Eryk Sun <[email protected]> added the comment:
> Windows has the GetBinaryTypeW function
ShellExecute[Ex] doesn't check for a PE image. It uses the file extension, and
a tangled web of registry settings to determine what to execute. If a file
should run directly via CreateProcess, you'll find the template command starts
with the target file ("%1" or "%L"). For example:
>>> AssocQueryStringW(ASSOCF_INIT_IGNOREUNKNOWN, ASSOCSTR_COMMAND,
... '.exe', 'open', command, n)
0
>>> print(command.value)
"%1" %*
OTOH, a script requires an interpreter, e.g for .py files:
>>> AssocQueryStringW(ASSOCF_INIT_IGNOREUNKNOWN, ASSOCSTR_COMMAND,
... '.py', 'open', command, n)
0
>>> print(command.value)
"C:\WINDOWS\py.exe" "%L" %*
Except .bat and .cmd scripts are executed directly via the %ComSpec%
interpreter:
>>> AssocQueryStringW(ASSOCF_INIT_IGNOREUNKNOWN, ASSOCSTR_COMMAND,
... '.bat', 'open', command, n)
0
>>> print(command.value)
"%1" %*
One bit of metadata we can check is the file's "PerceivedType": unknown=0,
text, image, audio, video, compressed, document, system, application,
game-media, contacts. If a file's type is unknown (0), system (7), or
application (8), or if getting the type fails, we probably don't want to run
it. For example:
>>> _ = AssocGetPerceivedType(".txt", ptype, flags, None); print(ptype[0])
1
>>> _ = AssocGetPerceivedType(".jpg", ptype, flags, None); print(ptype[0])
2
>>> _ = AssocGetPerceivedType(".mp3", ptype, flags, None); print(ptype[0])
3
>>> _ = AssocGetPerceivedType(".mp4", ptype, flags, None); print(ptype[0])
4
>>> _ = AssocGetPerceivedType(".zip", ptype, flags, None); print(ptype[0])
5
>>> _ = AssocGetPerceivedType(".html", ptype, flags, None); print(ptype[0])
6
>>> _ = AssocGetPerceivedType(".sys", ptype, flags, None); print(ptype[0])
7
>>> _ = AssocGetPerceivedType(".exe", ptype, flags, None); print(ptype[0])
8
>>> _ = AssocGetPerceivedType(".com", ptype, flags, None); print(ptype[0])
8
>>> _ = AssocGetPerceivedType(".bat", ptype, flags, None); print(ptype[0])
8
>>> _ = AssocGetPerceivedType(".cmd", ptype, flags, None); print(ptype[0])
8
Except for a small number of hard-code definitions, the PerceivedType has to be
defined for a filetype, and it's optional. It gets set either in the
file-extension key under [HKCU|HKLM]\Software\Classes, or in the
SystemFileAssocations subkey, or probably in 10 other locations sprawled across
the registry. Python's installer doesn't set the PerceivedType of .py files to
the application type (8), but it should.
Another bit of metadata is the MIME "Content Type". This is also optional
information provided in a filetype definition. For example:
>>> AssocQueryStringW(ASSOCF_INIT_IGNOREUNKNOWN, ASSOCSTR_CONTENTTYPE,
... '.exe', 'open', mtype, n)
0
>>> print(mtype.value)
application/x-msdownload
>>> AssocQueryStringW(ASSOCF_INIT_IGNOREUNKNOWN, ASSOCSTR_CONTENTTYPE,
... '.html', 'open', mtype, n)
0
>>> print(mtype.value)
text/html
----------
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<https://bugs.python.org/issue36021>
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