libparted: Fix handling of msdos partition types

This restores the previous behavior by testing the partition type
against the list of known types and skipping the filesystem type reset.
Now the sequence of:

ped_partition_new(...)
ped_partition_set_flag(part, PED_PARTITION_BLS_BOOT, 1);
ped_partition_set_system(part, ped_file_system_type_get("ext4"));

Will keep the type set to PED_PARTITION_BLS_BOOT, which is how it used
to behave.

1 files changed, 46 insertions, 8 deletions

diff --git a/libparted/labels/dos.c b/libparted/labels/dos.c
index bd7465d..4359276 100644
--- a/libparted/labels/dos.c
+++ b/libparted/labels/dos.c
@@ -121,6 +121,22 @@ static const struct flag_id_mapping_t flag_id_mapping[] =
     { PED_PARTITION_SWAP,               PARTITION_LINUX_SWAP },
 };
 
+static const unsigned char skip_set_system_types[] =
+{
+    PARTITION_EXT_LBA,
+    PARTITION_DOS_EXT,
+    PARTITION_COMPAQ_DIAG,
+    PARTITION_MSFT_RECOVERY,
+    PARTITION_LINUX_LVM,
+    PARTITION_LINUX_SWAP,
+    PARTITION_LINUX_RAID,
+    PARTITION_PALO,
+    PARTITION_PREP,
+    PARTITION_IRST,
+    PARTITION_ESP,
+    PARTITION_BLS_BOOT
+};
+
 static const struct flag_id_mapping_t* _GL_ATTRIBUTE_CONST
 dos_find_flag_id_mapping (PedPartitionFlag flag)
 {
@@ -1540,6 +1556,21 @@ msdos_partition_destroy (PedPartition* part)
 	free (part);
 }
 
+/* is_skip_type checks the type against the list of types that should not be
+ * overridden by set_system. It returns a 1 if it is in the list.
+*/
+static bool
+is_skip_type(unsigned char type_id) {
+    int n = sizeof(skip_set_system_types) / sizeof(skip_set_system_types[0]);
+    for (int i = 0; i < n; ++i) {
+        if (type_id == skip_set_system_types[i]) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 static int
 msdos_partition_set_system (PedPartition* part,
 			    const PedFileSystemType* fs_type)
@@ -1548,6 +1579,11 @@ msdos_partition_set_system (PedPartition* part,
 
 	part->fs_type = fs_type;
 
+	// Is this a type that should skip fs_type checking?
+	if (is_skip_type(dos_data->system)) {
+		return 1;
+	}
+
 	if (part->type & PED_PARTITION_EXTENDED) {
 		dos_data->system = PARTITION_EXT_LBA;
 		return 1;
@@ -1590,15 +1626,17 @@ msdos_partition_set_flag (PedPartition* part,
 	const struct flag_id_mapping_t* p = dos_find_flag_id_mapping (flag);
 	if (p)
 	{
-	    if (part->type & PED_PARTITION_EXTENDED)
-		return 0;
-
-	    if (state)
-		dos_data->system = p->type_id;
-	    else if (dos_data->system == p->type_id || dos_data->system == p->alt_type_id)
-		return ped_partition_set_system (part, part->fs_type);
+		if (part->type & PED_PARTITION_EXTENDED)
+			return 0;
 
-	    return 1;
+		if (state) {
+			dos_data->system = p->type_id;
+		} else if (dos_data->system == p->type_id || dos_data->system == p->alt_type_id) {
+			// Clear the type so that fs_type will be used to return it to the default
+			dos_data->system = PARTITION_LINUX;
+			return ped_partition_set_system (part, part->fs_type);
+		}
+		return 1;
 	}
 
 	switch (flag) {