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The function mbstowcs, by an XSI extension to POSIX, accepts a null pointer for the destination wchar_t array. This API behaviour allows you to use the function to compute the length of the required wchar_t array i.e. does the conversion without storing it and returns the number of wide characters required. We remove the __write_only__ markup for the first argument because it is not true since the destination may be a null pointer, and so the length argument may not apply. We remove the markup otherwise the new test case cannot be compiled with -Werror=nonnull. We add a new test case for mbstowcs which exercises the destination is a null pointer behaviour which we have now explicitly documented. The mbsrtowcs and mbsnrtowcs behave similarly, and mbsrtowcs is documented as doing this in C11, even if the standard doesn't come out and call out this specific use case. We add one note to each of mbsrtowcs and mbsnrtowcs to call out that they support a null pointer for the destination. The wcsrtombs function behaves similarly but in the other way around and allows you to use a null destination pointer to compute how many bytes you would need to convert the wide character input. We document this particular case also, but leave wcsnrtombs as a references to wcsrtombs, so the reader must still read the details of the semantics for wcsrtombs. |
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| ChangeLog.old | ||
| conform | ||
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| debug | ||
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| include | ||
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| locale | ||
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| malloc | ||
| manual | ||
| math | ||
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| misc | ||
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| stdio-common | ||
| stdlib | ||
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| support | ||
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| config.h.in | ||
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| configure | ||
| configure.ac | ||
| COPYING | ||
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| extra-lib.mk | ||
| gen-locales.mk | ||
| INSTALL | ||
| libc-abis | ||
| libof-iterator.mk | ||
| LICENSES | ||
| MAINTAINERS | ||
| Makeconfig | ||
| Makefile | ||
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| Makefile.in | ||
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| NEWS | ||
| o-iterator.mk | ||
| README | ||
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| test-skeleton.c | ||
| version.h | ||
This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 ia64-*-linux-gnu m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.