ISO C2x defines printf length modifiers wN (for intN_t / int_leastN_t
/ uintN_t / uint_leastN_t) and wfN (for int_fastN_t / uint_fastN_t).
Add support for those length modifiers (such a feature was previously
requested in bug 24466). scanf support is to be added separately.
GCC 13 has format checking support for these modifiers.
When used with the support for registering format specifiers, these
modifiers are translated to existing flags in struct printf_info,
rather than trying to add some way of distinguishing them without
breaking the printf_info ABI. C2x requires an error to be returned
for unsupported values of N; this is implemented for printf-family
functions, but the parse_printf_format interface doesn't support error
returns, so such an error gets discarded by that function.
Tested for x86_64 and x86.
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.
I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah. I don't
know why I run into these diagnostics whereas others evidently do not.
remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines
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).
I used these shell commands:
../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")
and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master
Add strfromf128 to stdlib when _Float128 support is enabled.
* stdio-common/printf-parsemb.c (__parse_one_specmb): Initialize
spec->info.is_binary128 to zero.
* stdio-common/printf.h (printf_info): Add new member is_binary128
to indicate that the number being converted to string is compatible
with the IEC 60559 binary128 format.
* stdio-common/printf_fp.c (__printf_fp_l): Add code to deal with
_Float128 numbers.
* stdio-common/printf_fphex.c: Include ieee754_float128.h and
ldbl-128/printf_fphex_macros.h
(__printf_fphex): Add code to deal with _Float128 numbers.
* stdio-common/printf_size.c (__printf_size): Likewise.
* stdio-common/vfprintf.c (process_arg): Initialize member
info.is_binary128 to zero.
* stdlib/fpioconst.h (FLT128_MAX_10_EXP_LOG): New macro.
* stdlib/stdlib.h: Include bits/floatn.h for _Float128 support.
(strfromf128): New declaration.
* stdlib/strfrom-skeleton.c (STRFROM): Set member info.is_binary128
to one.
* sysdeps/ieee754/float128/Makefile: Add strfromf128.
* sysdeps/ieee754/float128/Versions: Likewise.
* sysdeps/ieee754/float128/strfromf128.c: New file.
With help from Paul Eggert, Carlos O'Donell, and Roland McGrath.
* stdio-common/printf-parse.h (read_int): Change return type to
'int', return -1 on INT_MAX overflow.
* stdio-common/vfprintf.c (vfprintf): Validate width and precision
against overflow of INT_MAX. Set errno to EOVERFLOW when 'done'
overflows INT_MAX. Check for overflow of in-format-string precision
values properly. Use EOVERFLOW rather than ERANGE throughout. Use
SIZE_MAX not INT_MAX for integer overflow test.
* stdio-common/printf-parsemb.c: If read_int signals an overflow,
skip the construct in the format string but do not record anything.
* stdio-common/bug22.c: Adjust to test both width/prevision
INT_MAX overflow as well as total length INT_MAX overflow. Check
explicitly for proper errno values.
New types printf_arginfo_size_function, printf_va_arg_function.
Declare register_printf_specifier, register_printf_modifier,
register_printf_type.
* stdio-common/printf-parse.h (struct printf_spec): Add size element.
(union printf_arg): Add pa_user element.
Adjust __printf_arginfo_table type.
Add __printf_va_arg_table, __printf_modifier_table,
__handle_registered_modifier_mb, and __handle_registered_modifier_wc
declarations.
* stdio-common/printf-parsemb.c: Recognize registered modifiers.
If registered arginfo call failed try normal specifier.
* stdio-common/printf-prs.c: Pass additional parameter to arginfo
function.
* stdio-common/Makefile (routines): Add reg-modifier and reg-type.
* stdio-common/Versions: Export register_printf_modifier,
register_printf_type, and register_printf_specifier for GLIBC_2.10.
* stdio-common/reg-modifier.c: New file.
* stdio-common/reg-type.c: New file.
* stdio-common/reg-printf.c (__register_printf_specifier): New
function. Mostly the old __register_printf_function function but
uses locking and type of third parameter changed.
(__register_printf_function): Implement using
__register_printf_specifier.
* stdio-common/vfprintf.c (vfprintf): Collect argument sizes in
calls to arginfo functions. Allocate enough memory for user-defined
types. Call new va_arg functions to get user-defined types.
Try installed handlers even for existing format specifiers first.
