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glibc/stdio-common/printf-parsemb.c
Joseph Myers 309548bec3 Support C2X printf %b, %B 
C2X adds a printf %b format (see
<http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2630.pdf>, accepted
for C2X), for outputting integers in binary.  It also has recommended
practice for a corresponding %B format (like %b, but %#B starts the
output with 0B instead of 0b).  Add support for these formats to
glibc.

One existing test uses %b as an example of an unknown format, to test
how glibc printf handles unknown formats; change that to %v.  Use of
%b and %B as user-registered format specifiers continues to work (and
we already have a test that covers that, tst-printfsz.c).

Note that C2X also has scanf %b support, plus support for binary
constants starting 0b in strtol (base 0 and 2) and scanf %i (strtol
base 0 and scanf %i coming from a previous paper that added binary
integer literals).  I intend to implement those features in a separate
patch or patches; as discussed in the thread starting at
<https://sourceware.org/pipermail/libc-alpha/2020-December/120414.html>,
they will be more complicated because they involve adding extra public
symbols to ensure compatibility with existing code that might not
expect 0b constants to be handled by strtol base 0 and 2 and scanf %i,
whereas simply adding a new format specifier poses no such
compatibility concerns.

Note that the actual conversion from integer to string uses existing
code in _itoa.c.  That code has special cases for bases 8, 10 and 16,
probably so that the compiler can optimize division by an integer
constant in the code for those bases.  If desired such special cases
could easily be added for base 2 as well, but that would be an
optimization, not actually needed for these printf formats to work.

Tested for x86_64 and x86.  Also tested with build-many-glibcs.py for
aarch64-linux-gnu with GCC mainline to make sure that the test does
indeed build with GCC 12 (where format checking warnings are enabled
for most of the test).
2021-11-10 15:52:21 +00:00

