[PATCH v2] posix: Fix getconf symbolic constants defined in limits.h (BZ# 29147)
Adhemerval Zanella Netto
adhemerval.zanella@linaro.org
Tue Dec 9 13:44:09 GMT 2025
On 08/12/25 12:44, Yury Khrustalev wrote:
> * Adhemerval
>
> On Wed, Dec 03, 2025 at 01:37:27PM -0300, Adhemerval Zanella wrote:
>> From: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
>>
>> POSIX-1.2018 defines that getconf utility shall print symbolic constant
>> listed under the heading Maximum value and Minimum Values [1], however
>> current behaviour is to print the values using pathconf or sysconf,
>> which represents the specific implementation values instead of the
>> system agnostics ones.
>>
>> Another issue is for such the symbolic constants, getconf handles them
>> as a path_var which requires an additional pathname (which does not
>> make sense for constants values).
>>
>> The patch fixes it adding a new internal type, LIMITS_H, which only
>> prints the constant symbolic without requiring an additional path.
>> Only the values define in glibc provided limits.h plust the GNU
>> extensions are handled.
>>
>> Checked on x86_64-linux-gnu.
>>
>> [1] https://pubs.opengroup.org/onlinepubs/9699919799/utilities/getconf.html)
>> ---
>> posix/Makefile | 15 ++++++-
>> posix/getconf.c | 86 +++++++++++++++++++++++++++++--------
>> posix/tst-getconf-limits.py | 72 +++++++++++++++++++++++++++++++
>> 3 files changed, 155 insertions(+), 18 deletions(-)
>> create mode 100755 posix/tst-getconf-limits.py
>>
>> diff --git a/posix/Makefile b/posix/Makefile
>> index f6421e5379..490e89f7b8 100644
>> --- a/posix/Makefile
>> +++ b/posix/Makefile
>> @@ -476,7 +476,10 @@ endif
>> # XXX Please note that for now we ignore the result of this test.
>> tests-special += $(objpfx)annexc.out
>> ifeq ($(run-built-tests),yes)
>> -tests-special += $(objpfx)tst-getconf.out
>> +tests-special += \
>> + $(objpfx)tst-getconf.out \
>> + $(objpfx)tst-getconf-limits.out \
>
> This upsets lint-makefiles, it seems that it expect order
>
> $(objpfx)tst-getconf-limits.out \
> $(objpfx)tst-getconf.out \
>
> Otherwise tests pass on AArch64.
Ack.
>
>> + # tests-special
>> ifeq (yes,$(build-shared))
>> ifneq ($(PERL),no)
>> tests-special += \
>> @@ -729,6 +732,16 @@ $(objpfx)tst-getconf.out: tst-getconf.sh $(objpfx)getconf
>> $(SHELL) $< $(common-objpfx) '$(built-program-cmd)'; \
>> $(evaluate-test)
>>
>> +$(objpfx)tst-getconf-limits.out: tst-getconf-limits.py $(objpfx)getconf
>> + PYTHONPATH=../scripts \
