1 files changed, 56 insertions, 8 deletions

diff --git a/kernel/tty.c b/kernel/tty.c
index 1946110..75c3701 100644
--- a/kernel/tty.c
+++ b/kernel/tty.c
@@ -16,11 +16,8 @@ static struct tty_struct *ttys[] = {
   &tty_rs
 };
 
-/* check if the buffer's empty and if so, go to sleep */
+/* check if a buffer's empty and if so, go to sleep */
 static int sleep_while_empty(struct tty_queue *q) {
-  if(q->pread != q->pwrite)
-    return 0;
-
   cli();
   while(1) {
     if(q->pread == q->pwrite)
@@ -37,6 +34,24 @@ static int sleep_while_empty(struct tty_queue *q) {
   }
 }
 
+/* check if a buffer's full and if so, go to sleep */
+static int sleep_while_full(struct tty_queue *q) {
+  cli();
+  while(1) {
+    if(q->pwrite == (q->pread - 1 % sizeof(q->buf)))
+      interruptible_sleep_on(&q->waiting);
+
+    /* check again to see if anything was removed, or we were interrupted */
+    if(q->pwrite == (q->pread - 1 % sizeof(q->buf))) {
+      sti();
+      return -1;
+    }
+
+    sti();
+    return 0;
+  }
+}
+
 ssize_t tty_read(unsigned tty, void *buf, size_t len) {
   size_t i;
   char *b = buf;
@@ -61,9 +76,45 @@ ssize_t tty_read(unsigned tty, void *buf, size_t len) {
     }
 
     *b++ = q->buf[q->pread];
-    q->pread = q->pread + 1 % TTY_BUF_SIZE;
+    q->pread = (q->pread + 1) % TTY_BUF_SIZE;
+  }
+
+  return len;
+}
+
+ssize_t tty_write(unsigned tty, void *buf, size_t len) {
+  size_t i;
+  char *b = buf;
+  struct tty_queue *q = &ttys[tty]->wqueue;
+
+  if(tty > NRTTY || ttys[tty] == NULL)
+    return -1;
+
+  if(len == 0)
+    return 0;
+
+  if(len > SSIZE_MAX)
+    len = SSIZE_MAX;
+
+  for(i = 0; i < len; i++) {
+    /* check if the buffer's full and if so, go to sleep */
+    if(sleep_while_full(q) < 0) {
+      if(i == 0)
+        return -EINTR;
+
+      return i;
+    }
+
+    q->buf[q->pwrite] = *b++;
+    q->pwrite = (q->pwrite + 1) % TTY_BUF_SIZE;
   }
 
+  /* tell the driver that new data is available */
+  cli();
+  if(ttys[tty]->write)
+    ttys[tty]->write();
+  sti();
+
   return len;
 }
 
@@ -77,9 +128,6 @@ void tty_init(void) {
     memset(&ttys[i]->rqueue, 0, sizeof(struct tty_queue));
     memset(&ttys[i]->wqueue, 0, sizeof(struct tty_queue));
 
-    ttys[i]->rqueue.pwrite = 1;
-    ttys[i]->wqueue.pwrite = 1;
-
     if(ttys[i]->init)
       ttys[i]->init();
   }