C2x strtol binary constant handling

C2x adds binary integer constants starting with 0b or 0B, and supports
those constants in strtol-family functions when the base passed is 0
or 2.  Implement that strtol support for glibc.

As discussed at
<https://sourceware.org/pipermail/libc-alpha/2020-December/120414.html>,
this is incompatible with previous C standard versions, in that such
an input string starting with 0b or 0B was previously required to be
parsed as 0 (with the rest of the string unprocessed).  Thus, as
proposed there, this patch adds 20 new __isoc23_* functions with
appropriate header redirection support.  This patch does *not* do
anything about scanf %i (which will need 12 new functions per long
double variant, so 12, 24 or 36 depending on the glibc configuration),
instead leaving that for a future patch.  The function names would
remain as __isoc23_* even if C2x ends up published in 2024 rather than
2023.

Making this change leads to the question of what should happen to
internal uses of these functions in glibc and its tests.  The header
redirection (which applies for _GNU_SOURCE or any other feature test
macros enabling C2x features) has the effect of redirecting internal
uses but without those uses then ending up at a hidden alias (see the
comment in include/stdio.h about interaction with libc_hidden_proto).
It seems desirable for the default for internal uses to be the same
versions used by normal code using _GNU_SOURCE, so rather than doing
anything to disable that redirection, similar macro definitions to
those in include/stdio.h are added to the include/ headers for the new
functions.

Given that the default for uses in glibc is for the redirections to
apply, the next question is whether the C2x semantics are correct for
all those uses.  Uses with the base fixed to 10, 16 or any other value
other than 0 or 2 can be ignored.  I think this leaves the following
internal uses to consider (an important consideration for review of
this patch will be both whether this list is complete and whether my
conclusions on all entries in it are correct):

benchtests/bench-malloc-simple.c
benchtests/bench-string.h
elf/sotruss-lib.c
math/libm-test-support.c
nptl/perf.c
nscd/nscd_conf.c
nss/nss_files/files-parse.c
posix/tst-fnmatch.c
posix/wordexp.c
resolv/inet_addr.c
rt/tst-mqueue7.c
soft-fp/testit.c
stdlib/fmtmsg.c
support/support_test_main.c
support/test-container.c
sysdeps/pthread/tst-mutex10.c

I think all of these places are OK with the new semantics, except for
resolv/inet_addr.c, where the POSIX semantics of inet_addr do not
allow for binary constants; thus, I changed that file (to use
__strtoul_internal, whose semantics are unchanged) and added a test
for this case.  In the case of posix/wordexp.c I think accepting
binary constants is OK since POSIX explicitly allows additional forms
of shell arithmetic expressions, and in stdlib/fmtmsg.c SEV_LEVEL is
not in POSIX so again I think accepting binary constants is OK.

Functions such as __strtol_internal, which are only exported for
compatibility with old binaries from when those were used in inline
functions in headers, have unchanged semantics; the __*_l_internal
versions (purely internal to libc and not exported) have a new
argument to specify whether to accept binary constants.

As well as for the standard functions, the header redirection also
applies to the *_l versions (GNU extensions), and to legacy functions
such as strtoq, to avoid confusing inconsistency (the *q functions
redirect to __isoc23_*ll rather than needing their own __isoc23_*
entry points).  For the functions that are only declared with
_GNU_SOURCE, this means the old versions are no longer available for
normal user programs at all.  An internal __GLIBC_USE_C2X_STRTOL macro
is used to control the redirections in the headers, and cases in glibc
that wish to avoid the redirections - the function implementations
themselves and the tests of the old versions of the GNU functions -
then undefine and redefine that macro to allow the old versions to be
accessed.  (There would of course be greater complexity should we wish
to make any of the old versions into compat symbols / avoid them being
defined at all for new glibc ABIs.)

strtol_l.c has some similarity to strtol.c in gnulib, but has already
diverged some way (and isn't listed at all at
https://sourceware.org/glibc/wiki/SharedSourceFiles unlike strtoll.c
and strtoul.c); I haven't made any attempts at gnulib compatibility in
the changes to that file.

I note incidentally that inttypes.h and wchar.h are missing the
__nonnull present on declarations of this family of functions in
stdlib.h; I didn't make any changes in that regard for the new
declarations added.

