vfs_writev.c 文件参考

浏览源代码.

函数
static int	iov_trans_to_buf (char *buf, ssize_t totallen, const struct iovec *iov, int iovcnt)
ssize_t	vfs_writev (int fd, const struct iovec *iov, int iovcnt, off_t *offset)
ssize_t	writev (int fd, const struct iovec *iov, int iovcnt)

函数说明

iov_trans_to_buf()

static int iov_trans_to_buf ( char *  buf, ssize_t  totallen, const struct iovec *  iov, int  iovcnt  )

static

在文件 vfs_writev.c 第 41 行定义.

{
    int i;
    size_t ret, writepart;
    size_t bytestowrite;
    char *writebuf = NULL;
    char *curbuf = buf;
 
    for (i = 0; i < iovcnt; ++i) {
        writebuf = (char *)iov[i].iov_base;
        bytestowrite = iov[i].iov_len;
        if (bytestowrite == 0) {
            continue;
        }
 
        if (totallen == 0) {
            break;
        }
 
        bytestowrite = (totallen < bytestowrite) ? totallen : bytestowrite;
        ret = LOS_CopyToKernel(curbuf, bytestowrite, writebuf, bytestowrite);
        if (ret != 0) {
            if (ret == bytestowrite) {
                set_errno(EFAULT);
                return VFS_ERROR;
            } else {
                writepart = bytestowrite - ret;
                curbuf += writepart;
                totallen -= writepart;
                break;
            }
        }
        curbuf += bytestowrite;
        totallen -= bytestowrite;
    }
 
    return (int)((intptr_t)curbuf - (intptr_t)buf);
}

函数调用图:

这是这个函数的调用关系图:

vfs_writev()

ssize_t vfs_writev	(	int	fd,
		const struct iovec *	iov,
		int	iovcnt,
		off_t *	offset
	)

在文件 vfs_writev.c 第 80 行定义.

{
    int i, ret;
    char *buf = NULL;
    size_t buflen = 0;
    size_t bytestowrite;
    ssize_t totalbyteswritten;
    size_t totallen;
 
    if ((iov == NULL) || (iovcnt > IOV_MAX)) {
        return VFS_ERROR;
    }
 
    for (i = 0; i < iovcnt; ++i) {
        if (SSIZE_MAX - buflen < iov[i].iov_len) {
            set_errno(EINVAL);
            return VFS_ERROR;
        }
        buflen += iov[i].iov_len;
    }
 
    if (buflen == 0) {
        return 0;
    }
 
    totallen = buflen * sizeof(char);
#ifdef LOSCFG_KERNEL_VM
    buf = (char *)LOS_VMalloc(totallen);
#else
    buf = (char *)malloc(totallen);
#endif
    if (buf == NULL) {
        return VFS_ERROR;
    }
 
    ret = iov_trans_to_buf(buf, totallen, iov, iovcnt);
    if (ret <= 0) {
#ifdef LOSCFG_KERNEL_VM
        LOS_VFree(buf);
#else
        free(buf);
#endif
        return VFS_ERROR;
    }
 
    bytestowrite = (ssize_t)ret;
    totalbyteswritten = (offset == NULL) ? write(fd, buf, bytestowrite)
                                         : pwrite(fd, buf, bytestowrite, *offset);
#ifdef LOSCFG_KERNEL_VM
    LOS_VFree(buf);
#else
    free(buf);
#endif
    return totalbyteswritten;
}

函数调用图:

这是这个函数的调用关系图:

writev()

ssize_t writev	(	int	fd,
		const struct iovec *	iov,
		int	iovcnt
	)

在文件 vfs_writev.c 第 136 行定义.

{
    return vfs_writev(fd, iov, iovcnt, NULL);
}

函数调用图:

这是这个函数的调用关系图: