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authorDenys Vlasenko <vda.linux@googlemail.com>2011-05-11 21:56:11 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2011-05-11 21:56:11 (GMT)
commit9d6cbafe728c9100a35e29ba7a3729c5303e73ea (patch)
tree585f11bce3f1afad08ad00453fe355a460f5fff1
parent10c0131a8a1b3db7fd6b23b72ebd7b33afc7b018 (diff)
downloadbusybox-9d6cbafe728c9100a35e29ba7a3729c5303e73ea.tar.gz
busybox-9d6cbafe728c9100a35e29ba7a3729c5303e73ea.tar.bz2
hush: replace signal handling machinery
With new version of signal handling, read builtin should be less buggy wrt signals. function old new delta install_sighandlers - 121 +121 switch_off_special_sigs - 84 +84 pick_sighandler - 58 +58 install_special_sighandlers - 47 +47 builtin_wait 284 319 +35 record_pending_signo - 21 +21 execvp_or_die 43 48 +5 file_get 290 288 -2 run_list 1004 998 -6 static.zero_timespec 8 - -8 sigprocmask_set 14 - -14 sigwaitinfo 23 - -23 record_signal 23 - -23 __GI_sigwaitinfo 23 - -23 sigtimedwait 25 - -25 builtin_trap 417 392 -25 __GI_sigtimedwait 25 - -25 hush_main 1003 965 -38 check_and_run_traps 263 217 -46 __rt_sigtimedwait 52 - -52 reset_traps_to_defaults 213 126 -87 init_sigmasks 198 - -198 builtin_read 536 197 -339 ------------------------------------------------------------------------------ (add/remove: 5/10 grow/shrink: 2/7 up/down: 371/-934) Total: -563 bytes text data bss dec hex filename 903075 936 17736 921747 e1093 busybox_old 902547 936 17736 921219 e0e83 busybox_unstripped Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--shell/hush.c510
1 files changed, 278 insertions, 232 deletions
diff --git a/shell/hush.c b/shell/hush.c
index 509bd41..b2c3a75 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -106,6 +106,10 @@
# define PIPE_BUF 4096 /* amount of buffering in a pipe */
#endif
+/* Not every libc has sighandler_t. Fix it */
+typedef void (*hush_sighandler_t)(int);
+#define sighandler_t hush_sighandler_t
+
//config:config HUSH
//config: bool "hush"
//config: default y
@@ -764,7 +768,6 @@ struct globals {
smalluint last_exitcode;
/* are global_argv and global_argv[1..n] malloced? (note: not [0]) */
smalluint global_args_malloced;
- smalluint inherited_set_is_saved;
/* how many non-NULL argv's we have. NB: $# + 1 */
int global_argc;
char **global_argv;
@@ -794,21 +797,20 @@ struct globals {
#endif
/* Which signals have non-DFL handler (even with no traps set)?
* Set at the start to:
- * (SIGQUIT + maybe SPECIAL_INTERACTIVE_SIGS + maybe SPECIAL_JOB_SIGS)
+ * (SIGQUIT + maybe SPECIAL_INTERACTIVE_SIGS + maybe SPECIAL_JOBSTOP_SIGS)
* SPECIAL_INTERACTIVE_SIGS are cleared after fork.
+ * The rest is cleared right before execv syscalls.
* Other than these two times, never modified.
*/
unsigned special_sig_mask;
+#if ENABLE_HUSH_JOB
+ unsigned fatal_sig_mask;
+#define G_fatal_sig_mask G.fatal_sig_mask
+#else
+#define G_fatal_sig_mask 0
+#endif
char **traps; /* char *traps[NSIG] */
- /* Signal mask on the entry to the (top-level) shell. Never modified. */
- sigset_t inherited_set;
- /* Starts equal to inherited_set,
- * but shell-special signals are added and SIGCHLD is removed.
- * When a trap is set/cleared, signal is added to/removed from it:
- */
- sigset_t blocked_set;
- /* Used by read() */
- sigset_t detected_set;
+ sigset_t pending_set;
#if HUSH_DEBUG
unsigned long memleak_value;
int debug_indent;
@@ -1337,8 +1339,8 @@ static void restore_G_args(save_arg_t *sv, char **argv)
* (What happens to signals which are IGN on shell start?)
* (What happens with signal mask on shell start?)
*
- * Implementation in hush
- * ======================
+ * Old implementation
+ * ==================
* We use in-kernel pending signal mask to determine which signals were sent.
