cosmopolitan/third_party/regex/tre-mem.c

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  tre-mem.c - TRE memory allocator                                            │
│                                                                              │
│  Copyright (c) 2001-2009 Ville Laurikari <vl@iki.fi>                         │
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│  Musl Libc                                                                   │
│  Copyright © 2005-2014 Rich Felker, et al.                                   │
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╚─────────────────────────────────────────────────────────────────────────────*/
#include "third_party/regex/tre.inc"

/*
  This memory allocator is for allocating small memory blocks efficiently
  in terms of memory overhead and execution speed.  The allocated blocks
  cannot be freed individually, only all at once.  There can be multiple
  allocators, though.
*/

/*
  This memory allocator is for allocating small memory blocks efficiently
  in terms of memory overhead and execution speed.  The allocated blocks
  cannot be freed individually, only all at once.  There can be multiple
  allocators, though.
*/

/* Returns a new memory allocator or NULL if out of memory. */
tre_mem_t tre_mem_new_impl(int provided, void *provided_block) {
  tre_mem_t mem;
  if (provided) {
    mem = provided_block;
    bzero(mem, sizeof(*mem));
  } else
    mem = calloc(1, sizeof(*mem));
  if (mem == NULL) return NULL;
  return mem;
}

/* Frees the memory allocator and all memory allocated with it. */
void tre_mem_destroy(tre_mem_t mem) {
  tre_list_t *tmp, *l = mem->blocks;
  while (l != NULL) {
    free(l->data), l->data = NULL;
    tmp = l->next;
    free(l), l = tmp;
  }
  free(mem), mem = NULL;
}

/* Allocates a block of `size' bytes from `mem'.  Returns a pointer to the
   allocated block or NULL if an underlying malloc() failed. */
void *tre_mem_alloc_impl(tre_mem_t mem, int provided, void *provided_block,
                         int zero, size_t size) {
  void *ptr;
  if (mem->failed) {
    return NULL;
  }
  if (mem->n < size) {
    /* We need more memory than is available in the current block.
       Allocate a new block. */
    tre_list_t *l;
    if (provided) {
      if (provided_block == NULL) {
        mem->failed = 1;
        return NULL;
      }
      mem->ptr = provided_block;
      mem->n = TRE_MEM_BLOCK_SIZE;
    } else {
      int block_size;
      if (size * 8 > TRE_MEM_BLOCK_SIZE)
        block_size = size * 8;
      else
        block_size = TRE_MEM_BLOCK_SIZE;
      l = malloc(sizeof(*l));
      if (l == NULL) {
        mem->failed = 1;
        return NULL;
      }
      l->data = malloc(block_size);
      if (l->data == NULL) {
        free(l), l = NULL;
        mem->failed = 1;
        return NULL;
      }
      l->next = NULL;
      if (mem->current != NULL) mem->current->next = l;
      if (mem->blocks == NULL) mem->blocks = l;
      mem->current = l;
      mem->ptr = l->data;
      mem->n = block_size;
    }
  }
  /* Make sure the next pointer will be aligned. */
  size += ALIGN(mem->ptr + size, long);
  /* Allocate from current block. */
  ptr = mem->ptr;
  mem->ptr += size;
  mem->n -= size;
  /* Set to zero if needed. */
  if (zero) bzero(ptr, size);
  return ptr;
}