path: root/libarchive/test/test_short_writes.c

/*-
 * Copyright (c) 2021 Red Hat, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``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(S) 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.
 */
#include "test.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>

/*
 * This test checks whether things work correctly when the archive_write_callback
 * passed to archive_write_open() does a short write and only writes some of the
 * data passed in. The way the test works is that two archives are constructed
 * in parallel - one with short writes, one with full writes - and the results
 * are compared to see if they are identical.
 */

struct checker {
        struct archive *short_archive;
        char *shortbuf;
        size_t shortbuf_len;

        struct archive *full_archive;
        char *fullbuf;
        size_t fullbuf_len;
};

static ssize_t
short_write_callback(struct archive *a, void *client_data, const void *buffer, size_t length)
{
        (void)a;

        struct checker *checker = client_data;
        size_t to_write = length < 100 ? length : 100;
        size_t new_len = checker->shortbuf_len + to_write;
        char *new_buf = realloc(checker->shortbuf, new_len);
        assert(new_buf != NULL);

        checker->shortbuf = new_buf;
        memcpy(checker->shortbuf + checker->shortbuf_len, buffer, to_write);
        checker->shortbuf_len = new_len;

        return to_write;
}

static ssize_t
full_write_callback(struct archive *a, void *client_data, const void *buffer, size_t length)
{
        (void)a;

        struct checker *checker = client_data;
        size_t to_write = length;
        size_t new_len = checker->fullbuf_len + to_write;
        char *new_buf = realloc(checker->fullbuf, new_len);
        assert(new_buf != NULL);

        checker->fullbuf = new_buf;
        memcpy(checker->fullbuf + checker->fullbuf_len, buffer, to_write);
        checker->fullbuf_len = new_len;

        return to_write;
}

static struct archive *
create_archive(struct checker *checker, archive_write_callback write_cb, int buffered)
{
        struct archive *a;

        assert((a = archive_write_new()) != NULL);

        if (!buffered)
                assertEqualIntA(a, ARCHIVE_OK,
                    archive_write_set_bytes_per_block(a, 0));

        /* With the default value of bytes_in_last_block, the writing code will
         * pad out the final write to make it a full block. This causes problems
         * for us because the size of the final write can be different depending
         * on the size of previous writes, causing the "short" and "full" paths
         * to get different amounts of padding. Setting it to 1 results in no
         * padding other than that defined by the archive format. */
        assertEqualIntA(a, ARCHIVE_OK,
            archive_write_set_bytes_in_last_block(a, 1));

        /* We write a pax archive, but other formats would work fine too. */
        assertEqualIntA(a, ARCHIVE_OK,
            archive_write_set_format_pax(a));
        assertEqualIntA(a, ARCHIVE_OK,
            archive_write_add_filter_none(a));

        assertEqualIntA(a, ARCHIVE_OK,
            archive_write_open(a, checker, NULL, write_cb, NULL));

        return a;
}

static struct checker *
checker_new(int buffered)
{
        struct checker *checker;

        assert ((checker = calloc(1, sizeof *checker)) != NULL);

        checker->short_archive = create_archive(checker, short_write_callback, buffered);
        checker->full_archive = create_archive(checker, full_write_callback, buffered);

        return checker;
}

static void
checker_add_file(struct checker *checker, const char *name, char *buffer, size_t len)
{
        struct archive_entry *entry;
        assert((entry = archive_entry_new()) != NULL);

        archive_entry_set_pathname(entry, name);
        archive_entry_set_mode(entry, AE_IFREG | 0755);
        archive_entry_set_size(entry, len);

        assertEqualIntA(checker->short_archive, ARCHIVE_OK,
            archive_write_header(checker->short_archive, entry));
        assertEqualIntA(checker->short_archive, len,
            archive_write_data(checker->short_archive, buffer, len));

        assertEqualIntA(checker->full_archive, ARCHIVE_OK,
            archive_write_header(checker->full_archive, entry));
        assertEqualIntA(checker->full_archive, len,
            archive_write_data(checker->full_archive, buffer, len));

        archive_entry_free(entry);
}

static void
checker_close(struct checker *checker)
{
        assertEqualIntA(checker->short_archive, ARCHIVE_OK,
            archive_write_close(checker->short_archive));
        assertEqualIntA(checker->short_archive, ARCHIVE_OK,
            archive_write_close(checker->full_archive));
}

static void
checker_check(struct checker *checker)
{
        assertEqualInt(checker->shortbuf_len, checker->fullbuf_len);
        assert(memcmp(checker->shortbuf, checker->fullbuf, checker->fullbuf_len) == 0);
}

static void
checker_free(struct checker *checker)
{
        free(checker->shortbuf);
        free(checker->fullbuf);
        free(checker);
}

DEFINE_TEST(test_short_writes)
{
        struct checker *checker;
        uint16_t test_data[16384];
        int i;

        for (i = 0; i < 16384; i++)
                test_data[i] = i;


        /* Write a file smaller than the default buffer size (10 * 1024);
         * this will be written out at close.
         */
        checker = checker_new(1);
        checker_add_file(checker, "a", (char *)test_data, 1024);
        checker_close(checker);
        assert(checker->shortbuf_len > 1024);
        checker_check(checker);
        checker_free(checker);

        /* Write a file larger larger than twice default buffer size (10 * 1024);
         * this both fills the buffer and writes it out, and also exercises
         * the "write out full blocks directly" code path.
         */
        checker = checker_new(1);
        checker_add_file(checker, "a", (char *)test_data, 21 * 1024);
        checker_close(checker);
        assert(checker->shortbuf_len > 21 * 1024);
        checker_check(checker);
        checker_free(checker);

        /* Test unbuffered writes - a different code path.
         */
        checker = checker_new(0);
        checker_add_file(checker, "a", (char *)test_data, 1024);
        checker_close(checker);
        assert(checker->shortbuf_len > 1024);
        checker_check(checker);
        checker_free(checker);
}