Thanks for your pointsers, Pavel; they were all helpful.
On Tuesday 22 July 2008, Pavel Roskin wrote:
> Quoting Chris Knadle <[EMAIL PROTECTED]>:
> > Since I want the first (high) 16 bits, I
> > think I need to make the comparison in a way such as:
> >
> > if ((apart.first_phys_block & 0xFFFF0000) == (0x4552 << 16))
>
> That won't work on little endian systems, including ordinary PC. You
> are assuming big endian byte order here. Instead, the data from the
> disk should be converted to CPU-endian from whatever it is and
> compared to the magic value.
Yes, I did suspect that problem; so this needs a #ifdef for CPU
architecture and choosing the appropriate conversion with one of the
functions in include/grub/type.h -- okay.
The next problem is that I'm not able to figure out how to get partition.c
to "give up" the Apple_partition_map that is detected, and to re-detect for
others. Right now part_map_iterate() detects an Apple partition based on
Sector 0 [which is unavoidable, since Sector 0 is not going to have an HFS+
magic number], after which it becomes "fixated" on it. Calling
grub_partition_map_unregister() does lead to secceding in detection of a
pc_partition_map, but then still isn't fully successful in a grub-probe.
Below is a patch based on the git tree if you want to see where I'm
currently at.
--
Chris Knadle
[EMAIL PROTECTED]
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
diff --git a/partmap/apple.c b/partmap/apple.c
index 4e5c481..3786301 100644
--- a/partmap/apple.c
+++ b/partmap/apple.c
@@ -23,6 +23,7 @@
#include <grub/partition.h>
#define GRUB_APPLE_PART_MAGIC 0x504D
+#define GRUB_APPLE_HFSPLUS_MAGIC 0x4552
struct grub_apple_part
{
@@ -102,6 +103,7 @@ apple_partition_map_iterate (grub_disk_t disk,
struct grub_disk raw;
int partno = 0;
unsigned pos = GRUB_DISK_SECTOR_SIZE;
+ grub_uint16_t magic;
/* Enforce raw disk access. */
raw = *disk;
@@ -111,6 +113,21 @@ apple_partition_map_iterate (grub_disk_t disk,
for (;;)
{
+
+ /* load + check partition magic number */
+ if (grub_disk_read (&raw, 0, 0, sizeof(grub_uint16_t), (char *)
&magic))
+ return grub_errno;
+ if (grub_be_to_cpu16(magic) != GRUB_APPLE_HFSPLUS_MAGIC && partno >
0 ) {
+ grub_dprintf("partition",
+ "non-Apple partition %d: bad magic (found 0x%x; wanted 0x%x\n",
+ partno, grub_be_to_cpu16 (magic),
+ GRUB_APPLE_HFSPLUS_MAGIC);
+ grub_errno = 1;
+ grub_partition_map_unregister(part.partmap);
+ return 1;
+ }
+
+
if (grub_disk_read (&raw, pos / GRUB_DISK_SECTOR_SIZE,
pos % GRUB_DISK_SECTOR_SIZE,
sizeof (struct grub_apple_part), (char *) &apart))
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