fix misleading/wrong fd checks

sys/src/ape/cmd/pax/pass.c

@@ -153,7 +153,7 @@ char           *dir;
     if ((ofd = openout(to, asb, islink(to, asb), 1)) < 0) {
 	return (-1);
     }
-    if (ofd > 0) {
+    if (ofd >= 0) {
 	passdata(from, ifd, to, ofd);
     }
     tstamp[0] = asb->sb_atime;

sys/src/cmd/acme/xfid.c

@@ -129,7 +129,7 @@ xfidopen(Xfid *x)
 			 * though, we'd need to squirrel away the data in case it's
 			 * modified during the operation, e.g. by |sort
 			 */
-			if(w->rdselfd > 0){
+			if(w->rdselfd >= 0){
 				winunlock(w);
 				respond(x, &fc, Einuse);
 				return;

sys/src/cmd/cpu.c

@@ -127,7 +127,7 @@ main(int argc, char **argv)
 	origargs = procgetname();
 	/* see if we should use a larger message size */
 	fd = open("/dev/draw", OREAD);
-	if(fd > 0){
+	if(fd >= 0){
 		ms = iounit(fd);
 		if(msgsize < ms+IOHDRSZ)
 			msgsize = ms+IOHDRSZ;

sys/src/cmd/ip/ftpfs/file.c

@@ -77,7 +77,7 @@ filefree(Node *node)
 	if(fp == 0)
 		return;
 
-	if(fp->fd > 0){
+	if(fp->fd >= 0){
 		ntmp--;
 		close(fp->fd);
 		remove(fp->template);

sys/src/cmd/ip/httpd/log.c

@@ -52,7 +52,7 @@ writelog(HConnect *c, char *fmt, ...)
 
 	/* verbose logfile, for research on web traffic */
 	logfd = logall[today & 1];
-	if(logfd > 0){
+	if(logfd >= 0){
 		if(c->hstop == c->header || c->hstop[-1] != '\n')
 			*c->hstop = '\n';
 		*c->hstop = '\0';

sys/src/cmd/ip/httpd/man2html.c

@@ -55,7 +55,7 @@ lookup(char *object, int section, Hit **list)
 
 	snprint(file, sizeof(file), "/sys/man/%d/INDEX", section);
 	fd = open(file, OREAD);
-	if(fd > 0){
+	if(fd >= 0){
 		Binit(&b, fd, OREAD);
 		for(;;){
 			p = Brdline(&b, '\n');

sys/src/cmd/ip/ppp/ppp.c

@@ -2758,7 +2758,7 @@ main(int argc, char **argv)
 			snprint(buf, sizeof buf, "%sctl", dev);
 			cfd = open(buf, ORDWR);
 		}
-		if(cfd > 0){
+		if(cfd >= 0){
 			if(baud)
 				fprint(cfd, "b%d", baud);
 			fprint(cfd, "m1");	/* cts/rts flow control (and fifo's) on */

sys/src/cmd/ndb/dnudpserver.c

@@ -110,7 +110,7 @@ redistrib(uchar *buf, int len)
 
 	uh = (Udphdr *)buf;
 	for (tp = forwtarg; tp < forwtarg + forwtcount; tp++)
-		if (tp->fd > 0) {
+		if (tp->fd >= 0) {
 			memmove(uh->raddr, tp->addr, sizeof tp->addr);
 			hnputs(uh->rport, 53);		/* dns port */
 			if (write(tp->fd, buf, len) != len) {

sys/src/cmd/sam/sam.c

@@ -516,7 +516,7 @@ cd(String *str)
 	if(chdir(s))
 		syserror("chdir");
 	fd = open("/dev/wdir", OWRITE);
-	if(fd > 0)
+	if(fd >= 0)
 		write(fd, s, strlen(s));
 	dprint("!\n");
 	Strinit(&owd);

sys/src/cmd/samterm/mesg.c

@@ -670,7 +670,7 @@ hplumb(int nc)
 	s = alloc(nc);
 	for(i=0; i<nc; i++)
 		s[i] = getch();
-	if(plumbfd > 0){
+	if(plumbfd >= 0){
 		m = plumbunpack(s, nc);
 		if(m != 0)
 			plumbsend(plumbfd, m);

sys/src/cmd/split.c

@@ -151,7 +151,7 @@ openf(void)
 
 	Bflush(output);
 	Bterm(output);
-	if(fd > 0)
+	if(fd >= 0)
 		close(fd);
 	fd = create(name,OWRITE,0666);
 	if(fd < 0) {

sys/src/cmd/upas/Mail/reply.c

@@ -336,7 +336,7 @@ print2(int fd, int ofd, char *fmt, ...)
 		return -1;
 	m = strlen(s);
 	n = write(fd, s, m);
-	if(ofd > 0)
+	if(ofd >= 0)
 		write(ofd, s, m);
 	return n;
 }
@@ -350,7 +350,7 @@ write2(int fd, int ofd, char *buf, int n, int nofrom)
 	if(fd >= 0)
 		m = write(fd, buf, n);
 
-	if(ofd <= 0)
+	if(ofd < 0)
 		return m;
 
 	if(nofrom == 0)
@@ -463,7 +463,7 @@ mesgsend(Message *m)
 	}
 
 	ofd = open(outgoing, OWRITE|OCEXEC);	/* no error check necessary */
-	if(ofd > 0){
+	if(ofd >= 0){
 		/* From dhog Fri Aug 24 22:13:00 EDT 2001 */
 		now = ctime(time(0));
 		fprint(ofd, "From %s %s", user, now);
@@ -537,14 +537,14 @@ mesgsend(Message *m)
 		write2(p[1], ofd, "\n", 1, 0);
 
 	/* these look like pseudo-attachments in the "outgoing" box */
-	if(ofd>0 && natt>0){
+	if(ofd>=0 && natt>0){
 		for(i=0; i<natt; i++)
 			if(included[i])
 				fprint(ofd, "=====> Include: %s\n", attlist[i]);
 			else
 				fprint(ofd, "=====> Attach: %s\n", attlist[i]);
 	}
-	if(ofd > 0)
+	if(ofd >= 0)
 		write(ofd, "\n", 1);
 
 	for(i=0; i<natt; i++)