initial import

sysdeps/posix/writev.c

@@ -0,0 +1,64 @@
+/* Copyright (C) 1991, 1992 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., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/uio.h>
+
+/* Write data pointed by the buffers described by VECTOR, which
+   is a vector of COUNT `struct iovec's, to file descriptor FD.
+   The data is written in the order specified.
+   Operates just like `write' (see <unistd.h>) except that the data
+   are taken from VECTOR instead of a contiguous buffer.  */
+int
+DEFUN(writev, (fd, vector, count),
+      int fd AND CONST struct iovec *vector AND size_t count)
+{
+  char *buffer;
+  register char *bp;
+  size_t bytes, to_copy;
+  register size_t i;
+
+  /* Find the total number of bytes to be written.  */
+  bytes = 0;
+  for (i = 0; i < count; ++i)
+    bytes += vector[i].iov_len;
+
+  /* Allocate a temporary buffer to hold the data.  */
+  buffer = (char *) __alloca(bytes);
+
+  /* Copy the data into BUFFER.  */
+  to_copy = bytes;
+  bp = buffer;
+  for (i = 0; i < count; ++i)
+    {
+#define	min(a, b)	((a) > (b) ? (b) : (a))
+      size_t copy = min(vector[i].iov_len, to_copy);
+
+      (void) memcpy((PTR) bp, (PTR) vector[i].iov_base, copy);
+
+      bp += copy;
+      to_copy -= copy;
+      if (bytes == 0)
+	break;
+    }
+
+  return write(fd, buffer, bytes);
+}