From 95a57280ebc3996547fccd6065a5652a846d1447 Mon Sep 17 00:00:00 2001
From: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Mon, 16 Dec 2013 13:12:22 +0100
Subject: libcsupport: Add and use rtems_libio_iovec_eval()

---
 cpukit/libcsupport/src/writev.c | 98 +++++++----------------------------------
 1 file changed, 16 insertions(+), 82 deletions(-)

(limited to 'cpukit/libcsupport/src/writev.c')

diff --git a/cpukit/libcsupport/src/writev.c b/cpukit/libcsupport/src/writev.c
index 47605a4cd9..4a8dc735b8 100644
--- a/cpukit/libcsupport/src/writev.c
+++ b/cpukit/libcsupport/src/writev.c
@@ -1,5 +1,5 @@
 /*
- *  writev() - POSIX 1003.1 - Read a Vector
+ *  writev() - POSIX 1003.1 - Write a Vector
  *
  *  OpenGroup URL:
  *
@@ -17,11 +17,9 @@
 #include "config.h"
 #endif
 
-#include <sys/types.h>
 #include <sys/uio.h>
 
 #include <rtems/libio_.h>
-#include <rtems/seterr.h>
 
 ssize_t writev(
   int                 fd,
@@ -31,95 +29,31 @@ ssize_t writev(
 {
   ssize_t        total;
   int            v;
-  int            bytes;
   rtems_libio_t *iop;
-  ssize_t        old;
-  bool           all_zeros;
 
-  rtems_libio_check_fd( fd );
-  iop = rtems_libio_iop( fd );
-  rtems_libio_check_is_open( iop );
-  rtems_libio_check_permissions_with_error( iop, LIBIO_FLAGS_WRITE, EBADF );
-
-  /*
-   *  Argument validation on IO vector
-   */
-  if ( !iov )
-    rtems_set_errno_and_return_minus_one( EINVAL );
-
-  if ( iovcnt <= 0 )
-    rtems_set_errno_and_return_minus_one( EINVAL );
-
-  if ( iovcnt > IOV_MAX )
-    rtems_set_errno_and_return_minus_one( EINVAL );
-
-  /*
-   *  OpenGroup says that you are supposed to return EINVAL if the
-   *  sum of the iov_len values in the iov array would overflow a
-   *  ssize_t.
-   *
-   *  Also we would like to ensure that no IO is performed if there
-   *  are obvious errors in the iovec.  So this extra loop ensures
-   *  that we do not do anything if there is an argument error.
-   *
-   *  In addition,the OpenGroup specification says that if all the
-   *  iov_len entries are zero, then the call has no effect.  So
-   *  this loop does that check as well and sets "all-zero" appropriately.
-   *  The variable "all_zero" is used as an early exit point before
-   *  entering the write loop.
-   */
-  all_zeros = true;
-  for ( old=0, total=0, v=0 ; v < iovcnt ; v++ ) {
+  total = rtems_libio_iovec_eval( fd, iov, iovcnt, LIBIO_FLAGS_WRITE, &iop );
 
+  if ( total > 0 ) {
     /*
-     *  iov[v].iov_len cannot be less than 0 because size_t is unsigned.
-     *  So we only check for zero.
+     *  Now process the writev().
      */
-    if ( iov[v].iov_base == 0 )
-      rtems_set_errno_and_return_minus_one( EINVAL );
-
-    if ( iov[v].iov_len )
-      all_zeros = false;
-
-    /* check for wrap */
-    old    = total;
-    total += iov[v].iov_len;
-    if ( total < old || total > SSIZE_MAX )
-      rtems_set_errno_and_return_minus_one( EINVAL );
-  }
-
-  /*
-   * A writev with all zeros is supposed to have no effect per OpenGroup.
-   */
-  if ( all_zeros == true ) {
-    return 0;
-  }
+    total = 0;
+    for ( v = 0 ; v < iovcnt ; v++ ) {
+      ssize_t bytes = ( *iop->pathinfo.handlers->write_h )(
+        iop,
+        iov[ v ].iov_base,
+        iov[ v ].iov_len
+      );
 
-  /*
-   *  Now process the writev().
-   */
-  for ( total=0, v=0 ; v < iovcnt ; v++ ) {
-    /* all zero lengths has no effect */
-    if ( iov[v].iov_len == 0 )
-      continue;
+      if ( bytes < 0 )
+        return -1;
 
-    bytes = (*iop->pathinfo.handlers->write_h)(
-      iop,
-      iov[v].iov_base,
-      iov[v].iov_len
-    );
+      total += bytes;
 
-    if ( bytes < 0 )
-      return -1;
-
-    if ( bytes > 0 ) {
-      total       += bytes;
+      if ( bytes != iov[ v ].iov_len )
+        break;
     }
-
-    if (bytes != iov[ v ].iov_len)
-      break;
   }
 
   return total;
 }
-
-- 
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