1 files changed, 128 insertions, 0 deletions
diff --git a/cpukit/libcsupport/src/writev.c b/cpukit/libcsupport/src/writev.c
new file mode 100644
index 0000000000..380e325365
--- /dev/null
+++ b/cpukit/libcsupport/src/writev.c
@@ -0,0 +1,128 @@
+/*
+ *  writev() - POSIX 1003.1 - Read a Vector
+ *
+ *  OpenGroup URL:
+ *
+ *  http://www.opengroup.org/onlinepubs/009695399/functions/writev.html
+ *
+ *  COPYRIGHT (c) 1989-2007.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  The license and distribution terms for this file may be
+ *  found in the file LICENSE in this distribution or at
+ *  http://www.rtems.com/license/LICENSE.
+ *
+ *  $Id$
+ */
+
+#if HAVE_CONFIG_H
+#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,
+  const struct iovec *iov,
+  int                 iovcnt
+)
+{
+  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( iop, LIBIO_FLAGS_WRITE );
+
+  /*
+   *  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++ ) {
+
+    /*
+     *  iov[v].iov_len cannot be less than 0 because size_t is unsigned.
+     *  So we only check for zero.
+     */
+    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;
+  }
+
+  /*
+   *  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;
+
+    bytes = (*iop->pathinfo.handlers->write_h)(
+      iop,
+      iov[v].iov_base,
+      iov[v].iov_len
+    );
+
+    if ( bytes < 0 )
+      return -1;
+
+    if ( bytes > 0 ) {
+      iop->offset += bytes;
+      total       += bytes;
+    }
+
+    if (bytes != iov[ v ].iov_len)
+      break;
+  }
+
+  return total;
+}
+