drivers/serial/serial.c: only adapt readv api to avoid block on secound read in readv()

Signed-off-by: chao an <[email protected]>

Author: anchao

drivers/serial/serial.c

@@ -99,8 +99,6 @@ static int     uart_putxmitchar(FAR uart_dev_t *dev, int ch,
 static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
                                     FAR const char *buffer,
                                     size_t buflen);
-static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
-                                     FAR struct uio *uio);
 static int     uart_tcdrain(FAR uart_dev_t *dev,
                             bool cancelable, clock_t timeout);
 
@@ -112,8 +110,12 @@ static int     uart_tcsendbreak(FAR uart_dev_t *dev,
 
 static int     uart_open(FAR struct file *filep);
 static int     uart_close(FAR struct file *filep);
+static ssize_t uart_read(FAR struct file *filep,
+                         FAR char *buffer, size_t buflen);
+static ssize_t uart_write(FAR struct file *filep,
+                          FAR const char *buffer,
+                          size_t buflen);
 static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio);
-static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio);
 static int     uart_ioctl(FAR struct file *filep,
                           int cmd, unsigned long arg);
 static int     uart_poll(FAR struct file *filep,
@@ -140,15 +142,15 @@ static const struct file_operations g_serialops =
 {
   uart_open,    /* open */
   uart_close,   /* close */
-  NULL,         /* read */
-  NULL,         /* write */
+  uart_read,    /* read */
+  uart_write,   /* write */
   NULL,         /* seek */
   uart_ioctl,   /* ioctl */
   NULL,         /* mmap */
   NULL,         /* truncate */
   uart_poll,    /* poll */
   uart_readv,   /* readv */
-  uart_writev   /* writev */
+  NULL          /* writev */
 #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
   , uart_unlink /* unlink */
 #endif
@@ -440,50 +442,6 @@ static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
   return buflen;
 }
 
-/****************************************************************************
- * Name: uart_irqwritev
- ****************************************************************************/
-
-static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
-                                     FAR struct uio *uio)
-{
-  ssize_t error = 0;
-  ssize_t total = 0;
-  int iovcnt = uio->uio_iovcnt;
-  int i;
-
-  for (i = 0; i < iovcnt; i++)
-    {
-      const struct iovec *iov = &uio->uio_iov[i];
-      if (iov->iov_len == 0)
-        {
-          continue;
-        }
-
-      ssize_t written = uart_irqwrite(dev, iov->iov_base, iov->iov_len);
-      if (written < 0)
-        {
-          error = written;
-          break;
-        }
-
-      if (SSIZE_MAX - total < written)
-        {
-          error = -EOVERFLOW;
-          break;
-        }
-
-      total += written;
-    }
-
-  if (error != 0 && total == 0)
-    {
-      return error;
-    }
-
-  return total;
-}
-
 /****************************************************************************
  * Name: uart_tcdrain
  *
@@ -890,10 +848,11 @@ static int uart_close(FAR struct file *filep)
 }
 
 /****************************************************************************
- * Name: uart_readv
+ * Name: uart_read
  ****************************************************************************/
 
-static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
+static ssize_t uart_read_internal(FAR struct file *filep, FAR char *buffer,
+                                  size_t buflen, bool nonblock)
 {
   FAR struct inode *inode = filep->f_inode;
   FAR uart_dev_t *dev = inode->i_private;
@@ -904,7 +863,6 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
 #endif
   irqstate_t flags;
   ssize_t recvd = 0;
-  ssize_t buflen;
   bool echoed = false;
   int16_t tail;
   char ch;
@@ -928,8 +886,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
    * data from the end of the buffer.
    */
 
