upb/mem/alloc.h

// Protocol Buffers - Google's data interchange format
// Copyright 2023 Google LLC.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

#ifndef UPB_MEM_ALLOC_H_
#define UPB_MEM_ALLOC_H_

// Must be last.
#include "upb/port/def.inc"

#ifdef __cplusplus
extern "C" {
#endif

typedef struct upb_alloc upb_alloc;

/* A combined `malloc()`/`free()` function.
 * If `size` is 0 then the function acts like `free()`, otherwise it acts like
 * `realloc()`.  Only `oldsize` bytes from a previous allocation are
 * preserved. */
typedef void* upb_alloc_func(upb_alloc* alloc, void* ptr, size_t oldsize,
                             size_t size);

/* A upb_alloc is a possibly-stateful allocator object.
 *
 * It could either be an arena allocator (which doesn't require individual
 * `free()` calls) or a regular `malloc()` (which does).  The client must
 * therefore free memory unless it knows that the allocator is an arena
 * allocator. */
struct upb_alloc {
  upb_alloc_func* func;
};

UPB_INLINE void* upb_malloc(upb_alloc* alloc, size_t size) {
  UPB_ASSERT(alloc);
  return alloc->func(alloc, NULL, 0, size);
}

UPB_INLINE void* upb_realloc(upb_alloc* alloc, void* ptr, size_t oldsize,
                             size_t size) {
  UPB_ASSERT(alloc);
  return alloc->func(alloc, ptr, oldsize, size);
}

UPB_INLINE void upb_free(upb_alloc* alloc, void* ptr) {
  UPB_ASSERT(alloc);
  alloc->func(alloc, ptr, 0, 0);
}

// The global allocator used by upb. Uses the standard malloc()/free().

extern upb_alloc upb_alloc_global;

/* Functions that hard-code the global malloc.
 *
 * We still get benefit because we can put custom logic into our global
 * allocator, like injecting out-of-memory faults in debug/testing builds. */

UPB_INLINE void* upb_gmalloc(size_t size) {
  return upb_malloc(&upb_alloc_global, size);
}

UPB_INLINE void* upb_grealloc(void* ptr, size_t oldsize, size_t size) {
  return upb_realloc(&upb_alloc_global, ptr, oldsize, size);
}

UPB_INLINE void upb_gfree(void* ptr) { upb_free(&upb_alloc_global, ptr); }

#ifdef __cplusplus
} /* extern "C" */
#endif

#include "upb/port/undef.inc"

#endif /* UPB_MEM_ALLOC_H_ */