* We block all signals which we don't want to take action immediately,
* i.e. we block all signals which need to have special handling as described
@@ -1369,6 +1371,49 @@ static void restore_G_args(save_arg_t *sv, char **argv)
* Standard says "When a subshell is entered, traps that are not being ignored
* are set to the default actions". bash interprets it so that traps which
* are set to '' (ignore) are NOT reset to defaults. We do the same.
+ *
+ * Problem: the above approach makes it unwieldy to catch signals while
+ * we are in read builtin, of while we read commands from stdin:
+ * masked signals are not visible!
+ *
+ * New implementation
+ * ==================
+ * We record each signal we are interested in by installing signal handler
+ * for them - a bit like emulating kernel pending signal mask in userspace.
+ * We are interested in: signals which need to have special handling
+ * as described above, and all signals which have traps set.
+ * Signals are rocorded in pending_set.
+ * After each pipe execution, we extract any pending signals
+ * and act on them.
+ *
+ * unsigned special_sig_mask: a mask of shell-special signals.
+ * unsigned fatal_sig_mask: a mask of signals on which we restore tty pgrp.
+ * char *traps[sig] if trap for sig is set (even if it's '').
+ * sigset_t pending_set: set of sigs we received.
+ *
+ * "trap - SIGxxx":
+ * if sig is in special_sig_mask, set handler back to:
+ * record_pending_signo, or to IGN if it's a tty stop signal
+ * if sig is in fatal_sig_mask, set handler back to sigexit.
+ * else: set handler back to SIG_DFL
+ * "trap 'cmd' SIGxxx":
+ * set handler to record_pending_signo.
+ * "trap '' SIGxxx":
+ * set handler to SIG_IGN.
+ * after [v]fork, if we plan to be a shell:
+ * set signals with special interactive handling to SIG_DFL
+ * (because child shell is not interactive),
+ * unset all traps except '' (note: regardless of child shell's type - {}, (), etc)
+ * after [v]fork, if we plan to exec:
+ * POSIX says fork clears pending signal mask in child - no need to clear it.
+ *
+ * To make wait builtin interruptible, we handle SIGCHLD as special signal,
+ * otherwise (if we leave it SIG_DFL) sigsuspend in wait builtin will not wake up on it.
+ *
+ * Note (compat):
+ * Standard says "When a subshell is entered, traps that are not being ignored
+ * are set to the default actions". bash interprets it so that traps which
+ * are set to '' (ignore) are NOT reset to defaults. We do the same.
*/
enum {
SPECIAL_INTERACTIVE_SIGS = 0
@@ -1376,26 +1421,25 @@ enum {
| (1 << SIGINT)
| (1 << SIGHUP)
,
- SPECIAL_JOB_SIGS = 0
+ SPECIAL_JOBSTOP_SIGS = 0
#if ENABLE_HUSH_JOB
| (1 << SIGTTIN)
| (1 << SIGTTOU)
| (1 << SIGTSTP)
#endif
+ ,
};
-static void sigprocmask_set(sigset_t *set)
+static void record_pending_signo(int sig)
{
- sigprocmask(SIG_SETMASK, set, NULL);
-}
-
+ sigaddset(&G.pending_set, sig);
#if ENABLE_HUSH_FAST
-static void SIGCHLD_handler(int sig UNUSED_PARAM)
-{
- G.count_SIGCHLD++;
+ if (sig == SIGCHLD) {
+ 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
@@ -1433,6 +1477,31 @@ static void sigexit(int sig)
#endif
+static sighandler_t pick_sighandler(unsigned sig)
+{
+ sighandler_t handler = SIG_DFL;
+ if (sig < sizeof(unsigned)*8) {
+ unsigned sigmask = (1 << sig);
+
+#if ENABLE_HUSH_JOB
+ /* sig is fatal? */
+ if (G_fatal_sig_mask & sigmask)
+ handler = sigexit;
+#endif
+ /* sig has special handling? */
+ else if (G.special_sig_mask & sigmask)
+ handler = record_pending_signo;
+ /* TTIN/TTOU/TSTS can't be set to record_pending_signo
+ * in order to ignore them: they will be raised
+ * in an endless loop then when we try to do some
+ * terminal ioctls! We do nave to _ignore_ these.
+ */
+ if (SPECIAL_JOBSTOP_SIGS & sigmask)
+ handler = SIG_IGN;
+ }
+ return handler;
+}
+
/* Restores tty foreground process group, and exits. */
static void hush_exit(int exitcode) NORETURN;
static void hush_exit(int exitcode)
@@ -1478,39 +1547,30 @@ static void hush_exit(int exitcode)
}
-static int check_and_run_traps(int sig)
+//TODO: return a mask of ALL handled sigs?
