Add a few things to make $&waiting more flexible.

doc/es.1

@@ -1856,7 +1856,7 @@ as input to
 and executes its contents.
 The options are a subset of the invocation options for the shell (see below).
 .TP
-.Cr "access \fR[\fP-n \fIname\fP\fR]\fP \fR[\fP-1e\fR]\fP \fR[\fP-rwx\fR]\fP  \fR[\fP-fdcblsp\fR]\fP \fIpath ...\fP"
+.Cr "access \fR[\fP-n \fIname\fP\fR]\fP \fR[\fP-1e\fR]\fP \fR[\fP-rwx\fR]\fP \fR[\fP-fdcblsp\fR]\fP \fIpath ...\fP"
 Tests if the named paths are accessible according to the options presented.
 Normally,
 .Cr access
@@ -2192,14 +2192,19 @@ are specified,
 .Cr \-e
 is used.
 .TP
-.Cr "wait \fI\fR[\fPpid\fR]"
+.Cr "wait \fR[\fP-n\fR]\fP \fI\fR[\fPpid\fR]"
 Waits for the specified
 .IR pid ,
 which must have been started by
 .IR es .
 If no
 .I pid
 is specified, waits for any child process to exit.
+If
+.Cr \-n
+is specified and the process(es) to be waited for is (are) not ready
+at call time, returns immediately instead of blocking or throwing an
+error.
 .TP
 .Cr "whatis \fIprogram ...\fP"
 For each named
@@ -2293,6 +2298,19 @@ copied (via
 to file descriptor
 .IR newfd .
 .TP
+.Cr "%echo-status \fIpid did status\fP"
+Inspects the exit
+.I status
+of an exited (and waited-for) process
+.IR pid ,
+where
+.I did
+indicates if the process
+.Cr exited
+or was
+.Cr signaled ,
+and prints any interesting condition.
+.TP
 .Cr "%eval-noprint \fIcmd\fP"
 Run the command.
 (Passed as the argument to
@@ -2740,7 +2758,7 @@ variable, which signals to the
 library how much of the history file should be read into the in-memory
 history log.
 .PP
-Several primitives are not directly associated with other function.
+Several primitives are not directly associated with other functions.
 They are:
 .TP
 .Cr "$&collect"
@@ -2750,7 +2768,7 @@ The garbage collector in
 runs rather frequently;
 there should be no reason for a user to issue this command.
 .TP
-.Cr "$&noreturn \fIlambda args ...\fP"
+.Cr "$&noreturn \fIlambda args ..."
 Call the
 .IR lambda ,
 but in such a way that it does not catch the
@@ -2765,6 +2783,11 @@ and
 .Cr "&&" )
 can be implemented as lambdas rather than primitives.
 .TP
+.Cr "$&sigmessage"
+converts a signal name such as
+.Cr sigint
+to a short message describing the signal, used for error reporting.
+.TP
 .Cr "$&primitives"
 Returns a list of the names of es primitives.
 .TP

es.h

@@ -222,12 +222,12 @@ extern char *checkexecutable(char *file);
 /* proc.c */
 
 extern Boolean hasforked;
-extern int efork(Boolean parent, Boolean background);
+extern int efork(Boolean parent);
 extern pid_t spgrp(pid_t pgid);
 extern int tctakepgrp(void);
 extern void initpgrp(void);
-extern int ewait(int pid, Boolean interruptible, void *rusage);
-#define	ewaitfor(pid)	ewait(pid, FALSE, NULL)
+extern int ewait(int pid, int opts, void *rusage);
+#define	ewaitfor(pid)	ewait(pid, 0, NULL)
 
 #if JOB_PROTECT
 extern void tcreturnpgrp(void);

eval.c

@@ -28,7 +28,7 @@ extern List *forkexec(char *file, List *list, Boolean inchild) {
 	Vector *env;
 	gcdisable();
 	env = mkenv();
-	pid = efork(!inchild, FALSE);
+	pid = efork(!inchild);
 	if (pid == 0) {
 		execve(file, vectorize(list)->vector, env->vector);
 		failexec(file, list);
@@ -41,7 +41,6 @@ extern List *forkexec(char *file, List *list, Boolean inchild) {
 		sigint_newline = TRUE;
 	} else
 		SIGCHK();
-	printstatus(0, status);
 	return mklist(mkterm(mkstatus(status), NULL), NULL);
 }
 

initial.es

@@ -76,7 +76,6 @@ fn-newpgrp	= $&newpgrp
 fn-result	= $&result
 fn-throw	= $&throw
 fn-umask	= $&umask
-fn-wait		= $&wait
 
 fn-%read	= $&read
 
@@ -579,6 +578,26 @@ fn %pathsearch name { access -n $name -1e -xf $path }
 
 if {~ <=$&primitives execfailure} {fn-%exec-failure = $&execfailure}
 
+#	The %echo-status hook is used to print any potentially interesting
+#	status from an exec()ed binary.
+
+fn %echo-status pid did status {
+	if {~ $did signaled && !~ $status (sigint sigpipe)} {
+		let (msg = <={if {$echo-status-pid} {result $pid^': '} {result ''}}) {
+			msg = $msg^<={$&sigmessage $status}
+			if {~ $status *+core} {
+				msg = $msg^'--core dumped'
+			}
+			echo >[1=2] $msg
+		}
+	}
+}
+
+echo-status-pid = false
+
+fn wait {
+	local (echo-status-pid = true) $&wait $*
+}
 
