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[Patch 988444]

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Read multiple special headers
- fixed/improved handling of extended/special headers
in read-mode (adding new extended headers should be
less painful now).
- improved nts() function.
- removed TarFile.chunks datastructure which is not
(and was never) needed.
- fixed TarInfo.tobuf(), fields could overflow with too
large values, values are now clipped.
This commit is contained in:
Andrew M. Kuchling 2004-07-10 22:02:11 +00:00
parent f027ca8167
commit 864bba1981
1 changed files with 31 additions and 34 deletions
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65
Lib/tarfile.py
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@ -135,7 +135,7 @@ TOEXEC = 0001 # execute/search by other
def nts(s): def nts(s):
"""Convert a null-terminated string buffer to a python string. """Convert a null-terminated string buffer to a python string.
""" """
return s.split(NUL, 1)[0] return s.rstrip(NUL)
def calc_chksum(buf): def calc_chksum(buf):
"""Calculate the checksum for a member's header. It's a simple addition """Calculate the checksum for a member's header. It's a simple addition
@ -713,7 +713,7 @@ class TarInfo(object):
(self.prefix, 155) (self.prefix, 155)
): ):
l = len(value) l = len(value)
parts.append(value + (fieldsize - l) * NUL) parts.append(value[:fieldsize] + (fieldsize - l) * NUL)
buf = "".join(parts) buf = "".join(parts)
chksum = calc_chksum(buf) chksum = calc_chksum(buf)
@ -796,7 +796,6 @@ class TarFile(object):
self.closed = False self.closed = False
self.members = [] # list of members as TarInfo objects self.members = [] # list of members as TarInfo objects
self.membernames = [] # names of members self.membernames = [] # names of members
self.chunks = [0] # chunk cache
self._loaded = False # flag if all members have been read self._loaded = False # flag if all members have been read
self.offset = 0L # current position in the archive file self.offset = 0L # current position in the archive file
self.inodes = {} # dictionary caching the inodes of self.inodes = {} # dictionary caching the inodes of
@ -1281,9 +1280,7 @@ class TarFile(object):
blocks += 1 blocks += 1
self.offset += blocks * BLOCKSIZE self.offset += blocks * BLOCKSIZE
self.members.append(tarinfo) self._record_member(tarinfo)
self.membernames.append(tarinfo.name)
self.chunks.append(self.offset)
def extract(self, member, path=""): def extract(self, member, path=""):
"""Extract a member from the archive to the current working directory, """Extract a member from the archive to the current working directory,
@ -1551,7 +1548,7 @@ class TarFile(object):
return m return m
# Read the next block. # Read the next block.
self.fileobj.seek(self.chunks[-1]) self.fileobj.seek(self.offset)
while True: while True:
buf = self.fileobj.read(BLOCKSIZE) buf = self.fileobj.read(BLOCKSIZE)
if not buf: if not buf:
@ -1569,7 +1566,7 @@ class TarFile(object):
continue continue
else: else:
# Block is empty or unreadable. # Block is empty or unreadable.
if self.chunks[-1] == 0: if self.offset == 0:
# If the first block is invalid. That does not # If the first block is invalid. That does not
# look like a tar archive we can handle. # look like a tar archive we can handle.
raise ReadError,"empty, unreadable or compressed file" raise ReadError,"empty, unreadable or compressed file"
@ -1592,20 +1589,18 @@ class TarFile(object):
# Check if the TarInfo object has a typeflag for which a callback # Check if the TarInfo object has a typeflag for which a callback
# method is registered in the TYPE_METH. If so, then call it. # method is registered in the TYPE_METH. If so, then call it.
if tarinfo.type in self.TYPE_METH: if tarinfo.type in self.TYPE_METH:
tarinfo = self.TYPE_METH[tarinfo.type](self, tarinfo) return self.TYPE_METH[tarinfo.type](self, tarinfo)
else:
tarinfo.offset_data = self.offset tarinfo.offset_data = self.offset
if tarinfo.isreg() or tarinfo.type not in SUPPORTED_TYPES: if tarinfo.isreg() or tarinfo.type not in SUPPORTED_TYPES:
# Skip the following data blocks. # Skip the following data blocks.
self.offset += self._block(tarinfo.size) self.offset += self._block(tarinfo.size)
if tarinfo.isreg() and tarinfo.name[:-1] == "/": if tarinfo.isreg() and tarinfo.name[:-1] == "/":
# some old tar programs don't know DIRTYPE # some old tar programs don't know DIRTYPE
tarinfo.type = DIRTYPE tarinfo.type = DIRTYPE
self.members.append(tarinfo) self._record_member(tarinfo)
self.membernames.append(tarinfo.name)
self.chunks.append(self.offset)
return tarinfo return tarinfo
#-------------------------------------------------------------------------- #--------------------------------------------------------------------------
@ -1620,7 +1615,9 @@ class TarFile(object):
# if there is data to follow. # if there is data to follow.
# 2. set self.offset to the position where the next member's header will # 2. set self.offset to the position where the next member's header will
# begin. # begin.
# 3. return a valid TarInfo object. # 3. call self._record_member() if the tarinfo object is supposed to
# appear as a member of the TarFile object.
# 4. return tarinfo or another valid TarInfo object.
def proc_gnulong(self, tarinfo): def proc_gnulong(self, tarinfo):
"""Evaluate the blocks that hold a GNU longname """Evaluate the blocks that hold a GNU longname
@ -1636,24 +1633,16 @@ class TarFile(object):
self.offset += BLOCKSIZE self.offset += BLOCKSIZE
count -= BLOCKSIZE count -= BLOCKSIZE
# Fetch the next header
next = self.next()
next.offset = tarinfo.offset
if tarinfo.type == GNUTYPE_LONGNAME: if tarinfo.type == GNUTYPE_LONGNAME:
name = nts(buf) next.name = nts(buf)
if tarinfo.type == GNUTYPE_LONGLINK: elif tarinfo.type == GNUTYPE_LONGLINK:
linkname = nts(buf) next.linkname = nts(buf)
buf = self.fileobj.read(BLOCKSIZE) return next
tarinfo = TarInfo.frombuf(buf)
tarinfo.offset = self.offset
self.offset += BLOCKSIZE
tarinfo.offset_data = self.offset
tarinfo.name = name or tarinfo.name
tarinfo.linkname = linkname or tarinfo.linkname
if tarinfo.isreg() or tarinfo.type not in SUPPORTED_TYPES:
# Skip the following data blocks.
self.offset += self._block(tarinfo.size)
return tarinfo
def proc_sparse(self, tarinfo): def proc_sparse(self, tarinfo):
"""Analyze a GNU sparse header plus extra headers. """Analyze a GNU sparse header plus extra headers.
@ -1709,6 +1698,8 @@ class TarFile(object):
tarinfo.offset_data = self.offset tarinfo.offset_data = self.offset
self.offset += self._block(tarinfo.size) self.offset += self._block(tarinfo.size)
tarinfo.size = origsize tarinfo.size = origsize
self._record_member(tarinfo)
return tarinfo return tarinfo
# The type mapping for the next() method. The keys are single character # The type mapping for the next() method. The keys are single character
@ -1745,6 +1736,12 @@ class TarFile(object):
if name == self.membernames[i]: if name == self.membernames[i]:
return self.members[i] return self.members[i]
def _record_member(self, tarinfo):
"""Record a tarinfo object in the internal datastructures.
"""
self.members.append(tarinfo)
self.membernames.append(tarinfo.name)
def _load(self): def _load(self):
"""Read through the entire archive file and look for readable """Read through the entire archive file and look for readable
members. members.