C2x scanf %b support

ISO C2x defines scanf %b for input of binary integers (with an
optional 0b or 0B prefix).  Implement such support, along with the
corresponding SCNb* macros in <inttypes.h>.  Unlike the support for
binary integers with 0b or 0B prefix with scanf %i, this is supported
in all versions of scanf (independent of the standards mode used for
compilation), because there are no backwards compatibility concerns
(%b wasn't previously a supported format) the way there were for %i.

Tested for x86_64 and x86.

5 files changed, 248 insertions, 9 deletions

diff --git a/NEWS b/NEWS
index 7cec03cc76..709ee40e50 100644
--- a/NEWS
+++ b/NEWS
@@ -17,9 +17,12 @@ Major new features:
   wcstoull_l, wcstoimax, wcstoumax, wcstoq, wcstouq.  Similarly, the
   following functions support binary integers prefixed by 0b or 0B as
   input to the %i format: fscanf, scanf, sscanf, vscanf, vsscanf,
-  vfscanf, fwscanf, wscanf, swscanf, vfwscanf, vwscanf, vswscanf.
+  vfscanf, fwscanf, wscanf, swscanf, vfwscanf, vwscanf, vswscanf; those
+  functions also support the %b format for binary integers, with or
+  without such a prefix and independent of standards mode.
 
-* PRIb* and PRIB* macros from C2X have been added to <inttypes.h>.
+* PRIb*, PRIB* and SCNb* macros from C2X have been added to
+  <inttypes.h>.
 
 * printf-family functions now support the wN format length modifiers for
   arguments of type intN_t, int_leastN_t, uintN_t or uint_leastN_t (for
diff --git a/manual/stdio.texi b/manual/stdio.texi
index a981e6512a..9cf622403f 100644
--- a/manual/stdio.texi
+++ b/manual/stdio.texi
@@ -3545,6 +3545,10 @@ Matches an optionally signed integer in any of the formats that the C
 language defines for specifying an integer constant.  @xref{Numeric
 Input Conversions}.
 
+@item @samp{%b}
+Matches an unsigned integer written in binary radix.  This is an ISO
+C2X feature.  @xref{Numeric Input Conversions}.
+
 @item @samp{%o}
 Matches an unsigned integer written in octal radix.
 @xref{Numeric Input Conversions}.
@@ -3652,11 +3656,13 @@ For example, any of the strings @samp{10}, @samp{0xa}, or @samp{012}
 could be read in as integers under the @samp{%i} conversion.  Each of
 these specifies a number with decimal value @code{10}.
 
-The @samp{%o}, @samp{%u}, and @samp{%x} conversions match unsigned
-integers in octal, decimal, and hexadecimal radices, respectively.  The
+The @samp{%b}, @samp{%o}, @samp{%u}, and @samp{%x} conversions match unsigned
+integers in binary, octal, decimal, and hexadecimal radices, respectively.  The
 syntax that is recognized is the same as that for the @code{strtoul}
 function (@pxref{Parsing of Integers}) with the appropriate value
-(@code{8}, @code{10}, or @code{16}) for the @var{base} argument.
+(@code{2}, @code{8}, @code{10}, or @code{16}) for the @var{base}
+argument.  The @samp{%b} conversion accepts an optional leading
+@samp{0b} or @samp{0B} in all standards modes.
 
 The @samp{%X} conversion is identical to the @samp{%x} conversion.  They
 both permit either uppercase or lowercase letters to be used as digits.
diff --git a/stdio-common/tst-scanf-binary-main.c b/stdio-common/tst-scanf-binary-main.c
index 6b75cb32e5..f9b45178db 100644
--- a/stdio-common/tst-scanf-binary-main.c
+++ b/stdio-common/tst-scanf-binary-main.c
@@ -16,10 +16,12 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#include <inttypes.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <wchar.h>
 
+#include <libc-diag.h>
 #include <support/check.h>
 #include <support/xstdio.h>
 
@@ -176,6 +178,195 @@ one_check (const CHAR *s, int expected, char expected_c)
   TEST_COMPARE (ret_c, expected_c);
 }
 
