Python判断某个用户对某个文件的权限

在Python我们要判断一个文件对当前用户有没有读、写、执行权限，我们通常可以使用os.access函数来实现，比如：

# 判断读权限
os.access(<my file>, os.R_OK)
# 判断写权限
os.access(<my file>, os.W_OK)
# 判断执行权限
os.access(<my file>, os.X_OK)
# 判断读、写、执行权限
os.access(<my file>, os.R_OK | os.W_OK | os.X_OK)
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但是如果要判断任意一个指定的用户对某个文件是否有读、写、执行权限，Python中是没有默认实现的，此时我们可以通过下面的代码断来判断

import os
import pwd
import stat

def is_readable(cls, path, user):
user_info = pwd.getpwnam(user)
uid = user_info.pw_uid
gid = user_info.pw_gid
s = os.stat(path)
mode = s[stat.ST_MODE]
return (
((s[stat.ST_UID] == uid) and (mode & stat.S_IRUSR > 0)) or
((s[stat.ST_GID] == gid) and (mode & stat.S_IRGRP > 0)) or
(mode & stat.S_IROTH > 0)
)

def is_writable(cls, path, user):
user_info = pwd.getpwnam(user)
uid = user_info.pw_uid
gid = user_info.pw_gid
s = os.stat(path)
mode = s[stat.ST_MODE]
return (
((s[stat.ST_UID] == uid) and (mode & stat.S_IWUSR > 0)) or
((s[stat.ST_GID] == gid) and (mode & stat.S_IWGRP > 0)) or
(mode & stat.S_IWOTH > 0)
)

def is_executable(cls, path, user):
user_info = pwd.getpwnam(user)
uid = user_info.pw_uid
gid = user_info.pw_gid
s = os.stat(path)
mode = s[stat.ST_MODE]
return (
((s[stat.ST_UID] == uid) and (mode & stat.S_IXUSR > 0)) or
((s[stat.ST_GID] == gid) and (mode & stat.S_IXGRP > 0)) or
(mode & stat.S_IXOTH > 0)
)