This patch makes tests in conformtest use unique identifiers, in
preparation for trying to cover more tests in a single compilation to
speed up these tests as suggested in
<https://sourceware.org/ml/libc-alpha/2018-11/msg00229.html>.
Tests are assigned a number, used in generating identifiers; where a
single call to a run method does multiple compilations (sharing that
number), identifiers are changed as needed to avoid duplication
between those compilations, so they can be combined in future.
Large numbers of positional arguments to format strings make the code
harder to follow, and using the test numbers serves to increase the
number of arguments to such format strings, so the code is generally
changed to use %(name)s where all the arguments come from attributes
of the test object and so vars(self) is sufficient to provide all
those names for the format string. Cases where some arguments aren't
attributes of self still use positional format arguments.
Tested for x86_64, and with build-many-glibcs.py.
* conform/conformtest.py (ElementTest.run): Use unique identifiers
in tests. Use names for format arguments.
(ConstantTest.run): Likewise.
(SymbolTest.run): Likewise.
(TypeTest.run): Likewise.
(TagTest.run): Likewise.
(FunctionTest.run): Likewise.
(VariableTest.run): Likewise.
(MacroFunctionTest.run): Likewise.
(MacroStrTest.run): Likewise.
(HeaderTests.__init__): Set self.num_tests.
(HeaderTests.handle_test_line): Set test.num. Increment
self.num_tests.
This is sometimes useful to determine if a test truly got stuck, or if
it was making progress (logging information to standard output) and
was merely slow to finish.
On platforms where long double used to have the same format as double,
but later switched to a different format (alpha, s390, sparc, and
powerpc), accessing the older behavior is possible and it happens via
__nldbl_* functions (not on the API, but accessible from header
redirection and from compat symbols). These functions write to the
global flag __ldbl_is_dbl, which tells other functions that long double
variables should be handled as double. This patch takes the first step
towards removing this global flag and creates __vstrfmon_l_internal,
which takes an explicit flags parameter.
This change arguably makes the generated code slightly worse on
architectures where __ldbl_is_dbl is never true; right now, on those
architectures, it's a compile-time constant; after this change, the
compiler could theoretically prove that __vstrfmon_l_internal was
never called with a nonzero flags argument, but it would probably need
LTO to do it. This is not performance critical code and I tend to
think that the maintainability benefits of removing action at a
distance are worth it. However, we _could_ wrap the runtime flag
check with a macro that was defined to ignore its argument and always
return false on architectures where __ldbl_is_dbl is never true, if
people think the codegen benefits are important.
Tested for powerpc and powerpc64le.
The DEBUG_MKTIME code no longer works in glibc or in Gnulib.
And it’s no longer needed now that glibc and Gnulib both have
their own testing mechanisms for mktime.
* time/mktime.c (DEBUG_MKTIME): Remove. All uses removed.
[BZ#23789]
mktime was not properly reporting failures when the underlying
localtime_r fails with errno != EOVERFLOW; it incorrectly treated
them like EOVERFLOW failures, and set errno to EOVERFLOW.
The problem could happen on non-glibc platforms, with Gnulib.
* time/mktime.c (guess_time_tm): Remove, replacing with ...
(tm_diff): ... this simpler function, which does not change errno.
All callers changed to deal with errno themselves.
(ranged_convert, __mktime_internal): Return failure immediately if
the underlying function reports any failure other than EOVERFLOW.
(__mktime_internal): Set errno to EOVERFLOW if the spring-forward
gap code fails.
[BZ#23789]
* time/mktime.c (ranged_convert): On 32-bit platforms, don’t
mishandle a DST transition that jumps over the Y2038 boundary.
No such DST transitions are known so this is only a theoretical
bug, but we might as well do things right.
[BZ#23789]
* time/mktime.c (long_int): Now 4⨯ int, not just 3⨯.
This is so that we can add tm_diff results to a previous guess,
which will be useful in a later patch.
[BZ#23789]
* time/mktime.c [!_LIBC && !DEBUG_MKTIME]:
Include libc-config.h, not config.h, for __set_errno.
(guess_time_tm, __mktime_internal): Set errno to EOVERFLOW on overflow.
* sysdeps/mach/hurd/dl-sysdep.c (check_no_hidden): Use
__attribute_copy__ to copy attributes from name. Drop static qualifier
to avoid warnings about leaf attribute not having effect on static
functions.
