From: Alan Cox <alan@linux.intel.com>
Date: Thu, 1 Oct 2015 21:19:29 +0000 (+0100)
Subject: tty: fix O_NDELAY proposal
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=f3d57154d8dc6111be892b2f5925e6cb4e79b905;p=FUZIX.git

tty: fix O_NDELAY proposal

Bug as noticed by Brett M Gordon

Try a different fix giving us a call that will generalize for other users
of psleep_flags who will need this eventually.
---

diff --git a/Kernel/devio.c b/Kernel/devio.c
index 5f7f7929..608b1e6b 100644
--- a/Kernel/devio.c
+++ b/Kernel/devio.c
@@ -442,20 +442,32 @@ bool uninsq(struct s_queue *q, unsigned char *cp)
              Miscellaneous helpers
 **********************************************************************/
 
-int psleep_flags(void *p, unsigned char flags)
+int psleep_flags_io(void *p, unsigned char flags, usize_t *n)
 {
 	if (flags & O_NDELAY) {
-		udata.u_error = EAGAIN;
-		return (-1);
+	        if (*n) {
+	                *n = (usize_t)-1;
+			udata.u_error = EAGAIN;
+                }
+		return -1;
 	}
 	psleep(p);
 	if (udata.u_cursig || udata.u_ptab->p_pending) {	/* messy */
-		udata.u_error = EINTR;
-		return (-1);
+	        if (*n) {
+	                *n = (usize_t)-1;
+                        udata.u_error = EINTR;
+                }
+		return -1;
 	}
 	return 0;
 }
 
+int psleep_flags(void *p, unsigned char flags)
+{
+        usize_t dummy = 0;
+        return psleep_flags_io(p, flags, &dummy);
+}
+
 void kputs(const char *p)
 {
 	while (*p)
diff --git a/Kernel/include/kernel.h b/Kernel/include/kernel.h
index 6f4180e7..7fda5d01 100644
--- a/Kernel/include/kernel.h
+++ b/Kernel/include/kernel.h
@@ -654,6 +654,7 @@ extern bool insq(struct s_queue *q, unsigned char c);
 extern bool remq(struct s_queue *q, unsigned char *cp);
 extern void clrq(struct s_queue *q);
 extern bool uninsq(struct s_queue *q, unsigned char *cp);
+extern int psleep_flags_io(void *event, unsigned char flags, usize_t *n);
 extern int psleep_flags(void *event, unsigned char flags);
 extern int nxio_open(uint8_t minor, uint16_t flag);
 extern int no_open(uint8_t minor, uint16_t flag);
diff --git a/Kernel/tty.c b/Kernel/tty.c
index f5731af1..40e298a5 100644
--- a/Kernel/tty.c
+++ b/Kernel/tty.c
@@ -27,7 +27,7 @@ struct tty ttydata[NUM_DEV_TTY + 1];	/* ttydata[0] is not used */
 
 int tty_read(uint8_t minor, uint8_t rawflag, uint8_t flag)
 {
-	uint16_t nread;
+	usize_t nread;
 	unsigned char c;
 	struct s_queue *q;
 	struct tty *t;
@@ -56,8 +56,8 @@ int tty_read(uint8_t minor, uint8_t rawflag, uint8_t flag)
 			        if (n)
 			                udata.u_ptab->p_timeout = n + 1;
                         }
-			if (psleep_flags(q, flag))
-			        return -1;
+			if (psleep_flags_io(q, flag, &nread))
+			        return nread;
                         /* timer expired */
                         if (udata.u_ptab->p_timeout == 1)
                                 goto out;
@@ -90,7 +90,7 @@ out:
 int tty_write(uint8_t minor, uint8_t rawflag, uint8_t flag)
 {
 	struct tty *t;
-	int towrite;
+	usize_t written = 0;
 	uint8_t c;
 
 	used(rawflag);
@@ -98,8 +98,6 @@ int tty_write(uint8_t minor, uint8_t rawflag, uint8_t flag)
 
 	t = &ttydata[minor];
 
-	towrite = udata.u_count;
-
 	while (udata.u_count-- != 0) {
 		for (;;) {	/* Wait on the ^S/^Q flag */
 		        if (t->flag & TTYF_DEAD) {
@@ -108,8 +106,8 @@ int tty_write(uint8_t minor, uint8_t rawflag, uint8_t flag)
                         }
 			if (!(t->flag & TTYF_STOP))
 				break;
-			if (psleep_flags(&t->flag, flag))
-				return -1;
+			if (psleep_flags_io(&t->flag, flag, &written))
+				return written;
 		}
 
 		if (!(t->flag & TTYF_DISCARD)) {
@@ -127,8 +125,9 @@ int tty_write(uint8_t minor, uint8_t rawflag, uint8_t flag)
 			tty_putc_wait(minor, c);
 		}
 		++udata.u_base;
+		++written;
 	}
-	return towrite;
+	return written;
 }
 
 int tty_open(uint8_t minor, uint16_t flag)