+static int check_and_run_traps(void)
{
- /* I want it in rodata, not in bss.
- * gcc 4.2.1 puts it in rodata only if it has { 0, 0 }
- * initializer. But other compilers may still use bss.
- * TODO: find more portable solution.
- */
- static const struct timespec zero_timespec = { 0, 0 };
- smalluint save_rcode;
int last_sig = 0;
- if (sig)
- goto got_sig;
-
while (1) {
- if (!sigisemptyset(&G.detected_set)) {
- sig = 0;
- do {
- sig++;
- if (sigismember(&G.detected_set, sig)) {
- sigdelset(&G.detected_set, sig);
- goto got_sig;
- }
- } while (sig < NSIG);
- }
+ int sig;
- sig = sigtimedwait(&G.blocked_set, NULL, &zero_timespec);
- if (sig <= 0)
+ if (sigisemptyset(&G.pending_set))
break;
+ sig = 0;
+ do {
+ sig++;
+ if (sigismember(&G.pending_set, sig)) {
+ sigdelset(&G.pending_set, sig);
+ goto got_sig;
+ }
+ } while (sig < NSIG);
+ break;
got_sig:
if (G.traps && G.traps[sig]) {
if (G.traps[sig][0]) {
/* We have user-defined handler */
+ smalluint save_rcode;
char *argv[3];
/* argv[0] is unused */
argv[1] = G.traps[sig];
@@ -1524,12 +1584,6 @@ static int check_and_run_traps(int sig)
}
/* not a trap: special action */
switch (sig) {
-#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');
@@ -1551,11 +1605,21 @@ static int check_and_run_traps(int sig)
sigexit(SIGHUP);
}
#endif
+#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);
+ /* Note:
+ * We dont do 'last_sig = sig' here -> NOT returning this sig.
+ * This simplifies wait builtin a bit.
+ */
+ break;
+#endif
default: /* ignored: */
/* SIGTERM, SIGQUIT, SIGTTIN, SIGTTOU, SIGTSTP */
- /* note:
- * we dont do 'last_sig = sig' here -> NOT returning this sig.
- * example: wait is not interrupted by TERM
+ /* Note:
+ * We dont do 'last_sig = sig' here -> NOT returning this sig.
+ * Example: wait is not interrupted by TERM
* in interactive shell, because TERM is ignored.
*/
break;
@@ -1948,7 +2012,7 @@ static void get_user_input(struct in_str *i)
* only after <Enter>. (^C will work) */
r = read_line_input(G.line_input_state, prompt_str, G.user_input_buf, CONFIG_FEATURE_EDITING_MAX_LEN-1, /*timeout*/ -1);
/* catch *SIGINT* etc (^C is handled by read_line_input) */
- check_and_run_traps(0);
+ check_and_run_traps();
} while (r == 0 || G.flag_SIGINT); /* repeat if ^C or SIGINT */
i->eof_flag = (r < 0);
if (i->eof_flag) { /* EOF/error detected */
@@ -1964,7 +2028,7 @@ static void get_user_input(struct in_str *i)
* $ <[enter], repeatedly...>
* Without check_and_run_traps, handler never runs.
*/
- check_and_run_traps(0);
+ check_and_run_traps();
fputs(prompt_str, stdout);
}
fflush_all();
@@ -5368,6 +5432,25 @@ void re_execute_shell(char ***to_free, const char *s,
char *g_argv0, char **g_argv,
char **builtin_argv) NORETURN;
+static void switch_off_special_sigs(unsigned mask)
+{
+ unsigned sig = 0;
+ while ((mask >>= 1) != 0) {
+ sig++;
+ if (!(mask & 1))
+ continue;
+ if (G.traps) {
+ if (G.traps[sig] && !G.traps[sig][0])
+ /* trap is '', has to remain SIG_IGN */
+ continue;
+ free(G.traps[sig]);
+ G.traps[sig] = NULL;
+ }
+ /* We are here only if no trap or trap was not '' */
+ signal(sig, SIG_DFL);
+ }
+}
+
static void reset_traps_to_defaults(void)
{
/* This function is always called in a child shell
@@ -5381,44 +5464,35 @@ static void reset_traps_to_defaults(void)
* Testcase: (while :; do :; done) + ^Z should background.
* Same goes for SIGTERM, SIGHUP, SIGINT.
