No wrapper for magic_setparam()

[seirl]

Sometimes we need to change the parameters of magic, like MAGIC_PARAM_NAME_MAX. There should be a way to call magic_setparam() from the library.

[ahupp]

I'd accept a pull request for that feature.

[seirl]

Thanks. Could you leave the issue open? Generally, issues aren't meant as a way to ask people to work on something, but rather as a way to track what's left to do, so even if you don't want to work on it I think it makes sense for it to remain open in case someone (maybe I) offers to work on it.

[ahupp]

Sure.

[cbiedl]

Here's what looking into the existing calls and wisdom of stackexchange brought me - within 60 minutes.
Roughly tested, both getter and setter work as expected. What did I miss?

diff --git a/magic.py b/magic.py
index 83b906d..d48526d 100644
--- a/magic.py
+++ b/magic.py
@@ -23,7 +23,7 @@ import ctypes
 import ctypes.util
 import threading
 
-from ctypes import c_char_p, c_int, c_size_t, c_void_p
+from ctypes import c_char_p, c_int, c_size_t, c_void_p, byref, POINTER
 
 
 class MagicException(Exception):
@@ -99,6 +99,12 @@ class Magic:
         else:
             raise e
 
+    def setparam(self, param, val):
+        return magic_setparam(self.cookie, param, val)
+
+    def getparam(self, param):
+        return magic_getparam(self.cookie, param)
+
     def __del__(self):
         # no _thread_check here because there can be no other
         # references to this object at this point.
@@ -277,7 +283,24 @@ magic_compile = libmagic.magic_compile
 magic_compile.restype = c_int
 magic_compile.argtypes = [magic_t, c_char_p]
 
+_magic_setparam = libmagic.magic_setparam
+_magic_setparam.restype = c_int
+_magic_setparam.argtypes = [magic_t, c_int, POINTER(c_size_t)]
+_magic_setparam.errcheck = errorcheck_negative_one
+
+def magic_setparam(cookie, param, val):
+    v = c_size_t(val)
+    return _magic_setparam(cookie, param, byref(v))
 
+_magic_getparam = libmagic.magic_getparam
+_magic_getparam.restype = c_int
+_magic_getparam.argtypes = [magic_t, c_int, POINTER(c_size_t)]
+_magic_getparam.errcheck = errorcheck_negative_one
+
+def magic_getparam(cookie, param):
+    val = c_size_t()
+    _magic_getparam(cookie, param, byref(val))
+    return val
 
 MAGIC_NONE = 0x000000 # No flags
 MAGIC_DEBUG = 0x000001 # Turn on debugging
@@ -301,3 +324,11 @@ 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
+
+MAGIC_PARAM_INDIR_MAX = 0
+MAGIC_PARAM_NAME_MAX = 1
+MAGIC_PARAM_ELF_PHNUM_MAX = 2
+MAGIC_PARAM_ELF_SHNUM_MAX = 3
+MAGIC_PARAM_ELF_NOTES_MAX = 4
+MAGIC_PARAM_REGEX_MAX = 5
+MAGIC_PARAM_BYTES_MAX = 6

[ahupp]

@cbiedl that looks good to me. Would you be able to write a test for this as well?

[cbiedl]

Okay, here is an attempt for this: The test uses the parameter to limit the size of the file to check. If set to very small values, detection will change.

Otherwise the testing might be a bit too much in detail, but this way both getparam and setparam are tested, and the default value as well. Feel free to trim.

About the API, I'm not sure whether the c_int conversion using .value should rather happen in the library than putting the burden on the caller as it is right now. I'm not that much into Python style yet to decide.

FWIW, the related file invocation is

file --mime --parameter bytes=1 test/testdata/keep-going.jpg

Note: This test requires at least libmagic 5.26 (released April 2016)

[cbiedl]

Web frontends hate me, something ate the attachment. I'll create to create a pull request, what could possibly?

[cbiedl]

Seems I'm getting to old for this, or to impatient. But I hate it when using tools take more time than everything else. Please fetch manually from https://github.com/cbiedl/python-magic and sorry for the hassle.

[ahupp]

This is released, thanks!