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10.46.52 reallocarray ¶

POSIX specification:
https://pubs.opengroup.org/onlinepubs/9799919799/functions/reallocarray.html

Documentation:

• https://www.gnu.org/software/libc/manual/html_node/Changing-Block-Size.html,
• man reallocarray.

Gnulib module: reallocarray

Portability problems fixed by Gnulib:

• This function is missing on many platforms: glibc 2.25, macOS 14, FreeBSD 10, NetBSD 7, OpenBSD 5.5, Minix 3.3.0, AIX 7.2, HP-UX 11, Solaris 11.4, Cygwin 1.7.x, mingw, MSVC 14, Android 9.0.
• On some platforms, when the function fails it might set errno to EAGAIN instead of to ENOMEM. Although POSIX allows EAGAIN, the reallocarray module insists on ENOMEM which also conforms to POSIX and is GNU-compatible: Solaris 11.4.
• On some platforms, reallocarray (p, n, s) can succeed even if multiplying n by s would exceed PTRDIFF_MAX, which can lead to undefined behavior later: FreeBSD 13, NetBSD 9, OpenBSD 6, musl 1.2.
• It is not portable to call reallocarray (p, n, s) when either n or s is zero, as reallocarray has the same issues with zero sizes that realloc does. See realloc.

Portability problems not fixed by Gnulib:

• When not growing an already-allocated region, reallocarray, like realloc, can fail and return a null pointer: glibc 2.40 and probably other platforms.