This patch fixes the build for MIPS (o32) with GCC 9 by stopping MIPS
__longjmp from using strong_alias, instead defining the alias
manually, so that the intended effect of not copying the nomips16
attribute is achieved, as explained in the included comment.
Tested with build-many-glibcs.py compilers build for mips64-linux-gnu
(which includes glibc builds for all three ABIs).
* sysdeps/mips/__longjmp.c (__longjmp): Define alias manually with
alias attribute, not with strong_alias.
Soft-float powerpc fails to build with current GCC mainline because of
use of libc_hidden_data_def for TLS variables, resulting in a non-TLS
alias being defined, to which the tls_model attribute is now copied,
resulting in a warning about it being ignored.
The problem here appears to be the non-TLS alias. This patch adds a
hidden_tls_def macro family, corresponding to the hidden_tls_proto
macros, to define TLS aliases properly in such a case, and uses it for
those powerpc soft-float variables.
Tested with build-many-glibcs.py compilers build for powerpc-linux-gnu
soft-float. Also tested for x86_64.
* include/libc-symbols.h [SHARED && !NO_HIDDEN && !__ASSEMBLER__]
(__hidden_ver2): New macro. Use old definition of __hidden_ver1
with additional parameter thread.
[SHARED && !NO_HIDDEN && !__ASSEMBLER__] (__hidden_ver1): Define
in terms of __hidden_ver2.
(hidden_tls_def): New macro.
(libc_hidden_tls_def): Likewise.
(rtld_hidden_tls_def): Likewise.
(libm_hidden_tls_def): Likewise.
(libmvec_hidden_tls_def): Likewise.
(libresolv_hidden_tls_def): Likewise.
(librt_hidden_tls_def): Likewise.
(libdl_hidden_tls_def): Likewise.
(libnss_files_hidden_tls_def): Likewise.
(libnsl_hidden_tls_def): Likewise.
(libnss_nisplus_hidden_tls_def): Likewise.
(libutil_hidden_tls_def): Likewise.
(libutil_hidden_tls_def): Likweise.
* sysdeps/powerpc/nofpu/sim-full.c (__sim_exceptions_thread): Use
libc_hidden_tls_def.
(__sim_disabled_exceptions_thread): Likewise.
(__sim_round_mode_thread): Likewise.
Similar to the x86_64 and armv7 build issues, glibc fails to build for
sparc64 with current mainline GCC because of aliases declared in the
course of defining IFUNCs, which copy their attributes from a header
declaration, ending up with fewer attributes than the (built-in)
string function they alias. This patch fixes the issue similarly to
the fixes for those other architectures.
Tested with build-many-glibcs.py compilers build for
sparc64-linux-gnu.
* sysdeps/sparc/sparc-ifunc.h [SHARED]
(sparc_ifunc_redirected_hidden_def): Use __attribute_copy__ to
copy attributes from name.
Similar to the x86_64 build issues, glibc fails to build for armv7
with current mainline GCC because of aliases declared in the course of
defining IFUNCs, which copy their attributes from a header
declaration, ending up with fewer attributes than the (built-in)
string function they alias: the relevant attributes (nonnull, leaf)
are present on the header declaration, but elided therefrom when glibc
itself if being built (whatever the reasons are for disabling the
nonnull and leaf attributes in that case, and whether or not those
reasons are actually still valid). This patch fixes the issue
similarly to the x86_64 fix, by adding an addition __attribute_copy__
use (in this case, on the definition of arm_libc_ifunc_hidden_def).
Tested with build-many-glibcs.py build for armeb-linux-gnueabi-be8.
* sysdeps/arm/arm-ifunc.h [SHARED] (arm_libc_ifunc_hidden_def):
Use __attribute_copy__ to copy attributes from name.
This patch fixes the glibc build for i686 with current mainline GCC,
where there are warnings about inconsistent attributes for aliases in
certain files defining libm IFUNCs.
In three of the files, the aliases were defined in terms of internal
symbols such as __sinf, and copied attributes from file-local
declarations of those functions which lacked the nothrow attribute.
Since the nothrow attribute is present on the declarations from
<math.h> (which include declarations of those __-prefixed functions),
the natural fix was to include <math.h> in those files, replacing the
local declarations.
