa, NULL);
} }
#endif
/* Signals are grouped, we handle them in batches */ /* Signals are grouped, we handle them in batches */
static void set_fatal_sighandler(void (*handler)(int)) static void set_fatal_sighandler(void (*handler)(int))
@ -508,7 +506,6 @@ static void set_misc_sighandler(void (*handler)(int))
} }
/* SIGCHLD is special and handled separately */ /* SIGCHLD is special and handled separately */
#if ENABLE_FEATURE_SH_STANDALONE
static void set_every_sighandler(void (*handler)(int)) static void set_every_sighandler(void (*handler)(int))
{ {
set_fatal_sighandler(handler); set_fatal_sighandler(handler);
@ -517,53 +514,57 @@ static void set_every_sighandler(void (*handler)(int))
signal(SIGCHLD, handler); signal(SIGCHLD, handler);
} }
static struct pipe *nofork_pipe; static struct pipe *toplevel_list;
static sigjmp_buf toplevel_jb;
smallint ctrl_z_flag;
#if ENABLE_FEATURE_SH_STANDALONE
struct nofork_save_area nofork_save; struct nofork_save_area nofork_save;
static sigjmp_buf nofork_jb; #endif
static void handler_ctrl_c(int sig) static void handler_ctrl_c(int sig)
{ {
debug_printf_jobs("got sig %d\n", sig); debug_printf_jobs("got sig %d\n", sig);
// as usual we can have all kinds of nasty problems with leaked malloc data here // as usual we can have all kinds of nasty problems with leaked malloc data here
siglongjmp(nofork_jb, 1); siglongjmp(toplevel_jb, 1);
} }
static void handler_ctrl_z(int sig) static void handler_ctrl_z(int sig)
{ {
pid_t pid; pid_t pid;
debug_printf_jobs("got tty sig %d\n", sig); debug_printf_jobs("got tty sig %d in pid %d\n", sig, getpid());
pid = fork(); pid = fork();
if (pid < 0) /* can't fork. Pretend there were no Ctrl-Z */ if (pid < 0) /* can't fork. Pretend there were no ctrl-Z */
return; return;
debug_printf_jobs("bg'ing nofork\n"); ctrl_z_flag = 1;
nofork_save.saved = 0; /* flag the fact that Ctrl-Z was handled */ //vda: wrong!!
nofork_pipe->running_progs = 1; // toplevel_list->running_progs = 1;
nofork_pipe->stopped_progs = 0; // toplevel_list->stopped_progs = 0;
//
if (!pid) { /* child */ if (!pid) { /* child */
debug_printf_jobs("setting pgrp for child\n");
setpgrp(); setpgrp();
debug_printf_jobs("set pgrp for child %d ok\n", getpid());
set_every_sighandler(SIG_DFL); set_every_sighandler(SIG_DFL);
raise(SIGTSTP); /* resend TSTP so that child will be stopped */ raise(SIGTSTP); /* resend TSTP so that child will be stopped */
debug_printf_jobs("returning to child\n"); debug_printf_jobs("returning in child\n");
/* return to nofork, it will eventually exit now, /* return to nofork, it will eventually exit now,
* not return back to shell */ * not return back to shell */
return; return;
} }
/* parent */ /* parent */
/* finish filling up pipe info */ /* finish filling up pipe info */
nofork_pipe->pgrp = pid; /* child is in its own pgrp */ toplevel_list->pgrp = pid; /* child is in its own pgrp */
nofork_pipe->progs[0].pid = pid; toplevel_list->progs[0].pid = pid;
nofork_pipe->running_progs = 1; //vda: wrong!!
nofork_pipe->stopped_progs = 0; // toplevel_list->running_progs = 1;
// toplevel_list->stopped_progs = 0;
/* parent needs to longjmp out of running nofork. /* parent needs to longjmp out of running nofork.
* we will "return" exitcode 0, with child put in background */ * we will "return" exitcode 0, with child put in background */
// as usual we can have all kinds of nasty problems with leaked malloc data here // as usual we can have all kinds of nasty problems with leaked malloc data here
siglongjmp(nofork_jb, 1); debug_printf_jobs("siglongjmp in parent\n");
siglongjmp(toplevel_jb, 1);
} }
#endif
/* Restores tty foreground process group, and exits. /* Restores tty foreground process group, and exits.
