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

--- a/sys/man/2/time

+++ b/sys/man/2/time

@@ -28,8 +28,7 @@

 is also set to the answer.

 .PP

 These functions work by reading

-.BR /dev/bintime ,

-opening that file when they are first called.

+.BR /dev/bintime .

 .SH SOURCE

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

 .br

@@ -40,5 +39,3 @@

 .SH DIAGNOSTICS

 Sets

 .IR errstr .

-.SH BUGS

-These routines maintain a static file descriptor.

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

+++ b/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 @@

 		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;

-	/*

-	 * Threaded programs may have multiple procs

-	 * with different fd tables, so we may need to open

-	 * /dev/bintime on a per-pid basis

-	 */

-

-	/* 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){

+	t = 0;

+	fd = open("/dev/bintime", OREAD);

+	if(fd >= 0){

+		if(pread(fd, b, sizeof b, 0) == sizeof b)

 			be2vlong(&t, b);

-			return t;

-		}

-		close(f);

-		if(i < nelem(fds))

-			fds[i].fd = -1;

-	}while(tries++ == 0);	/* retry once */

-	USED(tries);

-	return 0;

+		close(fd);

+	}

+	return t;

 }

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

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

@@ -1,42 +1,6 @@

 #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)

 {

@@ -43,8 +7,6 @@

 	vlong t;

 	t = nsec()/1000000000LL;

-	if(t == 0)

-		t = oldtime(0);

 	if(tp != nil)

 		*tp = t;

 	return t;