In the other three files, a more complicated __hidden_ver1 call was
involved in the warnings. <math.h> has not been included at this
point and, furthermore, it is included indirectly only later in the
source file after macros have been defined to remap a function name
therein. So there isn't an obvious declaration from which to copy the
attribute and it seems simplest and safest just to add __THROW to the
hidden_ver1 calls.
Tested for i686 (build-many-glibcs.py compilers build for
x86_64-linux-gnu with GCC mainline; full testsuite run with GCC 7).
* sysdeps/i386/i686/fpu/multiarch/e_expf.c [SHARED]: Use __THROW
with __hidden_ver1 call.
* sysdeps/i386/i686/fpu/multiarch/e_log2f.c [SHARED]: Likewise.
* sysdeps/i386/i686/fpu/multiarch/e_logf.c [SHARED]: Likewise.
* sysdeps/i386/i686/fpu/multiarch/s_cosf.c: Include <math.h>.
(__cosf): Do not declare here.
* sysdeps/i386/i686/fpu/multiarch/s_sincosf.c: Include <math.h>.
(__sincosf): Do not declare here.
* sysdeps/i386/i686/fpu/multiarch/s_sinf.c: Include <math.h>.
(__sinf): Do not declare here.
After the changes to use the copy attribute, building glibc for ia64
fails, even with older compilers, because
sysdeps/ia64/fpu/sfp-machine.h has a definition of _strong_alias that
now differs from the one in libc-symbols.h.
That definition is a relic of this file coming from libgcc, as are
some other such macro definitions in this file; in the glibc context,
there is no need for those macros, and this patch removes them to fix
the build.
Tested with build-many-glibcs.py for ia64-linux-gnu.
* sysdeps/ia64/fpu/sfp-machine.h (__LITTLE_ENDIAN): Remove.
(__BIG_ENDIAN): Likewise.
(__BYTE_ORDER): Likewise.
(strong_alias): Likewise.
(_strong_alias): Likewise.
This commit is in preparation of turning the macro into a proper
function. The output arguments of the macro were in fact unused.
Also clean up uses of __builtin_expect.
* hurd/hurd/userlink.h (_hurd_userlink_move): New function.
* hurd/hurd/port.h (_hurd_port_move): New function.
* sysdeps/mach/hurd/spawni.c (NEW_ULINK_TABLE): New macro.
(EXPAND_DTABLE): Use NEW_ULINK_TABLE macro for ulink_dtable.
This fixes build-many-glibcs.py on i686-gnu.
Thanks Florian Weimer for the initial version.
* sysdeps/mach/hurd/spawni.c (__spawni): Add ccwdir port. Test and use
it, free it if needed.
(reauthenticate): Test and use ccwdir.
(child_init_port): In non-resetids case, test and use ccwdir.
(child_chdir): New nested function to set ccwdir.
GCC 9 has gained an enhancement to help detect attribute mismatches
between alias declarations and their targets. It consists of a new
warning, -Wattribute-alias, an enhancement to an existing warning,
-Wmissing-attributes, and a new attribute called copy.
The purpose of the warnings is to help identify either possible bugs
(an alias declared with more restrictive attributes than its target
promises) or optimization or diagnostic opportunities (an alias target
missing some attributes that it could be declared with that might
benefit analysis and code generation). The purpose of the new
attribute is to easily apply (almost) the same set of attributes
to one declaration as those already present on another.
As expected (and intended) the enhancement triggers warnings for
many alias declarations in Glibc code. This change, tested on
x86_64-linux, avoids all instances of the new warnings by making
use of the attribute where appropriate. To fully benefit from
the enhancement Glibc will need to be compiled with
-Wattribute-alias=2 and remaining warnings reviewed and dealt with
(there are a couple of thousand but most should be straightforward
to deal with).
ChangeLog:
* include/libc-symbols.h (__attribute_copy__): Define macro unless
it's already defined.
(_strong_alias): Use __attribute_copy__.
(_weak_alias, __hidden_ver1, __hidden_nolink2): Same.
* misc/sys/cdefs.h (__attribute_copy__): New macro.
* sysdeps/x86_64/multiarch/memchr.c (memchr): Use __attribute_copy__.
