1MALLOC_GET_STATE(3)        Linux Programmer's Manual       MALLOC_GET_STATE(3)
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NAME

6       malloc_get_state, malloc_set_state - record and restore state of malloc
7       implementation
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SYNOPSIS

10       #include <malloc.h>
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12       void* malloc_get_state(void);
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14       int malloc_set_state(void *state);
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DESCRIPTION

17       Note: these function are removed in glibc version 2.25.
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19       The malloc_get_state() function records the current state of  all  mal‐
20       loc(3)  internal  bookkeeping variables (but not the actual contents of
21       the heap or the state of malloc_hook(3) functions pointers).  The state
22       is  recorded  in  a  system-dependent opaque data structure dynamically
23       allocated via malloc(3), and  a  pointer  to  that  data  structure  is
24       returned as the function result.  (It is the caller's responsibility to
25       free(3) this memory.)
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27       The malloc_set_state() function restores the  state  of  all  malloc(3)
28       internal  bookkeeping  variables  to  the values recorded in the opaque
29       data structure pointed to by state.
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RETURN VALUE

32       On success, malloc_get_state() returns a pointer to a  newly  allocated
33       opaque  data  structure.   On  error  (for example, memory could not be
34       allocated for the data structure), malloc_get_state() returns NULL.
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36       On  success,  malloc_set_state()  returns  0.   If  the  implementation
37       detects that state does not point to a correctly formed data structure,
38       malloc_set_state() returns -1.  If the implementation detects that  the
39       version  of  the  data  structure referred to by state is a more recent
40       version  than  this  implementation  knows  about,   malloc_set_state()
41       returns -2.
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ATTRIBUTES

44       For   an   explanation   of   the  terms  used  in  this  section,  see
45       attributes(7).
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47       ┌────────────────────┬───────────────┬─────────┐
48Interface           Attribute     Value   
49       ├────────────────────┼───────────────┼─────────┤
50malloc_get_state(), │ Thread safety │ MT-Safe │
51malloc_set_state()  │               │         │
52       └────────────────────┴───────────────┴─────────┘
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CONFORMING TO

55       These functions are GNU extensions.
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NOTES

58       These  functions are useful when using this malloc(3) implementation as
59       part of a shared library, and the heap contents are saved/restored  via
60       some  other  method.   This technique is used by GNU Emacs to implement
61       its "dumping" function.
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63       Hook function pointers are never saved or restored by these  functions,
64       with  two  exceptions:  if  malloc checking (see mallopt(3)) was in use
65       when malloc_get_state() was called, then malloc_set_state() resets mal‐
66       loc  checking  hooks  if possible; if malloc checking was not in use in
67       the recorded state, but the caller has requested malloc checking,  then
68       the hooks are reset to 0.
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SEE ALSO

71       malloc(3), mallopt(3)
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COLOPHON

74       This  page  is  part of release 4.16 of the Linux man-pages project.  A
75       description of the project, information about reporting bugs,  and  the
76       latest     version     of     this    page,    can    be    found    at
77       https://www.kernel.org/doc/man-pages/.
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81GNU                               2017-09-15               MALLOC_GET_STATE(3)
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