svn commit: trunk/busybox/shell
vda at busybox.net
vda at busybox.net
Wed Dec 3 10:36:26 UTC 2008
Author: vda
Date: 2008-12-03 02:36:26 -0800 (Wed, 03 Dec 2008)
New Revision: 24239
Log:
ash: finally installed it as /bin/sh on my machine.
some breakage noticed, the most dire is mishandled ^C.
fixing it.
function old new delta
blocking_wait_with_raise_on_sig - 40 +40
waitforjob 85 100 +15
setsignal 280 278 -2
evalvar 1376 1374 -2
waitcmd 186 182 -4
dowait 350 316 -34
redirect 1231 1185 -46
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/5 up/down: 55/-88) Total: -33 bytes
Modified:
trunk/busybox/shell/ash.c
Changeset:
Modified: trunk/busybox/shell/ash.c
===================================================================
--- trunk/busybox/shell/ash.c 2008-12-03 09:02:46 UTC (rev 24238)
+++ trunk/busybox/shell/ash.c 2008-12-03 10:36:26 UTC (rev 24239)
@@ -201,14 +201,13 @@
/*
* Sigmode records the current value of the signal handlers for the various
* modes. A value of zero means that the current handler is not known.
- * S_HARD_IGN indicates that the signal was ignored on entry to the shell,
+ * S_HARD_IGN indicates that the signal was ignored on entry to the shell.
*/
char sigmode[NSIG - 1];
-#define S_DFL 1 /* default signal handling (SIG_DFL) */
-#define S_CATCH 2 /* signal is caught */
-#define S_IGN 3 /* signal is ignored (SIG_IGN) */
+#define S_DFL 1 /* default signal handling (SIG_DFL) */
+#define S_CATCH 2 /* signal is caught */
+#define S_IGN 3 /* signal is ignored (SIG_IGN) */
#define S_HARD_IGN 4 /* signal is ignored permenantly */
-#define S_RESET 5 /* temporary - to reset a hard ignored sig */
/* indicates specified signal received */
char gotsig[NSIG - 1]; /* offset by 1: "signal" 0 is meaningless */
@@ -368,7 +367,7 @@
} while (0)
/*
- * Ignore a signal. Only one usage site - in forkchild()
+ * Ignore a signal. Avoids unnecessary system calls.
*/
static void
ignoresig(int signo)
@@ -3295,81 +3294,90 @@
static void
setsignal(int signo)
{
- int action;
- char *t, tsig;
+ char *t;
+ char cur_act, new_act;
struct sigaction act;
t = trap[signo];
- action = S_IGN;
- if (t == NULL)
- action = S_DFL;
- else if (*t != '\0')
- action = S_CATCH;
- if (rootshell && action == S_DFL) {
+ new_act = S_DFL;
+ if (t != NULL) { /* trap for this sig is set */
+ new_act = S_CATCH;
+ if (t[0] == '\0') /* trap is "": ignore this sig */
+ new_act = S_IGN;
+ }
+
+ if (rootshell && new_act == S_DFL) {
switch (signo) {
case SIGINT:
if (iflag || minusc || sflag == 0)
- action = S_CATCH;
+ new_act = S_CATCH;
break;
case SIGQUIT:
#if DEBUG
if (debug)
break;
#endif
- /* FALLTHROUGH */
+ /* man bash:
+ * "In all cases, bash ignores SIGQUIT. Non-builtin
+ * commands run by bash have signal handlers
+ * set to the values inherited by the shell
+ * from its parent". */
+ new_act = S_IGN;
+ break;
case SIGTERM:
if (iflag)
- action = S_IGN;
+ new_act = S_IGN;
break;
#if JOBS
case SIGTSTP:
case SIGTTOU:
if (mflag)
- action = S_IGN;
+ new_act = S_IGN;
break;
#endif
}
}
+//TODO: if !rootshell, we reset SIGQUIT to DFL,
+//whereas we have to restore it to what shell got on entry
+//from the parent. See comment above
t = &sigmode[signo - 1];
- tsig = *t;
- if (tsig == 0) {
- /*
- * current setting unknown
- */
- if (sigaction(signo, NULL, &act) == -1) {
- /*
- * Pretend it worked; maybe we should give a warning
- * here, but other shells don't. We don't alter
- * sigmode, so that we retry every time.
- */
+ cur_act = *t;
+ if (cur_act == 0) {
+ /* current setting is not yet known */
+ if (sigaction(signo, NULL, &act)) {
+ /* pretend it worked; maybe we should give a warning,
+ * but other shells don't. We don't alter sigmode,
+ * so we retry every time.
