Michael Felt added the comment:
Question - before I submit a patch.
A. Is there a PEP I should read re: ctypes/util and/or ctypes/cdll?
B. I show two different behaviors of responding - My question is, what does the
community think should be the response? My preference is to bring the request
back to it's stub - (strip lib from the beginning, and .so* or .a from the
suffix, so that it is in it's -lFOO form - as if being offered to a linker
(with -lFOO, we do not use -lFOO.so.6 (e.g., for libc.so.6).
I have seen a lot of variance in how cdll is used (in only two python based
projects I am currently interested in porting). Calls are frequently made using
some variation including .so somewhere in the name and/or code is basing
decesions based on a the number (###) returned by find_library (e.g.,
libFOO.so.###, and ### MUST be one of a list - and is rejected if not a match
(even if newer)). I would think if there is a version dependancy this should be
a call to the library loaded rather than an external string.
In any case, - for one example - as libc.so.* will never exist, by default, on
AIX, for ease of use I believe that translating libFOO.* to FOO and then doing
the 'find' comes closest to what was intended (long long ago) - again, is there
a PEP with guidance on this AND my preference, for AIX, is to look in .a
archives first for a .so member, and then look for an AIX legacy member
(shr.*.o) and then look for an external .so.* file.
With my current working version - this is the output of the test in util.py:
root@x064:[/data/prj/aixtools/python/python-2.7.11.3/Lib/ctypes]../../python
./util.py
libm.a
libc.a
libbz2.a
<CDLL 'None', handle b at 700000000216630>
<CDLL 'libcrypt.a(shr_64.o)', handle c at 700000000216630>
libcrypt.a
Additional Tests for AIX
call find_library("foo")
c: libc.a
c.a: None
c.so: None
libc: libc.a
libc.a: libc.a
libc.so.6: libc.a
crypt: libcrypt.a
crypto: libcrypto.a
crypto.so: None
libcrypto.so: libcrypto.a
call cdll.LoadLibrary("foo")
m: <CDLL 'None', handle d at 700000000216860>
libm.so: <CDLL 'None', handle e at 700000000216860>
c: <CDLL 'libc.a(shr_64.o)', handle f at 700000000216860>
c.a: <CDLL 'libc.a(shr_64.o)', handle 10 at 700000000216860>
libc.a: <CDLL 'libc.a(shr_64.o)', handle 11 at 700000000216860>
libc.so.6: <CDLL 'libc.a(shr_64.o)', handle 12 at 700000000216860>
libc.so.9: <CDLL 'libc.a(shr_64.o)', handle 13 at 700000000216860>
bz2: <CDLL 'libbz2.a(libbz2.so.1)', handle 14 at 700000000216860>
libbz2: <CDLL 'libbz2.a(libbz2.so.1)', handle 15 at 700000000216860>
crypt: <CDLL 'libcrypt.a(shr_64.o)', handle 16 at 700000000216860>
crypto: <CDLL 'libcrypto.a(libcrypto64.so)', handle 17 at 700000000216860>
crypto.so: <CDLL 'libcrypto.a(libcrypto64.so)', handle 18 at 700000000216860>
libcrypto.so: <CDLL 'libcrypto.a(libcrypto64.so)', handle 19 at
700000000216860>
iconv: <CDLL 'libiconv.a(libiconv.so.2)', handle 1a at 700000000216860>
intl: <CDLL 'libintl.a(libintl.so.1)', handle 1b at 700000000216860>
The test looks like:
################################################################
# test code
def test():
from ctypes import cdll
if os.name == "nt":
print cdll.msvcrt
print cdll.load("msvcrt")
print find_library("msvcrt")
if os.name == "posix":
# find and load_version
print find_library("m")
print find_library("c")
print find_library("bz2")
# getattr
## print cdll.m
## print cdll.bz2
# load
if sys.platform == "darwin":
print cdll.LoadLibrary("libm.dylib")
print cdll.LoadLibrary("libcrypto.dylib")
print cdll.LoadLibrary("libSystem.dylib")
print cdll.LoadLibrary("System.framework/System")
else:
print cdll.LoadLibrary("libm.so")
print cdll.LoadLibrary("libcrypt.so")
print find_library("crypt")
if sys.platform.startswith("aix"):
print "\nAdditional Tests for AIX"
print "call find_library(\"foo\")"
print "c: ", find_library("c")
print "c.a: ", find_library("c.a")
print "c.so: ", find_library("c.so")
print "libc: ", find_library("libc")
print "libc.a: ", find_library("libc.a")
print "libc.so.6: ", find_library("libc.so.6")
print "crypt: ", find_library("crypt")
print "crypto: ", find_library("crypto")
print "crypto.so: ", find_library("crypto.so")
print "libcrypto.so: ", find_library("libcrypto.so")
###
print "\ncall cdll.LoadLibrary(\"foo\")"
print "m: ", cdll.LoadLibrary("m")
print "libm.so: ", cdll.LoadLibrary("libm.so")
print "c: ", cdll.LoadLibrary("c")
print "c.a: ", cdll.LoadLibrary("c.a")
print "libc.a: ", cdll.LoadLibrary("libc.a")
print "libc.so.6: ", cdll.LoadLibrary("libc.so.6")
print "libc.so.9: ", cdll.LoadLibrary("libc.so.9")
print "bz2: ", cdll.LoadLibrary("bz2")
print "libbz2: ", cdll.LoadLibrary("libbz2")
print "crypt: ", cdll.LoadLibrary("crypt")
print "crypto: ", cdll.LoadLibrary("crypto")
print "crypto.so: ", cdll.LoadLibrary("crypto.so")
print "libcrypto.so: ", cdll.LoadLibrary("libcrypto.so")
print "iconv: ", cdll.LoadLibrary("iconv")
print "intl: ", cdll.LoadLibrary("intl")
if __name__ == "__main__":
test()
Thank you for your considered comments. My goal is ease of use for (porting)
existing projects to AIX, i.e., ideally without code change.
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<http://bugs.python.org/issue26439>
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