>> + $(PYTHON) tst-getconf-limits.py \
>> + --cc="$(CC) $(patsubst -DMODULE_NAME=%, \
>> + -DMODULE_NAME=testsuite, \
>> + $(CPPFLAGS)) -D_ISOMAC" \
>> + '$(built-program-cmd)' \
>> + < /dev/null > $@ 2>&1; $(evaluate-test)
>> +
>> +
>> $(objpfx)bug-ga2-mem.out: $(objpfx)bug-ga2.out
>> { test -r $(objpfx)bug-ga2.mtrace \
>> || ( echo "bug-ga2.mtrace does not exist"; exit 77; ) \
>> diff --git a/posix/getconf.c b/posix/getconf.c
>> index 4ba9c0dee8..9bee1badf3 100644
>> --- a/posix/getconf.c
>> +++ b/posix/getconf.c
>> @@ -49,24 +49,18 @@
>> struct conf
>> {
>> const char *name;
>> - const int call_name;
>> - const enum { SYSCONF, CONFSTR, PATHCONF } call;
>> + const long int call_name;
>> + const enum { SYSCONF, CONFSTR, PATHCONF, LIMITS_H } call;
>> };
>>
>> static const struct conf vars[] =
>> {
>> { "LINK_MAX", _PC_LINK_MAX, PATHCONF },
>> - { "_POSIX_LINK_MAX", _PC_LINK_MAX, PATHCONF },
>> { "MAX_CANON", _PC_MAX_CANON, PATHCONF },
>> - { "_POSIX_MAX_CANON", _PC_MAX_CANON, PATHCONF },
>> { "MAX_INPUT", _PC_MAX_INPUT, PATHCONF },
>> - { "_POSIX_MAX_INPUT", _PC_MAX_INPUT, PATHCONF },
>> { "NAME_MAX", _PC_NAME_MAX, PATHCONF },
>> - { "_POSIX_NAME_MAX", _PC_NAME_MAX, PATHCONF },
>> { "PATH_MAX", _PC_PATH_MAX, PATHCONF },
>> - { "_POSIX_PATH_MAX", _PC_PATH_MAX, PATHCONF },
>> { "PIPE_BUF", _PC_PIPE_BUF, PATHCONF },
>> - { "_POSIX_PIPE_BUF", _PC_PIPE_BUF, PATHCONF },
>> { "SOCK_MAXBUF", _PC_SOCK_MAXBUF, PATHCONF },
>> { "_POSIX_ASYNC_IO", _PC_ASYNC_IO, PATHCONF },
>> { "_POSIX_CHOWN_RESTRICTED", _PC_CHOWN_RESTRICTED, PATHCONF },
>> @@ -125,9 +119,7 @@ static const struct conf vars[] =
>> { "_NPROCESSORS_ONLN", _SC_NPROCESSORS_ONLN, SYSCONF },
>> { "NPROCESSORS_ONLN", _SC_NPROCESSORS_ONLN, SYSCONF },
>> { "_PHYS_PAGES", _SC_PHYS_PAGES, SYSCONF },
>> - { "_POSIX_ARG_MAX", _SC_ARG_MAX, SYSCONF },
>> { "_POSIX_ASYNCHRONOUS_IO", _SC_ASYNCHRONOUS_IO, SYSCONF },
>> - { "_POSIX_CHILD_MAX", _SC_CHILD_MAX, SYSCONF },
>> { "_POSIX_FSYNC", _SC_FSYNC, SYSCONF },
>> { "_POSIX_JOB_CONTROL", _SC_JOB_CONTROL, SYSCONF },
>> { "_POSIX_MAPPED_FILES", _SC_MAPPED_FILES, SYSCONF },
>> @@ -135,8 +127,6 @@ static const struct conf vars[] =
>> { "_POSIX_MEMLOCK_RANGE", _SC_MEMLOCK_RANGE, SYSCONF },
>> { "_POSIX_MEMORY_PROTECTION", _SC_MEMORY_PROTECTION, SYSCONF },
>> { "_POSIX_MESSAGE_PASSING", _SC_MESSAGE_PASSING, SYSCONF },
>> - { "_POSIX_NGROUPS_MAX", _SC_NGROUPS_MAX, SYSCONF },
>> - { "_POSIX_OPEN_MAX", _SC_OPEN_MAX, SYSCONF },
>> { "_POSIX_PII", _SC_PII, SYSCONF },