-  buflen = uio->uio_resid;
-  while (recvd < buflen)
+  while ((size_t)recvd < buflen)
     {
 #ifdef CONFIG_SERIAL_REMOVABLE
       /* If the removable device is no longer connected, refuse to read any
@@ -1005,8 +962,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
             {
               if (recvd > 0)
                 {
-                  static const char zero = '\0';
-                  uio_copyfrom(uio, recvd, &zero, 1);
+                  *buffer-- = '\0';
                   recvd--;
                   if (dev->tc_lflag & ECHO)
                     {
@@ -1035,7 +991,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
 
           /* Store the received character */
 
-          uio_copyfrom(uio, recvd, &ch, 1);
+          *buffer++ = ch;
           recvd++;
 
           if (dev->tc_lflag & ECHO)
@@ -1105,7 +1061,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
        * return what we have.
        */
 
-      else if ((filep->f_oflags & O_NONBLOCK) != 0)
+      else if ((filep->f_oflags & O_NONBLOCK) != 0 || nonblock)
         {
           /* If nothing was transferred, then return the -EAGAIN
            * error (not zero which means end of file).
@@ -1147,7 +1103,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
        * wait.
        */
 
-      else if ((filep->f_oflags & O_NONBLOCK) != 0)
+      else if ((filep->f_oflags & O_NONBLOCK) != 0 || nonblock)
         {
           /* Break out of the loop returning -EAGAIN */
 
@@ -1370,24 +1326,69 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
 #endif
 
   nxmutex_unlock(&dev->recv.lock);
-  if (recvd >= 0)
+  return recvd;
+}
+
+static ssize_t uart_read(FAR struct file *filep,
+                         FAR char *buffer, size_t buflen)
+{
+  return uart_read_internal(filep, buffer, buflen, false);
+}
+
+/****************************************************************************
+ * Name: uart_readv
+ ****************************************************************************/
+
+static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
+{
+  FAR const struct iovec *iov = uio->uio_iov;
+  int iovcnt = uio->uio_iovcnt;
+  bool nonblock = !!(filep->f_oflags & O_NONBLOCK);
+  ssize_t ntotal;
+  ssize_t nread;
+  int i;
+
+  for (i = 0, ntotal = 0; i < iovcnt; i++)
     {
-      uio_advance(uio, recvd);
+      nread = uart_read_internal(filep, iov[i].iov_base,
+                                 iov[i].iov_len, nonblock);
+      if (nread < 0)
+        {
+          if (ntotal > 0)
+            {
+              break;
+            }
+
+          return nread;
+        }
+
+      ntotal += nread;
+
+      /* Check for a parital success condition, including an end-of-file */
+
+      if (nread < iov[i].iov_len)
+        {
+          break;
+        }
+
+      /* set nonblock flag after first read */
+
+      nonblock = true;
     }
 
-  return recvd;
+  return ntotal;
 }
 
 /****************************************************************************
- * Name: uart_writev
+ * Name: uart_write
  ****************************************************************************/
 
-static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
+static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
+                          size_t buflen)
 {
   FAR struct inode *inode    = filep->f_inode;
   FAR uart_dev_t   *dev      = inode->i_private;
-  ssize_t           nwritten;
-  ssize_t           buflen;
+  ssize_t           nwritten = buflen;
   bool              oktoblock;
   int               ret;
   char              ch;
@@ -1413,14 +1414,12 @@ static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
 #endif
 
       flags = enter_critical_section();
-      ret = uart_irqwritev(dev, uio);
+      ret = uart_irqwrite(dev, buffer, buflen);
       leave_critical_section(flags);
 
       return ret;
     }
 
-  buflen = nwritten = uio->uio_resid;
-
   /* Only one user can access dev->xmit.head at a time */
 
   ret = nxmutex_lock(&dev->xmit.lock);
@@ -1460,9 +1459,9 @@ static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
    */
 
   uart_disabletxint(dev);
-  for (; buflen; uio_advance(uio, 1), buflen--)
+  for (; buflen; buflen--)
     {
-      uio_copyto(uio, 0, &ch, 1);
+      ch  = *buffer++;
       ret = OK;
 
       /* Do output post-processing */