Implement more hob handling methods

Author: elicn

qiling/os/uefi/hob.py

@@ -4,7 +4,8 @@
 #
 
 from qiling import Qiling
-from qiling.os.uefi.utils import GetEfiConfigurationTable
+from qiling.os.uefi.context import UefiContext
+from qiling.os.uefi.utils import GetEfiConfigurationTable, CompareGuid, str_to_guid
 from qiling.os.uefi.UefiBaseType import STRUCT, EFI_GUID, UINT32, UINT16
 from qiling.os.uefi.UefiSpec import EFI_CONFIGURATION_TABLE
 
@@ -25,31 +26,25 @@ class EFI_HOB_GUID_TYPE(STRUCT):
 		('Name',	EFI_GUID)
 	]
 
-def GetHobList(ql: Qiling) -> int:
+def GetHobList(ql: Qiling, context: UefiContext) -> int:
 	"""Get HOB list location in memory (ostensibly set by PEI).
 	"""
 
 	conftable_guid = ql.os.profile['HOB_LIST']['Guid']
-	conftable_ptr = GetEfiConfigurationTable(ql.loader.dxe_context, conftable_guid)
+	conftable_ptr = GetEfiConfigurationTable(context, conftable_guid)
 	conftable = EFI_CONFIGURATION_TABLE.loadFrom(ql, conftable_ptr)
 
 	return ql.unpack64(conftable.VendorTable)
 
-def CreateHob(ql: Qiling, hob) -> int:
+def CreateHob(ql: Qiling, context: UefiContext, hob) -> int:
 	"""Add a HOB to the end of the HOB list.
 	"""
 
-	hoblist = GetHobList(ql)
+	hoblist = GetHobList(ql, context)
 
 	# look for the list end marker; uefi codebase assumes there is
 	# always one
-	while True:
-		header = EFI_HOB_GENERIC_HEADER.loadFrom(ql, hoblist)
-
-		if header.HobType == EFI_HOB_TYPE_END_OF_HOB_LIST:
-			break
-
-		hoblist += header.HobLength
+	hoblist = GetNextHob(ql, EFI_HOB_TYPE_END_OF_HOB_LIST, hoblist)
 
 	# overwrite end marker with the hob
 	pHob = hoblist
@@ -65,3 +60,46 @@ def CreateHob(ql: Qiling, hob) -> int:
 
 	# return the address the hob was written to; it might be useful
 	return pHob
+
+def GetNextHob(ql: Qiling, hobtype: int, hoblist: int) -> int:
+	"""Get next HOB on the list.
+	"""
+
+	hobaddr = hoblist
+
+	while True:
+		header = EFI_HOB_GENERIC_HEADER.loadFrom(ql, hobaddr)
+
+		# found the hob?
+		if header.HobType == hobtype:
+			break
+
+		# reached end of hob list?
+		if header.HobType == EFI_HOB_TYPE_END_OF_HOB_LIST:
+			return 0
+
+		hobaddr += header.HobLength
+
+	return hobaddr
+
+def GetNextGuidHob(ql: Qiling, guid: str, hoblist: int):
+	"""Find next HOB with the specified GUID.
+	"""
+
+	hobguid = str_to_guid(guid)
+	hobaddr = hoblist
+
+	while True:
+		hobaddr = GetNextHob(ql, EFI_HOB_TYPE_GUID_EXTENSION, hobaddr)
+
+		if not hobaddr:
+			return 0
+
+		hob = EFI_HOB_GUID_TYPE.loadFrom(ql, hobaddr)
+
+		if CompareGuid(hob.Name, hobguid):
+			break
+
+		hobaddr += hob.Header.HobLength
+
+	return hobaddr