[PATCH v2] Initial support for the android bootimg filesystem.

[Shea Levy]

Currently, the kernel and, if present, the ramdisk are made available as
regular files.
---
 grub-core/Makefile.core.def    |   7 ++
 grub-core/fs/android_bootimg.c | 271 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 278 insertions(+)
 create mode 100644 grub-core/fs/android_bootimg.c

diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 0cc40bb..a726abd 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -1231,6 +1231,13 @@ module = {
 };
 
 module = {
+  name = android_bootimg;
+  common = fs/android_bootimg.c;
+  cflags = '$(CFLAGS_POSIX) $(CFLAGS_GNULIB)';
+  cppflags = '$(CPPFLAGS_POSIX) $(CPPFLAGS_GNULIB)';
+};
+
+module = {
   name = bfs;
   common = fs/bfs.c;
 };
diff --git a/grub-core/fs/android_bootimg.c b/grub-core/fs/android_bootimg.c
new file mode 100644
index 0000000..093307a
--- /dev/null
+++ b/grub-core/fs/android_bootimg.c
@@ -0,0 +1,271 @@
+/* android-bootimg.c - android bootimg filesystem.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2016 Free Software Foundation, Inc.
+ *
+ *  This program 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.
+ *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <grub/dl.h>
+#include <grub/file.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+/* from 
https://android.googlesource.com/platform/system/core/+/506d233e7ac8ca4efa80768153d842c296477f99/mkbootimg/bootimg.h
 */
+/* From here until the end of struct boot_img_hdr available under the 
following terms:
+ *
+ * Copyright 2007, The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#define BOOT_MAGIC     "ANDROID!"
+#define BOOT_MAGIC_SIZE        8
+#define BOOT_NAME_SIZE 16
+#define BOOT_ARGS_SIZE 512
+#define BOOT_EXTRA_ARGS_SIZE   1024
+
+struct boot_img_hdr
+{
+  uint8_t magic[BOOT_MAGIC_SIZE];
+
+  uint32_t kernel_size;
+  uint32_t kernel_addr;
+
+  uint32_t ramdisk_size;
+  uint32_t ramdisk_addr;
+
+  uint32_t second_size;
+  uint32_t second_addr;
+
+  uint32_t tags_addr;
+  uint32_t page_size;
+  uint32_t unused[2];
+
+  uint8_t name[BOOT_NAME_SIZE];
+
+  uint8_t cmdline[BOOT_ARGS_SIZE];
+
+  uint32_t id[8];
+
+  uint8_t extra_cmdline[BOOT_EXTRA_ARGS_SIZE];
+} GRUB_PACKED;
+
+typedef enum
+  {
+    ROOT,
+    KERNEL,
+    RAMDISK,
+    NOT_FOUND,
+    BAD_NAME
+  }
+grub_android_bootimg_filename_t;
+
+static grub_android_bootimg_filename_t
+handle_path (const char *path)
+{
+  if (!path || path[0] != '/')
+    return BAD_NAME;
+
+  const char *path_iter;
+  for (path_iter = path + 1; *path_iter; ++path_iter) {
+    if (*path_iter == '/')
+      continue;
+    if (*path_iter == '.') {
+      if (*(++path_iter) == '/')
+       continue;
+      else if (*path_iter == '.' && *(++path_iter) == '/')
+       continue;
+      else
+       return NOT_FOUND;
+    }
+    break;
+  }
+
+  if (!*path_iter)
+    return ROOT;
+  else if (grub_strcmp (path_iter, "kernel") == 0)
+    return KERNEL;
+  else if (grub_strcmp (path_iter, "ramdisk") == 0)
+    return RAMDISK;
+  else
+    return NOT_FOUND;
+}
+
+static grub_err_t
+read_hdr (grub_disk_t disk, struct boot_img_hdr *hd)
+{
+  if (grub_disk_read (disk, 0, 0, sizeof *hd, hd))
+    goto fail;
+
+  if (grub_memcmp (hd->magic, BOOT_MAGIC, BOOT_MAGIC_SIZE))
+    goto fail;
+
+  if (hd->unused[0] || hd->unused[1])
+    goto fail;
+
+  return GRUB_ERR_NONE;
+
+fail:
+  return grub_error (GRUB_ERR_BAD_FS, N_("%s not an android bootimg"),
+                     disk->name);
+}
+
+static grub_err_t
+grub_android_bootimg_dir (grub_device_t device, const char *path,
