标识Linux passwd文件

Question

我需要帮助编写一个函数(最好是python)，以确定一个文件是/etc/passwd还是etc/影子。到目前为止，我已经尝试使用print(pw.getpwall())，但是它从os env读取文件。我需要一个接受输入的库，它可以判断一个文件是否是passwd/影子文件。

Answer 1

passwd文件格式和阴影文件格式不同。

您可以编写一个简短的函数或类。第一次迭代将是：

1. 查找根用户，几乎100%的事实是，根是第一次输入
2. 检查第2列、第6列和第7列(分隔符是符号)

H 19如果第2列是E 110xE 211>，第6列是E 112/根<代码>E 213，第7列是E 114/code>/bin/*shE 215，那么它几乎是一个密码文件，在100%H 216H 117/code>如果第二个是盐类和散列(格式：E 118代码$$6)，并且代码是第7位，并且代码是<<100%<

<代码><<<><><><220>

当然，可能会出现以下问题：

• Linux配置为不使用阴影文件。在本例中，pasword文件第2列包含password
• Linux，配置为不使用salt (我猜是否可能)

请查看手册：man 5 passwd和man 5 shadow

编辑，2020-04-24:这是我更正的pwd.py：

#!/usr/bin/env python3

import os
import sys

passwd_file=('./passwd')

# path conversion handlers
def __nullpathconv(path):
    return path

def __unixpathconv(path):
    return path

# decide what field separator we can try to use - Unix standard, with
# the platform's path separator as an option.  No special field conversion
# handler is required when using the platform's path separator as field
# separator, but are required for the home directory and shell fields when
# using the standard Unix (":") field separator.
__field_sep = {':': __unixpathconv}
if os.pathsep:
    if os.pathsep != ':':
        __field_sep[os.pathsep] = __nullpathconv

# helper routine to identify which separator character is in use
def __get_field_sep(record):
    fs = None
    for c in list(__field_sep.keys()):
        # there should be 6 delimiter characters (for 7 fields)
        if record.count(c) == 6:
            fs = c
            break
    if fs:
        return fs
    else:
        raise KeyError

# class to match the new record field name accessors.
# the resulting object is intended to behave like a read-only tuple,
# with each member also accessible by a field name.
class Passwd:
    def __init__(self, name, passwd, uid, gid, gecos, dir, shell):
        self.__dict__['pw_name'] = name
        self.__dict__['pw_passwd'] = passwd
        self.__dict__['pw_uid'] = uid
        self.__dict__['pw_gid'] = gid
        self.__dict__['pw_gecos'] = gecos
        self.__dict__['pw_dir'] = dir
        self.__dict__['pw_shell'] = shell
        self.__dict__['_record'] = (self.pw_name, self.pw_passwd,
                                    self.pw_uid, self.pw_gid,
                                    self.pw_gecos, self.pw_dir,
                                    self.pw_shell)

    def __len__(self):
        return 7

    def __getitem__(self, key):
        return self._record[key]

    def __setattr__(self, name, value):
        raise AttributeError('attribute read-only: %s' % name)

    def __repr__(self):
        return str(self._record)

    def __cmp__(self, other):
        this = str(self._record)
        if this == other:
            return 0
        elif this < other:
            return -1
        else:
            return 1

# read the whole file, parsing each entry into tuple form
# with dictionaries to speed recall by UID or passwd name
def __read_passwd_file():
    if passwd_file:
        passwd = open(passwd_file, 'r')
    else:
        raise KeyError
    uidx = {}
    namx = {}
    sep = None
    while 1:
        entry = passwd.readline().strip()
        if len(entry) > 6:
            if sep is None:
                sep = __get_field_sep(entry)
            fields = entry.split(sep)
            for i in (2, 3):
                fields[i] = int(fields[i])
            for i in (5, 6):
                fields[i] = __field_sep[sep](fields[i])
            record = Passwd(*fields)
            if fields[2] not in uidx:
                uidx[fields[2]] = record
            if fields[0] not in namx:
                namx[fields[0]] = record
        elif len(entry) > 0:
            pass                         # skip empty or malformed records
        else:
            break
    passwd.close()
    if len(uidx) == 0:
        raise KeyError
    return (uidx, namx)

# return the passwd database entry by UID
def getpwuid(uid):
    u, n = __read_passwd_file()
    return u[uid]

# return the passwd database entry by passwd name
def getpwnam(name):
    u, n = __read_passwd_file()
    return n[name]

# return all the passwd database entries
def getpwall():
    u, n = __read_passwd_file()
    return list(n.values())

# test harness
if __name__ == '__main__':
    print(getpwall())