libparted: Fix MacOS boot support

boot_region_length (or BootSize in the MacOS dialect) is the length
of the driver code in the driver partition. This length is used
to compute the checksum of the driver.

libparted updates this value by setting the whole size of the partition
without computing the checksum of the driver using this size.

As the checksum is wrong, the driver is broken and cannot be loaded
by the MacOS ROM, and thus the disk is not bootable anymore.

Moreover, parted try to update the driver list and makes it disappear.

As parted is not able to insert a driver in a partition,
the driver is generally inserted by the Apple HD Tool,
this patch removes the line updating the driver size.

We also simplify the driver list scan and fix endianess use.

This has been tested... and it works, now.

I have updated a bootable disk with parted on x86_64 and
then been able to boot it (again) on a Mac LC III.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Brian C. Lane <bcl@redhat.com>

1 files changed, 20 insertions, 21 deletions

diff --git a/libparted/labels/mac.c b/libparted/labels/mac.c
index d8da941..fa4e43f 100644
--- a/libparted/labels/mac.c
+++ b/libparted/labels/mac.c
@@ -411,14 +411,14 @@ _rawpart_has_driver (const MacRawPartition* raw_part, MacDiskData* mac_disk_data
 {
 	MacDeviceDriver *driverlist;
 	uint16_t i;
-	uint32_t driver_bs, driver_be, part_be;
+	uint32_t start_block, block_count;
 
+	start_block = PED_BE32_TO_CPU(raw_part->start_block);
+	block_count = PED_BE32_TO_CPU(raw_part->block_count);
 	driverlist = &mac_disk_data->driverlist[0];
 	for (i = 0; i < mac_disk_data->driver_count; i++) {
-		driver_bs = driverlist->block;
-		driver_be = driver_bs + driverlist->size;
-		part_be = raw_part->start_block + raw_part->block_count;
-		if (driver_bs >= raw_part->start_block && driver_be <= part_be)
+		if (start_block == PED_BE32_TO_CPU(driverlist->block) &&
+                    block_count == PED_BE16_TO_CPU(driverlist->size))
 			return 1;
 		driverlist++;
 	}
@@ -751,11 +751,12 @@ mac_read (PedDisk* disk)
 	if (!ped_disk_delete_all (disk))
 		goto error;
 
-	if (raw_disk->driver_count && raw_disk->driver_count < 62) {
+	if (PED_BE16_TO_CPU(raw_disk->driver_count) &&
+            PED_BE16_TO_CPU(raw_disk->driver_count) < 62) {
 		memcpy(&mac_disk_data->driverlist[0], &raw_disk->driverlist[0],
 				sizeof(mac_disk_data->driverlist));
-		mac_disk_data->driver_count = raw_disk->driver_count;
-		mac_disk_data->block_size = raw_disk->block_size;
+		mac_disk_data->driver_count = PED_BE16_TO_CPU(raw_disk->driver_count);
+		mac_disk_data->block_size = PED_BE16_TO_CPU(raw_disk->block_size);
 	}
 
 	/* If _disk_analyse_block_size has increased the sector_size,
@@ -877,17 +878,16 @@ static void
 _update_driver_count (MacRawPartition* part_map_entry,
 		      MacDiskData *mac_driverdata, const MacDiskData* mac_disk_data)
 {
-	uint16_t	i, count_orig, count_cur;
-	uint32_t	driver_bs, driver_be, part_be;
-
-	count_cur = mac_driverdata->driver_count;
-	count_orig = mac_disk_data->driver_count;
-	for (i = 0; i < count_orig; i++) {
-		driver_bs = mac_disk_data->driverlist[i].block;
-		driver_be = driver_bs + mac_disk_data->driverlist[i].size;
-		part_be = part_map_entry->start_block + part_map_entry->block_count;
-		if (driver_bs >= part_map_entry->start_block
-				&& driver_be <= part_be) {
+	uint16_t	i;
+	uint32_t	start_block, block_count;
+
+	start_block = PED_BE32_TO_CPU(part_map_entry->start_block);
+	block_count = PED_BE32_TO_CPU(part_map_entry->block_count);
+
+	for (i = 0; i < mac_disk_data->driver_count; i++) {
+		if (start_block == PED_BE32_TO_CPU(mac_disk_data->driverlist[i].block) &&
+		    block_count == PED_BE16_TO_CPU(mac_disk_data->driverlist[i].size)) {
+		        uint16_t count_cur = mac_driverdata->driver_count;
 			mac_driverdata->driverlist[count_cur].block
 				= mac_disk_data->driverlist[i].block;
 			mac_driverdata->driverlist[count_cur].size
@@ -934,7 +934,6 @@ _generate_raw_part (PedDisk* disk, PedPartition* part,
 	strncpy (part_map_entry->type, mac_part_data->system_name, 32);
 
 	if (mac_part_data->is_driver) {
-		mac_part_data->boot_region_length = part->geom.length;
 		if (mac_part_data->has_driver)
 			_update_driver_count(part_map_entry, mac_driverdata,
 					mac_disk_data);
@@ -1042,7 +1041,7 @@ write_block_zero (PedDisk* disk, MacDiskData* mac_driverdata)
 	raw_disk->block_size = PED_CPU_TO_BE16 (dev->sector_size);
 	raw_disk->block_count = PED_CPU_TO_BE32 (dev->length);
 
-	raw_disk->driver_count = mac_driverdata->driver_count;
+	raw_disk->driver_count = PED_CPU_TO_BE16(mac_driverdata->driver_count);
 	memcpy(&raw_disk->driverlist[0], &mac_driverdata->driverlist[0],
 			sizeof(raw_disk->driverlist));