 #
 # Read-eval-print loops
@@ -642,7 +661,7 @@ fn %interactive-loop {
 				$fn-%dispatch false
 			} {~ $e signal} {
 				if {!~ $type sigint sigterm sigquit} {
-					echo >[1=2] caught unexpected signal: $type
+					echo >[1=2] caught unexpected signal: $type: <={$&sigmessage $type}
 				}
 			} {
 				echo >[1=2] uncaught exception: $e $type $msg
@@ -756,7 +775,7 @@ max-eval-depth	= 640
 #	is does.  fn-%dispatch is really only important to the current
 #	interpreter loop.
 
-noexport = noexport pid signals apid bqstatus fn-%dispatch path home matchexpr
+noexport = noexport pid signals apid bqstatus fn-%dispatch path home matchexpr print-status-pid
 
 
 #

mksignal

@@ -34,12 +34,14 @@ sed -n '
 		mesg["SIGHUP"]		= "hangup"
 		mesg["SIGILL"]		= "illegal instruction"
 		mesg["SIGINFO"]		= "information request"
+		mesg["SIGINT"]		= "interrupt"
 		mesg["SIGIO"]		= "input/output possible"
 		mesg["SIGIOT"]		= "IOT instruction"
 		mesg["SIGKILL"]		= "killed"
 		mesg["SIGLOST"]		= "resource lost"
 		mesg["SIGLWP"]		= "lightweight process library signal"
 		mesg["SIGMIGRATE"]	= "migrate process"
+		mesg["SIGPIPE"]		= "broken pipe"
 		mesg["SIGPOLL"]		= "pollable event occurred"
 		mesg["SIGPROF"]		= "profiling timer alarm"
 		mesg["SIGPWR"]		= "power failure"
@@ -82,13 +84,6 @@ sed -n '
 		mesg["SIGVIRT"]		= "virtual time alarm"
 		mesg["SIGWINDOW"]	= "window size changed"
 
-
-		# set nomesg["SIGNAME"] to suppress message printing
-
-		nomesg["SIGINT"] = 1
-		nomesg["SIGPIPE"] = 1
-
-
 		# set ignore["SIGNAME"] to explicitly ignore a named signal (usually, this
 		# is just for things that look like signals but really are not)
 
@@ -117,7 +112,7 @@ sed -n '
 	sig[$1] == 0 && ignore[$1] == 0 {
 		sig[$1] = ++nsig
 		signame[nsig] = $1
-		if (mesg[$1] == "" && nomesg[$1] == 0) {
+		if (mesg[$1] == "") {
 			str = $3
 			for (i = 4; i <= NF; i++)
 				str = str " " $i

prim-io.c

@@ -141,7 +141,7 @@ static int pipefork(int p[2], int *extra) {
 		registerfd(extra, FALSE);
 
 	ExceptionHandler
-		pid = efork(TRUE, FALSE);
+		pid = efork(TRUE);
 	CatchExceptionIf (pid != 0, e)
 		unregisterfd(&p[0]);
 		unregisterfd(&p[1]);
@@ -205,7 +205,7 @@ PRIM(pipe) {
 	for (;; list = list->next) {
 		int p[2], pid;
 
-		pid = (list->next == NULL) ? efork(TRUE, FALSE) : pipefork(p, &inpipe);
+		pid = (list->next == NULL) ? efork(TRUE) : pipefork(p, &inpipe);
 
 		if (pid == 0) {		/* child */
 			if (inpipe != -1) {
@@ -234,9 +234,9 @@ PRIM(pipe) {
 
 	Ref(List *, result, NULL);
 	do {
+		int pid = pids[--n];
 		Term *t;
-		int status = ewaitfor(pids[--n]);
-		printstatus(0, status);
+		int status = ewaitfor(pid);
 		t = mkstr(mkstatus(status));
 		result = mklist(t, result);
 	} while (0 < n);
@@ -247,7 +247,7 @@ PRIM(pipe) {
 
 #if HAVE_DEV_FD
 PRIM(readfrom) {
-	int pid, p[2], status;
+	int pid, p[2];
 	Push push;
 
 	caller = "$&readfrom";
@@ -279,15 +279,14 @@ PRIM(readfrom) {
 	EndExceptionHandler
 
 	close(p[0]);
-	status = ewaitfor(pid);
-	printstatus(0, status);
+	ewaitfor(pid);
 	varpop(&push);
 	RefEnd3(cmd, input, var);
 	RefReturn(lp);
 }
 
