fs/vfs: initialize uio only if lower implement readv/writev

to simple signle read/write logic, initialize uio only if lower implement readv/writev

Signed-off-by: chao an <anchao.archer@bytedance.com>

fs/vfs/fs_read.c

@@ -70,19 +70,14 @@
  *
  ****************************************************************************/
 
-static ssize_t file_readv_compat(FAR struct file *filep, FAR struct uio *uio)
+static ssize_t file_readv_compat(FAR struct file *filep,
+                                 FAR const struct iovec *iov, int iovcnt)
 {
-  FAR const struct iovec *iov = uio->uio_iov;
-  int iovcnt = uio->uio_iovcnt;
   FAR struct inode *inode = filep->f_inode;
   ssize_t ntotal;
   ssize_t nread;
-  size_t remaining;
-  FAR uint8_t *buffer;
   int i;
 
-  DEBUGASSERT(inode->u.i_ops->read != NULL);
-
   /* Process each entry in the struct iovec array */
 
   for (i = 0, ntotal = 0; i < iovcnt; i++)
@@ -94,36 +89,41 @@ static ssize_t file_readv_compat(FAR struct file *filep, FAR struct uio *uio)
           continue;
         }
 
-      buffer    = iov[i].iov_base;
+      /* Sanity check to avoid total length overflow */
-      remaining = iov[i].iov_len;
 
-      nread = inode->u.i_ops->read(filep, (void *)buffer, remaining);
+      if (SSIZE_MAX - ntotal < iov[i].iov_len)
+        {
+          if (ntotal > 0)
+            {
+              break;
+            }
+
+          return -EINVAL;
+        }
+
+      nread = inode->u.i_ops->read(filep, iov[i].iov_base,
+                                   iov[i].iov_len);
 
       /* Check for a read error */
 
       if (nread < 0)
         {
-          return ntotal ? ntotal : nread;
+          if (ntotal > 0)
+            {
+              break;
+            }
+
+          return nread;
         }
 
       ntotal += nread;
 
       /* Check for a parital success condition, including an end-of-file */
 
-      if (nread < remaining)
+      if (nread < iov[i].iov_len)
         {
-          return ntotal;
+          break;
         }
-
-      /* Update the pointer */
-
-      buffer    += nread;
-      remaining -= nread;
-    }
-
-  if (ntotal >= 0)
-    {
-      uio_advance(uio, ntotal);
     }
 
   return ntotal;
@@ -146,7 +146,8 @@ static ssize_t file_readv_compat(FAR struct file *filep, FAR struct uio *uio)
  *
  * Input Parameters:
  *   filep  - File structure instance
- *   uio    - User buffer information
+ *   iov    - User-provided iovec to save the data
+ *   iovcnt - The number of iovec
  *
  * Returned Value:
  *   The positive non-zero number of bytes read on success, 0 on if an
@@ -154,7 +155,8 @@ static ssize_t file_readv_compat(FAR struct file *filep, FAR struct uio *uio)
  *
  ****************************************************************************/
 
-ssize_t file_readv(FAR struct file *filep, FAR struct uio *uio)
+ssize_t file_readv(FAR struct file *filep,
+                   FAR const struct iovec *iov, int iovcnt)
 {
   FAR struct inode *inode;
   ssize_t ret = -EBADF;
@@ -182,11 +184,17 @@ ssize_t file_readv(FAR struct file *filep, FAR struct uio *uio)
     {
       if (inode->u.i_ops->readv)
         {
-          ret = inode->u.i_ops->readv(filep, uio);
+          struct uio uio;
+
+          ret = uio_init(&uio, iov, iovcnt);
+          if (ret == 0)
+            {
+              ret = inode->u.i_ops->readv(filep, &uio);
+            }
         }
       else if (inode->u.i_ops->read)
         {
-          ret = file_readv_compat(filep, uio);
+          ret = file_readv_compat(filep, iov, iovcnt);
         }
     }
 
@@ -227,18 +235,11 @@ ssize_t file_readv(FAR struct file *filep, FAR struct uio *uio)
 ssize_t file_read(FAR struct file *filep, FAR void *buf, size_t nbytes)
 {
   struct iovec iov;
-  struct uio uio;
-  ssize_t ret;
 
   iov.iov_base = buf;
   iov.iov_len = nbytes;
-  ret = uio_init(&uio, &iov, 1);
-  if (ret != 0)
-    {
-      return ret;
-    }
 
-  return file_readv(filep, &uio);
+  return file_readv(filep, &iov, 1);
 }
 
 /****************************************************************************
@@ -264,7 +265,6 @@ ssize_t file_read(FAR struct file *filep, FAR void *buf, size_t nbytes)
 
 ssize_t nx_readv(int fd, FAR const struct iovec *iov, int iovcnt)
 {
-  struct uio uio;
   FAR struct file *filep;
   ssize_t ret;
 
@@ -273,20 +273,15 @@ ssize_t nx_readv(int fd, FAR const struct iovec *iov, int iovcnt)
    */
 
   ret = (ssize_t)fs_getfilep(fd, &filep);
-  if (ret < 0)
+  if (ret >= 0)
     {
-      return ret;
+      /* Then let file_readv do all of the work. */
+
+      ret = file_readv(filep, iov, iovcnt);
+
+      fs_putfilep(filep);
     }
 
-  /* Then let file_readv do all of the work. */
-
-  ret = uio_init(&uio, iov, iovcnt);
-  if (ret == 0)
-    {
-      ret = file_readv(filep, &uio);
-    }
-
-  fs_putfilep(filep);
   return ret;
 }
 

fs/vfs/fs_write.c

@@ -53,19 +53,13 @@
  ****************************************************************************/
 
 static ssize_t file_writev_compat(FAR struct file *filep,
-                                  FAR struct uio *uio)
+                                  FAR const struct iovec *iov, int iovcnt)
 {
-  FAR const struct iovec *iov = uio->uio_iov;
-  int iovcnt = uio->uio_iovcnt;
   FAR struct inode *inode = filep->f_inode;
-  ssize_t ntotal;
   ssize_t nwritten;
-  size_t remaining;
+  ssize_t ntotal;
-  FAR uint8_t *buffer;
   int i;
 
