+/* loopback.c - command to add loopback devices. */
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2005,2006,2007 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/dl.h>
+#include <grub/misc.h>
+#include <grub/file.h>
+#include <grub/disk.h>
+#include <grub/mm.h>
+#include <grub/extcmd.h>
+#include <grub/i18n.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+struct grub_loopback
+{
+ char *devname;
+ grub_file_t file;
+ struct grub_loopback *next;
+ unsigned long id;
+ grub_off_t skip;
+};
+
+static struct grub_loopback *loopback_list;
+static unsigned long last_id = 0;
+
+static const struct grub_arg_option options[] =
+ {
+ /* TRANSLATORS: The disk is simply removed from the list of available ones,
+ not wiped, avoid to scare user. */
+ {"delete", 'd', 0, N_("Delete the specified loopback drive."), 0, 0},
+ {"skip", 's', 0, "skip sectors of the file.", "SECTORS", ARG_TYPE_INT },
+ {0, 0, 0, 0, 0, 0}
+ };
+
+/* Delete the loopback device NAME. */
+static grub_err_t
+delete_loopback (const char *name)
+{
+ struct grub_loopback *dev;
+ struct grub_loopback **prev;
+
+ /* Search for the device. */
+ for (dev = loopback_list, prev = &loopback_list;
+ dev;
+ prev = &dev->next, dev = dev->next)
+ if (grub_strcmp (dev->devname, name) == 0)
+ break;
+
+ if (! dev)
+ return grub_error (GRUB_ERR_BAD_DEVICE, "device not found");
+
+ /* Remove the device from the list. */
+ *prev = dev->next;
+
+ grub_free (dev->devname);
+ grub_file_close (dev->file);
+ grub_free (dev);
+
+ return 0;
+}
+
+/* The command to add and remove loopback devices. */
+static grub_err_t
+grub_cmd_loopback (grub_extcmd_context_t ctxt, int argc, char **args)
+{
+ struct grub_arg_list *state = ctxt->state;
+ grub_file_t file;
+ struct grub_loopback *newdev;
+ grub_err_t ret;
+ grub_off_t skip = 0;
+
+ if (argc < 1)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, "device name required");
+
+ /* Check if `-d' was used. */
+ if (state[0].set)
+ return delete_loopback (args[0]);
+
+ if (state[1].set)
+ skip = (grub_off_t)grub_strtoull(state[1].arg, NULL, 10);
+
+ if (argc < 2)
+ return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("filename expected"));
+
+ file = grub_file_open (args[1], GRUB_FILE_TYPE_LOOPBACK
+ | GRUB_FILE_TYPE_NO_DECOMPRESS);
+ if (! file)
+ return grub_errno;
+
+ /* First try to replace the old device. */
+ for (newdev = loopback_list; newdev; newdev = newdev->next)
+ if (grub_strcmp (newdev->devname, args[0]) == 0)
+ break;
+
+ if (newdev)
+ {
+ grub_file_close (newdev->file);
+ newdev->file = file;
+ newdev->skip = skip;
+
+ return 0;
+ }
+
+ /* Unable to replace it, make a new entry. */
+ newdev = grub_malloc (sizeof (struct grub_loopback));
+ if (! newdev)
+ goto fail;
+
+ newdev->devname = grub_strdup (args[0]);
+ if (! newdev->devname)
+ {
+ grub_free (newdev);
+ goto fail;
+ }
+
+ newdev->file = file;
+ newdev->skip = skip;
+ newdev->id = last_id++;
+
+ /* Add the new entry to the list. */
+ newdev->next = loopback_list;
+ loopback_list = newdev;
+
+ return 0;
+
+fail:
