diff options
Diffstat (limited to 'grub-core/disk/loopback.c')
| -rw-r--r-- | grub-core/disk/loopback.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/grub-core/disk/loopback.c b/grub-core/disk/loopback.c new file mode 100644 index 0000000..d50f353 --- /dev/null +++ b/grub-core/disk/loopback.c @@ -0,0 +1,232 @@ +/* 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; +}; + +static struct grub_loopback *loopback_list; + +static const struct grub_arg_option options[] = + { + {"delete", 'd', 0, N_("Delete the loopback device entry."), 0, 0}, + {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; + + 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 (argc < 2) + return grub_error (GRUB_ERR_BAD_ARGUMENT, "file name required"); + + file = grub_file_open (args[1]); + 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; + + 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; + + /* 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; +} + + +static int +grub_loopback_iterate (int (*hook) (const char *name)) +{ + struct grub_loopback *d; + for (d = loopback_list; d; d = d->next) + { + if (hook (d->devname)) + 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; + disk->id = (unsigned long) dev; + + 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 pos; + + grub_file_seek (file, sector << 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 + 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_ERR_NOT_IMPLEMENTED_YET; +} + +static struct grub_disk_dev grub_loopback_dev = + { + .name = "loopback", + .id = GRUB_DISK_DEVICE_LOOPBACK_ID, + .iterate = grub_loopback_iterate, + .open = grub_loopback_open, + .read = grub_loopback_read, + .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."), + N_("Make a device of 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); +} |