-  DEBUGASSERT(inode->u.i_ops->write != NULL);
-
   /* Process each entry in the struct iovec array */
 
   for (i = 0, ntotal = 0; i < iovcnt; i++)
@@ -77,36 +71,41 @@ static ssize_t file_writev_compat(FAR struct file *filep,
           continue;
         }
 
-      buffer    = iov[i].iov_base;
+      /* Sanity check to avoid total length overflow */
-      remaining = iov[i].iov_len;
 
-      nwritten = inode->u.i_ops->write(filep, (void *)buffer, remaining);
+      if (SSIZE_MAX - ntotal < iov[i].iov_len)
+        {
+          if (ntotal > 0)
+            {
+              break;
+            }
+
+          return -EINVAL;
+        }
+
+      nwritten = inode->u.i_ops->write(filep, iov[i].iov_base,
+                                       iov[i].iov_len);
 
       /* Check for a write error */
 
       if (nwritten < 0)
         {
-          return ntotal ? ntotal : nwritten;
+          if (ntotal > 0)
+            {
+              break;
+            }
+
+          return nwritten;
         }
 
       ntotal += nwritten;
 
       /* Check for a parital success condition */
 
-      if (nwritten < remaining)
+      if (nwritten < iov[i].iov_len)
         {
-          return ntotal;
+          break;
         }
-
-      /* Update the pointer */
-
-      buffer    += nwritten;
-      remaining -= nwritten;
-    }
-
-  if (ntotal >= 0)
-    {
-      uio_advance(uio, ntotal);
     }
 
   return ntotal;
@@ -130,7 +129,8 @@ static ssize_t file_writev_compat(FAR struct file *filep,
  *
  * Input Parameters:
  *   filep  - Instance of struct file to use with the write
- *   uio    - User buffer information
+ *   iov    - Data to write
+ *   iovcnt - The number of vectors
  *
  * Returned Value:
  *  On success, the number of bytes written are returned (zero indicates
@@ -140,7 +140,8 @@ static ssize_t file_writev_compat(FAR struct file *filep,
  *
  ****************************************************************************/
 
-ssize_t file_writev(FAR struct file *filep, FAR struct uio *uio)
+ssize_t file_writev(FAR struct file *filep,
+                    FAR const struct iovec *iov, int iovcnt)
 {
   FAR struct inode *inode;
   ssize_t ret = -EBADF;
@@ -161,11 +162,17 @@ ssize_t file_writev(FAR struct file *filep, FAR struct uio *uio)
     {
       if (inode->u.i_ops->writev)
         {
-          ret = inode->u.i_ops->writev(filep, uio);
+          struct uio uio;
+
+          ret = uio_init(&uio, iov, iovcnt);
+          if (ret == 0)
+            {
+              ret = inode->u.i_ops->writev(filep, &uio);
+            }
         }
       else if (inode->u.i_ops->write)
         {
-          ret = file_writev_compat(filep, uio);
+          ret = file_writev_compat(filep, iov, iovcnt);
         }
     }
 
@@ -208,18 +215,11 @@ ssize_t file_write(FAR struct file *filep, FAR const void *buf,
                    size_t nbytes)
 {
   struct iovec iov;
-  struct uio uio;
-  ssize_t ret;
 
   iov.iov_base = (FAR void *)buf;
   iov.iov_len = nbytes;
-  ret = uio_init(&uio, &iov, 1);
-  if (ret != 0)
-    {
-      return ret;
-    }
 
-  return file_writev(filep, &uio);
+  return file_writev(filep, &iov, 1);
 }
 
 /****************************************************************************
@@ -249,7 +249,6 @@ ssize_t file_write(FAR struct file *filep, FAR const void *buf,
 
 ssize_t nx_writev(int fd, FAR const struct iovec *iov, int iovcnt)
 {
-  struct uio uio;
   FAR struct file *filep;
   ssize_t ret;
 
@@ -264,11 +263,7 @@ ssize_t nx_writev(int fd, FAR const struct iovec *iov, int iovcnt)
        * index.  Note that file_writev() will return the errno on failure.
        */
 
-      ret = uio_init(&uio, iov, iovcnt);
+      ret = file_writev(filep, iov, iovcnt);
-      if (ret == 0)
-        {
-          ret = file_writev(filep, &uio);
-        }
 
       fs_putfilep(filep);
     }

include/nuttx/fs/fs.h

@@ -1419,7 +1419,8 @@ int close_mtddriver(FAR struct inode *pinode);
  ****************************************************************************/
 
 ssize_t file_read(FAR struct file *filep, FAR void *buf, size_t nbytes);
-ssize_t file_readv(FAR struct file *filep, FAR struct uio *uio);
+ssize_t file_readv(FAR struct file *filep,
+                   FAR const struct iovec *iov, int iovcnt);
 
 /****************************************************************************
  * Name: nx_read
@@ -1473,7 +1474,8 @@ ssize_t nx_readv(int fd, FAR const struct iovec *iov, int iovcnt);
 
 ssize_t file_write(FAR struct file *filep, FAR const void *buf,
                    size_t nbytes);
-ssize_t file_writev(FAR struct file *filep, FAR struct uio *uio);
+ssize_t file_writev(FAR struct file *filep,
+                    FAR const struct iovec *iov, int iovcnt);
 
 /****************************************************************************
  * Name: nx_write