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#ifndef JEMALLOC_INTERNAL_HOOK_H
#define JEMALLOC_INTERNAL_HOOK_H
#include "jemalloc/internal/tsd.h"
/*
* This API is *extremely* experimental, and may get ripped out, changed in API-
* and ABI-incompatible ways, be insufficiently or incorrectly documented, etc.
*
* It allows hooking the stateful parts of the API to see changes as they
* happen.
*
* Allocation hooks are called after the allocation is done, free hooks are
* called before the free is done, and expand hooks are called after the
* allocation is expanded.
*
* For realloc and rallocx, if the expansion happens in place, the expansion
* hook is called. If it is moved, then the alloc hook is called on the new
* location, and then the free hook is called on the old location (i.e. both
* hooks are invoked in between the alloc and the dalloc).
*
* If we return NULL from OOM, then usize might not be trustworthy. Calling
* realloc(NULL, size) only calls the alloc hook, and calling realloc(ptr, 0)
* only calls the free hook. (Calling realloc(NULL, 0) is treated as malloc(0),
* and only calls the alloc hook).
*
* Reentrancy:
* Reentrancy is guarded against from within the hook implementation. If you
* call allocator functions from within a hook, the hooks will not be invoked
* again.
* Threading:
* The installation of a hook synchronizes with all its uses. If you can
* prove the installation of a hook happens-before a jemalloc entry point,
* then the hook will get invoked (unless there's a racing removal).
*
* Hook insertion appears to be atomic at a per-thread level (i.e. if a thread
* allocates and has the alloc hook invoked, then a subsequent free on the
* same thread will also have the free hook invoked).
*
* The *removal* of a hook does *not* block until all threads are done with
* the hook. Hook authors have to be resilient to this, and need some
* out-of-band mechanism for cleaning up any dynamically allocated memory
* associated with their hook.
* Ordering:
* Order of hook execution is unspecified, and may be different than insertion
* order.
*/
#define HOOK_MAX 4
enum hook_alloc_e {
hook_alloc_malloc,
hook_alloc_posix_memalign,
hook_alloc_aligned_alloc,
hook_alloc_calloc,
hook_alloc_memalign,
hook_alloc_valloc,
hook_alloc_mallocx,
/* The reallocating functions have both alloc and dalloc variants */
hook_alloc_realloc,
hook_alloc_rallocx,
};
/*
* We put the enum typedef after the enum, since this file may get included by
* jemalloc_cpp.cpp, and C++ disallows enum forward declarations.
*/
typedef enum hook_alloc_e hook_alloc_t;
enum hook_dalloc_e {
hook_dalloc_free,
hook_dalloc_dallocx,
hook_dalloc_sdallocx,
/*
* The dalloc halves of reallocation (not called if in-place expansion
* happens).
*/
hook_dalloc_realloc,
hook_dalloc_rallocx,
};
typedef enum hook_dalloc_e hook_dalloc_t;
enum hook_expand_e {
hook_expand_realloc,
hook_expand_rallocx,
hook_expand_xallocx,
};
typedef enum hook_expand_e hook_expand_t;
typedef void (*hook_alloc)(
void *extra, hook_alloc_t type, void *result, uintptr_t result_raw,
uintptr_t args_raw[3]);
typedef void (*hook_dalloc)(
void *extra, hook_dalloc_t type, void *address, uintptr_t args_raw[3]);
typedef void (*hook_expand)(
void *extra, hook_expand_t type, void *address, size_t old_usize,
size_t new_usize, uintptr_t result_raw, uintptr_t args_raw[4]);
typedef struct hooks_s hooks_t;
struct hooks_s {
hook_alloc alloc_hook;
hook_dalloc dalloc_hook;
hook_expand expand_hook;
void *extra;
};
/*
* Begin implementation details; everything above this point might one day live
* in a public API. Everything below this point never will.
*/
/*
* The realloc pathways haven't gotten any refactoring love in a while, and it's
* fairly difficult to pass information from the entry point to the hooks. We
* put the informaiton the hooks will need into a struct to encapsulate
* everything.
*
* Much of these pathways are force-inlined, so that the compiler can avoid
* materializing this struct until we hit an extern arena function. For fairly
* goofy reasons, *many* of the realloc paths hit an extern arena function.
* These paths are cold enough that it doesn't matter; eventually, we should
* rewrite the realloc code to make the expand-in-place and the
* free-then-realloc paths more orthogonal, at which point we don't need to
* spread the hook logic all over the place.
*/
typedef struct hook_ralloc_args_s hook_ralloc_args_t;
struct hook_ralloc_args_s {
/* I.e. as opposed to rallocx. */
bool is_realloc;
/*
* The expand hook takes 4 arguments, even if only 3 are actually used;
* we add an extra one in case the user decides to memcpy without
* looking too closely at the hooked function.
*/
uintptr_t args[4];
};
/*
* Returns an opaque handle to be used when removing the hook. NULL means that
* we couldn't install the hook.
*/
bool hook_boot();
void *hook_install(tsdn_t *tsdn, hooks_t *hooks);
/* Uninstalls the hook with the handle previously returned from hook_install. */
void hook_remove(tsdn_t *tsdn, void *opaque);
/* Hooks */
void hook_invoke_alloc(hook_alloc_t type, void *result, uintptr_t result_raw,
uintptr_t args_raw[3]);
void hook_invoke_dalloc(hook_dalloc_t type, void *address,
uintptr_t args_raw[3]);
void hook_invoke_expand(hook_expand_t type, void *address, size_t old_usize,
size_t new_usize, uintptr_t result_raw, uintptr_t args_raw[4]);
#endif /* JEMALLOC_INTERNAL_HOOK_H */
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