3 files changed, 101 insertions, 7 deletions

diff --git a/include/features.h b/include/features.h
index 26534f2b52..9eae86a2d8 100644
--- a/include/features.h
+++ b/include/features.h
@@ -151,6 +151,7 @@
 #undef	__GLIBC_USE_ISOC2X
 #undef	__GLIBC_USE_DEPRECATED_GETS
 #undef	__GLIBC_USE_DEPRECATED_SCANF
+#undef	__GLIBC_USE_C2X_STRTOL
 
 /* Suppress kernel-name space pollution unless user expressedly asks
    for it.  */
@@ -464,6 +465,17 @@
 # define __GLIBC_USE_DEPRECATED_SCANF 0
 #endif
 
+/* ISO C2X added support for a 0b or 0B prefix on binary constants as
+   inputs to strtol-family functions (base 0 or 2).  This macro is
+   used to condition redirection in headers to allow that redirection
+   to be disabled when building those functions, despite _GNU_SOURCE
+   being defined.  */
+#if __GLIBC_USE (ISOC2X)
+# define __GLIBC_USE_C2X_STRTOL 1
+#else
+# define __GLIBC_USE_C2X_STRTOL 0
+#endif
+
 /* Get definitions of __STDC_* predefined macros, if the compiler has
    not preincluded this header automatically.  */
 #include <stdc-predef.h>
diff --git a/include/stdlib.h b/include/stdlib.h
index db51f4a4f6..7deb8193d7 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -1,6 +1,7 @@
 #ifndef _STDLIB_H
 
 #ifndef _ISOMAC
+# include <stdbool.h>
 # include <stddef.h>
 #endif
 
@@ -35,6 +36,45 @@ libc_hidden_proto (__strtod_l)
 libc_hidden_proto (__strtof_l)
 libc_hidden_proto (__strtold_l)
 
+extern __typeof (strtol) __isoc23_strtol __attribute_copy__ (strtol);
+extern __typeof (strtoul) __isoc23_strtoul __attribute_copy__ (strtoul);
+extern __typeof (strtoll) __isoc23_strtoll __attribute_copy__ (strtoll);
+extern __typeof (strtoull) __isoc23_strtoull __attribute_copy__ (strtoull);
+extern __typeof (strtol_l) __isoc23_strtol_l __attribute_copy__ (strtol_l);
+extern __typeof (strtoul_l) __isoc23_strtoul_l __attribute_copy__ (strtoul_l);
+extern __typeof (strtoll_l) __isoc23_strtoll_l __attribute_copy__ (strtoll_l);
+extern __typeof (strtoull_l) __isoc23_strtoull_l __attribute_copy__ (strtoull_l);
+libc_hidden_proto (__isoc23_strtol)
+libc_hidden_proto (__isoc23_strtoul)
+libc_hidden_proto (__isoc23_strtoll)
+libc_hidden_proto (__isoc23_strtoull)
+libc_hidden_proto (__isoc23_strtol_l)
+libc_hidden_proto (__isoc23_strtoul_l)
+libc_hidden_proto (__isoc23_strtoll_l)
+libc_hidden_proto (__isoc23_strtoull_l)
+
+#if __GLIBC_USE (C2X_STRTOL)
+/* Redirect internal uses of these functions to the C2X versions; the
+   redirection in the installed header does not work with
+   libc_hidden_proto.  */
+# undef strtol
+# define strtol __isoc23_strtol
+# undef strtoul
+# define strtoul __isoc23_strtoul
+# undef strtoll
+# define strtoll __isoc23_strtoll
+# undef strtoull
+# define strtoull __isoc23_strtoull
+# undef strtol_l
+# define strtol_l __isoc23_strtol_l
+# undef strtoul_l
+# define strtoul_l __isoc23_strtoul_l
+# undef strtoll_l
+# define strtoll_l __isoc23_strtoll_l
+# undef strtoull_l
+# define strtoull_l __isoc23_strtoull_l
+#endif
+
 libc_hidden_proto (exit)
 libc_hidden_proto (abort)
 libc_hidden_proto (getenv)
@@ -202,23 +242,25 @@ extern long double ____strtold_l_internal (const char *__restrict __nptr,
 extern long int ____strtol_l_internal (const char *__restrict __nptr,
 				       char **__restrict __endptr,
 				       int __base, int __group,
-				       locale_t __loc);
+				       bool __bin_cst, locale_t __loc);
 extern unsigned long int ____strtoul_l_internal (const char *
 						 __restrict __nptr,
 						 char **__restrict __endptr,
 						 int __base, int __group,
+						 bool __bin_cst,
 						 locale_t __loc);
 __extension__
 extern long long int ____strtoll_l_internal (const char *__restrict __nptr,
 					     char **__restrict __endptr,
 					     int __base, int __group,
-					     locale_t __loc);
+					     bool __bin_cst, locale_t __loc);
 __extension__
 extern unsigned long long int ____strtoull_l_internal (const char *
 						       __restrict __nptr,
 						       char **
 						       __restrict __endptr,
 						       int __base, int __group,
+						       bool __bin_cst,
 						       locale_t __loc);
 
 libc_hidden_proto (____strtof_l_internal)
diff --git a/include/wchar.h b/include/wchar.h
index db83297bca..ea7888f605 100644
--- a/include/wchar.h
+++ b/include/wchar.h
@@ -12,6 +12,7 @@
 # ifndef _ISOMAC
 
