vvfat: unify and correct computation of sector count

[qemu.git] / iov.c

/*
 * Helpers for getting linearized buffers from iov / filling buffers into iovs
 *
 * Copyright IBM, Corp. 2007, 2008
 * Copyright (C) 2010 Red Hat, Inc.
 *
 * Author(s):
 *  Anthony Liguori <aliguori@us.ibm.com>
 *  Amit Shah <amit.shah@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 */

#include "iov.h"

size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
                    const void *buf, size_t iov_off, size_t size)
{
    size_t iovec_off, buf_off;
    unsigned int i;

    iovec_off = 0;
    buf_off = 0;
    for (i = 0; i < iov_cnt && size; i++) {
        if (iov_off < (iovec_off + iov[i].iov_len)) {
            size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off, size);

            memcpy(iov[i].iov_base + (iov_off - iovec_off), buf + buf_off, len);

            buf_off += len;
            iov_off += len;
            size -= len;
        }
        iovec_off += iov[i].iov_len;
    }
    return buf_off;
}

size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
                  void *buf, size_t iov_off, size_t size)
{
    uint8_t *ptr;
    size_t iovec_off, buf_off;
    unsigned int i;

    ptr = buf;
    iovec_off = 0;
    buf_off = 0;
    for (i = 0; i < iov_cnt && size; i++) {
        if (iov_off < (iovec_off + iov[i].iov_len)) {
            size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);

            memcpy(ptr + buf_off, iov[i].iov_base + (iov_off - iovec_off), len);

            buf_off += len;
            iov_off += len;
            size -= len;
        }
        iovec_off += iov[i].iov_len;
    }
    return buf_off;
}

size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt,
                 size_t iov_off, size_t size)
{
    size_t iovec_off, buf_off;
    unsigned int i;

    iovec_off = 0;
    buf_off = 0;
    for (i = 0; i < iov_cnt && size; i++) {
        if (iov_off < (iovec_off + iov[i].iov_len)) {
            size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);

            memset(iov[i].iov_base + (iov_off - iovec_off), 0, len);

            buf_off += len;
            iov_off += len;
            size -= len;
        }
        iovec_off += iov[i].iov_len;
    }
    return buf_off;
}

size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
{
    size_t len;
    unsigned int i;

    len = 0;
    for (i = 0; i < iov_cnt; i++) {
        len += iov[i].iov_len;
    }
    return len;
}

void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
                 FILE *fp, const char *prefix, size_t limit)
{
    unsigned int i, v, b;
    uint8_t *c;

    c = iov[0].iov_base;
    for (i = 0, v = 0, b = 0; b < limit; i++, b++) {
        if (i == iov[v].iov_len) {
            i = 0; v++;
            if (v == iov_cnt) {
                break;
            }
            c = iov[v].iov_base;
        }
        if ((b % 16) == 0) {
            fprintf(fp, "%s: %04x:", prefix, b);
        }
        if ((b % 4) == 0) {
            fprintf(fp, " ");
        }
        fprintf(fp, " %02x", c[i]);
        if ((b % 16) == 15) {
            fprintf(fp, "\n");
        }
    }
    if ((b % 16) != 0) {
        fprintf(fp, "\n");
    }
}