+/* GCC does not know the %b format before GCC 12.  */
+DIAG_PUSH_NEEDS_COMMENT;
+#if !__GNUC_PREREQ (12, 0)
+DIAG_IGNORE_NEEDS_COMMENT (11, "-Wformat");
+DIAG_IGNORE_NEEDS_COMMENT (11, "-Wformat-extra-args");
+#endif
+
+static void
+one_check_b (const CHAR *s, int expected, char expected_c)
+{
+  int ret;
+  FILE *fp;
+  unsigned int ret_i;
+  unsigned long int ret_l;
+  unsigned long long int ret_ll;
+  char ret_c;
+  fp = xfopen (INFILE, "w");
+  ret = FNX (fput, s) (s, fp);
+  TEST_VERIFY_EXIT (0 <= ret);
+  xfclose (fp);
+
+  ret = FNX (s, scanf) (s, L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = FNX (f, scanf) (fp, L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = FNX (, scanf) (L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  ret = wrap_vsscanf (s, L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = wrap_vfscanf (fp, L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = wrap_vscanf (L_("%b %c"), &ret_i, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_i, (unsigned int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+
+  ret = FNX (s, scanf) (s, L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = FNX (f, scanf) (fp, L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = FNX (, scanf) (L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  ret = wrap_vsscanf (s, L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = wrap_vfscanf (fp, L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = wrap_vscanf (L_("%lb %c"), &ret_l, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_l, (unsigned long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+
+  ret = FNX (s, scanf) (s, L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = FNX (f, scanf) (fp, L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = FNX (, scanf) (L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  ret = wrap_vsscanf (s, L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  fp = xfopen (INFILE, "r");
+  ret = wrap_vfscanf (fp, L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+  xfclose (fp);
+  fp = xfreopen (INFILE, "r", stdin);
+  ret = wrap_vscanf (L_("%llb %c"), &ret_ll, &ret_c);
+  TEST_COMPARE (ret, 2);
+  TEST_COMPARE (ret_ll, (unsigned long long int) expected);
+  TEST_COMPARE (ret_c, expected_c);
+}
+
+#define CHECK_SCNB(TYPE, MACRO, S, EXPECTED, EXPECTED_C)		\
+  do									\
+    {									\
+      int ret;								\
+      FILE *fp;								\
+      TYPE ret_t;							\
+      char ret_c;							\
+      fp = xfopen (INFILE, "w");					\
+      ret = FNX (fput, s) (S, fp);					\
+      TEST_VERIFY_EXIT (0 <= ret);					\
+      xfclose (fp);							\
+      ret = FNX (s, scanf) (S, L_("%") MACRO " %c", &ret_t, &ret_c);	\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+      fp = xfopen (INFILE, "r");					\
+      ret = FNX (f, scanf) (fp, L_("%") MACRO " %c", &ret_t, &ret_c);	\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+      xfclose (fp);							\
+      fp = xfreopen (INFILE, "r", stdin);				\
+      ret = FNX (, scanf) (L_("%") MACRO " %c", &ret_t, &ret_c);	\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+      ret = wrap_vsscanf (S, L_("%") MACRO " %c", &ret_t, &ret_c);	\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+      fp = xfopen (INFILE, "r");					\
+      ret = wrap_vfscanf (fp, L_("%") MACRO " %c", &ret_t, &ret_c);	\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+      xfclose (fp);							\
+      fp = xfreopen (INFILE, "r", stdin);				\
+      ret = wrap_vscanf (L_("%") MACRO " %c", &ret_t, &ret_c);		\
+      TEST_COMPARE (ret, 2);						\
+      TEST_COMPARE (ret_t, EXPECTED);					\
+      TEST_COMPARE (ret_c, EXPECTED_C);					\
+    }									\
+  while (0)
+
+static void
+one_check_scnb (const CHAR *s, int expected, char expected_c)
+{
+#if TEST_C2X || defined _GNU_SOURCE
+  CHECK_SCNB (uint8_t, SCNb8, s, (uint8_t) expected, expected_c);
+  CHECK_SCNB (uint16_t, SCNb16, s, (uint16_t) expected, expected_c);
+  CHECK_SCNB (uint32_t, SCNb32, s, (uint32_t) expected, expected_c);
+  CHECK_SCNB (uint64_t, SCNb64, s, (uint64_t) expected, expected_c);
+  CHECK_SCNB (uint_least8_t, SCNbLEAST8, s, (uint_least8_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_least16_t, SCNbLEAST16, s, (uint_least16_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_least32_t, SCNbLEAST32, s, (uint_least32_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_least64_t, SCNbLEAST64, s, (uint_least64_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_fast8_t, SCNbFAST8, s, (uint_fast8_t) expected, expected_c);
+  CHECK_SCNB (uint_fast16_t, SCNbFAST16, s, (uint_fast16_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_fast32_t, SCNbFAST32, s, (uint_fast32_t) expected,
+	      expected_c);
+  CHECK_SCNB (uint_fast64_t, SCNbFAST64, s, (uint_fast64_t) expected,
+	      expected_c);
+  CHECK_SCNB (uintmax_t, SCNbMAX, s, (uintmax_t) expected, expected_c);
+  CHECK_SCNB (uintptr_t, SCNbPTR, s, (uintptr_t) expected, expected_c);
+#endif
+}
+
+DIAG_POP_NEEDS_COMMENT;
+
 static int
 do_test (void)
 {
@@ -183,6 +374,18 @@ do_test (void)
   one_check (L_("0B101 x"), 5, 'x');
   one_check (L_("-0b11111 y"), -31, 'y');
   one_check (L_("-0B11111 y"), -31, 'y');
+  one_check_b (L_("0b101 x"), 5, 'x');
+  one_check_b (L_("0B101 x"), 5, 'x');
+  one_check_b (L_("-0b11111 y"), -31, 'y');
+  one_check_b (L_("-0B11111 y"), -31, 'y');
+  one_check_b (L_("101 x"), 5, 'x');
+  one_check_b (L_("-11111 y"), -31, 'y');
+  one_check_scnb (L_("0b101 x"), 5, 'x');
+  one_check_scnb (L_("0B101 x"), 5, 'x');
+  one_check_scnb (L_("-0b11111 y"), -31, 'y');
+  one_check_scnb (L_("-0B11111 y"), -31, 'y');
+  one_check_scnb (L_("101 x"), 5, 'x');
+  one_check_scnb (L_("-11111 y"), -31, 'y');
   return 0;
 }
 