+ * btw, in Linux it never fails. --vda */
return;
}
- tsig = S_RESET; /* force to be set */
if (act.sa_handler == SIG_IGN) {
- tsig = S_HARD_IGN;
+ cur_act = S_HARD_IGN;
if (mflag
&& (signo == SIGTSTP || signo == SIGTTIN || signo == SIGTTOU)
) {
- tsig = S_IGN; /* don't hard ignore these */
+ cur_act = S_IGN; /* don't hard ignore these */
}
}
}
- if (tsig == S_HARD_IGN || tsig == action)
+ if (cur_act == S_HARD_IGN || cur_act == new_act)
return;
+
act.sa_handler = SIG_DFL;
- switch (action) {
+ switch (new_act) {
case S_CATCH:
act.sa_handler = onsig;
+ act.sa_flags = 0; /* matters only if !DFL and !IGN */
+ sigfillset(&act.sa_mask); /* ditto */
break;
case S_IGN:
act.sa_handler = SIG_IGN;
break;
}
- *t = action;
- act.sa_flags = 0;
- sigfillset(&act.sa_mask);
sigaction_set(signo, &act);
+
+ *t = new_act;
}
/* mode flags for set_curjob */
@@ -3790,15 +3798,9 @@
pid = waitpid(-1, &status,
(doing_jobctl ? (wait_flags | WUNTRACED) : wait_flags));
TRACE(("wait returns pid=%d, status=0x%x\n", pid, status));
+ if (pid <= 0)
+ return pid;
- if (pid <= 0) {
- /* If we were doing blocking wait and (probably) got EINTR,
- * check for pending sigs received while waiting.
- * (NB: can be moved into callers if needed) */
- if (wait_flags == DOWAIT_BLOCK && pendingsig)
- raise_exception(EXSIG);
- return pid;
- }
INT_OFF;
thisjob = NULL;
for (jp = curjob; jp; jp = jp->prev_job) {
@@ -3870,6 +3872,15 @@
return pid;
}
+static int
+blocking_wait_with_raise_on_sig(struct job *job)
+{
+ pid_t pid = dowait(DOWAIT_BLOCK, job);
+ if (pid <= 0 && pendingsig)
+ raise_exception(EXSIG);
+ return pid;
+}
+
#if JOBS
static void
showjob(FILE *out, struct job *jp, int mode)
@@ -3949,7 +3960,7 @@
TRACE(("showjobs(%x) called\n", mode));
- /* If not even one job changed, there is nothing to do */
+ /* Handle all finished jobs */
while (dowait(DOWAIT_NONBLOCK, NULL) > 0)
continue;
@@ -4041,7 +4052,14 @@
jp->waited = 1;
jp = jp->prev_job;
}
- dowait(DOWAIT_BLOCK, NULL);
+ /* man bash:
+ * "When bash is waiting for an asynchronous command via
+ * the wait builtin, the reception of a signal for which a trap
+ * has been set will cause the wait builtin to return immediately
+ * with an exit status greater than 128, immediately after which
+ * the trap is executed."
+ * Do we do it that way? */
+ blocking_wait_with_raise_on_sig(NULL);
}
}
@@ -4061,11 +4079,10 @@
job = getjob(*argv, 0);
/* loop until process terminated or stopped */
while (job->state == JOBRUNNING)
- dowait(DOWAIT_BLOCK, NULL);
+ blocking_wait_with_raise_on_sig(NULL);
job->waited = 1;
retval = getstatus(job);
- repeat:
- ;
+ repeat: ;
} while (*++argv);
ret:
@@ -4492,6 +4509,10 @@
oldlvl = shlvl;
shlvl++;
+ /* man bash: "Non-builtin commands run by bash have signal handlers
+ * set to the values inherited by the shell from its parent".
