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REALLOCARRAY(3) NetBSD Library Functions Manual REALLOCARRAY(3)
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reallocarray -- reallocate memory for an array of elements checking for
reallocarray(void *ptr, size_t nmemb, size_t size);
The reallocarray() function reallocates the pointer ptr to a size appro-
priate to handle an allocation of nmemb elements in an array where each
of the array elements is size bytes using realloc(3) and making sure that
overflow does not happen in the multiplication of ``nmemb * size''. Oth-
erwise it behaves like realloc(3).
The reallocarray() function will return NULL if there was overflow or if
realloc(3) failed setting errno to ENOMEM or preserving the value from
malloc(3), realloc(3), reallocarr(3)
The reallocarray() function first appeared in OpenBSD 5.6.
reallocarray() was redesigned in NetBSD 8 as reallocarr(3). Until
NetBSD 10, reallocarray was available in the _OPENBSD_SOURCE namespace.
The reallocarray() function was designed to facilitate safe, robust pro-
gramming and overcome the shortcomings of the malloc(3) and realloc(3)
functions by centralizing the overflow check in the multiplication of
nmemb and size.
There are still portability issues. (It does not solve the 0 sized allo-
cation return ambiguity in the C standard: does reallocarray() return
NULL or a unique pointer to memory that cannot be accessed? Does a NULL
mean that an error occurred, and can someone check errno in that case to
find out what happened?) For this reason NetBSD decided to go with an
alternative implementation, and created reallocarr(3).
NetBSD 10.99 September 9, 2022 NetBSD 10.99