iovec.h

Go to the documentation of this file.

/*
 * $Id: iovec.h 11456 2006-08-07 07:50:50Z cbiere $
 *
 * Copyright (c) 2004, Christian Biere
 *
 *----------------------------------------------------------------------
 * This file is part of gtk-gnutella.
 *
 *  gtk-gnutella is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  gtk-gnutella is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with gtk-gnutella; if not, write to the Free Software
 *  Foundation, Inc.:
 *      59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *----------------------------------------------------------------------
 */

#ifndef _lib_iovec_h_
#define _lib_iovec_h_

#include "common.h"

static inline struct iovec *
iov_alloc_n(size_t n)
{
    struct iovec *iov;

    if (n > (size_t) -1 / sizeof *iov) {
        g_assert_not_reached(); /* We don't want to handle failed allocations */
        return NULL;
    }
    iov = g_malloc(n * sizeof *iov);
    return iov;
}

static inline struct iovec
iov_get(gpointer base, size_t size)
{
    static const struct iovec zero_iov;
    struct iovec iov;

    iov = zero_iov;
    iov.iov_base = base;
    iov.iov_len = size;
    return iov;
}

static inline void
iov_reset_n(struct iovec *iov, size_t n)
{
    size_t i;

    g_assert(iov);
    for (i = 0; i < n; i++) {
        static const struct iovec zero_iov;
        iov[i] = zero_iov;
    }
}

static inline size_t 
iov_init_from_string_vector(struct iovec *iov, size_t iov_cnt,
    gchar *argv[], size_t argc)
{
    size_t i, n;

    g_assert(iov);
    g_assert(iov_cnt >= argc);
    g_assert(argv);

    n = MIN(iov_cnt, argc);
    for (i = 0; i < n; i++) {
        iov[i].iov_base = argv[i];
        iov[i].iov_len = argv[i] ? (1 + strlen(argv[i])) : 0;
    }
    return n;
}

static inline gboolean
iov_is_contiguous(const struct iovec * const a, const struct iovec * const b)
{
    g_assert(a);
    g_assert(b);

    return (size_t) a->iov_base + a->iov_len == (size_t) b->iov_base;
}

static inline size_t 
iov_contiguous_size(const struct iovec *iov, size_t iov_cnt)
{
    struct iovec iov0;
    size_t i;

    g_assert(iov);

    iov0 = iov[0];

    for (i = 1; i < iov_cnt && iov_is_contiguous(&iov0, &iov[i]); i++) {
        size_t n = iov[i].iov_len;

        if (n >= (size_t) -1 - iov0.iov_len) {
            /* Abort if size would overflow */
            iov0.iov_len = (size_t) -1;
            break;
        }
        iov0.iov_len += n;
    }
    return iov0.iov_len;
}

static inline void
iov_clear(struct iovec *iov, size_t byte_offset)
{
    g_assert(iov);
    
    if (byte_offset < iov->iov_len) {
        gchar *p = iov->iov_base;
        memset(&p[byte_offset], 0, iov->iov_len - byte_offset);
    }
}

static inline size_t
iov_calculate_size(struct iovec *iov, size_t iov_cnt)
{
    size_t size = 0;
    size_t i;

    g_assert(iov);

    for (i = 0; i < iov_cnt; i++) {
        size_t n = iov[i].iov_len;

        if (n >= (size_t) -1 - size) {
            /* Abort if size would overflow */
            size = (size_t) -1;
            break;
        }
        size += n;
    }
    return size;
}

static inline size_t
iov_scatter_string(struct iovec *iov, size_t iov_cnt, const gchar *s)
{
    size_t i, len, avail, size;

    g_assert(iov);
    g_assert(s);

    /* Reserve one byte for the trailing NUL */
    size = iov_calculate_size(iov, iov_cnt);
    len = strlen(s);
    if (len >= size) {
        len = size > 0 ? (size - 1) : 0;
    }
    avail = len;

    for (i = 0; i < iov_cnt; i++) {
        size_t n;

        n = MIN(iov[i].iov_len, avail);
        memmove(iov[i].iov_base, s, n);
        avail -= n;
        s += n;
        if (0 == avail) {
            iov_clear(&iov[i], n);
            i++;
            break;
        }
    }
    while (i < iov_cnt) {
        iov_clear(&iov[i], 0);
        i++;
    }
    return len;
}

#endif /* _lib_iovec_h_ */
/* vi: set ts=4 sw=4 cindent: */

---