MiNT 1.09/MinixFS 0.6pl9: FIONREAD broken

[Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>]

FIONREAD always returns 1 on tosfs and minixfs.  On the pipefs,
FIONREAD returns -1 if there are no writers, and FIONWRITE returns -1
if there are no readers.  This breaks cat from textutils 1.9.
FIONREAD should always return 0 on eof.  The patch fixes this.

************************* MiNT 1.09 *************************
--- orig/pipefs.c	Fri Jun 25 22:20:54 1993
+++ pipefs.c	Tue Dec 14 22:50:10 1993
@@ -747,12 +747,13 @@
 
 	this = (struct fifo *)f->fc.index;
 
-	if (mode == FIONREAD) {
+	switch (mode) {
+	case FIONREAD:
 			p = (f->flags & O_HEAD) ? this->outp : this->inp;
 			assert(p != 0);
 			if (p->writers <= 0 || p->writers == VIRGIN_PIPE) {
 				DEBUG(("pipe FIONREAD: no writers"));
-				r = -1;
+				r = 0;
 			} else {
 				r = p->tail - p->head;
 				if (r < 0) r += PIPESIZ;
@@ -760,12 +761,12 @@
 					r = r >> 2;	/* r /= 4 */
 			}
 			*((long *) buf) = r;
-	}
-	else if (mode == FIONWRITE) {
+			break;
+	case FIONWRITE:
 			p = (f->flags & O_HEAD) ? this->inp : this->outp;
 			assert(p != 0);
 			if (p->readers <= 0) {
-				r = -1;
+				r = 0;
 			} else {
 				r = p->tail - p->head;
 				if (r < 0) r += PIPESIZ;
@@ -774,8 +775,9 @@
 					r = r >> 2;	/* r /= 4 */
 			}
 			*((long *) buf) = r;
-	}
-	else if (mode == F_SETLK || mode == F_SETLKW) {
+			break;
+	case F_SETLK:
+	case F_SETLKW:
 		lck = (struct flock *)buf;
 		while (this->flags & O_LOCK) {
 			if (this->lockpid != curproc->pid) {
@@ -803,8 +805,8 @@
 			this->lockpid = curproc->pid;
 			f->flags |= O_LOCK;
 		}
-	}
-	else if (mode == F_GETLK) {
+		break;
+	case F_GETLK:
 		lck = (struct flock *)buf;
 		if (this->flags & O_LOCK) {
 			lck->l_type = F_WRLCK;
@@ -813,8 +815,8 @@
 		}
 		else
 			lck->l_type = F_UNLCK;
-	}
-	else if (mode == TIOCFLUSH) {
+		break;
+	case TIOCFLUSH:
 		if (this->inp) {
 			this->inp->head = this->inp->tail;
 			wake(IO_Q, (long)this->inp);
@@ -823,11 +825,20 @@
 			this->outp->head = this->outp->tail;
 			wake(IO_Q, (long)this->outp);
 		}
-	} else if (mode == TIOCIBAUD || mode == TIOCOBAUD) {
+		break;
+	case TIOCIBAUD:
+	case TIOCOBAUD:
 		*(long *)buf = -1L;
-	} else if (mode == TIOCGFLAGS) {
+		break;
+	case TIOCGFLAGS:
 		*((unsigned short *)buf) = 0;
-	} else if (mode >= TCURSOFF && mode <= TCURSGRATE) {
+		break;
+	case TCURSOFF:
+	case TCURSON:
+	case TCURSSRATE:
+	case TCURSBLINK:
+	case TCURSSTEADY:
+	case TCURSGRATE:
 	/* kludge: this assumes TOSWIN style escape sequences */
 		tty_putchar(f, (long)'\033', RAW);
 		switch (mode) {
@@ -851,7 +862,8 @@
 		case TCURSGRATE:
 			return this->cursrate;
 		}
-	} else {
+		break;
+	default:
 	/* if the file is a terminal, Fcntl will automatically
 	 * call tty_ioctl for us to handle 'generic' terminal
 	 * functions
--- orig/tosfs.c	Fri Jun 25 22:24:32 1993
+++ ./tosfs.c	Sat Nov 20 02:34:14 1993
@@ -1147,9 +1147,17 @@
 	extern int flk;		/* set in main.c if _FLK already installed */
 
-	if (mode == FIONREAD || mode == FIONWRITE) {
+	switch (mode) {
+	case FIONREAD:
+		r = Fseek (0L, (int) f->devinfo, 1);
+		if (r < 0) return r;
+		*(long *) buf = Fseek (0L, (int) f->devinfo, 2) - r;
+		(void) Fseek (r, (int) f->devinfo, 0);
+		return 0;
+	case FIONWRITE:
 		*((long *)buf) = 1;
 		return 0;
-	}
-	else if (mode == F_SETLK || mode == F_SETLKW || mode == F_GETLK) {
+	case F_SETLK:
+	case F_SETLKW:
+	case F_GETLK:
 		fl = ((struct flock *)buf);
 		t.l = *fl;
************************* MinixFS 0.6pl9 *************************
--- orig/minixfs/minixdev.c	Sat Nov 27 19:42:24 1993
+++ ./minixfs/minixdev.c	Tue Dec 14 19:37:26 1993
@@ -445,7 +445,18 @@
     switch (mode)
       {
       case FIONREAD:
+	{
+	  d_inode rip;
+	  long nread;
+	  read_inode (f->fc.index, &rip, f->fc.dev);
+	  nread = rip.i_size - f->pos;
+	  if (nread < 0)
+	    nread = 0;
+	  *(long *) buf = nread;
+	  return 0;
+	}
+
       case FIONWRITE:
 	{