Michael Felt added the comment:
I would like to say:
a) I am happy this is being considered for Python3-3.7
b) I still believe it is a "bug" plain and simple - it (find_library()) cannot
work in "normal" situations. Why "IBM" or others never addressed this is beyond
me - but - imho - that is a poor argument for not fixing it.
FYI: As I have documented in ... this does not mean that ctypes.CDLL is
incapable of loading a library. If you know the 'magic', aka what is not being
provided by this "implementation dependent" module - it is possible to load
either a .so file (actually a file by any name as long as it is a shared
archive) - or an AIX-style .a archive with shared libraries stored internally
as "archive members" - again, any member name is acceptable.
The bug: The "default code" behind an "else:" block depends on the presence of
the program "/sbin/ldconfig" to create a list of shared libraries. Normally,
this program is not installed on an AIX system (certainly not production -
maybe a system with gcc environment and using the gcc ld rather than the AIX ld
(the latter being normal).
Using python -m trace -C /tmp --count Lib/src/util.py The following (key)
counts are reported.
This is all that is being called - so when /sbin/ldonfig is not installed
(which is usual) - so this code can only return 'None'.
Environment: AIX 5.3, AIX 6.1, AIX 7.1 - all identical
root@x064:[/]ls -l /sbin/ld*
ls: 0653-341 The file /sbin/ld* does not exist.
michael@x071:[/home/michael]ls /sbin/ld*
ls: cannot access '/sbin/ld*': A file or directory in the path name does not
exist.
(GNU coreutils ls here)
root@x062:[/]ls /sbin/ld*
ls: 0653-341 The file /sbin/ld* does not exist.
So, obviously the sys.popen() call below will always 'fail'.
The basic trace from util.py:
1: if os.name == "posix":
# find and load_version
1: print find_library("m")
1: print find_library("c")
1: print find_library("bz2")
And how this is called:
else:
1: def _findSoname_ldconfig(name):
3: import struct
3: if struct.calcsize('l') == 4:
machine = os.uname()[4] + '-32'
else:
3: machine = os.uname()[4] + '-64'
3: mach_map = {
3: 'x86_64-64': 'libc6,x86-64',
3: 'ppc64-64': 'libc6,64bit',
3: 'sparc64-64': 'libc6,64bit',
3: 's390x-64': 'libc6,64bit',
3: 'ia64-64': 'libc6,IA-64',
}
3: abi_type = mach_map.get(machine, 'libc6')
# XXX assuming GLIBC's ldconfig (with option -p)
3: expr = r'\s+(lib%s\.[^\s]+)\s+\(%s' % (re.escape(name),
abi_type)
3: f = os.popen('LC_ALL=C LANG=C /sbin/ldconfig -p 2>/dev/null')
3: try:
3: data = f.read()
finally:
3: f.close()
3: res = re.search(expr, data)
3: if not res:
3: return None
return res.group(1)
1: def find_library(name):
3: return _findSoname_ldconfig(name) or
_get_soname(_findLib_gcc(name))
And with python2-2.7.13 - the counts start the same - but the result is the
same - by definition 'None' because subprocess.Popen() also
does not have any output to search...
1: if os.name == "posix":
# find and load_version
1: print find_library("m")
1: print find_library("c")
1: print find_library("bz2")
else:
1: def _findSoname_ldconfig(name):
3: import struct
3: if struct.calcsize('l') == 4:
3: machine = os.uname()[4] + '-32'
else:
machine = os.uname()[4] + '-64'
3: mach_map = {
3: 'x86_64-64': 'libc6,x86-64',
3: 'ppc64-64': 'libc6,64bit',
3: 'sparc64-64': 'libc6,64bit',
3: 's390x-64': 'libc6,64bit',
3: 'ia64-64': 'libc6,IA-64',
}
3: abi_type = mach_map.get(machine, 'libc6')
# XXX assuming GLIBC's ldconfig (with option -p)
3: expr = r'\s+(lib%s\.[^\s]+)\s+\(%s' % (re.escape(name),
abi_type)
3: env = dict(os.environ)
3: env['LC_ALL'] = 'C'
3: env['LANG'] = 'C'
3: null = open(os.devnull, 'wb')
3: try:
3: with null:
3: p = subprocess.Popen(['/sbin/ldconfig', '-p'],
3: stderr=null,
3: stdout=subprocess.PIPE,
3: env=env)
3: except OSError: # E.g. command not found
3: return None
[data, _] = p.communicate()
res = re.search(expr, data)
if not res:
return None
return res.group(1)
========
In closing:
a) this is an "issue" aka bug, plain and simple - even it is has been ignored
as such (other issues only complained about poorer performance because
/sbin/ldconfig was not available). Please do not say - not fixing it because
noone ever complained before. Otherwise, what is the point of ever accepting
bug-reports aka issues if they can just be ignored.
b) I want to thank Martin for his help on many (PEP8 et al) improvements to my
initial proposals for a patch.
c) more important to me right now is that this be recognized as a bug - that
should have been reported and resolved years ago. Personally, I do not care why
noone ever reported it BUT I would like to see it properly identified that the
default code is a specific implementation that is no way related to a normal
AIX system - and an AIX-specific implementation is needed for normal operation
of python2 and/or python3.
Thank you for your time and thought!
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<http://bugs.python.org/issue26439>
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