automake commit without merge history

grub-core/partmap/msdos.c

@@ -0,0 +1,152 @@
+/* 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>
+
+static struct grub_partition_map grub_msdos_partition_map;
+
+
+static grub_err_t
+pc_partition_map_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;
+
+  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);
+	  p.len = grub_le_to_cpu32 (e->length);
+
+	  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;
+}
+
+
+/* Partition map type.  */
+static struct grub_partition_map grub_msdos_partition_map =
+  {
+    .name = "msdos",
+    .iterate = pc_partition_map_iterate,
+  };
+
+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);
+}