libc: dont cache /dev/bintime filedescriptor for nsec()

sys/man/2/time

@@ -28,8 +28,7 @@ is not zero then
 is also set to the answer.
 .PP
 These functions work by reading
-.BR /dev/bintime ,
+.BR /dev/bintime .
-opening that file when they are first called.
 .SH SOURCE
 .B /sys/src/libc/9sys/time.c
 .br
@@ -40,5 +39,3 @@ opening that file when they are first called.
 .SH DIAGNOSTICS
 Sets
 .IR errstr .
-.SH BUGS
-These routines maintain a static file descriptor.

sys/src/libc/9sys/nsec.c

@@ -1,6 +1,5 @@
 #include <u.h>
 #include <libc.h>
-#include <tos.h>
 
 static uvlong order = 0x0001020304050607ULL;
 
@@ -16,60 +15,19 @@ be2vlong(vlong *to, uchar *f)
 		t[o[i]] = f[i];
 }
 
-static int fd = -1;
-static struct {
-	int	pid;
-	int	fd;
-} fds[64];
-
 vlong
 nsec(void)
 {
 	uchar b[8];
 	vlong t;
-	int pid, i, f, tries;
+	int fd;
 
-	/*
+	t = 0;
-	 * Threaded programs may have multiple procs
+	fd = open("/dev/bintime", OREAD);
-	 * with different fd tables, so we may need to open
+	if(fd >= 0){
-	 * /dev/bintime on a per-pid basis
+		if(pread(fd, b, sizeof b, 0) == sizeof b)
-	 */
-
-	/* First, look if we've opened it for this particular pid */
-	pid = _tos->pid;
-	do{
-		f = -1;
-		for(i = 0; i < nelem(fds); i++)
-			if(fds[i].pid == pid){
-				f = fds[i].fd;
-				break;
-			}
-		tries = 0;
-		if(f < 0){
-			/* If it's not open for this pid, try the global pid */
-			if(fd >= 0)
-				f = fd;
-			else{
-				/* must open */
-				if((f = open("/dev/bintime", OREAD|OCEXEC)) < 0)
-					return 0;
-				fd = f;
-				for(i = 0; i < nelem(fds); i++)
-					if(fds[i].pid == pid || fds[i].pid == 0){
-						fds[i].pid = pid;
-						fds[i].fd = f;
-						break;
-					}
-			}
-		}
-		if(pread(f, b, sizeof b, 0) == sizeof b){
 			be2vlong(&t, b);
-			return t;
+		close(fd);
 	}
-		close(f);
+	return t;
-		if(i < nelem(fds))
-			fds[i].fd = -1;
-	}while(tries++ == 0);	/* retry once */
-	USED(tries);
-	return 0;
 }

sys/src/libc/9sys/time.c

@@ -1,50 +1,12 @@
 #include <u.h>
 #include <libc.h>
 
-
-/*
- *  After a fork with fd's copied, both fd's are pointing to
- *  the same Chan structure.  Since the offset is kept in the Chan
- *  structure, the seek's and read's in the two processes can
- *  compete at moving the offset around.  Hence the unusual loop
- *  in the middle of this routine.
- */
-static long
-oldtime(long *tp)
-{
-	char b[20];
-	static int f = -1;
-	int i, retries;
-	long t;
-
-	memset(b, 0, sizeof(b));
-	for(retries = 0; retries < 100; retries++){
-		if(f < 0)
-			f = open("/dev/time", OREAD|OCEXEC);
-		if(f < 0)
-			break;
-		if(seek(f, 0, 0) < 0 || (i = read(f, b, sizeof(b))) < 0){
-			close(f);
-			f = -1;
-		} else {
-			if(i != 0)
-				break;
-		}
-	}
-	t = atol(b);
-	if(tp)
-		*tp = t;
-	return t;
-}
-
 long
 time(long *tp)
 {
 	vlong t;
 
 	t = nsec()/1000000000LL;
-	if(t == 0)
-		t = oldtime(0);
 	if(tp != nil)
 		*tp = t;
 	return t;