posix: Fix getconf symbolic constants defined in limits.h (BZ# 29147)

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)

Tested-by: Yury Khrustalev <yury.khrustalev@arm.com>
Reviewed-by: Yury Khrustalev <yury.khrustalev@arm.com>

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-limits.out \
+  $(objpfx)tst-getconf.out \
+  # tests-special
 ifeq (yes,$(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; ) \

posix/getconf.c

@@ -49,24 +49,18 @@
 struct conf
   {
     const char *name;
-    const int call_name;
+    const long int call_name;
-    const enum { SYSCONF, CONFSTR, PATHCONF } call;
+    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 },
 
+    /* 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),
+
     { 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);
     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 ();
+	    printf ("%ld\n", c->call_name);
+	    exit (0);
 	  }
       }
 

posix/tst-getconf-limits.py

@@ -0,0 +1,71 @@
+#!/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 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
+        else:
+            print('Symbol {} not presented in getconf'.format(cte))
+            ret = 1
+    sys.exit(ret)
+
+
+if __name__ == '__main__':
+    main()