*/
- if (!G.traps && !(G.special_sig_mask & SPECIAL_INTERACTIVE_SIGS))
- return; /* already no traps and no SPECIAL_INTERACTIVE_SIGS */
-
- /* Switching off SPECIAL_INTERACTIVE_SIGS.
- * Stupid. It can be done with *single* &= op, but we can't use
- * the fact that G.blocked_set is implemented as a bitmask
- * in libc... */
- mask = SPECIAL_INTERACTIVE_SIGS;
- sig = 0;
- while ((mask >>= 1) != 0) {
- sig++;
- if (mask & 1) {
- /* Careful. Only if no trap or trap is not "" */
- if (!G.traps || !G.traps[sig] || G.traps[sig][0])
- sigdelset(&G.blocked_set, sig);
- }
- }
- /* Our homegrown sig mask is saner to work with :) */
+ mask = (G.special_sig_mask & SPECIAL_INTERACTIVE_SIGS) | G_fatal_sig_mask;
+ if (!G.traps && !mask)
+ return; /* already no traps and no special sigs */
+
+ /* Switch off special sigs */
+ switch_off_special_sigs(mask);
+#if ENABLE_HUSH_JOB
+ G_fatal_sig_mask = 0;
+#endif
G.special_sig_mask &= ~SPECIAL_INTERACTIVE_SIGS;
+ /* SIGQUIT and maybe SPECIAL_JOBSTOP_SIGS remain set in G.special_sig_mask */
- /* Resetting all traps to default except empty ones */
- mask = G.special_sig_mask;
- if (G.traps) for (sig = 0; sig < NSIG; sig++, mask >>= 1) {
- if (!G.traps[sig] || !G.traps[sig][0])
- continue;
+ if (!G.traps)
+ return;
+
+ /* Reset all sigs to default except ones with empty traps */
+ for (sig = 0; sig < NSIG; sig++) {
+ if (!G.traps[sig])
+ continue; /* no trap: nothing to do */
+ if (!G.traps[sig][0])
+ continue; /* empty trap: has to remain SIG_IGN */
+ /* sig has non-empty trap, reset it: */
free(G.traps[sig]);
G.traps[sig] = NULL;
- /* There is no signal for 0 (EXIT) */
+ /* There is no signal for trap 0 (EXIT) */
if (sig == 0)
continue;
- /* There was a trap handler, we just removed it.
- * But if sig still has non-DFL handling,
- * we should not unblock the sig. */
- if (mask & 1)
- continue;
- sigdelset(&G.blocked_set, sig);
+ signal(sig, pick_sighandler(sig));
}
- sigprocmask_set(&G.blocked_set);
}
#else /* !BB_MMU */
@@ -5463,6 +5537,7 @@ static void re_execute_shell(char ***to_free, const char *s,
for (sig = 1; sig < NSIG; sig++) {
if (G.traps[sig] && !G.traps[sig][0])
empty_trap_mask |= 1LL << sig;
+///vda: optimize
}
}
@@ -5548,7 +5623,7 @@ static void re_execute_shell(char ***to_free, const char *s,
do_exec:
debug_printf_exec("re_execute_shell pid:%d cmd:'%s'\n", getpid(), s);
- sigprocmask_set(&G.inherited_set);
+ switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
execve(bb_busybox_exec_path, argv, pp);
/* Fallback. Useful for init=/bin/hush usage etc */
if (argv[0][0] == '/')
@@ -6202,7 +6277,7 @@ static void execvp_or_die(char **argv) NORETURN;
static void execvp_or_die(char **argv)
{
debug_printf_exec("execing '%s'\n", argv[0]);
- sigprocmask_set(&G.inherited_set);
+ switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
execvp(argv[0], argv);
bb_perror_msg("can't execute '%s'", argv[0]);
_exit(127); /* bash compat */
@@ -6334,7 +6409,7 @@ static NOINLINE void pseudo_exec_argv(nommu_save_t *nommu_save,
# endif
/* Re-exec ourselves */
debug_printf_exec("re-execing applet '%s'\n", argv[0]);
- sigprocmask_set(&G.inherited_set);
+ switch_off_special_sigs(G.special_sig_mask & SPECIAL_JOBSTOP_SIGS);
execv(bb_busybox_exec_path, argv);
/* If they called chroot or otherwise made the binary no longer
* executable, fall through */
@@ -7033,9 +7108,6 @@ static NOINLINE int run_pipe(struct pipe *pi)
if (setup_redirects(command, NULL))
_exit(1);
- /* Restore default handlers just prior to exec */
- /*signal(SIGCHLD, SIG_DFL); - so far we don't have any handlers */
-
/* Stores to nommu_save list of env vars putenv'ed
* (NOMMU, on MMU we don't need that) */
/* cast away volatility... */
@@ -7313,7 +7385,7 @@ static int run_list(struct pipe *pi)
* and we don't need to wait for anything. */
G.last_exitcode = rcode;
debug_printf_exec(": builtin/func exitcode %d\n", rcode);
- check_and_run_traps(0);
+ check_and_run_traps();
#if ENABLE_HUSH_LOOPS
/* Was it "break" or "continue"? */
if (G.flag_break_continue) {
@@ -7345,7 +7417,7 @@ static int run_list(struct pipe *pi)
/* even bash 3.2 doesn't do that well with nested bg:
* try "{ { sleep 10; echo DEEP; } & echo HERE; } &".