* sysdeps/x86_64/multiarch/memcmp.c (memcmp): Same.
* sysdeps/x86_64/multiarch/mempcpy.c (mempcpy): Same.
* sysdeps/x86_64/multiarch/memset.c (memset): Same.
* sysdeps/x86_64/multiarch/stpcpy.c (stpcpy): Same.
* sysdeps/x86_64/multiarch/strcat.c (strcat): Same.
* sysdeps/x86_64/multiarch/strchr.c (strchr): Same.
* sysdeps/x86_64/multiarch/strcmp.c (strcmp): Same.
* sysdeps/x86_64/multiarch/strcpy.c (strcpy): Same.
* sysdeps/x86_64/multiarch/strcspn.c (strcspn): Same.
* sysdeps/x86_64/multiarch/strlen.c (strlen): Same.
* sysdeps/x86_64/multiarch/strncmp.c (strncmp): Same.
* sysdeps/x86_64/multiarch/strncpy.c (strncpy): Same.
* sysdeps/x86_64/multiarch/strnlen.c (strnlen): Same.
* sysdeps/x86_64/multiarch/strpbrk.c (strpbrk): Same.
* sysdeps/x86_64/multiarch/strrchr.c (strrchr): Same.
* sysdeps/x86_64/multiarch/strspn.c (strspn): Same.
The function do_test, in tst-efgcvt.c, increments an error counter for
each error that it finds, then returns it to the test framework.
However, the test framework does not expect an error count as return,
but zero for a passing test, one for a failing test, or 77 for an
unsupported test. Alternatively, the framework provides the function
support_record_failure that records errors, which then allows the test
program to return zero unconditionally.
This patch removes the error counter, replaces each increment of the
counter with a call to support_record_failure, and makes do_test
unconditionally return zero.
Tested for powerpc64le (as-is and with a patched results table to check
that the error reporting actually works).
* misc/tst-efgcvt.c: Include support/check.h and
support/test-driver.c. Do not include test-skeleton.c.
(error_count): Remove.
(output_error): Replace increments to error_count with calls to
support_record_failure.
(output_r_error): Likewise.
(special): Likewise.
(do_test): Unconditionally return zero.
(TEST_FUNCTION): Remove.
conform/Makefile creates $(@D)/scratch for the per-standard per-header
tests. That directory was formerly used by the Perl scripts for
temporary files, but the Python implementations use
tempfile.TemporaryDirectory to get such files cleaned up
automatically. This patch changes the Makefile to create only $(@D)
(required for the output redirection to work), not the scratch
subdirectory.
Tested for x86_64.
* conform/Makefile ($(conformtest-header-tests)): Create $(@D),
not $(@D)/scratch.
($(linknamespace-header-tests)): Likewise.
Continuing the consolidation on Python for various miscellaneous build
and test scripts, this patch moves conformtest from Perl to Python.
The substance of the tests run is intended to be the same as before,
except that the previous test for tags did not actually achieve the
intended purpose of verifying whether a tag was already declared, so
is changed to one that would actually fail for a tag that wasn't
declared, and a typo in the old test for variables being available
($xyzzy instead of xyzzy) would have made that test not use the
correct type (but it would have passed anyway with warnings). No
attempt is made to keep the details of what the test output looks
like; instead, tests are given names which are made to follow PASS: /
FAIL: / XFAIL: / SKIP: / MISSING: as appropriate.
In the new version, there is more consistent parsing of test lines
(into a series of words, either surrounded by {} or separated by
spaces) that applies for all kinds of test lines, rather than the old
approach of different regular expressions for every kind of test. A
few of the conform/data/ files are adjusted so their syntax works with
the new script (which now requires spaces in certain cases where the
old script tolerated them being missing, and does not allow stray
semicolons at the end of "function" lines). Similarly, common logic
is used around what happens with a second subtest if a first one fails
(e.g., a test for a symbol's type if the test for availability fails),
rather than such logic being replicated separately for each kind of
test. Common parsing also applies for test lines both when they are
lines for the header under test and when they are lines for another
header specified with allow-header, again unlike the old script.
Tested for x86_64, and with build-many-glibcs.py.
* conform/conformtest.py: New file.
* conform/conformtest.pl: Remove.
* conform/GlibcConform.pm: Likewise.
* conform/glibcconform.py (KEYWORDS_C90): New constant.
