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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
MALLOC_GET_STATE(3) Linux Programmer's Manual MALLOC_GET_STATE(3)
malloc_get_state, malloc_set_state - record and restore state of mal‐
loc implementation
#include <malloc.h>
void* malloc_get_state(void);
int malloc_set_state(void *state);
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.
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.
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() │ │ │
└────────────────────┴───────────────┴─────────┘
These functions are GNU extensions.
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.
malloc(3), mallopt(3)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
GNU 2016-12-12 MALLOC_GET_STATE(3)
Pages that refer to this page: malloc(3)