Subversion Repositories HelenOS

#include "../../srv/rd/rd.h"

/** Read data from a block device.

 *

 * @param phone     Phone to be used to communicate with the device.

 * @param buffer    Communication buffer shared with the device.

 * @param bufpos    Pointer to the first unread valid offset within the

 *          communication buffer.

 * @param buflen    Pointer to the number of unread bytes that are ready in

 *          the communication buffer.

 * @param pos       Device position to be read.

 * @param dst       Destination buffer.

 * @param size      Size of the destination buffer.

 * @param block_size    Block size to be used for the transfer.

 *

 * @return      True on success, false on failure.

 */

bool libfs_blockread(int phone, void *buffer, off_t *bufpos, size_t *buflen,

    off_t *pos, void *dst, size_t size, size_t block_size)

{

    off_t offset = 0;

    size_t left = size;

    while (left > 0) {

        size_t rd;

        if (*bufpos + left < *buflen)

            rd = left;

        else

            rd = *buflen - *bufpos;

        if (rd > 0) {

            /*

             * Copy the contents of the communication buffer to the

             * destination buffer.

             */

            memcpy(dst + offset, buffer + *bufpos, rd);

            offset += rd;

            *bufpos += rd;

            *pos += rd;

            left -= rd;

        }

        if (*bufpos == *buflen) {

            /* Refill the communication buffer with a new block. */

            ipcarg_t retval;

            int rc = async_req_2_1(phone, RD_READ_BLOCK,

                *pos / block_size, block_size, &retval);

            if ((rc != EOK) || (retval != EOK))

                return false;

            *bufpos = 0;

            *buflen = block_size;

        }

    }

    return true;

}