@node stdlib.h
@section @file{stdlib.h}

POSIX specification:@* @url{https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/stdlib.h.html}

Gnulib module: stdlib-h, system-posix
@mindex stdlib-h
@mindex system-posix

Portability problems fixed by the Gnulib module @code{stdlib-h}:
@itemize
@item
The macros @code{EXIT_SUCCESS} and @code{EXIT_FAILURE} are not defined on
some platforms.
@item
Some platforms provide a @code{NULL} macro that cannot be used in arbitrary
expressions:
NetBSD 5.0
@item
Using the macro @code{MB_CUR_MAX} causes link errors on some platforms:
Android NDK r16.
@item
The value of @code{MB_CUR_MAX} is too small (3 instead of 4) in UTF-8 locales
on some platforms:
Solaris 10.
@end itemize

Portability problems fixed by the Gnulib module @code{system-posix}:
@itemize
@item
The macros @code{WIFSIGNALED}, @code{WIFEXITED}, @code{WIFSTOPPED},
@code{WTERMSIG}, @code{WEXITSTATUS}, @code{WNOHANG}, @code{WUNTRACED},
@code{WSTOPSIG} are not defined in this header file (only in
@code{<sys/wait.h>}) on some platforms:
MirBSD 10.
@item
The macro @code{WCOREDUMP} is not defined in this header file (only in
@code{<sys/wait.h>}) on some platforms:
@c https://sourceware.org/PR32551
glibc 2.42.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@item
The definition of the type @code{once_flag}, of the macro
@code{ONCE_FLAG_INIT}, and the declaration of the function
@code{call_once}, that are required by ISO C 23, are not provided.
@mindex call_once
To get them, import Gnulib module @code{call_once} and include
@code{<threads.h>} rather than @code{<stdlib.h>}.
@item
System status macros such as @code{WEXITSTATUS} require an lvalue
argument on some platforms.
macOS 11.1.

@item
POSIX.1-2024 allows, but does not require, this file to make visible
all symbols from the headers @code{<fcntl.h>}, @code{<limits.h>},
@code{<math.h>}, @code{<stddef.h>}, and @code{<sys/wait.h>}.
Programs should not assume that these other symbols are visible merely
because this file is included, or that they are invisible because only
this file is included.
@end itemize
