aboutsummaryrefslogtreecommitdiffstats
path: root/grub-core/partmap/msdos.c
diff options
context:
space:
mode:
Diffstat (limited to 'grub-core/partmap/msdos.c')
-rw-r--r--grub-core/partmap/msdos.c284
1 files changed, 284 insertions, 0 deletions
diff --git a/grub-core/partmap/msdos.c b/grub-core/partmap/msdos.c
new file mode 100644
index 0000000..1b71c69
--- /dev/null
+++ b/grub-core/partmap/msdos.c
@@ -0,0 +1,284 @@
+/* pc.c - Read PC style partition tables. */
+/*
+ * GRUB -- GRand Unified Bootloader
+ * Copyright (C) 2002,2004,2005,2006,2007,2008,2009 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/partition.h>
+#include <grub/msdos_partition.h>
+#include <grub/disk.h>
+#include <grub/mm.h>
+#include <grub/misc.h>
+#include <grub/dl.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+static struct grub_partition_map grub_msdos_partition_map;
+
+
+grub_err_t
+grub_partition_msdos_iterate (grub_disk_t disk,
+ int (*hook) (grub_disk_t disk,
+ const grub_partition_t partition))
+{
+ struct grub_partition p;
+ struct grub_msdos_partition_mbr mbr;
+ int labeln = 0;
+ grub_disk_addr_t lastaddr;
+ grub_disk_addr_t ext_offset;
+ grub_disk_addr_t delta = 0;
+
+ if (disk->partition && disk->partition->partmap == &grub_msdos_partition_map)
+ {
+ if (disk->partition->msdostype == GRUB_PC_PARTITION_TYPE_LINUX_MINIX)
+ delta = disk->partition->start;
+ else
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "no embedding supported");
+ }
+
+ p.offset = 0;
+ ext_offset = 0;
+ p.number = -1;
+ p.partmap = &grub_msdos_partition_map;
+
+ /* Any value different than `p.offset' will satisfy the check during
+ first loop. */
+ lastaddr = !p.offset;
+
+ while (1)
+ {
+ int i;
+ struct grub_msdos_partition_entry *e;
+
+ /* Read the MBR. */
+ if (grub_disk_read (disk, p.offset, 0, sizeof (mbr), &mbr))
+ goto finish;
+
+ /* This is our loop-detection algorithm. It works the following way:
+ It saves last position which was a power of two. Then it compares the
+ saved value with a current one. This way it's guaranteed that the loop
+ will be broken by at most third walk.
+ */
+ if (labeln && lastaddr == p.offset)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "loop detected");
+
+ labeln++;
+ if ((labeln & (labeln - 1)) == 0)
+ lastaddr = p.offset;
+
+ /* Check if it is valid. */
+ if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE))
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
+
+ for (i = 0; i < 4; i++)
+ if (mbr.entries[i].flag & 0x7f)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "bad boot flag");
+
+ /* Analyze DOS partitions. */
+ for (p.index = 0; p.index < 4; p.index++)
+ {
+ e = mbr.entries + p.index;
+
+ p.start = p.offset + grub_le_to_cpu32 (e->start) - delta;
+ p.len = grub_le_to_cpu32 (e->length);
+ p.msdostype = e->type;
+
+ grub_dprintf ("partition",
+ "partition %d: flag 0x%x, type 0x%x, start 0x%llx, len 0x%llx\n",
+ p.index, e->flag, e->type,
+ (unsigned long long) p.start,
+ (unsigned long long) p.len);
+
+ /* If this is a GPT partition, this MBR is just a dummy. */
+ if (e->type == GRUB_PC_PARTITION_TYPE_GPT_DISK && p.index == 0)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "dummy mbr");
+
+ /* If this partition is a normal one, call the hook. */
+ if (! grub_msdos_partition_is_empty (e->type)
+ && ! grub_msdos_partition_is_extended (e->type))
+ {
+ p.number++;
+
+ if (hook (disk, &p))
+ return grub_errno;
+ }
+ else if (p.number < 4)
+ /* If this partition is a logical one, shouldn't increase the
+ partition number. */
+ p.number++;
+ }
+
+ /* Find an extended partition. */
+ for (i = 0; i < 4; i++)
+ {
+ e = mbr.entries + i;
+
+ if (grub_msdos_partition_is_extended (e->type))
+ {
+ p.offset = ext_offset + grub_le_to_cpu32 (e->start);
+ if (! ext_offset)
+ ext_offset = p.offset;
+
+ break;
+ }
+ }
+
+ /* If no extended partition, the end. */
+ if (i == 4)
+ break;
+ }
+
+ finish:
+ return grub_errno;
+}
+
+#ifdef GRUB_UTIL
+static grub_err_t
+pc_partition_map_embed (struct grub_disk *disk, unsigned int *nsectors,
+ grub_embed_type_t embed_type,
+ grub_disk_addr_t **sectors)
+{
+ grub_disk_addr_t end = ~0ULL;
+ struct grub_msdos_partition_mbr mbr;
+ int labeln = 0;
+ /* Any value different than `p.offset' will satisfy the check during
+ first loop. */
+ grub_disk_addr_t lastaddr = 1;
+ grub_disk_addr_t ext_offset = 0;
+ grub_disk_addr_t offset = 0;
+
+ if (embed_type != GRUB_EMBED_PCBIOS)
+ return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
+ "PC-style partitions curently support "
+ "only PC-BIOS embedding");
+
+ if (disk->partition)
+ return grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "Embedding on MSDOS subpartition isn't supported");
+
+ while (1)
+ {
+ int i;
+ struct grub_msdos_partition_entry *e;
+ grub_err_t err;
+
+ /* Read the MBR. */
+ err = grub_disk_read (disk, offset, 0, sizeof (mbr), &mbr);
+ if (err)
+ return err;
+
+ /* This is our loop-detection algorithm. It works the following way:
+ It saves last position which was a power of two. Then it compares the
+ saved value with a current one. This way it's guaranteed that the loop
+ will be broken by at most third walk.
+ */
+ if (labeln && lastaddr == offset)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "loop detected");
+
+ labeln++;
+ if ((labeln & (labeln - 1)) == 0)
+ lastaddr = offset;
+
+ /* Check if it is valid. */
+ if (mbr.signature != grub_cpu_to_le16 (GRUB_PC_PARTITION_SIGNATURE))
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "no signature");
+
+ for (i = 0; i < 4; i++)
+ if (mbr.entries[i].flag & 0x7f)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "bad boot flag");
+
+ /* Analyze DOS partitions. */
+ for (i = 0; i < 4; i++)
+ {
+ e = mbr.entries + i;
+
+ if (!grub_msdos_partition_is_empty (e->type)
+ && end > offset + grub_le_to_cpu32 (e->start))
+ end = offset + grub_le_to_cpu32 (e->start);
+
+ /* If this is a GPT partition, this MBR is just a dummy. */
+ if (e->type == GRUB_PC_PARTITION_TYPE_GPT_DISK && i == 0)
+ return grub_error (GRUB_ERR_BAD_PART_TABLE, "dummy mbr");
+ }
+
+ /* Find an extended partition. */
+ for (i = 0; i < 4; i++)
+ {
+ e = mbr.entries + i;
+
+ if (grub_msdos_partition_is_extended (e->type))
+ {
+ offset = ext_offset + grub_le_to_cpu32 (e->start);
+ if (! ext_offset)
+ ext_offset = offset;
+
+ break;
+ }
+ }
+
+ /* If no extended partition, the end. */
+ if (i == 4)
+ break;
+ }
+
+ if (end >= *nsectors + 2)
+ {
+ unsigned i;
+ *nsectors = end - 2;
+ *sectors = grub_malloc (*nsectors * sizeof (**sectors));
+ if (!*sectors)
+ return grub_errno;
+ for (i = 0; i < *nsectors; i++)
+ (*sectors)[i] = 1 + i;
+ return GRUB_ERR_NONE;
+ }
+
+ if (end <= 1)
+ return grub_error (GRUB_ERR_FILE_NOT_FOUND,
+ "This msdos-style partition label has no "
+ "post-MBR gap; embedding won't be possible!");
+
+ if (*nsectors > 62)
+ return grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "Your core.img is unusually large. "
+ "It won't fit in the embedding area.");
+
+ return grub_error (GRUB_ERR_OUT_OF_RANGE,
+ "Your embedding area is unusually small. "
+ "core.img won't fit in it.");
+}
+#endif
+
+
+/* Partition map type. */
+static struct grub_partition_map grub_msdos_partition_map =
+ {
+ .name = "msdos",
+ .iterate = grub_partition_msdos_iterate,
+#ifdef GRUB_UTIL
+ .embed = pc_partition_map_embed
+#endif
+ };
+
+GRUB_MOD_INIT(part_msdos)
+{
+ grub_partition_map_register (&grub_msdos_partition_map);
+}
+
+GRUB_MOD_FINI(part_msdos)
+{
+ grub_partition_map_unregister (&grub_msdos_partition_map);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-21 08:25:05 +0000