* I'm NOT treating inner &'s as jobs */
- check_and_run_traps(0);
+ check_and_run_traps();
#if ENABLE_HUSH_JOB
if (G.run_list_level == 1)
insert_bg_job(pi);
@@ -7360,13 +7432,13 @@ static int run_list(struct pipe *pi)
/* Waits for completion, then fg's main shell */
rcode = checkjobs_and_fg_shell(pi);
debug_printf_exec(": checkjobs_and_fg_shell exitcode %d\n", rcode);
- check_and_run_traps(0);
+ check_and_run_traps();
} else
#endif
{ /* This one just waits for completion */
rcode = checkjobs(pi);
debug_printf_exec(": checkjobs exitcode %d\n", rcode);
- check_and_run_traps(0);
+ check_and_run_traps();
}
G.last_exitcode = rcode;
}
@@ -7437,58 +7509,61 @@ static int run_and_free_list(struct pipe *pi)
}
+static void install_sighandlers(unsigned mask)
+{
+ sighandler_t old_handler;
+ unsigned sig = 0;
+ while ((mask >>= 1) != 0) {
+ sig++;
+ if (!(mask & 1))
+ continue;
+ old_handler = signal(sig, pick_sighandler(sig));
+ /* POSIX allows shell to re-enable SIGCHLD
+ * even if it was SIG_IGN on entry.
+ * Therefore we skip IGN check for it:
+ */
+ if (sig == SIGCHLD)
+ continue;
+ if (old_handler == SIG_IGN) {
+ /* oops... restore back to IGN, and record this fact */
+ signal(sig, old_handler);
+ if (!G.traps)
+ G.traps = xzalloc(sizeof(G.traps[0]) * NSIG);
+ free(G.traps[sig]);
+ G.traps[sig] = xzalloc(1); /* == xstrdup(""); */
+ }
+ }
+}
+
/* Called a few times only (or even once if "sh -c") */
-static void init_sigmasks(void)
+static void install_special_sighandlers(void)
{
- unsigned sig;
unsigned mask;
- /* POSIX allows shell to re-enable SIGCHLD
- * even if it was SIG_IGN on entry */
- if (!G.inherited_set_is_saved) {
-#if ENABLE_HUSH_FAST
- signal(SIGCHLD, SIGCHLD_handler);
-#else
- signal(SIGCHLD, SIG_DFL);
-#endif
- sigprocmask(SIG_SETMASK, NULL, &G.blocked_set);
- G.inherited_set = G.blocked_set;
- }
+ if (G.special_sig_mask != 0)
+ return;
/* Which signals are shell-special? */
- mask = (1 << SIGQUIT);
+ mask = (1 << SIGQUIT) | (1 << SIGCHLD);
if (G_interactive_fd) {
mask |= SPECIAL_INTERACTIVE_SIGS;
if (G_saved_tty_pgrp) /* we have ctty, job control sigs work */
- mask |= SPECIAL_JOB_SIGS;
+ mask |= SPECIAL_JOBSTOP_SIGS;
}
G.special_sig_mask = mask;
- /* Block them. And unblock SIGCHLD */
- sig = 0;
- while ((mask >>= 1) != 0) {
- sig++;
- if (mask & 1)
- sigaddset(&G.blocked_set, sig);
- }
- sigdelset(&G.blocked_set, SIGCHLD);
-
- if (memcmp(&G.inherited_set, &G.blocked_set, sizeof(G.inherited_set)) != 0)
- sigprocmask_set(&G.blocked_set);
-
- G.inherited_set_is_saved = 1;
+ install_sighandlers(mask);
}
#if ENABLE_HUSH_JOB
/* helper */
/* Set handlers to restore tty pgrp and exit */
-static void set_fatal_handlers_to_sigexit(void)
+static void install_fatal_sighandlers(void)
{
- void (*handler)(int);
- unsigned fatal_sigs, sig;
+ unsigned mask;
/* We will restore tty pgrp on these signals */
- fatal_sigs = 0
+ mask = 0
+ (1 << SIGILL ) * HUSH_DEBUG
+ (1 << SIGFPE ) * HUSH_DEBUG
+ (1 << SIGBUS ) * HUSH_DEBUG
@@ -7505,22 +7580,13 @@ static void set_fatal_handlers_to_sigexit(void)
/*+ (1 << SIGTERM)*/
/*+ (1 << SIGINT )*/
;
-
- /* special_sig_mask'ed signals are, well, masked,
+ /* special_sig_mask'ed signals are set to record_pending_signo
* no need to set handler for them.
