thodg/libgit2/src/array.h

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• Hash : 3603cb09
  Author :
  Date : 2015-02-10T23:13:49
  

  git__*allocarray: safer realloc and malloc Introduce git__reallocarray that checks the product of the number of elements and element size for overflow before allocation. Also introduce git__mallocarray that behaves like calloc, but without the `c`. (It does not zero memory, for those truly worried about every cycle.)

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• src/array.h

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  #ifndef INCLUDE_array_h__
  #define INCLUDE_array_h__
  
  #include "common.h"
  
  /*
   * Use this to declare a typesafe resizable array of items, a la:
   *
   *     git_array_t(int) my_ints = GIT_ARRAY_INIT;
   *     ...
   *     int *i = git_array_alloc(my_ints);
   *     GITERR_CHECK_ALLOC(i);
   *     ...
   *     git_array_clear(my_ints);
   *
   * You may also want to do things like:
   *
   *     typedef git_array_t(my_struct) my_struct_array_t;
   */
  #define git_array_t(type) struct { type *ptr; uint32_t size, asize; }
  
  #define GIT_ARRAY_INIT { NULL, 0, 0 }
  
  #define git_array_init(a) \
  	do { (a).size = (a).asize = 0; (a).ptr = NULL; } while (0)
  
  #define git_array_init_to_size(a, desired) \
  	do { (a).size = 0; (a).asize = desired; (a).ptr = git__calloc(desired, sizeof(*(a).ptr)); } while (0)
  
  #define git_array_clear(a) \
  	do { git__free((a).ptr); git_array_init(a); } while (0)
  
  #define GITERR_CHECK_ARRAY(a) GITERR_CHECK_ALLOC((a).ptr)
  
  
  typedef git_array_t(char) git_array_generic_t;
  
  /* use a generic array for growth so this can return the new item */
  GIT_INLINE(void *) git_array_grow(void *_a, size_t item_size)
  {
  	volatile git_array_generic_t *a = _a;
  	uint32_t new_size;
  	char *new_array;
  
  	if (a->size < 8) {
  		new_size = 8;
  	} else {
  		if (GIT_ALLOC_OVERFLOW_MULTIPLY(a->size, 3 / 2))
  			goto on_oom;
  
  		new_size = a->size * 3 / 2;
  	}
  
  	if ((new_array = git__reallocarray(a->ptr, new_size, item_size)) == NULL)
  		goto on_oom;
  
  	a->ptr = new_array; a->asize = new_size; a->size++;
  	return a->ptr + (a->size - 1) * item_size;
  
  on_oom:
  	git_array_clear(*a);
  	return NULL;
  }
  
  #define git_array_alloc(a) \
  	(((a).size >= (a).asize) ? \
  	git_array_grow(&(a), sizeof(*(a).ptr)) : \
  	((a).ptr ? &(a).ptr[(a).size++] : NULL))
  
  #define git_array_last(a) ((a).size ? &(a).ptr[(a).size - 1] : NULL)
  
  #define git_array_pop(a) ((a).size ? &(a).ptr[--(a).size] : NULL)
  
  #define git_array_get(a, i) (((i) < (a).size) ? &(a).ptr[(i)] : NULL)
  
  #define git_array_size(a) (a).size
  
  #define git_array_valid_index(a, i) ((i) < (a).size)
  
  #endif
  

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