Re: [gentoo-portage-dev] [PATCH 2/2] pym/portage/util/locale.py: add a C module to check locale

[Michał Górny]

Dnia 19 maja 2016 14:43:38 CEST, "Anthony G. Basile" <basile@××××××××××××××.edu> napisał(a):
>From: "Anthony G. Basile" <blueness@g.o>
>
>The current method to check for the system locale is to use python's
>ctypes.util.find_library() to construct a full library path to the
>system libc.so which is then passed to ctypes.CDLL().  However,
>this gets bogged down in implementation dependant details and
>fails with musl.
>
>We work around this design flaw in ctypes with a small python module
>written in C called 'portage_c_check_locale', and only fall back on
>the current ctypes-based check when this module is not available.
>
>This has been tested on glibc, uClibc and musl systems.
>
>X-Gentoo-bug: 571444
>X-Gentoo-bug-url: https://bugs.gentoo.org/show_bug.cgi?id=571444
>Signed-off-by: Anthony G. Basile <blueness@g.o>

To be honest, I don't like this. Do we really want to duplicate all this, including duplicating the complete messages? This really looks messy and unmaintainable.

The only reason libc functions were being used was to workaround the hacky built-in case conversion functions. And this is the only part where CDLL was really used.

So please change this to provide trivial wrappers around the C library functions, and use them alternatively to ones obtained using CDLL. With a single common code doing all the check logic and messaging.


