186 lines
6.3 KiB
Python
186 lines
6.3 KiB
Python
import os
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from pandac.PandaModules import Filename, HashVal, VirtualFileSystem
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class FileSpec:
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""" This class represents a disk file whose hash and size
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etc. were read from an xml file. This class provides methods to
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verify whether the file on disk matches the version demanded by
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the xml. """
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def __init__(self):
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self.actualFile = None
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def fromFile(self, packageDir, filename, pathname = None, st = None):
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""" Reads the file information from the indicated file. If st
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is supplied, it is the result of os.stat on the filename. """
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vfs = VirtualFileSystem.getGlobalPtr()
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filename = Filename(filename)
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if pathname is None:
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pathname = Filename(packageDir, filename)
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self.filename = filename.cStr()
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self.basename = filename.getBasename()
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if st is None:
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st = os.stat(pathname.toOsSpecific())
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self.size = st.st_size
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self.timestamp = st.st_mtime
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hv = HashVal()
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hv.hashFile(pathname)
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self.hash = hv.asHex()
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def loadXml(self, xelement):
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""" Reads the file information from the indicated XML
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element. """
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self.filename = xelement.Attribute('filename')
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self.basename = None
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if self.filename:
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self.basename = Filename(self.filename).getBasename()
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size = xelement.Attribute('size')
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try:
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self.size = int(size)
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except:
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self.size = 0
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timestamp = xelement.Attribute('timestamp')
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try:
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self.timestamp = int(timestamp)
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except:
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self.timestamp = 0
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self.hash = xelement.Attribute('hash')
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def storeXml(self, xelement):
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""" Adds the file information to the indicated XML
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element. """
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if self.filename:
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xelement.SetAttribute('filename', self.filename)
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if self.size:
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xelement.SetAttribute('size', str(self.size))
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if self.timestamp:
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xelement.SetAttribute('timestamp', str(int(self.timestamp)))
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if self.hash:
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xelement.SetAttribute('hash', self.hash)
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def storeMiniXml(self, xelement):
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""" Adds the just the "mini" file information--size and
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hash--to the indicated XML element. """
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if self.size:
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xelement.SetAttribute('size', str(self.size))
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if self.hash:
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xelement.SetAttribute('hash', self.hash)
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def quickVerify(self, packageDir = None, pathname = None):
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""" Performs a quick test to ensure the file has not been
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modified. This test is vulnerable to people maliciously
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attempting to fool the program (by setting datestamps etc.).
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Returns true if it is intact, false if it needs to be
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redownloaded. """
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if not pathname:
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pathname = Filename(packageDir, self.filename)
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try:
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st = os.stat(pathname.toOsSpecific())
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except OSError:
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# If the file is missing, the file fails.
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#print "file not found: %s" % (pathname)
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return False
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if st.st_size != self.size:
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# If the size is wrong, the file fails.
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#print "size wrong: %s" % (pathname)
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return False
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if st.st_mtime == self.timestamp:
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# If the size is right and the timestamp is right, the
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# file passes.
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#print "file ok: %s" % (pathname)
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return True
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#print "modification time wrong: %s" % (pathname)
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# If the size is right but the timestamp is wrong, the file
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# soft-fails. We follow this up with a hash check.
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if not self.checkHash(packageDir, pathname, st):
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# Hard fail, the hash is wrong.
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#print "hash check wrong: %s" % (pathname)
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return False
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#print "hash check ok: %s" % (pathname)
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# The hash is OK after all. Change the file's timestamp back
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# to what we expect it to be, so we can quick-verify it
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# successfully next time.
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self.__updateTimestamp(pathname, st)
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return True
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def fullVerify(self, packageDir = None, pathname = None):
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""" Performs a more thorough test to ensure the file has not
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been modified. This test is less vulnerable to malicious
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attacks, since it reads and verifies the entire file.
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Returns true if it is intact, false if it needs to be
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redownloaded. """
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if not pathname:
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pathname = Filename(packageDir, self.filename)
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try:
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st = os.stat(pathname.toOsSpecific())
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except OSError:
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# If the file is missing, the file fails.
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#print "file not found: %s" % (pathname)
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return False
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if st.st_size != self.size:
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# If the size is wrong, the file fails;
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#print "size wrong: %s" % (pathname)
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return False
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if not self.checkHash(packageDir, pathname, st):
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# Hard fail, the hash is wrong.
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#print "hash check wrong: %s" % (pathname)
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return False
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#print "hash check ok: %s" % (pathname)
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# The hash is OK. If the timestamp is wrong, change it back
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# to what we expect it to be, so we can quick-verify it
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# successfully next time.
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if st.st_mtime != self.timestamp:
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self.__updateTimestamp(pathname, st)
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return True
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def __updateTimestamp(self, pathname, st):
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# On Windows, we have to change the file to read-write before
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# we can successfully update its timestamp.
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try:
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os.chmod(pathname.toOsSpecific(), 0755)
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os.utime(pathname.toOsSpecific(), (st.st_atime, self.timestamp))
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os.chmod(pathname.toOsSpecific(), 0555)
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except OSError:
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pass
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def checkHash(self, packageDir, pathname, st):
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""" Returns true if the file has the expected md5 hash, false
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otherwise. As a side effect, stores a FileSpec corresponding
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to the on-disk file in self.actualFile. """
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fileSpec = FileSpec()
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fileSpec.fromFile(packageDir, self.filename,
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pathname = pathname, st = st)
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self.actualFile = fileSpec
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return (fileSpec.hash == self.hash)
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