C2x scanf binary constant handling

C2x adds binary integer constants starting with 0b or 0B, and supports
those constants for the %i scanf format (in addition to the %b format,
which isn't yet implemented for scanf in glibc).  Implement that scanf
support for glibc.

As with the strtol support, 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 input
potentially matching subsequent parts of the scanf format string).
Thus this patch adds 12 new __isoc23_* functions per long double
format (12, 24 or 36 depending on how many long double formats the
glibc configuration supports), with appropriate header redirection
support (generally very closely following that for the __isoc99_*
scanf functions - note that __GLIBC_USE (DEPRECATED_SCANF) takes
precedence over __GLIBC_USE (C2X_STRTOL), so the case of GNU
extensions to C89 continues to get old-style GNU %a and does not get
this new feature).  The function names would remain as __isoc23_* even
if C2x ends up published in 2024 rather than 2023.

When scanf %b support is added, I think it will be appropriate for all
versions of scanf to follow C2x rules for inputs to the %b format
(given that there are no compatibility concerns for a new format).

Tested for x86_64 (full glibc testsuite).  The first version was also
tested for powerpc (32-bit) and powerpc64le (stdio-common/ and wcsmbs/
tests), and with build-many-glibcs.py.

1 files changed, 27 insertions, 2 deletions

diff --git a/include/stdio.h b/include/stdio.h
index c3e772ad9a..da47d1ce99 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -94,18 +94,34 @@ extern int __isoc99_vscanf (const char *__restrict __format,
 extern int __isoc99_vsscanf (const char *__restrict __s,
 			     const char *__restrict __format,
 			     __gnuc_va_list __arg) __THROW;
+extern int __isoc23_fscanf (FILE *__restrict __stream,
+			    const char *__restrict __format, ...) __wur;
+extern int __isoc23_scanf (const char *__restrict __format, ...) __wur;
+extern int __isoc23_sscanf (const char *__restrict __s,
+			    const char *__restrict __format, ...) __THROW;
+extern int __isoc23_vfscanf (FILE *__restrict __s,
+			     const char *__restrict __format,
+			     __gnuc_va_list __arg) __wur;
+extern int __isoc23_vscanf (const char *__restrict __format,
+			    __gnuc_va_list __arg) __wur;
+extern int __isoc23_vsscanf (const char *__restrict __s,
+			     const char *__restrict __format,
+			     __gnuc_va_list __arg) __THROW;
 
 libc_hidden_proto (__isoc99_sscanf)
 libc_hidden_proto (__isoc99_vsscanf)
 libc_hidden_proto (__isoc99_vfscanf)
+libc_hidden_proto (__isoc23_sscanf)
+libc_hidden_proto (__isoc23_vsscanf)
+libc_hidden_proto (__isoc23_vfscanf)
 
-/* Internal uses of sscanf should call the C99-compliant version.
+/* Internal uses of sscanf should call the C2X-compliant version.
    Unfortunately, symbol redirection is not transitive, so the
    __REDIRECT in the public header does not link up with the above
    libc_hidden_proto.  Bridge the gap with a macro.  */
 #  if !__GLIBC_USE (DEPRECATED_SCANF)
 #   undef sscanf
-#   define sscanf __isoc99_sscanf
+#   define sscanf __isoc23_sscanf
 #  endif
 
 #  if __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1  && IS_IN (libc)
@@ -114,12 +130,21 @@ libc_hidden_proto (__isoc99_vfscanf)
 extern __typeof (__isoc99_sscanf) ___ieee128_isoc99_sscanf __THROW;
 extern __typeof (__isoc99_vsscanf) ___ieee128_isoc99_vsscanf __THROW;
 extern __typeof (__isoc99_vfscanf) ___ieee128_isoc99_vfscanf __THROW;
+extern __typeof (__isoc23_sscanf) ___ieee128_isoc23_sscanf __THROW;
+extern __typeof (__isoc23_vsscanf) ___ieee128_isoc23_vsscanf __THROW;
+extern __typeof (__isoc23_vfscanf) ___ieee128_isoc23_vfscanf __THROW;
 libc_hidden_proto (___ieee128_isoc99_sscanf)
 libc_hidden_proto (___ieee128_isoc99_vsscanf)
 libc_hidden_proto (___ieee128_isoc99_vfscanf)
+libc_hidden_proto (___ieee128_isoc23_sscanf)
+libc_hidden_proto (___ieee128_isoc23_vsscanf)
+libc_hidden_proto (___ieee128_isoc23_vfscanf)
 #define __isoc99_sscanf ___ieee128_isoc99_sscanf
 #define __isoc99_vsscanf ___ieee128_isoc99_vsscanf
 #define __isoc99_vfscanf ___ieee128_isoc99_vfscanf
+#define __isoc23_sscanf ___ieee128_isoc23_sscanf
+#define __isoc23_vsscanf ___ieee128_isoc23_vsscanf
+#define __isoc23_vfscanf ___ieee128_isoc23_vfscanf
 #  endif
 
 /* Prototypes for compatibility functions.  */