1 files changed, 117 insertions, 0 deletions
diff --git a/grub-core/kern/buffer.c b/grub-core/kern/buffer.c
new file mode 100644
index 0000000..9f5f8b8
--- /dev/null
+++ b/grub-core/kern/buffer.c
@@ -0,0 +1,117 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2021  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/buffer.h>
+#include <grub/err.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/safemath.h>
+#include <grub/types.h>
+
+grub_buffer_t
+grub_buffer_new (grub_size_t sz)
+{
+  struct grub_buffer *ret;
+
+  ret = (struct grub_buffer *) grub_malloc (sizeof (*ret));
+  if (ret == NULL)
+    return NULL;
+
+  ret->data = (grub_uint8_t *) grub_malloc (sz);
+  if (ret->data == NULL)
+    {
+      grub_free (ret);
+      return NULL;
+    }
+
+  ret->sz = sz;
+  ret->pos = 0;
+  ret->used = 0;
+
+  return ret;
+}
+
+void
+grub_buffer_free (grub_buffer_t buf)
+{
+  grub_free (buf->data);
+  grub_free (buf);
+}
+
+grub_err_t
+grub_buffer_ensure_space (grub_buffer_t buf, grub_size_t req)
+{
+  grub_uint8_t *d;
+  grub_size_t newsz = 1;
+
+  /* Is the current buffer size adequate? */
+  if (buf->sz >= req)
+    return GRUB_ERR_NONE;
+
+  /* Find the smallest power-of-2 size that satisfies the request. */
+  while (newsz < req)
+    {
+      if (newsz == 0)
+	return grub_error (GRUB_ERR_OUT_OF_RANGE,
+			   N_("requested buffer size is too large"));
+      newsz <<= 1;
+    }
+
+  d = (grub_uint8_t *) grub_realloc (buf->data, newsz);
+  if (d == NULL)
+    return grub_errno;
+
+  buf->data = d;
+  buf->sz = newsz;
+
+  return GRUB_ERR_NONE;
+}
+
+void *
+grub_buffer_take_data (grub_buffer_t buf)
+{
+  void *data = buf->data;
+
+  buf->data = NULL;
+  buf->sz = buf->pos = buf->used = 0;
+
+  return data;
+}
+
+void
+grub_buffer_reset (grub_buffer_t buf)
+{
+  buf->pos = buf->used = 0;
+}
+
+grub_err_t
+grub_buffer_advance_read_pos (grub_buffer_t buf, grub_size_t n)
+{
+  grub_size_t newpos;
+
+  if (grub_add (buf->pos, n, &newpos))
+    return grub_error (GRUB_ERR_OUT_OF_RANGE, N_("overflow is detected"));
+
+  if (newpos > buf->used)
+    return grub_error (GRUB_ERR_OUT_OF_RANGE,
+		       N_("new read is position beyond the end of the written data"));
+
+  buf->pos = newpos;
+
+  return GRUB_ERR_NONE;
+}