Python中字节对象的项目赋值

Question

GAHH,代码不工作确实是错误的代码!

in RemoveRETNs toOutput [currentLoc - 0x00400000] = b'\ xCC'TypeError:'bytes'对象不支持项目赋值

我怎样才能解决这个问题:

inputFile = 'original.exe'
outputFile = 'output.txt'
patchedFile = 'original_patched.exe'

def GetFileContents(filename):
    f = open(filename, 'rb')
    fileContents = f.read()
    f.close()

    return fileContents

def FindAll(fileContents, strToFind):
    found = []

    lastOffset = -1

    while True:
        lastOffset += 1
        lastOffset = fileContents.find(b'\xC3\xCC\xCC\xCC\xCC', lastOffset)

        if lastOffset != -1:
            found.append(lastOffset)
        else:
            break

    return found

def FixOffsets(offsetList):
    for current in range(0, len(offsetList)):
        offsetList[current] += 0x00400000
    return offsetList

def AbsentFromList(toFind, theList):
    for i in theList:
        if i == toFind:
            return True
    return False

# Outputs the original file with all RETNs replaced with INT3s.
def RemoveRETNs(locationsOfRETNs, oldFilesContents, newFilesName):
    target = open(newFilesName, 'wb')

    toOutput = oldFilesContents

    for currentLoc in locationsOfRETNs:
        toOutput[currentLoc - 0x00400000] = b'\xCC'

    target.write(toOutput)

    target.close()

fileContents = GetFileContents(inputFile)
offsets = FixOffsets(FindAll(fileContents, '\xC3\xCC\xCC\xCC\xCC'))
RemoveRETNs(offsets, fileContents, patchedFile)

我做错了什么,我该怎么做才能解决它？代码示例？

Answer 1

将return声明更改GetFileContents为

return bytearray(fileContents)

其余的应该工作.你需要使用bytearray而不是bytes简单地因为前者是读/写,后者(你现在正在使用的)是只读的.

Answer 2

Bytestrings(和一般的字符串)是Python中的不可变对象.创建它们后,您无法更改它们.相反,你必须创建一个碰巧有一些旧内容的新的.(例如,使用基本字符串newString = oldString[:offset] + newChar + oldString[offset+1:]等.)

相反,您可能希望首先将bytestring转换为字节列表,或者将bytearray转换为bytearray,然后在完成所有操作后将bytearray/list转换回静态字符串.这避免了为每个替换操作创建新字符串.