+               grub_fs_dir_hook_t hook, void *hook_data)
+{
+  struct boot_img_hdr hd;
+
+  if (read_hdr (device->disk, &hd))
+    return grub_errno;
+
+  grub_android_bootimg_filename_t file = handle_path (path);
+  if (file == NOT_FOUND)
+    return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("directory `%s' not found"),
+                       path);
+  else if (file == BAD_NAME)
+    return grub_error (GRUB_ERR_BAD_FILENAME, N_("invalid directory name 
`%s'"),
+                       path);
+  else if (file != ROOT)
+    return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("`%s' not a directory"),
+                       path);
+
+  struct grub_dirhook_info info = {
+    .dir = 1,
+    .mtimeset = 0,
+    .case_insensitive = 0,
+    .inodeset = 0,
+    .mtime = 0,
+    .inode = 0
+  };
+
+  if (hook (".", &info, hook_data)) {
+    return grub_errno;
+  }
+
+  if (hook ("..", &info, hook_data)) {
+    return grub_errno;
+  }
+
+  info.dir = 0;
+
+  if (hook ("kernel", &info, hook_data)) {
+    return grub_errno;
+  }
+
+  if (hd.ramdisk_size != 0) {
+    if (hook ("ramdisk", &info, hook_data)) {
+      return grub_errno;
+    }
+  }
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_err_t
+grub_android_bootimg_open (grub_file_t file, const char *name)
+{
+  struct boot_img_hdr hd;
+
+  if (read_hdr (file->device->disk, &hd))
+    return grub_errno;
+
+  grub_off_t *begin_offset;
+
+  grub_android_bootimg_filename_t fn = handle_path (name);
+  switch (fn)
+    {
+    case NOT_FOUND:
+      return grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("file `%s' not found"),
+                         name);
+    case BAD_NAME:
+      return grub_error (GRUB_ERR_BAD_FILENAME, N_("bad file name `%s'"), 
name);
+    case ROOT:
+      return grub_error (GRUB_ERR_BAD_FILE_TYPE, N_("`%s' not a regular file"),
+                         name);
+    case KERNEL:
+      begin_offset = grub_malloc (sizeof *begin_offset);
+      *begin_offset = hd.page_size;
+      file->data = begin_offset;
+      file->size = hd.kernel_size;
+      break;
+    case RAMDISK:
+      begin_offset = grub_malloc (sizeof *begin_offset);
+      *begin_offset =
+        hd.page_size * (1 + (hd.kernel_size + hd.page_size - 1) / 
hd.page_size);
+      file->data = begin_offset;
+      file->size = hd.ramdisk_size;
+      break;
+    }
+
+  return GRUB_ERR_NONE;
+}
+
+static grub_ssize_t
+grub_android_bootimg_read (grub_file_t file, char *buf, grub_size_t len)
+{
+  grub_size_t len_left = file->size - file->offset;
+  len = len > len_left ? len_left : len;
+  grub_off_t *begin_offset = file->data;
+  grub_off_t actual_offset = *begin_offset + file->offset;
+  file->device->disk->read_hook = file->read_hook;
+  file->device->disk->read_hook_data = file->read_hook_data;
+  grub_errno = grub_disk_read (file->device->disk, 0, actual_offset, len, buf);
+  file->device->disk->read_hook = 0;
+
+  if (grub_errno)
+    return -1;
+  else
+    return len;
+}
+
+static grub_err_t
+grub_android_bootimg_close (grub_file_t file)
+{
+  grub_free (file->data);
+  return GRUB_ERR_NONE;
+}
+
+static struct grub_fs grub_android_bootimg_fs = {
+  .name = "android_bootimg",
+  .dir = grub_android_bootimg_dir,
+  .open = grub_android_bootimg_open,
+  .read = grub_android_bootimg_read,
+  .close = grub_android_bootimg_close,
+#ifdef GRUB_UTIL
+  .reserved_first_sector = 0,
+  .blocklist_install = 0,
+#endif
+};
+
+GRUB_MOD_INIT (android_bootimg)
+{
+  grub_fs_register (&grub_android_bootimg_fs);
+}
+
+GRUB_MOD_FINI (android_bootimg)
+{
+  grub_fs_unregister (&grub_android_bootimg_fs);
+}
-- 
2.7.0