WIP struct out_bufferfw/out_buffer

1 files changed, 50 insertions, 0 deletions

diff --git a/malloc/out_buffer_get_array.c b/malloc/out_buffer_get_array.c
new file mode 100644
index 0000000000..0c09e33bd4
--- /dev/null
+++ b/malloc/out_buffer_get_array.c
@@ -0,0 +1,50 @@
+/* Array allocation from a fixed-size buffer.
+   Copyright (C) 2017 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 Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <out_buffer.h>
+
+void *
+internal_function
+__libc_out_buffer_get_array (struct out_buffer *buf,
+                             size_t element_size, size_t align,
+                             size_t count, size_t count_limit)
+{
+  /* Avoid spurious success if count == 0.  */
+  if (out_buffer_has_failed (buf))
+    return NULL;
+
+  size_t current = buf->__out_buffer_current;
+  /* The caller asserts that align is a power of two.  */
+  size_t aligned = (current + align - 1) & ~(align - 1);
+  size_t size = element_size * count;
+  size_t new_current = aligned + size;
+  if (count <= count_limit     /* Multiplication did not overflow.  */
+      && aligned >= current    /* No overflow in align step.  */
+      && new_current >= size   /* No overflow in size computation.  */
+      && new_current <= buf->__out_buffer_end) /* Room in buffer.  */
+    {
+      buf->__out_buffer_current = new_current;
+      return (void *) aligned;
+    }
+  else
+    {
+      out_buffer_mark_failed (buf);
+      return NULL;
+    }
+}
+libc_hidden_def (__libc_out_buffer_get_array)