*/
- fatal_sigs &= ~G.special_sig_mask;
+ /*mask &= ~G.special_sig_mask; - they never overlap */
+ G_fatal_sig_mask = mask;
- /* For each sig in fatal_sigs... */
- sig = 0;
- while ((fatal_sigs >>= 1) != 0) {
- sig++;
- if (!(fatal_sigs & 1))
- continue;
- handler = signal(sig, sigexit);
- if (handler == SIG_IGN) /* oops... restore back to IGN! */
- signal(sig, handler);
- }
+ install_sighandlers(mask);
}
#endif
@@ -7682,10 +7748,11 @@ int hush_main(int argc, char **argv)
}
/* Shell is non-interactive at first. We need to call
- * init_sigmasks() if we are going to execute "sh <script>",
+ * install_special_sighandlers() if we are going to execute "sh <script>",
* "sh -c <cmds>" or login shell's /etc/profile and friends.
- * If we later decide that we are interactive, we run init_sigmasks()
+ * If we later decide that we are interactive, we run install_special_sighandlers()
* in order to intercept (more) signals.
+//FIXME: re-running is currently most likely broken, it's a no-op.
*/
/* Parse options */
@@ -7724,7 +7791,7 @@ int hush_main(int argc, char **argv)
/* -c 'builtin' [BARGV...] "" ARG0 [ARG1...] */
const struct built_in_command *x;
- init_sigmasks();
+ install_special_sighandlers();
x = find_builtin(optarg);
if (x) { /* paranoia */
G.global_argc -= builtin_argc; /* skip [BARGV...] "" */
@@ -7741,7 +7808,7 @@ int hush_main(int argc, char **argv)
G.global_argv[0] = argv[0];
G.global_argc++;
} /* else -c 'script' ARG0 [ARG1...]: $0 is ARG0 */
- init_sigmasks();
+ install_special_sighandlers();
parse_and_run_string(optarg);
goto final_return;
case 'i':
@@ -7773,15 +7840,15 @@ int hush_main(int argc, char **argv)
empty_trap_mask = bb_strtoull(optarg, &optarg, 16);
if (empty_trap_mask != 0) {
int sig;
- init_sigmasks();
+ install_special_sighandlers();
G.traps = xzalloc(sizeof(G.traps[0]) * NSIG);
for (sig = 1; sig < NSIG; sig++) {
+///vda: fixme: more efficient code
if (empty_trap_mask & (1LL << sig)) {
G.traps[sig] = xzalloc(1); /* == xstrdup(""); */
- sigaddset(&G.blocked_set, sig);
+ signal(sig, SIG_IGN);
}
}
- sigprocmask_set(&G.blocked_set);
}
# if ENABLE_HUSH_LOOPS
optarg++;
@@ -7831,7 +7898,7 @@ int hush_main(int argc, char **argv)
input = fopen_for_read("/etc/profile");
if (input != NULL) {
close_on_exec_on(fileno(input));
- init_sigmasks();
+ install_special_sighandlers();
parse_and_run_file(input);
fclose(input);
}
@@ -7856,7 +7923,7 @@ int hush_main(int argc, char **argv)
G.global_argc = argc - optind;
input = xfopen_for_read(argv[optind]);
close_on_exec_on(fileno(input));
- init_sigmasks();
+ install_special_sighandlers();
parse_and_run_file(input);
#if ENABLE_FEATURE_CLEAN_UP
fclose(input);
@@ -7865,7 +7932,7 @@ int hush_main(int argc, char **argv)
}
/* Up to here, shell was non-interactive. Now it may become one.
