los_seq_buf.c 文件参考

浏览源代码.

函数
static int	ExpandSeqBuf (struct SeqBuf *seqBuf, size_t oldCount)
struct SeqBuf *	LosBufCreat (void)
	创建seq buf 更多...
int	LosBufVprintf (struct SeqBuf *seqBuf, const char *fmt, va_list argList)
	真正写 buf 函数,调整 size/count的值,count可理解为偏移位 更多...
int	LosBufPrintf (struct SeqBuf *seqBuf, const char *fmt,...)
	支持可变参数 写 buf 更多...
int	LosBufRelease (struct SeqBuf *seqBuf)
	释放 seq buf 更多...

函数说明

ExpandSeqBuf()

static int ExpandSeqBuf ( struct SeqBuf *  seqBuf, size_t  oldCount  )

static

在文件 los_seq_buf.c 第 37 行定义.

{
    char *newBuf = NULL;
    int ret;
 
    if ((seqBuf == NULL) || (seqBuf->buf == NULL)) {
        return -LOS_NOK;
    }
 
    if (seqBuf->size >= SEQBUF_LIMIT_SIZE) {
        goto EXPAND_FAILED;
    }
 
    newBuf = (char*)malloc(seqBuf->size <<= 1);//将现有buf扩大一倍
    if (newBuf == NULL) {
        goto EXPAND_FAILED;
    }
    (void)memset_s(newBuf + oldCount, seqBuf->size - oldCount, 0, seqBuf->size - oldCount);
    //memset_s 注意 oldCount 位置,因为 newBuf头部要被旧buf覆盖,所以只set后部分
    ret = memcpy_s(newBuf, seqBuf->size, seqBuf->buf, oldCount);//拷贝旧buf数据到新buf,注意 oldCount 位置
    if (ret != LOS_OK) {
        free(newBuf);
        goto EXPAND_FAILED;
    }
    seqBuf->count = oldCount;//目前偏移量,可理解为seek 
 
    free(seqBuf->buf);//释放原有的buf
    seqBuf->buf = newBuf;//采用新的buf
 
    return LOS_OK;
EXPAND_FAILED:
    free(seqBuf->buf);
    seqBuf->buf = NULL;
    seqBuf->count = 0;
    seqBuf->size = 0;
 
    return -LOS_NOK;
}

函数调用图:

这是这个函数的调用关系图:

LosBufCreat()

struct SeqBuf * LosBufCreat

(

void

)

创建seq buf

在文件 los_seq_buf.c 第 76 行定义.

{
    struct SeqBuf *seqBuf = NULL;
 
    seqBuf = (struct SeqBuf *)malloc(sizeof(struct SeqBuf));
    if (seqBuf == NULL) {
        errno = -LOS_ENOMEM;
        return NULL;
    }
    (void)memset_s(seqBuf, sizeof(struct SeqBuf), 0, sizeof(struct SeqBuf));
 
    return seqBuf;
}

函数调用图:

这是这个函数的调用关系图:

LosBufPrintf()

int LosBufPrintf	(	struct SeqBuf *	seqBuf,
		const char *	fmt,
			...
	)

支持可变参数 写 buf

在文件 los_seq_buf.c 第 133 行定义.

{
    va_list argList;
    int ret;
 
    va_start(argList, fmt);//可变参数的实现,有点意思.
    ret = LosBufVprintf(seqBuf, fmt, argList);
    va_end(argList);
 
    return ret;
}

函数调用图:

这是这个函数的调用关系图:

LosBufRelease()

int LosBufRelease

(

struct SeqBuf *

seqBuf

)

释放 seq buf

在文件 los_seq_buf.c 第 145 行定义.

{
    if (seqBuf == NULL) {
        return -LOS_EPERM;
    }
 
    if (seqBuf->buf != NULL) {
        free(seqBuf->buf);
        seqBuf->buf = NULL;
    }
    free(seqBuf);
 
    return LOS_OK;
}

函数调用图:

这是这个函数的调用关系图:

LosBufVprintf()

int LosBufVprintf	(	struct SeqBuf *	seqBuf,
		const char *	fmt,
		va_list	argList
	)

真正写 buf 函数,调整 size/count的值,count可理解为偏移位

在文件 los_seq_buf.c 第 90 行定义.

{
    bool needreprintf = FALSE;
    int bufLen;
 
    if (seqBuf == NULL) {
        return -LOS_EPERM;
    }
 
    if (seqBuf->buf == NULL) {
        seqBuf->size = SEQBUF_PAGE_SIZE;
        seqBuf->buf = (char *)malloc(seqBuf->size);
        if (seqBuf->buf == NULL) {
            return -LOS_ENOMEM;
        }
        (void)memset_s(seqBuf->buf, seqBuf->size, 0, seqBuf->size);
        seqBuf->count = 0;
    }
 
    do {
        bufLen = vsnprintf_s(seqBuf->buf + seqBuf->count, seqBuf->size - seqBuf->count,
                             seqBuf->size - seqBuf->count - 1, fmt, argList);
        if (bufLen >= 0) {
            /* succeed write. */
            seqBuf->count += bufLen;//成功写入,count要增长
            return 0;
        }
        if (seqBuf->buf[seqBuf->count] == '\0') {//这里没看懂,为啥要有这个判断, @note_thinking
            free(seqBuf->buf);
            seqBuf->buf = NULL;
            break;
        }
 
        needreprintf = TRUE;
 
        if (ExpandSeqBuf(seqBuf, seqBuf->count) != 0) {
            break;
        }
    } while (needreprintf);
 
    return -LOS_NOK;
}

函数调用图:

这是这个函数的调用关系图: