malloc_get_state(3) — Linux manual page

malloc_get_state(3)     Library Functions Manual     malloc_get_state(3)

NAME

       malloc_get_state, malloc_set_state - record and restore state of
       malloc implementation

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

       #include <malloc.h>

       void *malloc_get_state(void);
       int malloc_set_state(void *state);

DESCRIPTION

       Note: these functions are removed in glibc 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

       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()                  │               │         │
       └─────────────────────────────────────┴───────────────┴─────────┘

STANDARDS

       GNU.

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)

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Linux man-pages 6.9.1          2024-05-02            malloc_get_state(3)

Pages that refer to this page: malloc(3)

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