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/* Helper functions for parsing printf format strings.
Copyright (C) 1995-2021 Free Software Foundation, Inc.
This file is part of th 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/>. */
#include <ctype.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h>
#include <wchar.h>
#include <wctype.h>
#ifndef COMPILE_WPRINTF
# define CHAR_T char
# define UCHAR_T unsigned char
# define INT_T int
# define L_(Str) Str
# define ISDIGIT(Ch) isdigit (Ch)
# define HANDLE_REGISTERED_MODIFIER __handle_registered_modifier_mb
#else
# define CHAR_T wchar_t
# define UCHAR_T unsigned int
# define INT_T wint_t
# define L_(Str) L##Str
# define ISDIGIT(Ch) iswdigit (Ch)
# define HANDLE_REGISTERED_MODIFIER __handle_registered_modifier_wc
#endif
#include "printf-parse.h"
#define NDEBUG 1
#include <assert.h>
/* FORMAT must point to a '%' at the beginning of a spec. Fills in *SPEC
with the parsed details. POSN is the number of arguments already
consumed. At most MAXTYPES - POSN types are filled in TYPES. Return
the number of args consumed by this spec; *MAX_REF_ARG is updated so it
remains the highest argument index used. */
size_t
attribute_hidden
#ifdef COMPILE_WPRINTF
__parse_one_specwc (const UCHAR_T *format, size_t posn,
struct printf_spec *spec, size_t *max_ref_arg)
#else
__parse_one_specmb (const UCHAR_T *format, size_t posn,
struct printf_spec *spec, size_t *max_ref_arg)
#endif
{
unsigned int n;
size_t nargs = 0;
/* Skip the '%'. */
++format;
/* Clear information structure. */
spec->data_arg = -1;
spec->info.alt = 0;
spec->info.space = 0;
spec->info.left = 0;
spec->info.showsign = 0;
spec->info.group = 0;
spec->info.i18n = 0;
spec->info.extra = 0;
spec->info.pad = ' ';
spec->info.wide = sizeof (UCHAR_T) > 1;
spec->info.is_binary128 = 0;
/* Test for positional argument. */
if (ISDIGIT (*format))
{
const UCHAR_T *begin = format;
n = read_int (&format);
if (n != 0 && *format == L_('$'))
/* Is positional parameter. */
{
++format; /* Skip the '$'. */
if (n != -1)
{
spec->data_arg = n - 1;
*max_ref_arg = MAX (*max_ref_arg, n);
}
}
else
/* Oops; that was actually the width and/or 0 padding flag.
Step back and read it again. */
format = begin;
}
/* Check for spec modifiers. */
do
{
switch (*format)
{
case L_(' '):
/* Output a space in place of a sign, when there is no sign. */
spec->info.space = 1;
continue;
case L_('+'):
/* Always output + or - for numbers. */
spec->info.showsign = 1;
continue;
case L_('-'):
/* Left-justify things. */
spec->info.left = 1;
continue;
case L_('#'):
/* Use the "alternate form":
Hex has 0x or 0X, FP always has a decimal point. */
spec->info.alt = 1;
continue;
case L_('0'):
/* Pad with 0s. */
spec->info.pad = '0';
continue;
case L_('\''):
/* Show grouping in numbers if the locale information
indicates any. */
spec->info.group = 1;
continue;
case L_('I'):
/* Use the internationalized form of the output. Currently
means to use the `outdigits' of the current locale. */
spec->info.i18n = 1;
continue;
default:
break;
}
break;
}
while (*++format);
if (spec->info.left)
spec->info.pad = ' ';
/* Get the field width. */
spec->width_arg = -1;
spec->info.width = 0;
if (*format == L_('*'))
{
/* The field width is given in an argument.
A negative field width indicates left justification. */
const UCHAR_T *begin = ++format;
if (ISDIGIT (*format))
{
/* The width argument might be found in a positional parameter. */
n = read_int (&format);
if (n != 0 && *format == L_('$'))
{
if (n != -1)
{
spec->width_arg = n - 1;
*max_ref_arg = MAX (*max_ref_arg, n);
}
++format; /* Skip '$'. */
}
}
if (spec->width_arg < 0)
{
/* Not in a positional parameter. Consume one argument. */
spec->width_arg = posn++;
++nargs;
format = begin; /* Step back and reread. */
}
}
else if (ISDIGIT (*format))
{
int n = read_int (&format);
/* Constant width specification. */
if (n != -1)
spec->info.width = n;
}
/* Get the precision. */
spec->prec_arg = -1;
/* -1 means none given; 0 means explicit 0. */
spec->info.prec = -1;
if (*format == L_('.'))
{
++format;
if (*format == L_('*'))
{
/* The precision is given in an argument. */
const UCHAR_T *begin = ++format;
if (ISDIGIT (*format))
{
n = read_int (&format);
if (n != 0 && *format == L_('$'))
{
if (n != -1)
{
spec->prec_arg = n - 1;
