pkg/runtime: Plan 9 signal handling in Go

This adds proper note handling for Plan 9,
and fixes the issue of properly killing go procs.
Without this change, the first go proc that dies
(using runtime·exit()) would kill all the running
go procs. Proper signal handling is needed.

R=golang-dev, ality, rminnich, rsc
CC=golang-dev, john, mirtchovski
https://golang.org/cl/5617048

src/pkg/runtime/os_plan9.h

@@ -14,6 +14,9 @@ int32	runtime·sleep(int32 ms);
 int32	runtime·rfork(int32 flags, void *stk, M *m, G *g, void (*fn)(void));
 int32	runtime·plan9_semacquire(uint32 *addr, int32 block);
 int32 	runtime·plan9_semrelease(uint32 *addr, int32 count);
+int32	runtime·notify(void (*fn)(void*, byte*));
+int32	runtime·noted(int32);
+void	runtime·gonote(void*, byte*);
 
 /* open */
 enum
@@ -45,6 +48,13 @@ enum
 	RFNOMNT         = (1<<14)
 };
 
+/* notify */
+enum
+{
+	NCONT	= 0,
+	NDFLT	= 1
+};
+
 typedef struct Tos Tos;
 typedef intptr Plink;
 

src/pkg/runtime/sys_plan9_386.s

@@ -48,6 +48,16 @@ TEXT runtime·plan9_semacquire(SB),7,$0
 	MOVL	$37, AX
 	INT	$64
 	RET
+
+TEXT runtime·notify(SB),7,$0
+	MOVL	$28, AX
+	INT	$64
+	RET
+
+TEXT runtime·noted(SB),7,$0
+	MOVL	$29, AX
+	INT	$64
+	RET
 	
 TEXT runtime·plan9_semrelease(SB),7,$0
 	MOVL	$38, AX

src/pkg/runtime/thread_plan9.c

@@ -7,6 +7,9 @@
 #include "arch_GOARCH.h"
 
 int8 *goos = "plan9";
+int8 *runtime·exitstatus;
+
+int32 runtime·postnote(int32, int8*);
 
 void
 runtime·minit(void)
@@ -36,10 +39,30 @@ getproccount(void)
 	return ncpu > 0 ? ncpu : 1;
 }
 
+static int32
+getpid(void)
+{
+	byte b[20], *c;
+	int32 fd, n;
+
+	runtime·memclr(b, sizeof(b));
+	fd = runtime·open((byte*)"#c/pid", 0);
+	if(fd >= 0) {
+		runtime·read(fd, b, sizeof(b));
+		runtime·close(fd);
+	}
+	c = b;
+	while(*c == ' ' || *c == '\t')
+		c++;
+	return runtime·atoi(c);
+}
+
 void
 runtime·osinit(void)
 {
 	runtime·ncpu = getproccount();
+	m->procid = getpid();
+	runtime·notify(runtime·gonote);
 }
 
 void
@@ -109,36 +132,122 @@ time·now(int64 sec, int32 nsec)
 	FLUSH(&nsec);
 }
 
-extern Tos *_tos;
 void
-runtime·exit(int32)
+runtime·itoa(int32 n, byte *p, uint32 len)
 {
-	int32 fd;
+	byte *q, c;
+	uint32 i;
+
+	if(len <= 1)
+		return;
+
+	runtime·memclr(p, len);
+	q = p;
+
+	if(n==0) {
+		*q++ = '0';
+		USED(q);
+		return;
+	}
+	if(n < 0) {
+		*q++ = '-';
+		p++;
+		n = -n;
+	}
+	for(i=0; n > 0 && i < len; i++) {
+		*q++ = '0' + (n%10);
+		n = n/10;
+	}
+	for(q--; q >= p; ) {
+		c = *p;
+		*p++ = *q;
+		*q-- = c;
+	}
+}
+
+void
+goexitsall(void)
+{
+	M *m;
+	int32 pid;
+
+	pid = getpid();
+	for(m=runtime·atomicloadp(&runtime·allm); m; m=m->alllink)
+		if(m->procid != pid)
+			runtime·postnote(m->procid, "gointr");
+}
+
+void
+runtime·gonote(void*, byte *s)
+{
+	uint8 buf[128];
+	int32 l;
+
+	l = runtime·findnull(s);
+	if(l > 4 && runtime·mcmp(s, (byte*)"sys:", 4) == 0) {
+		runtime·memclr(buf, sizeof buf);
+		runtime·memmove((void*)buf, (void*)s, runtime·findnull(s));
+		runtime·exitstatus = (int8*)buf;
+		goexitsall();
+		runtime·noted(NDFLT);
+	}
+
+	if(runtime·exitstatus)
+		runtime·exits(runtime·exitstatus);
+
+	if(runtime·strcmp(s, (byte*)"gointr") == 0)
+		runtime·noted(NCONT);
+
+	runtime·noted(NDFLT);
+}
+
+int32
+runtime·postnote(int32 pid, int8* msg)
+{
+	int32 fd, len;
 	uint8 buf[128];
 	uint8 tmp[16];
 	uint8 *p, *q;
-	int32 pid;
 
 	runtime·memclr(buf, sizeof buf);
-	runtime·memclr(tmp, sizeof tmp);
-	pid = _tos->pid;
 
-	/* build path string /proc/pid/notepg */
+	/* build path string /proc/pid/note */
-	for(q=tmp; pid > 0;) {
+	q = tmp;
-		*q++ = '0' + (pid%10);
-		pid = pid/10;
-	}
 	p = buf;
+	runtime·itoa(pid, tmp, sizeof tmp);
 	runtime·memmove((void*)p, (void*)"/proc/", 6);
-	p += 6;
+	for(p += 6; *p++ = *q++; );
-	for(q--; q >= tmp;)
+	p--;
-		*p++ = *q--;
+	runtime·memmove((void*)p, (void*)"/note", 5);
-	runtime·memmove((void*)p, (void*)"/notepg", 7);
 
-	/* post interrupt note */
 	fd = runtime·open(buf, OWRITE);
-	runtime·write(fd, "interrupt", 9);
+	if(fd < 0)
-	runtime·exits(nil);
+		return -1;
+
+	len = runtime·findnull((byte*)msg);
+	if(runtime·write(fd, msg, len) != len) {
+		runtime·close(fd);
+		return -1;
+	}
+	runtime·close(fd);
+	return 0;
+}
+
+void
+runtime·exit(int32 e)
+{
+	byte tmp[16];
+
+	if(e == 0)
+		runtime·exitstatus = "";
+	else {
+		/* build error string */
+		runtime·itoa(e, tmp, sizeof tmp);
+		runtime·exitstatus = (int8*)tmp;
+	}
+
+	goexitsall();
+	runtime·exits(runtime·exitstatus);
 }
 
 void