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man:malloc_get_state

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

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

     Note: these function are removed in glibc version 2.25.
     The malloc_get_state() function records the current state of  all  mal-
     loc(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 mal-
     loc  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

     This  page  is  part of release 4.16 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 2017-09-15 MALLOC_GET_STATE(3)

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