>---
> pym/portage/util/locale.py |  40 +++++++++----
> setup.py                   |   6 +-
>src/check_locale.c         | 144
>+++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 178 insertions(+), 12 deletions(-)
> create mode 100644 src/check_locale.c
>
>diff --git a/pym/portage/util/locale.py b/pym/portage/util/locale.py
>index 2a15ea1..fc5d052 100644
>--- a/pym/portage/util/locale.py
>+++ b/pym/portage/util/locale.py
>@@ -30,17 +30,17 @@ locale_categories = (
> _check_locale_cache = {}
>
>
>-def _check_locale(silent):
>+def _ctypes_check_locale():
> 	"""
>-	The inner locale check function.
>+	Check for locale using ctypes.
> 	"""
>
> 	libc_fn = find_library("c")
> 	if libc_fn is None:
>-		return None
>+		return (None, "")
> 	libc = LoadLibrary(libc_fn)
> 	if libc is None:
>-		return None
>+		return (None, "")
>
> 	lc = list(range(ord('a'), ord('z')+1))
> 	uc = list(range(ord('A'), ord('Z')+1))
>@@ -48,9 +48,6 @@ def _check_locale(silent):
> 	ruc = [libc.toupper(c) for c in lc]
>
> 	if lc != rlc or uc != ruc:
>-		if silent:
>-			return False
>-
> 		msg = ("WARNING: The LC_CTYPE variable is set to a locale " +
> 			"that specifies transformation between lowercase " +
> 			"and uppercase ASCII characters that is different than " +
>@@ -71,11 +68,32 @@ def _check_locale(silent):
> 			msg.extend([
> 				"  %s -> %s" % (chars(uc), chars(rlc)),
> 				"  %28s: %s" % ('expected', chars(lc))])
>-		writemsg_level("".join(["!!! %s\n" % l for l in msg]),
>-			level=logging.ERROR, noiselevel=-1)
>-		return False
>+		msg = "".join(["!!! %s\n" % l for l in msg]),
>+		return (False, msg)
>+
>+	return (True, "")
>+
>+
>+def _check_locale(silent):
>+	"""
>+	The inner locale check function.
>+	"""
>+
>+	try:
>+		from portage_c_check_locale import _c_check_locale
>+		(ret, msg) = _c_check_locale()
>+	except ImportError:
>+		writemsg_level("!!! Unable to import portage_c_check_locale\n",
>+			level=logging.WARNING, noiselevel=-1)
>+		(ret, msg) = _ctypes_check_locale()
>+
>+	if ret:
>+		return True
>+
>+	if not silent:
>+		writemsg_level(msg, level=logging.ERROR, noiselevel=-1)
>
>-	return True
>+	return False
>
>
> def check_locale(silent=False, env=None):
>diff --git a/setup.py b/setup.py
>index 25429bc..e44ac41 100755
>--- a/setup.py
>+++ b/setup.py
>@@ -47,7 +47,11 @@ x_scripts = {
> # Dictionary custom modules written in C/C++ here.  The structure is
> #   key   = module name
>#   value = list of C/C++ source code, path relative to top source
>directory
>-x_c_helpers = {}
>+x_c_helpers = {
>+	'portage_c_check_locale' : [
>+		'src/check_locale.c',
>+	],
>+}
>
> class x_build(build):
> 	""" Build command with extra build_man call. """
>diff --git a/src/check_locale.c b/src/check_locale.c
>new file mode 100644
>index 0000000..9762ef2
>--- /dev/null
>+++ b/src/check_locale.c
>@@ -0,0 +1,144 @@
>+/* Copyright 2005-2015 Gentoo Foundation
>+ * Distributed under the terms of the GNU General Public License v2
>+ */
>+
>+#include <Python.h>
>+#include <ctype.h>
>+#include <string.h>
>+
>+static PyObject * portage_c_check_locale(PyObject *, PyObject *);
>+
>+static PyMethodDef CheckLocaleMethods[] = {
>+	{"_c_check_locale", portage_c_check_locale, METH_NOARGS, "Check the
>system locale."},
>+	{NULL, NULL, 0, NULL}
>+};
>+
>+#if PY_MAJOR_VERSION >= 3
>+static struct PyModuleDef moduledef = {
>+	PyModuleDef_HEAD_INIT,
>+	"portage_c_check_locale",					/* m_name */
>+	"Module for checking the system locale for portage",		/* m_doc */
>+	-1,								/* m_size */
>+	CheckLocaleMethods,						/* m_methods */
>+	NULL,								/* m_reload */
>+	NULL,								/* m_traverse */
>+	NULL,								/* m_clear */
>+	NULL,								/* m_free */
>+};
>+#endif
>+
>+static PyObject *LocaleError;
>+
>+PyMODINIT_FUNC
>+#if PY_MAJOR_VERSION >= 3
>+PyInit_portage_c_check_locale(void)
>+#else
>+initportage_c_check_locale(void)
>+#endif
>+{
>+	PyObject *m;
>+
>+#if PY_MAJOR_VERSION >= 3
>+	m = PyModule_Create(&moduledef);
>+#else
>+	m = Py_InitModule("portage_c_check_locale", CheckLocaleMethods);
>+#endif
>+
>+	if (m == NULL)
>+#if PY_MAJOR_VERSION >= 3
>+		return NULL;
>+#else
>+		return;
>+#endif
>+
>+	LocaleError = PyErr_NewException("locale.LocaleError", NULL, NULL);
>+	Py_INCREF(LocaleError);
>+	PyModule_AddObject(m, "LocaleError", LocaleError);
>+
>+#if PY_MAJOR_VERSION >= 3
>+	return m;
>+#else
>+	return;
>+#endif
>+}
>+
>+
>+static void
>+error_msg(char msg[], int c[], int rc[], int ac[])
>+{
>+	int i, p;
>+
>+	strcat(msg, "  ");
>+	p = strlen(msg);
>+	for (i = 'a'; i <= 'z'; i++)
>+		msg[p++] = c[i-'a'];
>+
>+	strcat(msg, " -> ");
>+	p = strlen(msg);
>+	for (i = 'a'; i <= 'z'; i++)
>+		msg[p++] = rc[i-'a'];
>+	strcat(msg, "\n");
>+
>+	strcat(msg, "                      expected: ");
>+	p = strlen(msg);
>+	for (i = 'a'; i <= 'z'; i++)
>+		msg[p++] = ac[i-'a'];
>+	strcat(msg, "\n\n");
>+}
>+
>+
>+static PyObject *
>+portage_c_check_locale(PyObject *self, PyObject *args)
>+{
>+	int i, upper = 1, lower = 1;
>+	int lc[26], uc[26], rlc[26], ruc[26];
>+	char msg[1024];
>+
>+	memset(msg, 0, 1024);
>+
>+	for (i = 'a'; i <= 'z'; i++) {
>+		lc[i-'a'] = i;
>+		ruc[i-'a'] = toupper(i);
>+	}
>+
>+	for (i = 'A'; i <= 'Z'; i++) {
>+		uc[i-'A'] = i;
>+		rlc[i-'A'] = tolower(i);
>+	}
>+
>+	for (i = 'a'; i <= 'z'; i++)
>+		if(lc[i-'a'] != rlc[i-'a']) {
>+			lower = 0;
>+			break;
>+		}
>+
>+	for (i = 'A'; i <= 'Z'; i++)
>+		if(uc[i-'A'] != ruc[i-'A']) {
>+			upper = 0;
>+			break;
>+		}
>+
>+	if (lower == 0 || upper == 0) {
>+		strcpy(msg,
>+			"!!! WARNING: The LC_CTYPE variable is set to a locale that
>specifies\n"
>+			"!!! transformation between lowercase and uppercase ASCII
>characters that\n"
>+			"!!! is different than the one specified by POSIX locale. This can
>break\n"
>+			"!!! ebuilds and cause issues in programs that rely on the common
>character\n"
>+			"!!! conversion scheme.  Please consider enabling another locale
>(such as\n"
>+			"!!! en_US.UTF-8) in /etc/locale.gen and setting it as LC_CTYPE
>in\n"
>+			"!!! make.conf.\n\n"
>+		);
>+
>+		if (lower == 0)
>+			error_msg(msg, lc, ruc, uc);
>+
>+		if (upper == 0)
>+			error_msg(msg, uc, rlc, lc);
>+	}
>+
>+#if PY_MAJOR_VERSION >= 3
>+	return Py_BuildValue("iy", lower && upper, msg);
>+#else
>+	return Py_BuildValue("is", lower && upper, msg);
>+#endif
>+}


-- 
Best regards,
Michał Górny (by phone)