NAME

       malloc_get_state, malloc_set_state - record and restore state of malloc implementation

SYNOPSIS

       #include <malloc.h>

       void* malloc_get_state(void);

       int malloc_set_state(void *state);

DESCRIPTION

       The malloc_get_state() function records the current state of all malloc(3) internal bookkeeping variables
       (but not the actual contents of the heap or the state of malloc_hook(3) functions pointers).   The  state
       is  recorded  in  a  system-dependent  opaque  data  structure dynamically allocated via malloc(3), and a
       pointer to that data structure is returned as the function result.  (It is the caller's responsibility to
       free(3) this memory.)

       The malloc_set_state() function restores the state of all malloc(3) internal bookkeeping variables to the
       values recorded in the opaque data structure pointed to by state.

RETURN VALUE

       On success, malloc_get_state() returns a pointer to a newly allocated opaque data  structure.   On  error
       (for example, memory could not be allocated for the data structure), malloc_get_state() returns NULL.

       On  success,  malloc_set_state() returns 0.  If the implementation detects that state does not point to a
       correctly formed data structure, malloc_set_state() returns -1.  If the implementation detects  that  the
       version  of  the  data  structure  referred to by state is a more recent version than this implementation
       knows about, malloc_set_state() returns -2.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌────────────────────┬───────────────┬─────────┐
       │Interface           │ Attribute     │ Value   │
       ├────────────────────┼───────────────┼─────────┤
       │malloc_get_state(), │ Thread safety │ MT-Safe │
       │malloc_set_state()  │               │         │
       └────────────────────┴───────────────┴─────────┘

CONFORMING TO

       These functions are GNU extensions.

NOTES

       These  functions are useful when using this malloc(3) implementation as part of a shared library, and the
       heap contents are saved/restored via some other method.  This technique is used by GNU Emacs to implement
       its "dumping" function.

       Hook  function  pointers  are  never saved or restored by these functions, with two exceptions: if malloc
       checking (see mallopt(3)) was in use when malloc_get_state() was called, then  malloc_set_state()  resets
       malloc  checking  hooks  if  possible;  if  malloc checking was not in use in the recorded state, but the
       caller has requested malloc checking, then the hooks are reset to 0.

SEE ALSO

       malloc(3), mallopt(3)

COLOPHON

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