>> { "_POSIX_PII_INTERNET", _SC_PII_INTERNET, SYSCONF },
>> { "_POSIX_PII_INTERNET_DGRAM", _SC_PII_INTERNET_DGRAM, SYSCONF },
>> @@ -155,8 +145,6 @@ static const struct conf vars[] =
>> { "_POSIX_SELECT", _SC_SELECT, SYSCONF },
>> { "_POSIX_SEMAPHORES", _SC_SEMAPHORES, SYSCONF },
>> { "_POSIX_SHARED_MEMORY_OBJECTS", _SC_SHARED_MEMORY_OBJECTS, SYSCONF },
>> - { "_POSIX_SSIZE_MAX", _SC_SSIZE_MAX, SYSCONF },
>> - { "_POSIX_STREAM_MAX", _SC_STREAM_MAX, SYSCONF },
>> { "_POSIX_SYNCHRONIZED_IO", _SC_SYNCHRONIZED_IO, SYSCONF },
>> { "_POSIX_THREADS", _SC_THREADS, SYSCONF },
>> { "_POSIX_THREAD_ATTR_STACKADDR", _SC_THREAD_ATTR_STACKADDR, SYSCONF },
>> @@ -172,7 +160,6 @@ static const struct conf vars[] =
>> { "_POSIX_THREAD_SAFE_FUNCTIONS", _SC_THREAD_SAFE_FUNCTIONS, SYSCONF },
>> { "_POSIX_TIMERS", _SC_TIMERS, SYSCONF },
>> { "TIMER_MAX", _SC_TIMER_MAX, SYSCONF },
>> - { "_POSIX_TZNAME_MAX", _SC_TZNAME_MAX, SYSCONF },
>> { "_POSIX_VERSION", _SC_VERSION, SYSCONF },
>> { "_T_IOV_MAX", _SC_T_IOV_MAX, SYSCONF },
>> { "_XOPEN_CRYPT", _SC_XOPEN_CRYPT, SYSCONF },
>> @@ -209,7 +196,6 @@ static const struct conf vars[] =
>> { "POSIX2_EXPR_NEST_MAX", _SC_EXPR_NEST_MAX, SYSCONF },
>> { "POSIX2_FORT_DEV", _SC_2_FORT_DEV, SYSCONF },
>> { "POSIX2_FORT_RUN", _SC_2_FORT_RUN, SYSCONF },
>> - { "_POSIX2_LINE_MAX", _SC_LINE_MAX, SYSCONF },
>> { "POSIX2_LINE_MAX", _SC_LINE_MAX, SYSCONF },
>> { "POSIX2_LOCALEDEF", _SC_2_LOCALEDEF, SYSCONF },
>> { "POSIX2_RE_DUP_MAX", _SC_RE_DUP_MAX, SYSCONF },
>> @@ -405,6 +391,63 @@ static const struct conf vars[] =
>> { "_POSIX_IPV6", _SC_IPV6, SYSCONF },
>> { "_POSIX_RAW_SOCKETS", _SC_RAW_SOCKETS, SYSCONF },
>
> OK
>
>> + /* limits.h symbolic constants. */
>> +#define DEF_LIMIT_H(name) { #name, name, LIMITS_H }
>> + /* Maximum Values. */
>> + DEF_LIMIT_H (_POSIX_CLOCKRES_MIN),
>> +
>> + /* Minimum Values. */
>> + DEF_LIMIT_H (_POSIX_AIO_LISTIO_MAX),
>> + DEF_LIMIT_H (_POSIX_AIO_MAX),
>> + DEF_LIMIT_H (_POSIX_ARG_MAX),
>> + DEF_LIMIT_H (_POSIX_CHILD_MAX),
>> + DEF_LIMIT_H (_POSIX_DELAYTIMER_MAX),
>> + DEF_LIMIT_H (_POSIX_HOST_NAME_MAX),
>> + DEF_LIMIT_H (_POSIX_LINK_MAX),
>> + DEF_LIMIT_H (_POSIX_LOGIN_NAME_MAX),
>> + DEF_LIMIT_H (_POSIX_MAX_CANON),
>> + DEF_LIMIT_H (_POSIX_MAX_INPUT),
>> + DEF_LIMIT_H (_POSIX_MQ_OPEN_MAX),
>> + DEF_LIMIT_H (_POSIX_MQ_PRIO_MAX),
>> + DEF_LIMIT_H (_POSIX_NAME_MAX),
>> + DEF_LIMIT_H (_POSIX_NGROUPS_MAX),
>> + DEF_LIMIT_H (_POSIX_OPEN_MAX),
>> + DEF_LIMIT_H (_POSIX_PATH_MAX),