+ * Do we do it correctly? */
+
closescript();
clear_traps();
#if JOBS
@@ -4504,8 +4525,8 @@
pgrp = getpid();
else
pgrp = jp->ps[0].pid;
- /* This can fail because we are doing it in the parent also */
- (void)setpgid(0, pgrp);
+ /* this can fail because we are doing it in the parent also */
+ setpgid(0, pgrp);
if (mode == FORK_FG)
xtcsetpgrp(ttyfd, pgrp);
setsignal(SIGTSTP);
@@ -4513,6 +4534,8 @@
} else
#endif
if (mode == FORK_BG) {
+ /* man bash: "When job control is not in effect,
+ * asynchronous commands ignore SIGINT and SIGQUIT" */
ignoresig(SIGINT);
ignoresig(SIGQUIT);
if (jp->nprocs == 0) {
@@ -4521,10 +4544,18 @@
ash_msg_and_raise_error("can't open %s", bb_dev_null);
}
}
- if (!oldlvl && iflag) {
- setsignal(SIGINT);
+ if (!oldlvl) {
+ if (iflag) { /* why if iflag only? */
+ setsignal(SIGINT);
+ setsignal(SIGTERM);
+ }
+ /* man bash:
+ * "In all cases, bash ignores SIGQUIT. Non-builtin
+ * commands run by bash have signal handlers
+ * set to the values inherited by the shell
+ * from its parent".
+ * Take care of the second rule: */
setsignal(SIGQUIT);
- setsignal(SIGTERM);
}
for (jp = curjob; jp; jp = jp->prev_job)
freejob(jp);
@@ -4596,12 +4627,12 @@
/*
* Wait for job to finish.
*
- * Under job control we have the problem that while a child process is
- * running interrupts generated by the user are sent to the child but not
- * to the shell. This means that an infinite loop started by an inter-
- * active user may be hard to kill. With job control turned off, an
- * interactive user may place an interactive program inside a loop. If
- * the interactive program catches interrupts, the user doesn't want
+ * Under job control we have the problem that while a child process
+ * is running interrupts generated by the user are sent to the child
+ * but not to the shell. This means that an infinite loop started by
+ * an interactive user may be hard to kill. With job control turned off,
+ * an interactive user may place an interactive program inside a loop.
+ * If the interactive program catches interrupts, the user doesn't want
* these interrupts to also abort the loop. The approach we take here
* is to have the shell ignore interrupt signals while waiting for a
* foreground process to terminate, and then send itself an interrupt
@@ -4619,9 +4650,44 @@
int st;
TRACE(("waitforjob(%%%d) called\n", jobno(jp)));
+
+ INT_OFF;
while (jp->state == JOBRUNNING) {
+ /* In non-interactive shells, we _can_ get
+ * a keyboard signal here and be EINTRed,
+ * but we just loop back, waiting for command to complete.
+ *
+ * man bash:
+ * "If bash is waiting for a command to complete and receives
+ * a signal for which a trap has been set, the trap
+ * will not be executed until the command completes."
+ *
+ * Reality is that even if trap is not set, bash
+ * will not act on the signal until command completes.
+ * Try this. sleep5intoff.c:
+ * #include <signal.h>
+ * #include <unistd.h>
+ * int main() {
+ * sigset_t set;
+ * sigemptyset(&set);
+ * sigaddset(&set, SIGINT);
+ * sigaddset(&set, SIGQUIT);
+ * sigprocmask(SIG_BLOCK, &set, NULL);
+ * sleep(5);
+ * return 0;
+ * }
+ * $ bash -c './sleep5intoff; echo hi'
+ * ^C^C^C^C <--- pressing ^C once a second
+ * $ _
+ * TODO: we do not execute "echo hi" as bash does:
+ * $ bash -c './sleep5intoff; echo hi'
+ * ^\^\^\^\hi <--- pressing ^\ (SIGQUIT)
+ * $ _
+ */
dowait(DOWAIT_BLOCK, jp);
}
+ INT_ON;
+
st = getstatus(jp);
#if JOBS
if (jp->jobctl) {
@@ -4757,12 +4823,10 @@
if (forkshell((struct job *)NULL, (union node *)NULL, FORK_NOJOB) == 0) {
/* child */
close(pip[0]);
- signal(SIGINT, SIG_IGN);
- signal(SIGQUIT, SIG_IGN);
- signal(SIGHUP, SIG_IGN);
-#ifdef SIGTSTP
- signal(SIGTSTP, SIG_IGN);
-#endif
+ ignoresig(SIGINT); //signal(SIGINT, SIG_IGN);
+ ignoresig(SIGQUIT); //signal(SIGQUIT, SIG_IGN);
+ ignoresig(SIGHUP); //signal(SIGHUP, SIG_IGN);
+ ignoresig(SIGTSTP); //signal(SIGTSTP, SIG_IGN);
signal(SIGPIPE, SIG_DFL);
if (redir->type == NHERE)
full_write(pip[1], redir->nhere.doc->narg.text, len);
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