reference_monitor_sl8653 - Backup.r2py

TYPE="type"
ARGS="args"
RETURN="return"
EXCP="exceptions"
TARGET="target"
FUNC="func"
OBJC="objc"

class ABFile():
  def __init__(self,filename,create):
    if callfunc == 'initialize':
      mycontext['fileinuse'] = filename
    elif mycontext['fileinuse']== filename:
      raise Exception("FileInUseError")

    mycontext['debug'] = True
    mycontext['filesize'] = 2
    mycontext['filesizeb'] = 2
    mycontext[filename] = createlock()
    mycontext[filename].acquire(True)

    self.Afn = filename+'.a'
    mycontext['exists']=False
    if self.Afn in listfiles():
      mycontext['exists']=True
    self.Bfn = filename+'.b'
    #self.Cfn = filename+'.c'
    mycontext['abfile'] = filename
    # make the files and add 'SE' to the readat file...

    try:
      self.Afile = openfile(self.Afn,create)
    except:
      raise Exception("FileInUseError")

    self.Bfile = openfile(self.Bfn,create)
    #self.Cfile = openfile(self.Cfn,create)

    if mycontext['exists']==False:
      self.Afile.writeat('SE',0) ##### W r i t e   D A T A
      self.Bfile.writeat('SE',0) #seems a reasonable start???
    else:
       self.Bfile.writeat(self.readat(None,0),0)

    mycontext[filename].release()

  def writeat(self,data,offset):
    # Write the requested data to the B file using the sandbox's writeat call
      s = mycontext['filesizeb']
      l = len(data)
      end = offset + l -1
      if end > s:
        mycontext['filesizeb'] = end
      elif end < s:
        mycontext['filesizeb'] -= (s - end)

      if offset < s:
        #mycontext['monlock'].acquire(True)
        self.Bfile.writeat(data,offset) # w r i t e   D A T A
        #mycontext['monlock'].release()


  def readat(self,bytes,offset):
    # Read from the A file using the sandbox's readat...
    if bytes==None:
      return self.Afile.readat(None,offset)
    else:
      return self.Afile.readat(bytes,offset)
    """elif mycontext['filesize'] >= (offset + bytes): # plus bytes to not read off end
      return self.Afile.readat(bytes,offset) ##### R e a D   D A T A
    else:
      return None """

  def close(self):
    #mycontext[mycontext['fileinuse']].acquire(True)
    #mycontext['monlock'].release()
    ok = True
    #afile= self.Afn
    offset =  mycontext['filesizeb']
    data = self.Bfile.readat(None,0)
    if data == None:
      ok = false
    elif data[0] != 'S':
        ok = False
    elif data.endswith('E') == False:
        ok = False

    if ok == True:
      if mycontext['exists'] == True:
        self.Afile.writeat(data,0)        #removefile(self.Afn)         #temp =  openfile(afile,create)         #self.Cfile.writeat(data,0)
        mycontext['filesize'] = mycontext['filesizeb']
      else:  #######      this was a brand new file we can dump valid b file into it and close out
        self.Afile.writeat(data,0)
        mycontext['filesize'] = mycontext['filesizeb']

    self.Afile.close()
    self.Bfile.close()

def ABopenfile(filename, create):
   return ABFile(filename,create)



# The code here sets up type checking and variable hiding for you.  You
# should not need to change anything below here.
sec_file_def = {"obj-type":ABFile,
                "name":"ABFile",
                "writeat":{"type":"func","args":(str,int),"exceptions":Exception,"return":(int,type(None)),"target":ABFile.writeat},
                "readat":{"type":"func","args":((int,type(None)),(int)),"exceptions":Exception,"return":str,"target":ABFile.readat},
                "close":{"type":"func","args":None,"exceptions":None,"return":(bool,type(None)),"target":ABFile.close}
           }

CHILD_CONTEXT_DEF["ABopenfile"] = {TYPE:OBJC,ARGS:(str,bool),EXCP:Exception,RETURN:sec_file_def,TARGET:ABopenfile}

# Execute the user code
secure_dispatch_module()