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Patch #1484695: The tarfile module now raises a HeaderError exception

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if a buffer given to frombuf() is invalid.
This commit is contained in:
Georg Brandl 2006-12-19 22:06:46 +00:00
parent 8183c635bc
commit ebbeed781d
3 changed files with 27 additions and 10 deletions
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27
Lib/tarfile.py
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@ -280,6 +280,9 @@ class CompressionError(TarError):
class StreamError(TarError):
"""Exception for unsupported operations on stream-like TarFiles."""
pass
class HeaderError(TarError):
"""Exception for invalid headers."""
pass
#---------------------------
# internal stream interface
@ -819,9 +822,17 @@ class TarInfo(object):
"""Construct a TarInfo object from a 512 byte string buffer.
"""
if len(buf) != BLOCKSIZE:
raise ValueError("truncated header")
raise HeaderError("truncated header")
if buf.count(NUL) == BLOCKSIZE:
raise ValueError("empty header")
raise HeaderError("empty header")
try:
chksum = nti(buf[148:156])
except ValueError:
raise HeaderError("invalid header")
if chksum not in calc_chksums(buf):
raise HeaderError("bad checksum")
tarinfo = cls()
tarinfo.buf = buf
@ -831,7 +842,7 @@ class TarInfo(object):
tarinfo.gid = nti(buf[116:124])
tarinfo.size = nti(buf[124:136])
tarinfo.mtime = nti(buf[136:148])
tarinfo.chksum = nti(buf[148:156])
tarinfo.chksum = chksum
tarinfo.type = buf[156:157]
tarinfo.linkname = buf[157:257].rstrip(NUL)
tarinfo.uname = buf[265:297].rstrip(NUL)
@ -843,8 +854,6 @@ class TarInfo(object):
if prefix and not tarinfo.issparse():
tarinfo.name = prefix + "/" + tarinfo.name
if tarinfo.chksum not in calc_chksums(buf):
raise ValueError("invalid header")
return tarinfo
def tobuf(self, posix=False):
@ -1793,16 +1802,14 @@ class TarFile(object):
tarinfo = self.proc_member(tarinfo)
except ValueError, e:
except HeaderError, e:
if self.ignore_zeros:
self._dbg(2, "0x%X: empty or invalid block: %s" %
(self.offset, e))
self._dbg(2, "0x%X: %s" % (self.offset, e))
self.offset += BLOCKSIZE
continue
else:
if self.offset == 0:
raise ReadError("empty, unreadable or compressed "
"file: %s" % e)
raise ReadError(str(e))
return None
break