* May be called as signal handler for fatal signal * May be called as signal handler for fatal signal
* (will faithfully resend signal to itself, producing correct exit state) * (will faithfully resend signal to itself, producing correct exit state)
@ -1039,6 +1040,7 @@ static int static_peek(struct in_str *i)
} }
#if ENABLE_HUSH_INTERACTIVE #if ENABLE_HUSH_INTERACTIVE
#if ENABLE_FEATURE_EDITING
static void cmdedit_set_initial_prompt(void) static void cmdedit_set_initial_prompt(void)
{ {
#if !ENABLE_FEATURE_EDITING_FANCY_PROMPT #if !ENABLE_FEATURE_EDITING_FANCY_PROMPT
@ -1049,6 +1051,7 @@ static void cmdedit_set_initial_prompt(void)
PS1 = "\\w \\$ "; PS1 = "\\w \\$ ";
#endif #endif
} }
#endif
static const char* setup_prompt_string(int promptmode) static const char* setup_prompt_string(int promptmode)
{ {
@ -1072,7 +1075,7 @@ static const char* setup_prompt_string(int promptmode)
debug_printf("result %s\n", prompt_str); debug_printf("result %s\n", prompt_str);
return prompt_str; return prompt_str;
} }
#endif #endif /* ENABLE_HUSH_INTERACTIVE */
#if ENABLE_FEATURE_EDITING #if ENABLE_FEATURE_EDITING
static line_input_t *line_input_state; static line_input_t *line_input_state;
@ -1470,7 +1473,7 @@ static int checkjobs(struct pipe* fg_pipe)
/* Do we do this right? /* Do we do this right?
* bash-3.00# sleep 20 | false * bash-3.00# sleep 20 | false
* <Ctrl-Z pressed> * <ctrl-Z pressed>
* [3]+ Stopped sleep 20 | false * [3]+ Stopped sleep 20 | false
* bash-3.00# echo $? * bash-3.00# echo $?
* 1 <========== bg pipe is not fully done, but exitcode is already known! * 1 <========== bg pipe is not fully done, but exitcode is already known!
@ -1590,43 +1593,6 @@ static int checkjobs_and_fg_shell(struct pipe* fg_pipe)
} }
#endif #endif
#if ENABLE_FEATURE_SH_STANDALONE
/* run_pipe_real's helper */
static int run_single_fg_nofork(struct pipe *pi, const struct bb_applet *a,
char **argv)
{
#if ENABLE_HUSH_JOB
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);
signal(SIGINT, handler_ctrl_c);
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; or Ctrl-C.
* Sighandler has longjmped us here */
signal(SIGINT, SIG_IGN);
signal(SIGTSTP, SIG_IGN);
debug_printf_jobs("Exiting nofork early\n");
restore_nofork_data(&nofork_save);
if (nofork_save.saved == 0) /* Ctrl-Z, not Ctrl-C */
insert_bg_job(pi);
else
putchar('\n'); /* bash does this on Ctrl-C */
return 0;
#else
return run_nofork_applet(a, argv);
#endif
}
#endif
/* run_pipe_real() starts all the jobs, but doesn't wait for anything /* run_pipe_real() starts all the jobs, but doesn't wait for anything
* to finish. See checkjobs(). * to finish. See checkjobs().
* *
@ -1662,7 +1628,7 @@ static int run_pipe_real(struct pipe *pi)
#if ENABLE_HUSH_JOB #if ENABLE_HUSH_JOB
pi->pgrp = -1; pi->pgrp = -1;
#endif #endif
pi->running_progs = 0; pi->running_progs = 1;
pi->stopped_progs = 0; pi->stopped_progs = 0;
/* Check if this is a simple builtin (not part of a pipe). /* Check if this is a simple builtin (not part of a pipe).
@ -1673,8 +1639,6 @@ static int run_pipe_real(struct pipe *pi)
if (single_fg && child->group && child->subshell == 0) { if (single_fg && child->group && child->subshell == 0) {
debug_printf("non-subshell grouping\n"); debug_printf("non-subshell grouping\n");
setup_redirects(child, squirrel); setup_redirects(child, squirrel);
/* XXX could we merge code with following builtin case,
* by creating a pseudo builtin that calls run_list_real? */
debug_printf_exec(": run_list_real\n"); debug_printf_exec(": run_list_real\n");
rcode = run_list_real(child->group); rcode = run_list_real(child->group);
restore_redirects(squirrel); restore_redirects(squirrel);
@ -1758,8 +1722,9 @@ static int run_pipe_real(struct pipe *pi)
const struct bb_applet *a = find_applet_by_name(argv[i]); const struct bb_applet *a = find_applet_by_name(argv[i]);
if (a && a->nofork) { if (a && a->nofork) {
setup_redirects(child, squirrel); setup_redirects(child, squirrel);
debug_printf_exec(": run_single_fg_nofork '%s' '%s'...\n", argv[i], argv[i+1]); debug_printf_exec(": run_nofork_applet '%s' '%s'...\n", argv[i], argv[i+1]);
rcode = run_single_fg_nofork(pi, a, argv + i); save_nofork_data(&nofork_save);
rcode = run_nofork_applet_prime(&nofork_save, a, argv);
restore_redirects(squirrel); restore_redirects(squirrel);
