malloc_get_state(3)

✨ malloc_get_state — bestie edition ✨

okay so real talk, this is malloc_get_state(3) from section 3 of the manual (Library Functions Manual, iykyk) — and yes she's a removed girlie, so buckle up 🎀

💖 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. 💀 like, gone gone. not "deprecated," removed.

So. The malloc_get_state() function records the current state of all malloc(3) internal bookkeeping variables — but NOT the actual contents of the heap, and NOT the state of malloc_hook(3) function pointers, okay, don't get it twisted 🙈.

The state gets recorded into a system-dependent opaque data structure that's dynamically allocated via malloc(3), and a pointer to that data structure is what you get back as the function result. ✨ And bestie, heads up: it is the caller's responsibility to free(3) this memory. she does not clean up after you 💅

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. (she said "that's a future version, not my business" 😭)

👑 ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

• Interface: malloc_get_state(), malloc_set_state() — Attribute: Thread safety — Value: MT-Safe 🦋

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🌈 STANDARDS

GNU.

🧚 NOTES

These functions are useful when you're 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. (main character behavior fr fr 👑)

Hook function pointers are never saved or restored by these functions, with exactly 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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that's the whole page bestie, no cap 🌸 this was Linux man-pages 6.20, dated 2026-02-08 — mwah, slay, periodt 💅✨🎀