Copyright (c) 2012 by Michael Kerrisk <firstname.lastname@example.org> %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this on...
NAMEmalloc_usable_size - obtain size of block of memory allocated from heap
size_t malloc_usable_size (void *ptr);
DESCRIPTIONThe malloc_usable_size() function returns the number of usable bytes in the block pointed to by ptr, a pointer to a block of memory allocated by malloc(3) or a related function.
RETURN VALUEmalloc_usable_size() returns the number of usable bytes in the block of allocated memory pointed to by ptr. If ptr is NULL, 0 is returned.
ATTRIBUTESFor an explanation of the terms used in this section, see attributes(7).
CONFORMING TOThis function is a GNU extension.
NOTESThe value returned by malloc_usable_size() may be greater than the requested size of the allocation because of alignment and minimum size constraints. Although the excess bytes can be overwritten by the application without ill effects, this is not good programming practice: the number of excess bytes in an allocation depends on the underlying implementation.
The main use of this function is for debugging and introspection.