automake commit without merge history

grub-core/kern/file.c

@@ -0,0 +1,166 @@
+/* file.c - file I/O functions */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2002,2006,2007,2009  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/misc.h>
+#include <grub/err.h>
+#include <grub/file.h>
+#include <grub/mm.h>
+#include <grub/fs.h>
+#include <grub/device.h>
+
+/* Get the device part of the filename NAME. It is enclosed by parentheses.  */
+char *
+grub_file_get_device_name (const char *name)
+{
+  if (name[0] == '(')
+    {
+      char *p = grub_strchr (name, ')');
+      char *ret;
+
+      if (! p)
+	{
+	  grub_error (GRUB_ERR_BAD_FILENAME, "missing `)'");
+	  return 0;
+	}
+
+      ret = (char *) grub_malloc (p - name);
+      if (! ret)
+	return 0;
+
+      grub_memcpy (ret, name + 1, p - name - 1);
+      ret[p - name - 1] = '\0';
+      return ret;
+    }
+
+  return 0;
+}
+
+grub_file_t
+grub_file_open (const char *name)
+{
+  grub_device_t device;
+  grub_file_t file = 0;
+  char *device_name;
+  char *file_name;
+
+  device_name = grub_file_get_device_name (name);
+  if (grub_errno)
+    return 0;
+
+  /* Get the file part of NAME.  */
+  file_name = grub_strchr (name, ')');
+  if (file_name)
+    file_name++;
+  else
+    file_name = (char *) name;
+
+  device = grub_device_open (device_name);
+  grub_free (device_name);
+  if (! device)
+    goto fail;
+
+  file = (grub_file_t) grub_zalloc (sizeof (*file));
+  if (! file)
+    goto fail;
+
+  file->device = device;
+
+  if (device->disk && file_name[0] != '/')
+    /* This is a block list.  */
+    file->fs = &grub_fs_blocklist;
+  else
+    {
+      file->fs = grub_fs_probe (device);
+      if (! file->fs)
+	goto fail;
+    }
+
+  if ((file->fs->open) (file, file_name) != GRUB_ERR_NONE)
+    goto fail;
+
+  return file;
+
+ fail:
+  if (device)
+    grub_device_close (device);
+
+  /* if (net) grub_net_close (net);  */
+
+  grub_free (file);
+
+  return 0;
+}
+
+grub_ssize_t
+grub_file_read (grub_file_t file, void *buf, grub_size_t len)
+{
+  grub_ssize_t res;
+
+  if (file->offset > file->size)
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE,
+		  "attempt to read past the end of file");
+      return -1;
+    }
+
+  if (len == 0 || len > file->size - file->offset)
+    len = file->size - file->offset;
+
+  /* Prevent an overflow.  */
+  if ((grub_ssize_t) len < 0)
+    len >>= 1;
+
+  if (len == 0)
+    return 0;
+
+  res = (file->fs->read) (file, buf, len);
+  if (res > 0)
+    file->offset += res;
+
+  return res;
+}
+
+grub_err_t
+grub_file_close (grub_file_t file)
+{
+  if (file->fs->close)
+    (file->fs->close) (file);
+
+  if (file->device)
+    grub_device_close (file->device);
+  grub_free (file);
+  return grub_errno;
+}
+
+grub_off_t
+grub_file_seek (grub_file_t file, grub_off_t offset)
+{
+  grub_off_t old;
+
+  if (offset > file->size)
+    {
+      grub_error (GRUB_ERR_OUT_OF_RANGE,
+		  "attempt to seek outside of the file");
+      return -1;
+    }
+
+  old = file->offset;
+  file->offset = offset;
+  return old;
+}