 #include <bits/floatn.h>
+#include <stdbool.h>
 
 extern __typeof (wcscasecmp_l) __wcscasecmp_l;
 extern __typeof (wcsncasecmp_l) __wcsncasecmp_l;
@@ -34,6 +35,45 @@ libc_hidden_proto (__wcstof_l)
 libc_hidden_proto (__wcstold_l)
 libc_hidden_proto (__wcsftime_l)
 
+extern __typeof (wcstol) __isoc23_wcstol __attribute_copy__ (wcstol);
+extern __typeof (wcstoul) __isoc23_wcstoul __attribute_copy__ (wcstoul);
+extern __typeof (wcstoll) __isoc23_wcstoll __attribute_copy__ (wcstoll);
+extern __typeof (wcstoull) __isoc23_wcstoull __attribute_copy__ (wcstoull);
+extern __typeof (wcstol_l) __isoc23_wcstol_l __attribute_copy__ (wcstol_l);
+extern __typeof (wcstoul_l) __isoc23_wcstoul_l __attribute_copy__ (wcstoul_l);
+extern __typeof (wcstoll_l) __isoc23_wcstoll_l __attribute_copy__ (wcstoll_l);
+extern __typeof (wcstoull_l) __isoc23_wcstoull_l __attribute_copy__ (wcstoull_l);
+libc_hidden_proto (__isoc23_wcstol)
+libc_hidden_proto (__isoc23_wcstoul)
+libc_hidden_proto (__isoc23_wcstoll)
+libc_hidden_proto (__isoc23_wcstoull)
+libc_hidden_proto (__isoc23_wcstol_l)
+libc_hidden_proto (__isoc23_wcstoul_l)
+libc_hidden_proto (__isoc23_wcstoll_l)
+libc_hidden_proto (__isoc23_wcstoull_l)
+
+#if __GLIBC_USE (C2X_STRTOL)
+/* Redirect internal uses of these functions to the C2X versions; the
+   redirection in the installed header does not work with
+   libc_hidden_proto.  */
+# undef wcstol
+# define wcstol __isoc23_wcstol
+# undef wcstoul
+# define wcstoul __isoc23_wcstoul
+# undef wcstoll
+# define wcstoll __isoc23_wcstoll
+# undef wcstoull
+# define wcstoull __isoc23_wcstoull
+# undef wcstol_l
+# define wcstol_l __isoc23_wcstol_l
+# undef wcstoul_l
+# define wcstoul_l __isoc23_wcstoul_l
+# undef wcstoll_l
+# define wcstoll_l __isoc23_wcstoll_l
+# undef wcstoull_l
+# define wcstoull_l __isoc23_wcstoull_l
+#endif
+
 
 extern double __wcstod_internal (const wchar_t *__restrict __nptr,
 				 wchar_t **__restrict __endptr, int __group)
@@ -63,7 +103,7 @@ extern unsigned long long int __wcstoull_internal (const wchar_t *
 						   int __group) __THROW;
 extern unsigned long long int ____wcstoull_l_internal (const wchar_t *,
 						       wchar_t **, int, int,
-						       locale_t);
+						       bool, locale_t);
 libc_hidden_proto (__wcstof_internal)
 libc_hidden_proto (__wcstod_internal)
 libc_hidden_proto (__wcstold_internal)
@@ -86,17 +126,17 @@ extern double ____wcstod_l_internal (const wchar_t *, wchar_t **, int,
 extern long double ____wcstold_l_internal (const wchar_t *, wchar_t **,
 					   int, locale_t) attribute_hidden;
 extern long int ____wcstol_l_internal (const wchar_t *, wchar_t **, int,
-				       int, locale_t) attribute_hidden;
+				       int, bool, locale_t) attribute_hidden;
 extern unsigned long int ____wcstoul_l_internal (const wchar_t *,
 						 wchar_t **,
-						 int, int, locale_t)
+						 int, int, bool, locale_t)
      attribute_hidden;
 extern long long int ____wcstoll_l_internal (const wchar_t *, wchar_t **,
-					     int, int, locale_t)
+					     int, int, bool, locale_t)
      attribute_hidden;
 extern unsigned long long int ____wcstoull_l_internal (const wchar_t *,
 						       wchar_t **, int, int,
-						       locale_t)
+						       bool, locale_t)
      attribute_hidden;
 
 #if __HAVE_DISTINCT_FLOAT128