[Parted-maintainers] Bug#491797: libparted: trashes iPod Nano firmware partition

[Ben Hutchings]

Here's a patch for this.  I constructed a table with two FAT partitions
on a memory card, hid one partition by changing its type code, and then
verified that fatresize would destroy the hidden partition but would
leave it intact once I applied this patch to libparted.

I am not going to NMU because I'm unsure whether it's generally a good
idea to leave hidden partitions untouched.  If it is, please apply this.

Ben.

#! /bin/sh /usr/share/dpatch/dpatch-run
## preserve-hidden-parts.dpatch by Ben Hutchings <ben at decadent.org.uk>
##
## All lines beginning with `## DP:' are a description of the patch.
## DP: This is an attempt to fix bug #491797.  It changes the partition
## DP: rewriting code to set only the type code in entries for empty or
## DP: hidden partitions, so that hidden partitions should be preserved
## DP: so long as we don't resize another partition over them.

@DPATCH@
diff -urNad parted-1.8.8.git.2008.03.24~/libparted/labels/dos.c parted-1.8.8.git.2008.03.24/libparted/labels/dos.c
--- parted-1.8.8.git.2008.03.24~/libparted/labels/dos.c	2008-10-05 22:24:07.000000000 +0100
+++ parted-1.8.8.git.2008.03.24/libparted/labels/dos.c	2008-10-05 22:43:43.000000000 +0100
@@ -1148,13 +1148,17 @@
 	if (!table.mbr_signature)
 		table.mbr_signature = generate_random_id();
 
-	memset (table.partitions, 0, sizeof (DosRawPartition) * 4);
-	table.magic = PED_CPU_TO_LE16 (MSDOS_MAGIC);
+	if (table.magic != PED_CPU_TO_LE16 (MSDOS_MAGIC)) {
+		memset (table.partitions, 0, sizeof (DosRawPartition) * 4);
+		table.magic = PED_CPU_TO_LE16 (MSDOS_MAGIC);
+	}
 
 	for (i=1; i<=4; i++) {
 		part = ped_disk_get_partition (disk, i);
-		if (!part)
+		if (!part) {
+			table.partitions [i - 1].type = PARTITION_EMPTY;
 			continue;
+		}
 
 		if (!fill_raw_part (&table.partitions [i - 1], part, 0))
 			return 0;
--- END ---

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