diff --git a/stdio-common/vfscanf-internal.c b/stdio-common/vfscanf-internal.c
index a3ebf63554..bfb9baa21a 100644
--- a/stdio-common/vfscanf-internal.c
+++ b/stdio-common/vfscanf-internal.c
@@ -1381,6 +1381,10 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 	  base = 8;
 	  goto number;
 
+	case L_('b'):	/* Binary integer.  */
+	  base = 2;
+	  goto number;
+
 	case L_('u'):	/* Unsigned decimal integer.  */
 	  base = 10;
 	  goto number;
@@ -1428,10 +1432,11 @@ __vfscanf_internal (FILE *s, const char *format, va_list argptr,
 		      c = inchar ();
 		    }
 		}
-	      else if ((mode_flags & SCANF_ISOC23_BIN_CST) != 0
-		       && base == 0
-		       && width != 0
-		       && TOLOWER (c) == L_('b'))
+	      else if (width != 0
+		       && TOLOWER (c) == L_('b')
+		       && (base == 2
+			   || ((mode_flags & SCANF_ISOC23_BIN_CST) != 0
+			       && base == 0)))
 		{
 		  base = 2;
 		  if (width > 0)
diff --git a/stdlib/inttypes.h b/stdlib/inttypes.h
index 8f0fa8ab9f..42ecf681cc 100644
--- a/stdlib/inttypes.h
+++ b/stdlib/inttypes.h
@@ -302,6 +302,28 @@ typedef wchar_t __gwchar_t;
 # define SCNxPTR	__PRIPTR_PREFIX "x"
 
 
+/* Binary notation.  */
+# if __GLIBC_USE (ISOC2X)
+#  define SCNb8		"hhb"
+#  define SCNb16	"hb"
+#  define SCNb32	"b"
+#  define SCNb64	__PRI64_PREFIX "b"
+
+#  define SCNbLEAST8	"hhb"
+#  define SCNbLEAST16	"hb"
+#  define SCNbLEAST32	"b"
+#  define SCNbLEAST64	__PRI64_PREFIX "b"
+
+#  define SCNbFAST8	"hhb"
+#  define SCNbFAST16	__PRIPTR_PREFIX "b"
+#  define SCNbFAST32	__PRIPTR_PREFIX "b"
+#  define SCNbFAST64	__PRI64_PREFIX "b"
+
+#  define SCNbMAX	__PRI64_PREFIX "b"
+#  define SCNbPTR	__PRIPTR_PREFIX "b"
+# endif
+
+
 __BEGIN_DECLS
 
 #if __WORDSIZE == 64