malloc, realloc, free[manage memory]

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mallinfo, malloc_stats, mallopt

[malloc support]

SYNOPSIS

struct mallinfo mallinfo(void);

void malloc_stats(void);

int mallopt(int parameter , value );

struct mallinfo _mallinfo_r(void * reent );

void _malloc_stats_r(void * reent );

int _mallopt_r(void * reent , int parameter , value );

DESCRIPTION

mallinfo returns a structure describing the current state of memory allocation. The structure is defined in malloc.h. The following fields are defined:

arena is the total amount of space in the heap.
ordblks is the number of chunks which are not in use.
uordblks is the total amount of space allocated by malloc .
fordblks is the total amount of space not in use.
keepcost is the size of the top most memory block.

malloc_stats prints some statistics about memory allocation on standard error.

mallopt takes a parameter and a value. The parameters are defined in malloc.h, and may be one of the following:

M_TRIM_THRESHOLD sets the maximum amount of unused space in the top most block before releasing it back to the system in free (the space is released by calling _sbrk_r with a negative argument).
M_TOP_PAD is the amount of padding to allocate whenever _sbrk_r is called to allocate more space.

The alternate functions, _mallinfo_r, _malloc_stats_r, and _mallopt_r, are reentrant versions. The extra argument, reent, is a pointer to a reentrancy structure.

RETURNS

mallinfo returns a mallinfo structure. The structure is defined in malloc.h.

malloc_stats does not return a result.

mallopt returns zero if the parameter could not be set, or non-zero if it could be set.

COMPLIANCE

mallinfo and mallopt are provided by SVR4, but mallopt takes different parameters on different systems.

malloc_stats is not portable.