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"""
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magic is a wrapper around the libmagic file identification library.
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Usage:
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>>> import magic
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>>> magic.from_file("testdata/test.pdf")
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'PDF document, version 1.2'
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>>> magic.from_file("testdata/test.pdf", mime=True)
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'application/pdf'
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>>> magic.from_buffer(open("testdata/test.pdf").read(1024))
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'PDF document, version 1.2'
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>>>
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"""
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import sys
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import os.path
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class MagicException(Exception):
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pass
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class Magic:
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"""
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Magic is a wrapper around the libmagic C library.
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"""
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def __init__(self, mime=False, magic_file=None, mime_encoding=False):
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"""
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Create a new libmagic wrapper.
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mime - if True, mimetypes are returned instead of textual descriptions
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mime_encoding - if True, codec is returned
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magic_file - use a mime database other than the system default
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"""
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flags = MAGIC_NONE
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if mime:
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flags |= MAGIC_MIME
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elif mime_encoding:
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flags |= MAGIC_MIME_ENCODING
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self.cookie = magic_open(flags)
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magic_load(self.cookie, magic_file)
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def from_buffer(self, buf):
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"""
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Identify the contents of `buf`
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"""
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return magic_buffer(self.cookie, buf)
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def from_file(self, filename):
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"""
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Identify the contents of file `filename`
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raises IOError if the file does not exist
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"""
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if not os.path.exists(filename):
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raise IOError("File does not exist: " + filename)
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return magic_file(self.cookie, filename)
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def __del__(self):
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# 析构函数，确保在对象被垃圾回收时关闭 libmagic cookie
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if self.cookie and magic_close:
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magic_close(self.cookie)
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self.cookie = None
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# 全局变量，用于保存默认和MIME magic对象
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_magic_mime = None
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_magic = None
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# 获取默认和MIME magic对象的函数
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def _get_magic_mime():
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global _magic_mime
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if not _magic_mime:
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_magic_mime = Magic(mime=True)
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return _magic_mime
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def _get_magic():
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global _magic
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if not _magic:
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_magic = Magic()
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return _magic
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def _get_magic_type(mime):
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if mime:
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return _get_magic_mime()
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else:
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return _get_magic()
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# 公共函数，用于识别文件和缓冲区
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def from_file(filename, mime=False):
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m = _get_magic_type(mime)
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return m.from_file(filename)
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def from_buffer(buffer, mime=False):
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m = _get_magic_type(mime)
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return m.from_buffer(buffer)
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# 使用 ctypes 导入 libmagic 库
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try:
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libmagic = None
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import ctypes
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import ctypes.util
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from ctypes import c_char_p, c_int, c_size_t, c_void_p
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# 尝试找到 libmagic 库
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dll = ctypes.util.find_library('magic') or ctypes.util.find_library('magic1')
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# This is necessary because find_library returns None if it doesn't find the library
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if dll:
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try:
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libmagic = ctypes.CDLL(dll)
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except WindowsError:
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pass
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# 如果没有找到，尝试平台特定的路径
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if not libmagic or not libmagic._name:
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platform_to_lib = {'darwin': ['/opt/local/lib/libmagic.dylib',
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'/usr/local/lib/libmagic.dylib',
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'/usr/local/Cellar/libmagic/5.10/lib/libmagic.dylib'],
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'win32': ['magic1.dll']}
