1 files changed, 209 insertions, 0 deletions
diff --git a/grub-core/io/bufio.c b/grub-core/io/bufio.c
new file mode 100644
index 0000000..3b456c1
--- /dev/null
+++ b/grub-core/io/bufio.c
@@ -0,0 +1,209 @@
+/* bufio.c - buffered io access */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  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/err.h>
+#include <grub/types.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/fs.h>
+#include <grub/bufio.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+#define GRUB_BUFIO_DEF_SIZE	8192
+#define GRUB_BUFIO_MAX_SIZE	1048576
+
+struct grub_bufio
+{
+  grub_file_t file;
+  grub_size_t block_size;
+  grub_size_t buffer_len;
+  char buffer[0];
+};
+typedef struct grub_bufio *grub_bufio_t;
+
+static struct grub_fs grub_bufio_fs;
+
+grub_file_t
+grub_bufio_open (grub_file_t io, int size)
+{
+  grub_file_t file;
+  grub_bufio_t bufio = 0;
+
+  file = (grub_file_t) grub_malloc (sizeof (*file));
+  if (! file)
+    return 0;
+
+  if (size == 0)
+    size = GRUB_BUFIO_DEF_SIZE;
+  else if (size > GRUB_BUFIO_MAX_SIZE)
+    size = GRUB_BUFIO_MAX_SIZE;
+
+  if ((size < 0) || ((unsigned) size > io->size))
+    size = ((io->size > GRUB_BUFIO_MAX_SIZE) ? GRUB_BUFIO_MAX_SIZE :
+            io->size);
+
+  bufio = grub_malloc (sizeof (struct grub_bufio) + size);
+  if (! bufio)
+    {
+      grub_free (file);
+      return 0;
+    }
+
+  bufio->file = io;
+  bufio->block_size = size;
+  bufio->buffer_len = 0;
+
+  file->device = io->device;
+  file->offset = 0;
+  file->size = io->size;
+  file->data = bufio;
+  file->read_hook = 0;
+  file->fs = &grub_bufio_fs;
+  file->not_easily_seekable = io->not_easily_seekable;
+
+  return file;
+}
+
+grub_file_t
+grub_buffile_open (const char *name, int size)
+{
+  grub_file_t io, file;
+
+  io = grub_file_open (name);
+  if (! io)
+    return 0;
+
+  file = grub_bufio_open (io, size);
+  if (! file)
+    {
+      grub_file_close (io);
+      return 0;
+    }
+
+  return file;
+}
+
+static grub_ssize_t
+grub_bufio_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_size_t res = len;
+  grub_bufio_t bufio = file->data;
+  grub_uint32_t pos;
+
+  if ((file->offset >= bufio->file->offset) &&
+      (file->offset < bufio->file->offset + bufio->buffer_len))
+    {
+      grub_size_t n;
+
+      pos = file->offset - bufio->file->offset;
+      n = bufio->buffer_len - pos;
+      if (n > len)
+        n = len;
+
+      grub_memcpy (buf, &bufio->buffer[pos], n);
+      len -= n;
+      if (! len)
+        return res;
+
+      buf += n;
+      bufio->file->offset += bufio->buffer_len;
+      pos = 0;
+    }
+  else
+    {
+      bufio->file->offset = grub_divmod64 (file->offset, bufio->block_size,
+                                           &pos);
+      bufio->file->offset *= bufio->block_size;
+    }
+
+  if (pos + len >= bufio->block_size)
+    {
+      if (pos)
+        {
+          grub_size_t n;
+
+          bufio->file->fs->read (bufio->file, bufio->buffer,
+                                 bufio->block_size);
+          if (grub_errno)
+            return -1;
+
+          n = bufio->block_size - pos;
+          grub_memcpy (buf, &bufio->buffer[pos], n);
+          len -= n;
+          buf += n;
+          bufio->file->offset += bufio->block_size;
+          pos = 0;
+        }
+
+      while (len >= bufio->block_size)
+        {
+          bufio->file->fs->read (bufio->file, buf, bufio->block_size);
+          if (grub_errno)
+            return -1;
+
+          len -= bufio->block_size;
+          buf += bufio->block_size;
+          bufio->file->offset += bufio->block_size;
+        }
+
+      if (! len)
+        {
+          bufio->buffer_len = 0;
+          return res;
+        }
+    }
+
+  bufio->buffer_len = bufio->file->size - bufio->file->offset;
+  if (bufio->buffer_len > bufio->block_size)
+    bufio->buffer_len = bufio->block_size;
+
+  bufio->file->fs->read (bufio->file, bufio->buffer, bufio->buffer_len);
+  if (grub_errno)
+    return -1;
+
+  grub_memcpy (buf, &bufio->buffer[pos], len);
+
+  return res;
+}
+
+static grub_err_t
+grub_bufio_close (grub_file_t file)
+{
+  grub_bufio_t bufio = file->data;
+
+  grub_file_close (bufio->file);
+  grub_free (bufio);
+
+  file->device = 0;
+
+  return grub_errno;
+}
+
+static struct grub_fs grub_bufio_fs =
+  {
+    .name = "bufio",
+    .dir = 0,
+    .open = 0,
+    .read = grub_bufio_read,
+    .close = grub_bufio_close,
+    .label = 0,
+    .next = 0
+  };