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hush: fix SIGCHLD counting code, but keep it disabled for now.

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2009-05-25 16:38:32 +02:00
parent bf2af9acb2
commit 8d7be232a3
1 changed files with 66 additions and 19 deletions
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85
shell/hush.c
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@ -69,7 +69,7 @@
#endif
/* Debug build knobs */
/* Build knobs */
#define LEAK_HUNTING 0
#define BUILD_AS_NOMMU 0
/* Enable/disable sanity checks. Ok to enable in production,
@ -77,6 +77,13 @@
* Keeping 1 for now even in released versions.
*/
#define HUSH_DEBUG 1
/* Slightly bigger (+200 bytes), but faster hush.
* So far it only enables a trick with counting SIGCHLDs and forks,
* which allows us to do fewer waitpid's.
* (we can detect a case where neither forks were done nor SIGCHLDs happened
* and therefore waitpid will return the same result as last time)
*/
#define ENABLE_HUSH_FAST 0
#if BUILD_AS_NOMMU
@ -485,8 +492,11 @@ struct globals {
struct function *top_func;
#endif
/* Signal and trap handling */
// unsigned count_SIGCHLD;
// unsigned handled_SIGCHLD;
#if ENABLE_HUSH_FAST
unsigned count_SIGCHLD;
unsigned handled_SIGCHLD;
smallint last_waitpid_was_0;
#endif
/* which signals have non-DFL handler (even with no traps set)? */
unsigned non_DFL_mask;
char **traps; /* char *traps[NSIG] */
@ -1050,7 +1060,7 @@ static void restore_G_args(save_arg_t *sv, char **argv)
* Restore blocked signal set to one inherited by shell just prior to exec.
*
* Note: as a result, we do not use signal handlers much. The only uses
* are to count SIGCHLDs [disabled - bug somewhere, + bloat]
* are to count SIGCHLDs
* and to restore tty pgrp on signal-induced exit.
*/
enum {
@ -1067,10 +1077,13 @@ enum {
#endif
};
//static void SIGCHLD_handler(int sig UNUSED_PARAM)
//{
// G.count_SIGCHLD++;
//}
#if ENABLE_HUSH_FAST
static void SIGCHLD_handler(int sig UNUSED_PARAM)
{
G.count_SIGCHLD++;
//bb_error_msg("[%d] SIGCHLD_handler: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
}
#endif
#if ENABLE_HUSH_JOB
@ -1158,9 +1171,12 @@ static int check_and_run_traps(int sig)
}
/* not a trap: special action */
switch (sig) {
// case SIGCHLD:
// G.count_SIGCHLD++;
// break;
#if ENABLE_HUSH_FAST
case SIGCHLD:
G.count_SIGCHLD++;
//bb_error_msg("[%d] check_and_run_traps: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
break;
#endif
case SIGINT:
/* Builtin was ^C'ed, make it look prettier: */
bb_putchar('\n');
@ -2665,6 +2681,10 @@ static void setup_heredoc(struct redir_struct *redir)
#endif
}
/* parent */
#if ENABLE_HUSH_FAST
G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in setup_heredoc: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
free(to_free);
@ -3273,9 +3293,16 @@ static int checkjobs(struct pipe* fg_pipe)
debug_printf_jobs("checkjobs %p\n", fg_pipe);
errno = 0;
// if (G.handled_SIGCHLD == G.count_SIGCHLD)
// /* avoid doing syscall, nothing there anyway */
// return rcode;
#if ENABLE_HUSH_FAST
if (G.handled_SIGCHLD == G.count_SIGCHLD) {
//bb_error_msg("[%d] checkjobs: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d was 0?:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD, G.last_waitpid_was_0);
/* avoid doing syscall, nothing there anyway */
if (G.last_waitpid_was_0)
return 0;
errno = ECHILD;
return -1;
}
#endif
attributes = WUNTRACED;
if (fg_pipe == NULL)
@ -3294,13 +3321,20 @@ static int checkjobs(struct pipe* fg_pipe)
int i;
int dead;
// i = G.count_SIGCHLD;
#if ENABLE_HUSH_FAST
i = G.count_SIGCHLD;
#endif
childpid = waitpid(-1, &status, attributes);
if (childpid <= 0) {
if (childpid && errno != ECHILD)
bb_perror_msg("waitpid");
// else /* Until next SIGCHLD, waitpid's are useless */
// G.handled_SIGCHLD = i;
#if ENABLE_HUSH_FAST
else { /* Until next SIGCHLD, waitpid's are useless */
G.last_waitpid_was_0 = (childpid == 0);
G.handled_SIGCHLD = i;
//bb_error_msg("[%d] checkjobs: waitpid returned <= 0, G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
}
#endif
break;
}
dead = WIFEXITED(status) || WIFSIGNALED(status);
@ -3696,6 +3730,10 @@ static int run_pipe(struct pipe *pi)
}
/* parent or error */
#if ENABLE_HUSH_FAST
G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in run_pipe: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
/* Clean up after vforked child */
@ -4861,6 +4899,10 @@ static FILE *generate_stream_from_string(const char *s)
}
/* parent */
#if ENABLE_HUSH_FAST
G.count_SIGCHLD++;
//bb_error_msg("[%d] fork in generate_stream_from_string: G.count_SIGCHLD:%d G.handled_SIGCHLD:%d", getpid(), G.count_SIGCHLD, G.handled_SIGCHLD);
#endif
enable_restore_tty_pgrp_on_exit();
#if !BB_MMU
free(to_free);
@ -5990,9 +6032,14 @@ static void block_signals(int second_time)
second_time ? NULL : &G.inherited_set);
/* POSIX allows shell to re-enable SIGCHLD
* even if it was SIG_IGN on entry */
// G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
#if ENABLE_HUSH_FAST
G.count_SIGCHLD++; /* ensure it is != G.handled_SIGCHLD */
if (!second_time)
signal(SIGCHLD, SIG_DFL); // SIGCHLD_handler);
signal(SIGCHLD, SIGCHLD_handler);
#else
if (!second_time)
signal(SIGCHLD, SIG_DFL);
#endif
}
#if ENABLE_HUSH_JOB