(KEYWORDS_C99): Likewise.
(KEYWORDS): Likewise.
* conform/Makefile ($(conformtest-header-tests)): Use
conformtest.py instead of conformtest.pl. Do not pass --tmpdir
option. Use --header instead of --headers.
* conform/data/arpa/inet.h-data: Remove trailing semicolons on
function entries.
* conform/data/spawn.h-data: Likewise.
* conform/data/fcntl.h-data (openat): Add space after function
name.
* conform/data/wchar.h-data (wcscasecmp): Likewise.
(wcscasecmp_l): Likewise.
* conform/data/termios.h-data (c_cc): Add space after element
name.
The commit
commit 1df872fd74
Author: Florian Weimer <fweimer@redhat.com>
Date: Wed Nov 7 12:42:44 2018 +0100
support: Implement TEST_COMPARE_STRING
added the new macro TEST_COMPARE_STRING, which compares the output of
functions under test against expected strings, and, when there's a
mismatch, automatically reports an error and prints the differences.
This patch adapts recently added test cases to use this new macro.
Tested for powerpc64le (as is, and locally patched to intentionally fail
and produce error output).
* argp/tst-ldbl-argp.c (do_one_test): Use TEST_COMPARE_STRING,
instead of manually comparing and reporting mismatching strings.
* misc/tst-ldbl-error.c (do_one_test): Likewise.
* misc/tst-ldbl-warn.c (do_one_test): Likewise.
The __ASSUME_SOCKETCALL macro in kernel-features.h is no longer used
for anything. (It used to be used in defining other macros related to
accept4 / recvmmsg / sendmmsg availability, but the code in that area
was simplified once we could assume a kernel with those features,
whether through a syscall or through socketcall, so allowing those
functions to be handled much like other socket operations, without
requring __ASSUME_SOCKETCALL.) This patch removes that unused macro.
(Note: once we can assume a Linux 4.4 or later kernel, much of the
support for using socketcall at all can be removed from glibc,
although a few functions may need that support in glibc for longer.)
Tested with build-many-glibcs.py.
* sysdeps/unix/sysv/linux/kernel-features.h: Remove comment about
__ASSUME_SOCKETCALL.
* sysdeps/unix/sysv/linux/i386/kernel-features.h
(__ASSUME_SOCKETCALL): Remove.
* sysdeps/unix/sysv/linux/m68k/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
* sysdeps/unix/sysv/linux/powerpc/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
* sysdeps/unix/sysv/linux/s390/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
* sysdeps/unix/sysv/linux/sh/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
* sysdeps/unix/sysv/linux/sparc/kernel-features.h
(__ASSUME_SOCKETCALL): Likewise.
Linkers group input note sections with the same name into one output
note section with the same name. One output note section is placed in
one PT_NOTE segment. Since new linkers merge input .note.gnu.property
sections into one output .note.gnu.property section, there is only
one NT_GNU_PROPERTY_TYPE_0 note in one PT_NOTE segment with new linkers.
Since older linkers treat input .note.gnu.property section as a generic
note section and just concatenate all input .note.gnu.property sections
into one output .note.gnu.property section without merging them, we may
see multiple NT_GNU_PROPERTY_TYPE_0 notes in one PT_NOTE segment with
older linkers.
When an older linker is used to created the program on CET-enabled OS,
the linker output has a single .note.gnu.property section with multiple
NT_GNU_PROPERTY_TYPE_0 notes, some of which have IBT and SHSTK enable
bits set even if the program isn't CET enabled. Such programs will
crash on CET-enabled machines. This patch updates the note parser:
1. Skip note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
2. Check multiple NT_GNU_PROPERTY_TYPE_0 notes.
[BZ #23509]
* sysdeps/x86/dl-prop.h (_dl_process_cet_property_note): Skip
note parsing if a NT_GNU_PROPERTY_TYPE_0 note has been processed.
Update the l_cet field when processing NT_GNU_PROPERTY_TYPE_0 note.
Check multiple NT_GNU_PROPERTY_TYPE_0 notes.
* sysdeps/x86/link_map.h (l_cet): Expand to 3 bits, Add
lc_unknown.
