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image-hd: fix CHS addresses in EBR #249

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merged 1 commit into from
Jun 21, 2024
Merged

image-hd: fix CHS addresses in EBR #249

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20 changes: 13 additions & 7 deletions image-hd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -125,10 +125,12 @@ static void lba_to_chs(unsigned int lba, unsigned char *chs)
chs[2] = (c & 0xff);
}

static void hdimage_setup_chs(struct mbr_partition_entry *entry)
static void hdimage_setup_chs(struct mbr_partition_entry *entry,
unsigned long long offset_sectors)
{
lba_to_chs(entry->relative_sectors, entry->first_chs);
lba_to_chs(entry->relative_sectors + entry->total_sectors - 1,
lba_to_chs(entry->relative_sectors + offset_sectors,
entry->first_chs);
lba_to_chs(entry->relative_sectors + entry->total_sectors - 1 + offset_sectors,
entry->last_chs);
}

Expand Down Expand Up @@ -173,7 +175,7 @@ static int hdimage_insert_mbr(struct image *image, struct list_head *partitions)
entry->relative_sectors = (hd->extended_lba)/512;
entry->total_sectors = (image->size - hd->extended_lba)/512;
}
hdimage_setup_chs(entry);
hdimage_setup_chs(entry, 0);

if (part->extended)
break;
Expand All @@ -191,7 +193,7 @@ static int hdimage_insert_mbr(struct image *image, struct list_head *partitions)
entry->relative_sectors = 1;
entry->total_sectors = hd->gpt_location / 512 + GPT_SECTORS - 2;

hdimage_setup_chs(entry);
hdimage_setup_chs(entry, 0);
}

mbr.boot_signature = htole16(0xaa55);
Expand Down Expand Up @@ -226,7 +228,9 @@ static int hdimage_insert_ebr(struct image *image, struct partition *part)
entry->partition_type = part->partition_type;
entry->relative_sectors = hd->align/512;
entry->total_sectors = part->size/512;
hdimage_setup_chs(entry);
// absolute CHS address of the logical partition
// equals to absolute partition offset
hdimage_setup_chs(entry, (part->offset - hd->align) / 512);
struct partition *p = part;
list_for_each_entry_continue(p, &image->partitions, list) {
if (!p->extended)
Expand All @@ -236,7 +240,9 @@ static int hdimage_insert_ebr(struct image *image, struct partition *part)
entry->partition_type = 0x0F;
entry->relative_sectors = (p->offset - hd->align - hd->extended_lba)/512;
entry->total_sectors = (p->size + hd->align)/512;
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hdimage_setup_chs(entry);
// absolute CHS address of the next EBR
// equals to relative address within extended partition + partition start
hdimage_setup_chs(entry, hd->extended_lba / 512);
break;
}

Expand Down
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