 PRIM(writeto) {
-	int pid, p[2], status;
+	int pid, p[2];
 	Push push;
 
 	caller = "$&writeto";
@@ -319,8 +318,7 @@ PRIM(writeto) {
 	EndExceptionHandler
 
 	close(p[1]);
-	status = ewaitfor(pid);
-	printstatus(0, status);
+	ewaitfor(pid);
 	varpop(&push);
 	RefEnd3(cmd, output, var);
 	RefReturn(lp);
@@ -365,11 +363,10 @@ PRIM(backquote) {
 	}
 
 	close(p[1]);
-	gcdisable();
 	lp = bqinput(sep, p[0]);
 	close(p[0]);
 	status = ewaitfor(pid);
-	printstatus(0, status);
+	gcdisable();
 	lp = mklist(mkstr(mkstatus(status)), lp);
 	gcenable();
 	list = lp;

prim-sys.c

@@ -36,7 +36,7 @@ PRIM(newpgrp) {
 }
 
 PRIM(background) {
-	int pid = efork(TRUE, TRUE);
+	int pid = efork(TRUE);
 	if (pid == 0) {
 #if JOB_PROTECT
 		/* job control safe version: put it in a new pgroup, if interactive. */
@@ -51,12 +51,11 @@ PRIM(background) {
 
 PRIM(fork) {
 	int pid, status;
-	pid = efork(TRUE, FALSE);
+	pid = efork(TRUE);
 	if (pid == 0)
 		esexit(exitstatus(eval(list, NULL, evalflags | eval_inchild)));
 	status = ewaitfor(pid);
 	SIGCHK();
-	printstatus(0, status);
 	return mklist(mkstr(mkstatus(status)), NULL);
 }
 
@@ -128,6 +127,26 @@ PRIM(setsignals) {
 	return mksiglist();
 }
 
+PRIM(sigmessage) {
+	int sig;
+	char *s, *p;
+	if (list == NULL || list->next != NULL)
+		fail("$&sigmessage", "usage: $&sigmessage signal");
+	s = getstr(list->term);
+	if ((p = strchr(s, '+')) != NULL) {
+		if (streq(p, "+core"))
+			*p = '\0';
+		else
+			p = NULL;
+	}
+	sig = signumber(s);
+	if (p != NULL)
+		*p = '+';
+	if (sig < 0)
+		fail("$&sigmessage", "unknown signal: %s", s);
+	return mklist(mkstr(sigmessage(sig)), NULL);
+}
+
 /*
  * limit builtin -- this is too much code for what it gives you
  */
@@ -300,13 +319,12 @@ PRIM(time) {
 
 	gc();	/* do a garbage collection first to ensure reproducible results */
 	t0 = time(NULL);
-	pid = efork(TRUE, FALSE);
+	pid = efork(TRUE);
 	if (pid == 0)
 		esexit(exitstatus(eval(lp, NULL, evalflags | eval_inchild)));
-	status = ewait(pid, FALSE, &r);
+	status = ewait(pid, 0, &r);
 	t1 = time(NULL);
 	SIGCHK();
-	printstatus(0, status);
 
 	eprint(
 		"%6ldr %5ld.%ldu %5ld.%lds\t%L\n",
@@ -325,7 +343,7 @@ PRIM(time) {
 	Ref(List *, lp, list);
 
 	gc();	/* do a garbage collection first to ensure reproducible results */
-	pid = efork(TRUE, FALSE);
+	pid = efork(TRUE);
 	if (pid == 0) {
 		clock_t t0, t1;
 		struct tms tms;
@@ -335,14 +353,13 @@ PRIM(time) {
 			ticks = sysconf(_SC_CLK_TCK);
 
 		t0 = times(&tms);
-		pid = efork(TRUE, FALSE);
+		pid = efork(TRUE);
 		if (pid == 0)
 			esexit(exitstatus(eval(lp, NULL, evalflags | eval_inchild)));
 
 		status = ewaitfor(pid);
 		t1 = times(&tms);
 		SIGCHK();
-		printstatus(0, status);
 
 		tms.tms_cutime += ticks / 20;
 		tms.tms_cstime += ticks / 20;
@@ -358,7 +375,6 @@ PRIM(time) {
 	}
 	status = ewaitfor(pid);
 	SIGCHK();
-	printstatus(0, status);
 
 	RefEnd(lp);
 	return mklist(mkstr(mkstatus(status)), NULL);
@@ -439,6 +455,7 @@ extern Dict *initprims_sys(Dict *primdict) {
 	X(fork);
 	X(run);
 	X(setsignals);
+	X(sigmessage);
 #if BSD_LIMITS
 	X(limit);
 #endif