add awaitfor and waitfor

include/libc.h

@@ -693,6 +693,7 @@ extern	void	abort(void);
 /* extern	int	access(char*, int); */
 extern	long	p9alarm(ulong);
 extern	int	await(char*, int);
+extern	int	awaitfor(int, char*, int);
 extern	int	awaitnohang(char*, int);
 /* extern	int	bind(char*, char*, int); give up */
 /* extern	int	brk(void*); <unistd.h> */
@@ -746,6 +747,7 @@ extern	int	segfree(void*, ulong);
 extern	int	p9sleep(long);
 /* extern	int	stat(char*, uchar*, int); give up */
 extern	Waitmsg*	p9wait(void);
+extern	Waitmsg*	p9waitfor(int);
 extern	Waitmsg*	waitnohang(void);
 extern	int	p9waitpid(void);
 /* <unistd.h>
@@ -770,6 +772,7 @@ extern	ulong	rendezvous(ulong, ulong);
 #undef open
 #define open		p9open
 #define pipe		p9pipe
+#define	waitfor		p9waitfor
 #endif
 
 extern	Dir*	dirstat(char*);

src/lib9/await.c

@@ -74,7 +74,7 @@ _p9strsig(char *s)
 }
 
 static int
-_await(char *str, int n, int opt)
+_await(int pid4, char *str, int n, int opt)
 {
 	int pid, status, cd;
 	struct rusage ru;
@@ -82,7 +82,7 @@ _await(char *str, int n, int opt)
 	ulong u, s;
 
 	for(;;){
-		pid = wait3(&status, opt, &ru);
+		pid = wait4(pid4, &status, opt, &ru);
 		if(pid <= 0)
 			return -1;
 		u = ru.ru_utime.tv_sec*1000+((ru.ru_utime.tv_usec+500)/1000);
@@ -108,12 +108,18 @@ _await(char *str, int n, int opt)
 int
 await(char *str, int n)
 {
-	return _await(str, n, 0);
+	return _await(-1, str, n, 0);
 }
 
 int
 awaitnohang(char *str, int n)
 {
-	return _await(str, n, WNOHANG);
+	return _await(-1, str, n, WNOHANG);
+}
+
+int
+awaitfor(int pid, char *str, int n)
+{
+	return _await(pid, str, n, 0);
 }
 

src/lib9/wait.c

@@ -2,13 +2,12 @@
 #include <libc.h>
 
 static Waitmsg*
-_wait(int nohang)
+_wait(int n, char *buf)
 {
-	int n, l;
+	int l;
-	char buf[512], *fld[5];
+	char *fld[5];
 	Waitmsg *w;
 
-	n = (nohang ? awaitnohang : await)(buf, sizeof buf-1);
 	if(n <= 0)
 		return nil;
 	buf[n] = '\0';
@@ -32,12 +31,24 @@ _wait(int nohang)
 Waitmsg*
 wait(void)
 {
-	return _wait(0);
+	char buf[256];
+
+	return _wait(await(buf, sizeof buf-1), buf);
 }
 
 Waitmsg*
 waitnohang(void)
 {
-	return _wait(1);
+	char buf[256];
+
+	return _wait(awaitnohang(buf, sizeof buf-1), buf);
+}
+
+Waitmsg*
+waitfor(int pid)
+{
+	char buf[256];
+
+	return _wait(awaitfor(pid, buf, sizeof buf-1), buf);
 }