1 files changed, 68 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/writev.c b/sysdeps/unix/sysv/linux/writev.c
new file mode 100644
index 0000000000..11afd81d2e
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/writev.c
@@ -0,0 +1,68 @@
+/* writev supports all Linux kernels >= 2.0.
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <errno.h>
+#include <stddef.h>
+#include <sys/param.h>
+#include <sys/uio.h>
+
+extern ssize_t __syscall_writev __P ((int, const struct iovec *, int));
+
+/* Not all versions of the kernel support the large number of records.  */
+#undef MAX_IOVEC
+#ifdef UIO_FASTIOV
+# define MAX_IOVEC	UIO_FASTIOV
+#else
+# define MAX_IOVEC	8	/* 8 is a safe number. */
+#endif
+
+
+/* We should deal with kernel which have a smaller UIO_MAXIOV as well
+   as a very big count.  */
+ssize_t
+writev (fd, vector, count)
+     int fd;
+     const struct iovec *vector;
+     int count;
+{
+  int errno_saved = errno;
+  ssize_t bytes_written;
+
+  bytes_written = __syscall_writev (fd, vector, count);
+
+  if (bytes_written < 0 && errno == EINVAL && count > MAX_IOVEC)
+    {
+      int i;
+
+      /* Restore the old error value as if nothing happened.  */
+      __set_errno (errno_saved);
+
+      bytes_written = 0;
+      for (i = 0; i < count; i += MAX_IOVEC)
+	{
+	  ssize_t bytes = __syscall_writev (fd, vector + i,
+					    MIN (count - i, MAX_IOVEC));
+
+	  if (bytes < 0)
+	    return bytes_written > 0 ? bytes_written : bytes;
+	}
+    }
+
+  return bytes_written;
+}