debug_printf_exec("run_pipe_real return %d\n", rcode); debug_printf_exec("run_pipe_real return %d\n", rcode);
return rcode; return rcode;
@ -1769,6 +1734,7 @@ static int run_pipe_real(struct pipe *pi)
} }
/* Going to fork a child per each pipe member */ /* Going to fork a child per each pipe member */
pi->running_progs = 0;
/* Disable job control signals for shell (parent) and /* Disable job control signals for shell (parent) and
* for initial child code after fork */ * for initial child code after fork */
@ -1865,26 +1831,26 @@ static int run_pipe_real(struct pipe *pi)
static void debug_print_tree(struct pipe *pi, int lvl) static void debug_print_tree(struct pipe *pi, int lvl)
{ {
static const char *PIPE[] = { static const char *PIPE[] = {
[PIPE_SEQ] = "SEQ", [PIPE_SEQ] = "SEQ",
[PIPE_AND] = "AND", [PIPE_AND] = "AND",
[PIPE_OR ] = "OR", [PIPE_OR ] = "OR",
[PIPE_BG ] = "BG", [PIPE_BG ] = "BG",
}; };
static const char *RES[] = { static const char *RES[] = {
[RES_NONE ] = "NONE" , [RES_NONE ] = "NONE" ,
[RES_IF ] = "IF" , [RES_IF ] = "IF" ,
[RES_THEN ] = "THEN" , [RES_THEN ] = "THEN" ,
[RES_ELIF ] = "ELIF" , [RES_ELIF ] = "ELIF" ,
[RES_ELSE ] = "ELSE" , [RES_ELSE ] = "ELSE" ,
[RES_FI ] = "FI" , [RES_FI ] = "FI" ,
[RES_FOR ] = "FOR" , [RES_FOR ] = "FOR" ,
[RES_WHILE] = "WHILE", [RES_WHILE] = "WHILE",
[RES_UNTIL] = "UNTIL", [RES_UNTIL] = "UNTIL",
[RES_DO ] = "DO" , [RES_DO ] = "DO" ,
[RES_DONE ] = "DONE" , [RES_DONE ] = "DONE" ,
[RES_XXXX ] = "XXXX" , [RES_XXXX ] = "XXXX" ,
[RES_IN ] = "IN" , [RES_IN ] = "IN" ,
[RES_SNTX ] = "SNTX" , [RES_SNTX ] = "SNTX" ,
}; };
int pin, prn; int pin, prn;
@ -1897,7 +1863,9 @@ static void debug_print_tree(struct pipe *pi, int lvl)
while (prn < pi->num_progs) { while (prn < pi->num_progs) {
fprintf(stderr, "%*s prog %d", lvl*2, "", prn); fprintf(stderr, "%*s prog %d", lvl*2, "", prn);
if (pi->progs[prn].group) { if (pi->progs[prn].group) {
fprintf(stderr, " group: (argv=%p)\n", pi->progs[prn].argv); fprintf(stderr, " group %s: (argv=%p)\n",
(pi->subshell ? "()" : "{}"),
pi->progs[prn].argv);
debug_print_tree(pi->progs[prn].group, lvl+1); debug_print_tree(pi->progs[prn].group, lvl+1);
prn++; prn++;
continue; continue;
@ -1920,18 +1888,25 @@ static void debug_print_tree(struct pipe *pi, int lvl)
// global data until exec/_exit (we can be a child after vfork!) // global data until exec/_exit (we can be a child after vfork!)
static int run_list_real(struct pipe *pi) static int run_list_real(struct pipe *pi)
{ {
#if ENABLE_HUSH_JOB
static int level;
#else
enum { level = 0 };
#endif
char *save_name = NULL; char *save_name = NULL;
char **list = NULL; char **list = NULL;
char **save_list = NULL; char **save_list = NULL;
struct pipe *rpipe; struct pipe *rpipe;
int flag_rep = 0; int flag_rep = 0;
int save_num_progs; int save_num_progs;
int rcode = 0, flag_skip = 1; int flag_skip = 1;
int rcode = 0; /* probaly for gcc only */
int flag_restore = 0; int flag_restore = 0;
int if_code = 0, next_if_code = 0; /* need double-buffer to handle elif */ int if_code = 0, next_if_code = 0; /* need double-buffer to handle elif */
reserved_style rmode, skip_more_in_this_rmode = RES_XXXX; reserved_style rmode, skip_more_in_this_rmode = RES_XXXX;
debug_printf_exec("run_list_real start:\n"); debug_printf_exec("run_list_real start lvl %d\n", level + 1);
/* check syntax for "for" */ /* check syntax for "for" */
for (rpipe = pi; rpipe; rpipe = rpipe->next) { for (rpipe = pi; rpipe; rpipe = rpipe->next) {
@ -1939,17 +1914,60 @@ static int run_list_real(struct pipe *pi)
&& (rpipe->next == NULL) && (rpipe->next == NULL)
) { ) {
syntax(); syntax();
debug_printf_exec("run_list_real return 1\n"); debug_printf_exec("run_list_real lvl %d return 1\n", level);
return 1; return 1;
} }
if ((rpipe->r_mode == RES_IN && rpipe->next->r_mode == RES_IN && rpipe->next->progs->argv != NULL) if ((rpipe->r_mode == RES_IN && rpipe->next->r_mode == RES_IN && rpipe->next->progs->argv != NULL)
|| (rpipe->r_mode == RES_FOR && rpipe->next->r_mode != RES_IN) || (rpipe->r_mode == RES_FOR && rpipe->next->r_mode != RES_IN)
) { ) {
syntax(); syntax();
debug_printf_exec("run_list_real return 1\n"); debug_printf_exec("run_list_real lvl %d return 1\n", level);
return 1; return 1;
} }
} }
#if ENABLE_HUSH_JOB
/* Example of nested list: "while true; do { sleep 1 | exit 2; } done".
