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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | STANDARDS | NOTES | SEE ALSO | COLOPHON |
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malloc_get_state(3) Library Functions Manual malloc_get_state(3)
malloc_get_state, malloc_set_state - record and restore state of
malloc implementation
Standard C library (libc, -lc)
#include <malloc.h>
void *malloc_get_state(void);
int malloc_set_state(void *state);
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.
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() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
GNU.
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 the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Linux man-pages 6.15 2025-05-17 malloc_get_state(3)
Pages that refer to this page: malloc(3)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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