- * NB: don't forget to (re)run init_sigmasks() as needed.
+ * NB: don't forget to (re)run install_special_sighandlers() as needed.
*/
/* A shell is interactive if the '-i' flag was given,
@@ -7918,11 +7985,11 @@ int hush_main(int argc, char **argv)
}
/* Block some signals */
- init_sigmasks();
+ install_special_sighandlers();
if (G_saved_tty_pgrp) {
/* Set other signals to restore saved_tty_pgrp */
- set_fatal_handlers_to_sigexit();
+ install_fatal_sighandlers();
/* Put ourselves in our own process group
* (bash, too, does this only if ctty is available) */
bb_setpgrp(); /* is the same as setpgid(our_pid, our_pid); */
@@ -7933,7 +8000,7 @@ int hush_main(int argc, char **argv)
* (we reset die_sleep = 0 whereever we [v]fork) */
enable_restore_tty_pgrp_on_exit(); /* sets die_sleep = -1 */
} else {
- init_sigmasks();
+ install_special_sighandlers();
}
#elif ENABLE_HUSH_INTERACTIVE
/* No job control compiled in, only prompt/line editing */
@@ -7950,10 +8017,10 @@ int hush_main(int argc, char **argv)
if (G_interactive_fd) {
close_on_exec_on(G_interactive_fd);
}
- init_sigmasks();
+ install_special_sighandlers();
#else
/* We have interactiveness code disabled */
- init_sigmasks();
+ install_special_sighandlers();
#endif
/* bash:
* if interactive but not a login shell, sources ~/.bashrc
@@ -8087,7 +8154,7 @@ static int FAST_FUNC builtin_exec(char **argv)
tcsetpgrp(G_interactive_fd, G_saved_tty_pgrp);
/* TODO: if exec fails, bash does NOT exit! We do.
- * We'll need to undo sigprocmask (it's inside execvp_or_die)
+ * We'll need to undo trap cleanup (it's inside execvp_or_die)
* and tcsetpgrp, and this is inherently racy.
*/
execvp_or_die(argv);
@@ -8284,6 +8351,8 @@ static int FAST_FUNC builtin_trap(char **argv)
process_sig_list:
ret = EXIT_SUCCESS;
while (*argv) {
+ sighandler_t handler;
+
sig = get_signum(*argv++);
if (sig < 0 || sig >= NSIG) {
ret = EXIT_FAILURE;
@@ -8302,18 +8371,13 @@ static int FAST_FUNC builtin_trap(char **argv)
if (sig == 0)
continue;
- if (new_cmd) {
- sigaddset(&G.blocked_set, sig);
- } else {
- /* There was a trap handler, we are removing it
- * (if sig has non-DFL handling,
- * we don't need to do anything) */
- if (sig < sizeof(G.special_sig_mask)*8 && (G.special_sig_mask & (1 << sig)))
- continue;
- sigdelset(&G.blocked_set, sig);
- }
+ if (new_cmd)
+ handler = (new_cmd[0] ? record_pending_signo : SIG_IGN);
+ else
+ /* We are removing trap handler */
+ handler = pick_sighandler(sig);
+ signal(sig, handler);
}
- sigprocmask_set(&G.blocked_set);
return ret;
}
@@ -8535,11 +8599,6 @@ static int FAST_FUNC builtin_pwd(char **argv UNUSED_PARAM)
* if it has non-empty trap:
* - executes trap and returns to read;
*/
-/* helper */
-static void record_signal(int sig)
-{
- sigaddset(&G.detected_set, sig);
-}
static int FAST_FUNC builtin_read(char **argv)
{
const char *r;
@@ -8549,7 +8608,6 @@ static int FAST_FUNC builtin_read(char **argv)
char *opt_u = NULL;
const char *ifs;
int read_flags;
- sigset_t saved_blkd_set;
/* "!": do not abort on errors.
