简单的动态buff实现

darray.h

#ifndef __DYNAMINC_ARRAY_H__
#define __DYNAMINC_ARRAY_H__

#include <string.h>
#include <stdlib.h>
#include <assert.h>

#ifdef __cplusplus
extern "C" {
#endif

#define D_ARRAY_INIT() (D_ARRAY) { 0, 0, NULL }
#define D_ARRAY_RESET(_array) do { (_array)->len = 0; } while (0)

typedef struct _D_ARRAY {
	size_t size;	/* array的长度 */
	size_t len;	/* array填充了的长度 */
	char *array;
} D_ARRAY;

/* 失败返回负数, 成功返回0; len是array应该具有的最少长度 */
static inline int dynamic_array_resize(D_ARRAY *array, size_t len)
{
	char *newarr = NULL; 
	assert(len + array->size >= array->size); /* 断言不会溢出 */
	if ((newarr = realloc(array->array, len + array->size)) == NULL)
		return -1;
	array->array = newarr;
	array->size += len;
	return 0;
}

static inline int dynamic_array_prealloc(D_ARRAY *array, size_t len)
{
	assert(array->len <= array->size);
	assert(len + array->len >= array->len); /* 断言没有溢出 */
	if (array->size < len + array->len)
		return dynamic_array_resize(array, len + array->len);
	return 0;
}

static inline int dynamic_array_alloc(D_ARRAY *array, size_t len)
{
	int ret = 0;
	if (dynamic_array_prealloc(array, len) < 0)
		return -1;
	ret = array->len;
	array->len += len;
	return ret;
}

static inline int dynamic_array_put(D_ARRAY *array, const void *content, size_t len)
{
	int ret = dynamic_array_alloc(array, len);
	if (ret < 0)
		return -1;
	memcpy(array->array + ret, content, len);
	return 0;
}

static inline 
int dynamic_array_insert(D_ARRAY *array, size_t offset, const void *buf, size_t len)
{
	assert(array->len <= array->size);
	assert(offset + len >= offset); /* 断言没有溢出 */
	if (offset + len > array->len) {
		if (dynamic_array_alloc(array, len + offset - array->len) < 0)
			return -1;
	}
	memcpy(array->array + offset, buf, len);
	return 0;
}

static inline void dynamic_array_exit(D_ARRAY *array)
{
	free(array->array);
	*array = D_ARRAY_INIT();
}

#ifdef __cplusplus
}
#endif

#endif /* __DYNAMINC_ARRAY_H__ */