HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. |  |
NAME |LIBRARY |SYNOPSIS |DESCRIPTION |RETURN VALUE |ATTRIBUTES |STANDARDS |NOTES |SEE ALSO |COLOPHON | |
malloc_get_state(3) Library Functions Manualmalloc_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. Themalloc_get_state() function records the current state of allmalloc(3) internal bookkeeping variables (but not the actual contents of the heap or the state ofmalloc_hook(3) functions pointers). The state is recorded in a system-dependent opaque data structure dynamically allocated viamalloc(3), and a pointer to that data structure is returned as the function result. (It is the caller's responsibility tofree(3) this memory.) Themalloc_set_state() function restores the state of allmalloc(3) internal bookkeeping variables to the values recorded in the opaque data structure pointed to bystate.
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 thatstate 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 bystate 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, seeattributes(7). ┌──────────────────────────────────────┬───────────────┬─────────┐ │Interface│Attribute│Value│ ├──────────────────────────────────────┼───────────────┼─────────┤ │malloc_get_state(), │ Thread safety │ MT-Safe │ │malloc_set_state() │ │ │ └──────────────────────────────────────┴───────────────┴─────────┘
GNU.
These functions are useful when using thismalloc(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 (seemallopt(3)) was in use whenmalloc_get_state() was called, thenmalloc_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 theman-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 isnot part of the original manual page), send a mail to man-pages@man7.orgLinux man-pages 6.15 2025-05-17malloc_get_state(3)Pages that refer to this page:malloc(3)
HTML rendering created 2025-09-06 byMichael Kerrisk, author ofThe Linux Programming Interface. For details of in-depthLinux/UNIX system programming training courses that I teach, lookhere. Hosting byjambit GmbH. | |