* Option string must start with "sr" to match BUILTIN_READ_xxx
@@ -8561,41 +8619,6 @@ static int FAST_FUNC builtin_read(char **argv)
ifs = get_local_var_value("IFS"); /* can be NULL */
again:
- /* We need to temporarily unblock and record signals around read */
-
- saved_blkd_set = G.blocked_set;
- {
- unsigned sig;
- struct sigaction sa, old_sa;
-
- memset(&sa, 0, sizeof(sa));
- sigfillset(&sa.sa_mask);
- sa.sa_flags = SA_RESTART;
- sa.sa_handler = record_signal;
-
- sig = 0;
- do {
- sig++;
- if (sigismember(&G.blocked_set, sig)) {
- char *sig_trap = (G.traps && G.traps[sig]) ? G.traps[sig] : NULL;
- /* If has a nonempty trap... */
- if ((sig_trap && sig_trap[0])
- /* ...or has no trap and is SIGINT or SIGHUP */
- || (!sig_trap && (sig == SIGINT || sig == SIGHUP))
- ) {
- sigaction(sig, &sa, &old_sa);
- if (old_sa.sa_handler == SIG_IGN) /* oops... restore back to IGN! */
- sigaction_set(sig, &old_sa);
- else
- sigdelset(&G.blocked_set, sig);
- }
- }
- } while (sig < NSIG-1);
- }
-
- if (memcmp(&saved_blkd_set, &G.blocked_set, sizeof(saved_blkd_set)) != 0)
- sigprocmask_set(&G.blocked_set);
-
r = shell_builtin_read(set_local_var_from_halves,
argv,
ifs,
@@ -8606,13 +8629,8 @@ static int FAST_FUNC builtin_read(char **argv)
opt_u
);
- if (memcmp(&saved_blkd_set, &G.blocked_set, sizeof(saved_blkd_set)) != 0) {
- G.blocked_set = saved_blkd_set;
- sigprocmask_set(&G.blocked_set);
- }
-
if ((uintptr_t)r == 1 && errno == EINTR) {
- unsigned sig = check_and_run_traps(0);
+ unsigned sig = check_and_run_traps();
if (sig && sig != SIGINT)
goto again;
}
@@ -8849,7 +8867,7 @@ static int FAST_FUNC builtin_unset(char **argv)
static int FAST_FUNC builtin_wait(char **argv)
{
int ret = EXIT_SUCCESS;
- int status, sig;
+ int status;
argv = skip_dash_dash(argv);
if (argv[0] == NULL) {
@@ -8869,25 +8887,53 @@ static int FAST_FUNC builtin_wait(char **argv)
* ^C <-- after ~4 sec from keyboard
* $
*/
- sigaddset(&G.blocked_set, SIGCHLD);
- sigprocmask_set(&G.blocked_set);
while (1) {
- checkjobs(NULL);
- if (errno == ECHILD)
+ int sig;
+ sigset_t oldset, allsigs;
+
+ /* waitpid is not interruptible by SA_RESTARTed
+ * signals which we use. Thus, this ugly dance:
+ */
+
+ /* Make sure possible SIGCHLD is stored in kernel's
+ * pending signal mask before we call waitpid.
+ * Or else we may race with SIGCHLD, lose it,
+ * and get stuck in sigwaitinfo...
+ */
+ sigfillset(&allsigs);
+ sigprocmask(SIG_SETMASK, &allsigs, &oldset);
+
+ if (!sigisemptyset(&G.pending_set)) {
+ /* Crap! we raced with some signal! */
+ // sig = 0;
+ goto restore;
+ }
+
+ checkjobs(NULL); /* waitpid(WNOHANG) inside */
+ if (errno == ECHILD) {
+ sigprocmask(SIG_SETMASK, &oldset, NULL);
+ break;
+ }
+
+ /* Wait for SIGCHLD or any other signal */
+ //sig = sigwaitinfo(&allsigs, NULL);
+ /* It is vitally important for sigsuspend that SIGCHLD has non-DFL handler! */
+ /* Note: sigsuspend invokes signal handler */
+ sigsuspend(&oldset);
+ restore:
+ sigprocmask(SIG_SETMASK, &oldset, NULL);
+
+ /* So, did we get a signal? */
+ //if (sig > 0)
+ // raise(sig); /* run handler */
+ sig = check_and_run_traps();
+ if (sig /*&& sig != SIGCHLD - always true */) {
+ /* see note 2 */
+ ret = 128 + sig;
break;
- /* Wait for SIGCHLD or any other signal of interest */
- /* sigtimedwait with infinite timeout: */
- sig = sigwaitinfo(&G.blocked_set, NULL);
- if (sig > 0) {
- sig = check_and_run_traps(sig);
- if (sig && sig != SIGCHLD) { /* see note 2 */
- ret = 128 + sig;
- break;
- }
}
+ /* SIGCHLD, or no signal, or ignored one, such as SIGQUIT. Repeat */
}
- sigdelset(&G.blocked_set, SIGCHLD);
- sigprocmask_set(&G.blocked_set);
return ret;
}