前言:接触magic module是由于工作中对的文件类型判断需求,网上查了下,python内置的有mimetypes module,filetype module,与使用mimetypes库相比,更可靠的方法是使用magic软件包。
magic
magic是libmagic文件标识库的封装,libmagic是一个根据文件头识别文件类型的开发库,因此可以实现对文件类型的判断,在Django上,还可以确保MIME类型与UploadedFile.content_type相匹配。
libmagic
- module name:
magic
- pypi: file-magic
- source: https://github.com/file/file/tree/master/python
- man:
man libmagic
- install:
-
python setup.py install # or easy_install . # or pip install file-magic
-
- Usage:
-
import magic detected = magic.detect_from_filename('magic.py') print 'Detected MIME type: {}'.format(detected.mime_type) print 'Detected encoding: {}'.format(detected.encoding) print 'Detected file type name: {}'.format(detected.name)
-
确定文件mime-type时,选择的工具简称为file,
其后端称为libmagic
。如果您想将任何libmagic绑定与python一起使用,则需要使用此工具,该工具已经附带了自己的python绑定,称为file-magic。file-magic绑定包含到文件上。如果同时安装文件和python-magic,则python模块将magic引用前者。
python-magic
- module name:
magic
- pypi: python-magic
- source: https://github.com/ahupp/python-magic
- install:
-
pip install python-magic #window下依赖python-magic-bin, pip install python-magic-bin
-
- usage:
-
>>> import magic >>> magic.from_file("testdata/test.pdf") 'PDF document, version 1.2' # recommend using at least the first 2048 bytes, as less can produce incorrect identification >>> magic.from_buffer(open("testdata/test.pdf").read(2048)) 'PDF document, version 1.2' >>> magic.from_file("testdata/test.pdf", mime=True) 'application/pdf'
>>> f = magic.Magic(uncompress=True) >>> f.from_file('testdata/test.gz') 'ASCII text (gzip compressed data, was "test", last modified: Sat Jun 28 21:32:52 2008, from Unix)'
>>> f = magic.Magic(mime=True, uncompress=True) >>> f.from_file('testdata/test.gz') 'text/plain'
-
filemagic
- module name:
magic
- pypi: filemagic
- source: https://github.com/aliles/filemagic
- install:
-
pip install filemagic
-
这个库与file-magic有一些相似之处,包含在libmagic。
python-magic用例
import magic file_type = magic.from_buffer(open("file_types/Bs.tar.gz",'rb').read(2048)) #1 #or file_type = magic.from_file("file_types/Bs.tar.gz", mime=True) #2 f = magic.Magic(uncompress=True) ff=f.from_file('file_types/Bs.tar.gz') #3 print(file_type,ff) #gzip compressed data, last modified: Tue Dec 10 08:46:57 2019, from Unix
我更喜欢的是Magic方法,Magic是libmagic C库的包装。更强大更直接,包含magic的数据库方法,并且可以进行mime_encoding检测。
但有网友友情提示说不建议用于一般用途,特别是跨多个线程共享并不安全,如果尝试这样做会失败。这个还没深究,但是我们可以先了解magic对Magic方法的调用:
def _get_magic_type(mime): i = _instances.get(mime) if i is None: i = _instances[mime] = Magic(mime=mime) return i
可以看到,如果magic方法没有获取到mime,还调用了Magic,所以对于安全性和可行性,我们打个问号,等菜鸟我修炼一段时间,攒点经验值,再回来研究研究吧。
try: ms = magic.open(magic.MAGIC_NONE) ms.load() except: ms = None
magic的一些常量:
MAGIC_NONE = 0x000000 # No flags MAGIC_DEBUG = 0x000001 # Turn on debugging MAGIC_SYMLINK = 0x000002 # Follow symlinks MAGIC_COMPRESS = 0x000004 # Check inside compressed files MAGIC_DEVICES = 0x000008 # Look at the contents of devices MAGIC_MIME = 0x000010 # Return a mime string MAGIC_MIME_ENCODING = 0x000400 # Return the MIME encoding MAGIC_CONTINUE = 0x000020 # Return all matches MAGIC_CHECK = 0x000040 # Print warnings to stderr MAGIC_PRESERVE_ATIME = 0x000080 # Restore access time on exit MAGIC_RAW = 0x000100 # Don't translate unprintable chars MAGIC_ERROR = 0x000200 # Handle ENOENT etc as real errors MAGIC_NO_CHECK_COMPRESS = 0x001000 # Don't check for compressed files MAGIC_NO_CHECK_TAR = 0x002000 # Don't check for tar files MAGIC_NO_CHECK_SOFT = 0x004000 # Don't check magic entries MAGIC_NO_CHECK_APPTYPE = 0x008000 # Don't check application type MAGIC_NO_CHECK_ELF = 0x010000 # Don't check for elf details MAGIC_NO_CHECK_ASCII = 0x020000 # Don't check for ascii files MAGIC_NO_CHECK_TROFF = 0x040000 # Don't check ascii/troff MAGIC_NO_CHECK_FORTRAN = 0x080000 # Don't check ascii/fortran MAGIC_NO_CHECK_TOKENS = 0x100000 # Don't check ascii/tokens
分享文章:
cuckoo里的文件识别功能:https://www.cnblogs.com/viwilla/p/5051896.html
对文件格式的判断代码
def _get_filetype(self, data): """Gets filetype, uses libmagic if available. @param data: data to be analyzed. @return: file type or None. """ if not HAVE_MAGIC: return None try: ms = magic.open(magic.MAGIC_NONE) ms.load() file_type = ms.buffer(data) except: try: file_type = magic.from_buffer(data) except Exception: return None finally: try: ms.close() except: pass return file_type
分享找到的一个挺好的用例:https://www.cnblogs.com/17bdw/p/10042549.html
参考链接:https://stackoverflow.com/questions/43580/how-to-find-the-mime-type-of-a-file-in-python