MALLOC_USABLE_SIZE

Section: Linux Programmer's Manual (3)
Updated: 2014-06-13
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NAME

malloc_usable_size - obtain size of block of memory allocated from heap  

SYNOPSIS

#include <malloc.h>

size_t malloc_usable_size (void *ptr);  

DESCRIPTION

The 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 VALUE

malloc_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.  

ATTRIBUTES

 

Multithreading (see pthreads(7))

The malloc_usable_size() function is thread-safe.  

CONFORMING TO

This function is a GNU extension.  

NOTES

The 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.  

SEE ALSO

malloc(3)  

COLOPHON

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Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ATTRIBUTES
Multithreading (see pthreads(7))
CONFORMING TO
NOTES
SEE ALSO
COLOPHON