>> + DEF_LIMIT_H (_POSIX_PIPE_BUF),
>> + DEF_LIMIT_H (_POSIX_RE_DUP_MAX),
>> + DEF_LIMIT_H (_POSIX_RTSIG_MAX),
>> + DEF_LIMIT_H (_POSIX_SEM_NSEMS_MAX),
>> + DEF_LIMIT_H (_POSIX_SEM_VALUE_MAX),
>> + DEF_LIMIT_H (_POSIX_SIGQUEUE_MAX),
>> + DEF_LIMIT_H (_POSIX_SSIZE_MAX),
>> + DEF_LIMIT_H (_POSIX_STREAM_MAX),
>> + DEF_LIMIT_H (_POSIX_SYMLINK_MAX),
>> + DEF_LIMIT_H (_POSIX_SYMLOOP_MAX),
>> + DEF_LIMIT_H (_POSIX_THREAD_DESTRUCTOR_ITERATIONS),
>> + DEF_LIMIT_H (_POSIX_THREAD_KEYS_MAX),
>> + DEF_LIMIT_H (_POSIX_THREAD_THREADS_MAX),
>> + DEF_LIMIT_H (_POSIX_TIMER_MAX),
>> + DEF_LIMIT_H (_POSIX_TTY_NAME_MAX),
>> + DEF_LIMIT_H (_POSIX_TZNAME_MAX),
>> +
>> + DEF_LIMIT_H (_POSIX2_BC_BASE_MAX),
>> + DEF_LIMIT_H (_POSIX2_BC_DIM_MAX),
>> + DEF_LIMIT_H (_POSIX2_BC_SCALE_MAX),
>> + DEF_LIMIT_H (_POSIX2_BC_STRING_MAX),
>> + DEF_LIMIT_H (_POSIX2_CHARCLASS_NAME_MAX),
>> + DEF_LIMIT_H (_POSIX2_COLL_WEIGHTS_MAX),
>> + DEF_LIMIT_H (_POSIX2_EXPR_NEST_MAX),
>> + DEF_LIMIT_H (_POSIX2_LINE_MAX),
>> + DEF_LIMIT_H (_POSIX2_RE_DUP_MAX),
>> +
>> + DEF_LIMIT_H (_XOPEN_IOV_MAX),
>> +
>> + /* GNU extensions. */
>> + DEF_LIMIT_H (_POSIX_FD_SETSIZE),
>> + DEF_LIMIT_H (_POSIX_HIWAT),
>> + DEF_LIMIT_H (_POSIX_QLIMIT),
>> + DEF_LIMIT_H (_POSIX_UIO_MAXIOV),
>> +
>
> OK
>
>> { NULL, 0, SYSCONF }
>> };
>>
>> @@ -432,7 +475,7 @@ print_all (const char *path)
>> long int value;
>> char *cvalue;
>> for (c = vars; c->name != NULL; ++c) {
>> - printf("%-35s", c->name);
>> + printf("%-36s", c->name);
>
> I suppose there are no formatting requirements so we can widen the
> column here?
Afaik POSIX does not define the '-a' option, and the increase it required
to properly print _POSIX_THREAD_DESTRUCTOR_ITERATIONS.
Also, it seems that each system has a different format for -a (BSD, for
instance, shows in the form 'variable: value').
>
>> switch (c->call) {
>> case PATHCONF:
>> value = pathconf (path, c->call_name);
>> @@ -463,6 +506,9 @@ print_all (const char *path)
>> printf ("%.*s\n", (int) clen, cvalue);
>> free (cvalue);
>> break;
>> + case LIMITS_H:
>> + printf ("%ld\n", c->call_name);
>> + break;
>> }
>> }
>> exit (0);
>> @@ -703,6 +749,12 @@ environment SPEC.\n\n"));
>>
>> printf ("%.*s\n", (int) clen, cvalue);
>> exit (0);
>> +
>> + case LIMITS_H:
>> + if (argc - ai > 1)
>> + usage ();
>
> Requesting a value from limits.h with a path is now an error. This was
> discussed in the BZ [1]. Is it OK if an existing script using getconf
> with a path on the command line start failing?