The generic kernel-features.h defines __ASSUME_MLOCK2 for 4.4 and
later kernels. However, for 32-bit ARM binaries running on 64-bit ARM
kernels, and for MicroBlaze, the syscall was only wired up in the 4.7
kernel. (32-bit ARM kernels did have the syscall from 4.4 onwards.)
This patch duly arranges for the macro to be undefined for those
architectures for kernels before 4.7.
Tested with build-many-glibcs.py for its ARM and MicroBlaze
configurations.
[BZ #23867]
* sysdeps/unix/sysv/linux/arm/kernel-features.h
[__LINUX_KERNEL_VERSION < 0x040700] (__ASSUME_MLOCK2): Undefine.
* sysdeps/unix/sysv/linux/microblaze/kernel-features.h
[__LINUX_KERNEL_VERSION < 0x040700] (__ASSUME_MLOCK2): Undefine.
Fix the following on 32 bits targets:
support_test_compare_string.c: In function ‘support_test_compare_string’:
support_test_compare_string.c:80:37: error: format ‘%lu’ expects argument of
type ‘long unsigned int’, but argument 2 has type ‘size_t’ {aka ‘unsigned int’}
[-Werror=format=]
printf (" string length: %lu bytes\n", left_length);
~~^ ~~~~~~~~~~~
%u
Checked on arm-linux-gnueabihf.
* support/support_test_compare_string.c
(support_test_compare_string): Fix printf format.
The SH kernel-features.h undefines __ASSUME_RENAMEAT2 for kernel
versions before 4.8, but fails to undefine __ASSUME_EXECVEAT,
__ASSUME_MLOCK2 and __ASSUME_COPY_FILE_RANGE, although all those
syscalls (and several others) were added for SH in the same Linux
kernel commit (first released in 4.8). This patch adds the proper
undefines of those macros.
Tested with build-many-glibcs.py for its SH configurations.
[BZ #23862]
* sysdeps/unix/sysv/linux/sh/kernel-features.h
[__LINUX_KERNEL_VERSION < 0x040800] (__ASSUME_EXECVEAT): Undefine.
[__LINUX_KERNEL_VERSION < 0x040800] (__ASSUME_MLOCK2): Likewise.
[__LINUX_KERNEL_VERSION < 0x040800] (__ASSUME_COPY_FILE_RANGE):
Likewise.
Similarly to what has been done for argp_error, and argp_failure, as
well as for warn, warnx, vwarn, and vwarnx, this patch adds new tests
for the following functions: err, errx, verr, verrx, error, and
error_at_line. The new tests check that the conversion of long double
variables into string works correctly on the default format of the type.
Future patches will reuse these tests for other formats that long double
can take.
Tested for powerpc64le.
* misc/Makefile (tests): Add tst-ldbl-error.
* misc/tst-ldbl-error.c: New file.
Similarly to what has been done for argp_error and argp_failure, this
patch patch adds new tests for the warn, warnx, vwarn, and vwarnx
functions. The new tests use the format string to request the
conversion of long double parameters into string. Currently, these
tests only check that the default format of the long double type works.
Future patches will extend the test for platforms that can have an
optional format for long double.
Tested for powerpc64le.
* misc/Makefile (tests): Add tst-ldbl-warn.
* misc/tst-ldbl-warn.c: New file.
The functions argp_error and argp_failure, from argp.h, have a format
string as parameter, which can possibly request the printing of
floating-point values. These values could be of long double type, which
can have different formats, depending on the architecture and on
compilation parameters (for instance, on powerpc, long double values can
have double format (-mlong-double-64) or IBM Extended Precision format
(-mlong-double-128)).
This patch adds tests for argp_error and argp_failure that contain a
format string with double and long double conversion specifiers ('%f'
and '%Lf'). These tests automatically check that the default format of
the long double type works. A future patch will extend the test for
platforms that can have an optional format for long double.
Tested for powerpc64le.
* argp/Makefile (tests): Add tst-ldbl-argp.
* argp/tst-ldbl-argp.c: New file.
__gconv_read_conf is only ever called once during the program's lifetime.
This means that __gconv_path_elem is always uninitialized when the function
begins executing. __gconv_get_path has an assert to ensure that this
expected runtime behaviour is always exhibited. Given this, checking for a
NULL value before calling __gconv_get_path is unnecessary. This commit
drops the condition and calls __gconv_get_path unconditionally.