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for dll in platform_to_lib.get(sys.platform, []):
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try:
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libmagic = ctypes.CDLL(dll)
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except OSError:
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pass
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# 如果仍然没有找到，抛出 ImportError
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if not libmagic or not libmagic._name:
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# It is better to raise an ImportError since we are importing magic module
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raise ImportError('failed to find libmagic. Check your installation')
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# 定义 magic_t 类型和错误检查函数
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magic_t = ctypes.c_void_p
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def errorcheck(result, func, args):
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err = magic_error(args[0])
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if err is not None:
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raise MagicException(err)
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else:
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return result
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def coerce_filename(filename):
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if filename is None:
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return None
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return filename.encode(sys.getfilesystemencoding())
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# 使用 ctypes 定义 libmagic 函数
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magic_open = libmagic.magic_open
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magic_open.restype = magic_t
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magic_open.argtypes = [c_int]
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magic_close = libmagic.magic_close
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magic_close.restype = None
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magic_close.argtypes = [magic_t]
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magic_error = libmagic.magic_error
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magic_error.restype = c_char_p
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magic_error.argtypes = [magic_t]
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magic_errno = libmagic.magic_errno
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magic_errno.restype = c_int
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magic_errno.argtypes = [magic_t]
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_magic_file = libmagic.magic_file
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_magic_file.restype = c_char_p
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_magic_file.argtypes = [magic_t, c_char_p]
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_magic_file.errcheck = errorcheck
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def magic_file(cookie, filename):
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return _magic_file(cookie, coerce_filename(filename))
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_magic_buffer = libmagic.magic_buffer
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_magic_buffer.restype = c_char_p
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_magic_buffer.argtypes = [magic_t, c_void_p, c_size_t]
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_magic_buffer.errcheck = errorcheck
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def magic_buffer(cookie, buf):
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return _magic_buffer(cookie, buf, len(buf))
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_magic_load = libmagic.magic_load
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_magic_load.restype = c_int
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_magic_load.argtypes = [magic_t, c_char_p]
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_magic_load.errcheck = errorcheck
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def magic_load(cookie, filename):
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return _magic_load(cookie, coerce_filename(filename))
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magic_setflags = libmagic.magic_setflags
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magic_setflags.restype = c_int
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magic_setflags.argtypes = [magic_t, c_int]
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magic_check = libmagic.magic_check
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magic_check.restype = c_int
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magic_check.argtypes = [magic_t, c_char_p]
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magic_compile = libmagic.magic_compile
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magic_compile.restype = c_int
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magic_compile.argtypes = [magic_t, c_char_p]
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# 如果 libmagic 无法导入，定义回退函数
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except (ImportError, OSError):
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from_file = from_buffer = lambda *args, **kwargs: MAGIC_UNKNOWN_FILETYPE
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# 定义 libmagic 标志常量
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MAGIC_NONE = 0x000000 # 无标志
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MAGIC_DEBUG = 0x000001 # 打开调试
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MAGIC_SYMLINK = 0x000002 # 跟随符号链接
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MAGIC_COMPRESS = 0x000004 # 检查压缩文件内部
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MAGIC_DEVICES = 0x000008 # 查看设备内容
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MAGIC_MIME = 0x000010 # 返回 MIME 字符串
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MAGIC_MIME_ENCODING = 0x000400 # 返回 MIME 编码
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MAGIC_CONTINUE = 0x000020 # 返回所有匹配项
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MAGIC_CHECK = 0x000040 # 打印警告到标准错误
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MAGIC_PRESERVE_ATIME = 0x000080 # 退出时恢复访问时间
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MAGIC_RAW = 0x000100 # 不转换不可打印字符
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MAGIC_ERROR = 0x000200 # 将 ENOENT 等视为真实错误
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MAGIC_NO_CHECK_COMPRESS = 0x001000 # 不检查压缩文件
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MAGIC_NO_CHECK_TAR = 0x002000 # 不检查 tar 文件
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MAGIC_NO_CHECK_SOFT = 0x004000 # 不检查 magic 条目
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MAGIC_NO_CHECK_APPTYPE = 0x008000 # 不检查应用程序类型
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MAGIC_NO_CHECK_ELF = 0x010000 # 不检查 elf 详细信息
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MAGIC_NO_CHECK_ASCII = 0x020000 # 不检查 ascii 文件
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MAGIC_NO_CHECK_TROFF = 0x040000 # 不检查 ascii/troff
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MAGIC_NO_CHECK_FORTRAN = 0x080000 # 不检查 ascii/fortran
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MAGIC_NO_CHECK_TOKENS = 0x100000 # 不检查 ascii/tokens
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MAGIC_UNKNOWN_FILETYPE = b"unknown"
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