*max_ref_arg = MAX (*max_ref_arg, n);
}
++format;
}
}
if (spec->prec_arg < 0)
{
/* Not in a positional parameter. */
spec->prec_arg = posn++;
++nargs;
format = begin;
}
}
else if (ISDIGIT (*format))
{
int n = read_int (&format);
if (n != -1)
spec->info.prec = n;
}
else
/* "%.?" is treated like "%.0?". */
spec->info.prec = 0;
}
/* Check for type modifiers. */
spec->info.is_long_double = 0;
spec->info.is_short = 0;
spec->info.is_long = 0;
spec->info.is_char = 0;
spec->info.user = 0;
if (__builtin_expect (__printf_modifier_table == NULL, 1)
|| __printf_modifier_table[*format] == NULL
|| HANDLE_REGISTERED_MODIFIER (&format, &spec->info) != 0)
switch (*format++)
{
case L_('h'):
/* ints are short ints or chars. */
if (*format != L_('h'))
spec->info.is_short = 1;
else
{
++format;
spec->info.is_char = 1;
}
break;
case L_('l'):
/* ints are long ints. */
spec->info.is_long = 1;
if (*format != L_('l'))
break;
++format;
/* FALLTHROUGH */
case L_('L'):
/* doubles are long doubles, and ints are long long ints. */
case L_('q'):
/* 4.4 uses this for long long. */
spec->info.is_long_double = 1;
break;
case L_('z'):
case L_('Z'):
/* ints are size_ts. */
assert (sizeof (size_t) <= sizeof (unsigned long long int));
#if LONG_MAX != LONG_LONG_MAX
spec->info.is_long_double = (sizeof (size_t)
> sizeof (unsigned long int));
#endif
spec->info.is_long = sizeof (size_t) > sizeof (unsigned int);
break;
case L_('t'):
assert (sizeof (ptrdiff_t) <= sizeof (long long int));
#if LONG_MAX != LONG_LONG_MAX
spec->info.is_long_double = (sizeof (ptrdiff_t) > sizeof (long int));
#endif
spec->info.is_long = sizeof (ptrdiff_t) > sizeof (int);
break;
case L_('j'):
assert (sizeof (uintmax_t) <= sizeof (unsigned long long int));
#if LONG_MAX != LONG_LONG_MAX
spec->info.is_long_double = (sizeof (uintmax_t)
> sizeof (unsigned long int));
#endif
spec->info.is_long = sizeof (uintmax_t) > sizeof (unsigned int);
break;
default:
/* Not a recognized modifier. Backup. */
--format;
break;
}
/* Get the format specification. */
spec->info.spec = (wchar_t) *format++;
spec->size = -1;
if (__builtin_expect (__printf_function_table == NULL, 1)
|| spec->info.spec > UCHAR_MAX
|| __printf_arginfo_table[spec->info.spec] == NULL
/* We don't try to get the types for all arguments if the format
uses more than one. The normal case is covered though. If
the call returns -1 we continue with the normal specifiers. */
|| (int) (spec->ndata_args = (*__printf_arginfo_table[spec->info.spec])
(&spec->info, 1, &spec->data_arg_type,
&spec->size)) < 0)
{
/* Find the data argument types of a built-in spec. */
spec->ndata_args = 1;
switch (spec->info.spec)
{
case L'i':
case L'd':
case L'u':
case L'o':
case L'X':
case L'x':
case L'B':
case L'b':
#if LONG_MAX != LONG_LONG_MAX
if (spec->info.is_long_double)
spec->data_arg_type = PA_INT|PA_FLAG_LONG_LONG;
else
#endif
if (spec->info.is_long)
spec->data_arg_type = PA_INT|PA_FLAG_LONG;
else if (spec->info.is_short)
spec->data_arg_type = PA_INT|PA_FLAG_SHORT;
else if (spec->info.is_char)
spec->data_arg_type = PA_CHAR;
else
spec->data_arg_type = PA_INT;
break;
case L'e':
case L'E':
case L'f':
case L'F':
case L'g':
case L'G':
case L'a':
case L'A':
if (spec->info.is_long_double)
spec->data_arg_type = PA_DOUBLE|PA_FLAG_LONG_DOUBLE;
else
spec->data_arg_type = PA_DOUBLE;
break;
case L'c':
spec->data_arg_type = PA_CHAR;
break;
case L'C':
spec->data_arg_type = PA_WCHAR;
break;
case L's':
spec->data_arg_type = PA_STRING;
break;
case L'S':
spec->data_arg_type = PA_WSTRING;
break;
case L'p':
spec->data_arg_type = PA_POINTER;
break;
case L'n':
spec->data_arg_type = PA_INT|PA_FLAG_PTR;
break;
case L'm':
default:
/* An unknown spec will consume no args. */
spec->ndata_args = 0;
break;
}
}
if (spec->data_arg == -1 && spec->ndata_args > 0)
{
/* There are args consumed, but no positional spec. Use the
next sequential arg position. */
spec->data_arg = posn;
nargs += spec->ndata_args;
}
if (spec->info.spec == L'\0')
/* Format ended before this spec was complete. */
spec->end_of_fmt = spec->next_fmt = format - 1;
else
{
/* Find the next format spec. */
spec->end_of_fmt = format;
#ifdef COMPILE_WPRINTF
spec->next_fmt = __find_specwc (format);
#else
spec->next_fmt = __find_specmb (format);
#endif
}
return nargs;
}
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