malloc_set_state(3) — Linux manual page


MALLOC_GET_STATE(3)       Linux Programmer's Manual      MALLOC_GET_STATE(3)

NAME         top

       malloc_get_state, malloc_set_state - record and restore state of mal‐
       loc implementation

SYNOPSIS         top

       #include <malloc.h>

       void* malloc_get_state(void);

       int malloc_set_state(void *state);

DESCRIPTION         top

       Note: these function are removed in glibc version 2.25.

       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         top

       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         top

       For an explanation of the terms used in this section, see

       │Interface           Attribute     Value   │
       │malloc_get_state(), │ Thread safety │ MT-Safe │
       │malloc_set_state()  │               │         │

CONFORMING TO         top

       These functions are GNU extensions.

NOTES         top

       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         top

       malloc(3), mallopt(3)

COLOPHON         top

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GNU                              2017-09-15              MALLOC_GET_STATE(3)