According to the POSIX description [1], this usage fits in the 'system_var'
and it does not accept a path. My understanding is that POSIX does not specify
how to handle extra arguments, and I think ignoring them might add confusion,
as the caller might interpret it as meaning the constant might depend on
the input pathname (where it is independent).
Other systems also trigger error in such usage, BSDs issues a 'no such path
configuration parameter'.
[1] https://pubs.opengroup.org/onlinepubs/9799919799/utilities/getconf.html
>
>> + printf ("%ld\n", c->call_name);
>> + exit (0);
>> }
>> }
>>
>> diff --git a/posix/tst-getconf-limits.py b/posix/tst-getconf-limits.py
>> new file mode 100755
>> index 0000000000..e0db1619e1
>> --- /dev/null
>> +++ b/posix/tst-getconf-limits.py
>> @@ -0,0 +1,72 @@
>> +#!/usr/bin/python3
>> +#
>> +# Test if getconf returns the symbolic constants defined in limits.h.
>> +# Copyright (C) 2025 Free Software Foundation, Inc.
>> +# This file is part of the GNU C Library.
>> +#
>> +# The GNU C Library is free software; you can redistribute it and/or
>> +# modify it under the terms of the GNU Lesser General Public
>> +# License as published by the Free Software Foundation; either
>> +# version 2.1 of the License, or (at your option) any later version.
>> +#
>> +# The GNU C Library is distributed in the hope that it will be useful,
>> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
>> +# Lesser General Public License for more details.
>> +#
>> +# You should have received a copy of the GNU Lesser General Public
>> +# License along with the GNU C Library; if not, see
>> +# <https://www.gnu.org/licenses/>.
>> +
>> +import argparse
>> +import glibcextract
>> +import re
>
> Nit: the re module is unused.
Ack.
>
>> +import subprocess
>> +import sys
>> +
>> +
>> +def parse_getconf(cmd):
>> + getconf_out = subprocess.run(cmd + ['-a'], stdout=subprocess.PIPE,
>> + check=True, universal_newlines=True).stdout
>> + getconf_set = {}
>> + for line in getconf_out.splitlines():
>> + fields = line.split()
>> + if len(fields) == 2:
>> + getconf_set[fields[0]] = fields[1]
>> + return getconf_set
>> +
>> +
>> +def main():
>> + """The main entry point."""
>> + parser = argparse.ArgumentParser(
>> + description='Test if getconf returns the symbolic constants defined '
>> + 'in limits.h.')
>> + parser.add_argument('--cc', metavar='CC',
>> + help='C compiler (including options) to use')
>> + parser.add_argument('cmd',
>> + help='How to run getconf')
>> + args = parser.parse_args()
>> +
>> + ctes = glibcextract.compute_macro_consts(
>> + source_text='#include <limits.h>\n',
>> + cc=args.cc,
>> + macro_re='_POSIX.*',
>> + exclude_re='_POSIX_C_SOURCE|_POSIX_SOURCE')
>> +
>> + getconf_ctes = parse_getconf (args.cmd.split())
>> +
>> + ret = 0
>> + for cte,value in ctes.items():
>> + if cte in getconf_ctes:
>> + if getconf_ctes[cte] != value:
>> + print('Symbol {} is defined as {} on limits.h but getconf shows {}'
>> + .format(cte, value, getconf_ctes[cte]))
>> + ret = 1;
>
> Nit: unnecessary semi-colon
Ack.
>
>> + else:
>> + print('Symbol {} not presented in getconf'.format(cte))
>> + ret = 1;
>
> Nit: same as above
>
Ack.
>> + sys.exit(ret)
>> +
>> +
>> +if __name__ == '__main__':
>> + main()
>> --
>> 2.43.0
>>
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