source: mainline/uspace/lib/drv/generic/logbuf.c@ 7f620e8

/*
 * Copyright (c) 2011 Vojtech Horky
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libdrv
 * @{
 */

#include <libarch/common.h>
#include <stdio.h>
#include <ddf/log.h>
#include <assert.h>
#include <unistd.h>

/** Formatting string for printing number of not-printed items. */
#define REMAINDER_STR_FMT " (%zu)..."
/** Expected max size of the remainder string.
 * String + terminator + number width (enough for 4GB).*/
#define REMAINDER_STR_LEN (5 + 1 + 10)

/** Groups size. */
#define BUFFER_DUMP_GROUP_SIZE 4

/** Space between two items. */
#define SPACE_NORMAL " "
/** Space between two groups. */
#define SPACE_GROUP "  "

/** Dump one item into given buffer.
 *
 * @param buffer Data buffer.
 * @param item_size Size of the item (1, 2, 4).
 * @param index Index into the @p buffer (respecting @p item_size).
 * @param dump Where to store the dump.
 * @param dump_size Size of @p dump size.
 * @return Number of characters printed (see snprintf).
 */
static int dump_one_item(const void *buffer, size_t item_size, size_t index,
    char *dump, size_t dump_size)
{
        /* Determine space before the number. */
        const char *space_before;
        if (index == 0) {
                space_before = "";
        } else if ((index % BUFFER_DUMP_GROUP_SIZE) == 0) {
                space_before = SPACE_GROUP;
        } else {
                space_before = SPACE_NORMAL;
        }

        /* Let buf point to the item to be printed. */
        const uint8_t *buf = (const uint8_t *) buffer;
        buf += index * item_size;

/* Formats the dump with space before, takes care of type casting (ugly). */
#define _FORMAT(digits, bits) \
        snprintf(dump, dump_size, "%s%0" #digits PRIx##bits, \
            space_before, ((uint##bits##_t *)buf)[0]);

        switch (item_size) {
        case 4:
                return _FORMAT(8, 32);
        case 2:
                return _FORMAT(4, 16);
        default:
                return _FORMAT(2, 8);
        }
#undef _FORMAT
}

/** Count number of characters needed for dumping buffer of given size.
 *
 * @param item_size Item size in bytes.
 * @param items Number of items to print.
 * @return Number of characters the full dump would occupy.
 */
static size_t count_dump_length(size_t item_size, size_t items)
{
        size_t group_space_count = items / BUFFER_DUMP_GROUP_SIZE - 1;
        size_t normal_space_count = items - 1 - group_space_count;

        size_t dump_itself = item_size * 2 * items;
        size_t group_spaces = str_size(SPACE_GROUP) * group_space_count;
        size_t normal_spaces = str_size(SPACE_NORMAL) * normal_space_count;

        return dump_itself + group_spaces + normal_spaces;
}


/** Dumps data buffer to a string in hexadecimal format.
 *
 * Setting @p items_to_print to zero would dump the whole buffer together
 * with information how many items were omitted. Otherwise, no information
 * about omitted items is printed.
 *
 * @param dump Where to store the dumped buffer.
 * @param dump_size Size of @p dump in bytes.
 * @param buffer Data buffer to be dumped.
 * @param item_size Size of items in the @p buffer in bytes (1,2,4 allowed).
 * @param items Number of items in the @p buffer.
 * @param items_to_print How many items to actually print.
 */
void ddf_dump_buffer(char *dump, size_t dump_size,
    const void *buffer, size_t item_size, size_t items, size_t items_to_print)
{
        if ((dump_size == 0) || (dump == NULL)) {
                return;
        }
        /* We need space for one byte at least. */
        if (dump_size < 3) {
                str_cpy(dump, dump_size, "...");
                return;
        }

        /* Special cases first. */
        if (buffer == NULL) {
                str_cpy(dump, dump_size, "(null)");
                return;
        }
        if (items == 0) {
                str_cpy(dump, dump_size, "(empty)");
        }

        if (items_to_print > items) {
                items_to_print = items;
        }

        bool print_remainder = items_to_print == 0;

        /* How many available bytes we do have. */
        size_t dump_size_remaining = dump_size - 1;

        if (print_remainder) {
                /* Can't do much when user supplied small buffer. */
                if (dump_size_remaining < REMAINDER_STR_LEN) {
                        print_remainder = false;
                } else {
                        size_t needed_size = count_dump_length(item_size, items);
                        if (needed_size > dump_size_remaining) {
                                dump_size_remaining -= REMAINDER_STR_LEN;
                        } else {
                                print_remainder = false;
                        }
                }
                items_to_print = items;
        }

        str_cpy(dump, dump_size, "");

        size_t index = 0;
        while (index < items) {
                char current_item[32];
                int printed = dump_one_item(buffer, item_size, index,
                    current_item, 32);
                assert(printed >= 0);

                if ((size_t) printed > dump_size_remaining) {
                        break;
                }

                str_append(dump, dump_size, current_item);

                dump_size_remaining -= printed;
                index++;

                if (index >= items_to_print) {
                        break;
                }
        }

        if (print_remainder && (index < items)) {
                size_t s = str_size(dump);
                snprintf(dump + s, dump_size - s ,REMAINDER_STR_FMT,
                    items - index);
        }
}

/** @}
 */