+ ret = grub_errno;
+ grub_file_close (file);
+ return ret;
+}
+
+\f
+static int
+grub_loopback_iterate (grub_disk_dev_iterate_hook_t hook, void *hook_data,
+ grub_disk_pull_t pull)
+{
+ struct grub_loopback *d;
+ if (pull != GRUB_DISK_PULL_NONE)
+ return 0;
+ for (d = loopback_list; d; d = d->next)
+ {
+ if (hook (d->devname, hook_data))
+ return 1;
+ }
+ return 0;
+}
+
+static grub_err_t
+grub_loopback_open (const char *name, grub_disk_t disk)
+{
+ struct grub_loopback *dev;
+
+ for (dev = loopback_list; dev; dev = dev->next)
+ if (grub_strcmp (dev->devname, name) == 0)
+ break;
+
+ if (! dev)
+ return grub_error (GRUB_ERR_UNKNOWN_DEVICE, "can't open device");
+
+ /* Use the filesize for the disk size, round up to a complete sector. */
+ if (dev->file->size != GRUB_FILE_SIZE_UNKNOWN)
+ disk->total_sectors = ((dev->file->size + GRUB_DISK_SECTOR_SIZE - 1)
+ / GRUB_DISK_SECTOR_SIZE);
+ else
+ disk->total_sectors = GRUB_DISK_SIZE_UNKNOWN;
+ /* Avoid reading more than 512M. */
+ disk->max_agglomerate = 1 << (29 - GRUB_DISK_SECTOR_BITS
+ - GRUB_DISK_CACHE_BITS);
+
+ disk->id = dev->id;
+
+ disk->data = dev;
+
+ return 0;
+}
+
+static grub_err_t
+grub_loopback_read (grub_disk_t disk, grub_disk_addr_t sector,
+ grub_size_t size, char *buf)
+{
+ grub_file_t file = ((struct grub_loopback *) disk->data)->file;
+ grub_off_t skip = ((struct grub_loopback *) disk->data)->skip;
+ grub_off_t pos;
+
+ grub_file_seek (file, (sector + skip) << GRUB_DISK_SECTOR_BITS);
+
+ grub_file_read (file, buf, size << GRUB_DISK_SECTOR_BITS);
+ if (grub_errno)
+ return grub_errno;
+
+ /* In case there is more data read than there is available, in case
+ of files that are not a multiple of GRUB_DISK_SECTOR_SIZE, fill
+ the rest with zeros. */
+ pos = (sector + skip + size) << GRUB_DISK_SECTOR_BITS;
+ if (pos > file->size)
+ {
+ grub_size_t amount = pos - file->size;
+ grub_memset (buf + (size << GRUB_DISK_SECTOR_BITS) - amount, 0, amount);
+ }
+
+ return 0;
+}
+
+static grub_err_t
+grub_loopback_write (grub_disk_t disk __attribute ((unused)),
+ grub_disk_addr_t sector __attribute ((unused)),
+ grub_size_t size __attribute ((unused)),
+ const char *buf __attribute ((unused)))
+{
+ return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
+ "loopback write is not supported");
+}
+
+static struct grub_disk_dev grub_loopback_dev =
+ {
+ .name = "loopback",
+ .id = GRUB_DISK_DEVICE_LOOPBACK_ID,
+ .disk_iterate = grub_loopback_iterate,
+ .disk_open = grub_loopback_open,
+ .disk_read = grub_loopback_read,
+ .disk_write = grub_loopback_write,
+ .next = 0
+ };
+
+static grub_extcmd_t cmd;
+
+GRUB_MOD_INIT(loopback)
+{
+ cmd = grub_register_extcmd ("loopback", grub_cmd_loopback, 0,
+ N_("[-d] DEVICENAME FILE."),
+ /* TRANSLATORS: The file itself is not destroyed
+ or transformed into drive. */
+ N_("Make a virtual drive from a file."), options);
+ grub_disk_dev_register (&grub_loopback_dev);
+}
+
+GRUB_MOD_FINI(loopback)
+{
+ grub_unregister_extcmd (cmd);
+ grub_disk_dev_unregister (&grub_loopback_dev);
+}
projects / Ventoy.git / commitdiff