* We are saving state before entering outermost list ("while...done")
* so that ctrl-Z will correctly background _entire_ outermost list,
* not just a part of it (like "sleep 1 | exit 2") */
if (++level == 1 && interactive_fd) {
if (sigsetjmp(toplevel_jb, 1)) {
/* ctrl-Z forked and we are parent; or ctrl-C.
* Sighandler has longjmped us here */
signal(SIGINT, SIG_IGN);
signal(SIGTSTP, SIG_IGN);
/* Restore level (we can be coming from deep inside
* nested levels) */
level = 1;
#if ENABLE_FEATURE_SH_STANDALONE
if (nofork_save.saved) { /* if save area is valid */
debug_printf_jobs("exiting nofork early\n");
restore_nofork_data(&nofork_save);
}
#endif
if (ctrl_z_flag) {
/* ctrl-Z has forked and stored pid of the child in pi->pid.
* Remember this child as background job */
insert_bg_job(pi);
} else {
/* ctrl-C. We just stop doing whatever we was doing */
putchar('\n');
}
rcode = 0;
goto ret;
}
/* ctrl-Z handler will store pid etc in pi */
toplevel_list = pi;
ctrl_z_flag = 0;
#if ENABLE_FEATURE_SH_STANDALONE
nofork_save.saved = 0; /* in case we will run a nofork later */
#endif
signal_SA_RESTART(SIGTSTP, handler_ctrl_z);
signal(SIGINT, handler_ctrl_c);
}
#endif
for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) { for (; pi; pi = (flag_restore != 0) ? rpipe : pi->next) {
if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL if (pi->r_mode == RES_WHILE || pi->r_mode == RES_UNTIL
|| pi->r_mode == RES_FOR || pi->r_mode == RES_FOR
@ -1961,7 +1979,7 @@ static int run_list_real(struct pipe *pi)
} }
} }
rmode = pi->r_mode; rmode = pi->r_mode;
debug_printf("rmode=%d if_code=%d next_if_code=%d skip_more=%d\n", debug_printf_exec(": rmode=%d if_code=%d next_if_code=%d skip_more=%d\n",
rmode, if_code, next_if_code, skip_more_in_this_rmode); rmode, if_code, next_if_code, skip_more_in_this_rmode);
if (rmode == skip_more_in_this_rmode && flag_skip) { if (rmode == skip_more_in_this_rmode && flag_skip) {
if (pi->followup == PIPE_SEQ) if (pi->followup == PIPE_SEQ)
@ -2044,9 +2062,9 @@ static int run_list_real(struct pipe *pi)
{ {
rcode = checkjobs(pi); rcode = checkjobs(pi);
} }
debug_printf_exec("checkjobs returned %d\n", rcode); debug_printf_exec(": checkjobs returned %d\n", rcode);
} }
debug_printf_exec("setting last_return_code=%d\n", rcode); debug_printf_exec(": setting last_return_code=%d\n", rcode);
last_return_code = rcode; last_return_code = rcode;
pi->num_progs = save_num_progs; /* restore number of programs */ pi->num_progs = save_num_progs; /* restore number of programs */
if (rmode == RES_IF || rmode == RES_ELIF) if (rmode == RES_IF || rmode == RES_ELIF)
@ -2062,7 +2080,17 @@ static int run_list_real(struct pipe *pi)
} }
checkjobs(NULL); checkjobs(NULL);
} }
debug_printf_exec("run_list_real return %d\n", rcode);
#if ENABLE_HUSH_JOB
if (ctrl_z_flag) {
/* ctrl-Z forked somewhere in the past, we are the child,
* and now we completed running the list. Exit. */
exit(rcode);
}
ret:
level--;
#endif
debug_printf_exec("run_list_real lvl %d return %d\n", level + 1, rcode);
return rcode; return rcode;
} }