Macintosh-Tools/macresources
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Revise error model

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The problem is this: a user might want to edit a resource compressed
using an unknown algorithm. This should fail by default, because after
all, the resource is garbage. But the expert user (say Daniel wrote a
new algo) might know better, and set the expand_err_ok attribute on a
Resource object before accessing and editing its data attribute.
This commit is contained in:
Elliot Nunn 2018-12-11 17:18:41 +08:00
parent 5a318f78ef
commit 931529bc7c
2 changed files with 14 additions and 7 deletions
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3
macresources/FakeResDecompress.py
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@ -15,11 +15,12 @@ def GetEncoding(inf):
def DecompressResource(inf):
# print('DecompressResource', GetEncoding(inf))
GetEncoding(inf) # this will need to be called, of course
if GetEncoding(inf) == 'UnknownCompression': return inf
return b'decompressed ' + inf
def CompressResource(inf, encoding):
# print('CompressResource', encoding)
if encoding == 'UnknownCompression': return inf
if inf.startswith(b'decompressed '): inf = inf[16:]
return inf

18
macresources/main.py
View File

@ -129,6 +129,7 @@ class Resource:
self.attribs |= attribs
self.data = data
self.compression_format = None
self.expand_err_ok = False
# Maintain a hidden cache of the compressed System 7 data that got loaded
self._cache = None
@ -146,8 +147,8 @@ class Resource:
def __getattr__(self, attrname): # fear not, this is only for evil System 7 resource compression
if attrname == 'data':
if GetEncoding(self._cache) == 'UnknownCompression':
print('Warning: accessing %r %r, which is compressed in an unknown format' % (self.type, self.id))
if GetEncoding(self._cache) == 'UnknownCompression' and not self.expand_err_ok:
raise ResExpandError('Tried to expand unknown format (%r %r) without setting expand_err_ok' % (self.type, self.id))
self.data = DecompressResource(self._cache)
self._cache_hash = hash_mutable(self.data)
@ -170,13 +171,15 @@ class Resource:
self._cache = CompressResource(self.data, self.compression_format)
self._cache_hash = hash_mutable(self.data)
def _rez_repr(self, expand=False):
# decide now: what raw data will we slap down?
def _rez_repr(self, expand=False): # the Rez file will be annotated for re-compression
if self.compression_format:
if expand:
if self.compression_format == 'UnknownCompression':
if self.compression_format == 'UnknownCompression': # means I can have no data attribute
attribs = ResourceAttrs(self.attribs | 1) # at lease Rez will produce the right file
data = self.data # will throw a warning
if 'data' in self.__dict__:
data = self.data
else:
data = self._cache
compression_format = None # no comment
else:
attribs = ResourceAttrs(self.attribs & ~1)
@ -206,6 +209,9 @@ class Resource:
return data, attribs
class ResExpandError(Exception):
pass
def parse_file(from_resfile, fake_header_rsrc=False):
"""Get an iterator of Resource objects from a binary resource file."""