test/test_buffer.cpp

Tue, 04 Oct 2022 19:25:07 +0200

author
Mike Becker <universe@uap-core.de>
date
Tue, 04 Oct 2022 19:25:07 +0200
changeset 591
7df0bcaecffa
parent 569
cb63f3d1236a
permissions
-rw-r--r--

fix over-optimization of strstr

1. it's actually less performant to frequently read bytes
from an array instead of using the native word length
2. the SBO buffer should be local and not static to allow
multi-threading usage

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, Olaf Wintermann 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 COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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 "cx/buffer.h"

#include <gtest/gtest.h>
#include "util_allocator.h"

class BufferFixture : public ::testing::Test {
protected:
    void SetUp() override {
        cxBufferInit(&buf, nullptr, 16, cxDefaultAllocator, CX_BUFFER_DEFAULT);
        buf.size = 6;
        buf.pos = 3;
    }

    void TearDown() override {
        cxBufferDestroy(&buf);
    }

    CxBuffer buf{};
};

static void expect_default_flush_config(CxBuffer *buf) {
    EXPECT_EQ(buf->flush_blkmax, 0);
    EXPECT_EQ(buf->flush_blksize, 4096);
    EXPECT_EQ(buf->flush_threshold, SIZE_MAX);
    EXPECT_EQ(buf->flush_func, nullptr);
    EXPECT_EQ(buf->flush_target, nullptr);
}

TEST(BufferInit, WrapSpace) {
    CxTestingAllocator alloc;
    CxBuffer buf;
    void *space = cxMalloc(&alloc, 16);
    cxBufferInit(&buf, space, 16, &alloc, CX_BUFFER_DEFAULT);
    expect_default_flush_config(&buf);
    EXPECT_EQ(buf.space, space);
    EXPECT_EQ(buf.flags & CX_BUFFER_AUTO_EXTEND, 0);
    EXPECT_EQ(buf.flags & CX_BUFFER_FREE_CONTENTS, 0);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.capacity, 16);
    EXPECT_EQ(buf.allocator, &alloc);
    cxBufferDestroy(&buf);
    EXPECT_FALSE(alloc.verify());
    cxFree(&alloc, space);
    EXPECT_TRUE(alloc.verify());
}

TEST(BufferInit, WrapSpaceAutoExtend) {
    CxTestingAllocator alloc;
    CxBuffer buf;
    void *space = cxMalloc(&alloc, 16);
    cxBufferInit(&buf, space, 16, &alloc, CX_BUFFER_AUTO_EXTEND);
    expect_default_flush_config(&buf);
    EXPECT_EQ(buf.space, space);
    EXPECT_EQ(buf.flags & CX_BUFFER_AUTO_EXTEND, CX_BUFFER_AUTO_EXTEND);
    EXPECT_EQ(buf.flags & CX_BUFFER_FREE_CONTENTS, 0);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.capacity, 16);
    EXPECT_EQ(buf.allocator, &alloc);
    cxBufferDestroy(&buf);
    EXPECT_FALSE(alloc.verify());
    cxFree(&alloc, space);
    EXPECT_TRUE(alloc.verify());
}

TEST(BufferInit, WrapSpaceAutoFree) {
    CxTestingAllocator alloc;
    CxBuffer buf;
    void *space = cxMalloc(&alloc, 16);
    cxBufferInit(&buf, space, 16, &alloc, CX_BUFFER_FREE_CONTENTS);
    expect_default_flush_config(&buf);
    EXPECT_EQ(buf.space, space);
    EXPECT_EQ(buf.flags & CX_BUFFER_AUTO_EXTEND, 0);
    EXPECT_EQ(buf.flags & CX_BUFFER_FREE_CONTENTS, CX_BUFFER_FREE_CONTENTS);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.capacity, 16);
    EXPECT_EQ(buf.allocator, &alloc);
    EXPECT_FALSE(alloc.verify());
    cxBufferDestroy(&buf);
    EXPECT_TRUE(alloc.verify());
}

TEST(BufferInit, FreshSpace) {
    CxTestingAllocator alloc;
    CxBuffer buf;
    cxBufferInit(&buf, nullptr, 8, &alloc, CX_BUFFER_DEFAULT);
    expect_default_flush_config(&buf);
    EXPECT_NE(buf.space, nullptr);
    EXPECT_EQ(buf.flags & CX_BUFFER_AUTO_EXTEND, 0);
    EXPECT_EQ(buf.flags & CX_BUFFER_FREE_CONTENTS, CX_BUFFER_FREE_CONTENTS);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(buf.allocator, &alloc);
    EXPECT_FALSE(alloc.verify()); // space is still allocated
    cxBufferDestroy(&buf);
    EXPECT_TRUE(alloc.verify());
}

class BufferShiftFixture : public ::testing::Test {
protected:
    void SetUp() override {
        ASSERT_TRUE(alloc.verify());
        cxBufferInit(&buf, nullptr, 16, &alloc, CX_BUFFER_DEFAULT);
        memcpy(buf.space, "test____________", 16);
        buf.capacity = 8; // purposely pretend that the buffer has less capacity s.t. we can test beyond the range
        buf.pos = 4;
        buf.size = 4;
    }

    void TearDown() override {
        cxBufferDestroy(&buf);
        EXPECT_TRUE(alloc.verify());
    }

    CxTestingAllocator alloc;
    CxBuffer buf{};
};

class BufferShiftLeft : public BufferShiftFixture {
};

TEST_F(BufferShiftLeft, Zero) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShiftLeft(&buf, 0);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftLeft, ZeroOffsetInterface) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShift(&buf, -0);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftLeft, Standard) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShiftLeft(&buf, 2);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 2);
    EXPECT_EQ(buf.size, 2);
    EXPECT_TRUE(memcmp(buf.space, "stst________", 8) == 0);
}

TEST_F(BufferShiftLeft, Overshift) {
    ASSERT_LT(buf.pos, 6);
    ASSERT_LT(buf.size, 6);
    int ret = cxBufferShiftLeft(&buf, 6);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftLeft, OvershiftPosOnly) {
    buf.pos = 2;
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShiftLeft(&buf, 3);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 1);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftLeft, OffsetInterface) {
    buf.pos = 3;
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShift(&buf, -2);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 1);
    EXPECT_EQ(buf.size, 2);
    EXPECT_TRUE(memcmp(buf.space, "stst________", 8) == 0);
}

class BufferShiftRight : public BufferShiftFixture {
};

TEST_F(BufferShiftRight, Zero) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShiftRight(&buf, 0);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftRight, ZeroOffsetInterface) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShift(&buf, +0);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_TRUE(memcmp(buf.space, "test________", 8) == 0);
}

TEST_F(BufferShiftRight, Standard) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShiftRight(&buf, 3);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 7);
    EXPECT_EQ(buf.size, 7);
    EXPECT_TRUE(memcmp(buf.space, "testest_____", 8) == 0);
}

TEST_F(BufferShiftRight, OvershiftDiscard) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    ASSERT_EQ(buf.capacity, 8);
    int ret = cxBufferShiftRight(&buf, 6);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_TRUE(memcmp(buf.space, "test__te____", 8) == 0);
}

TEST_F(BufferShiftRight, OvershiftExtend) {
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    ASSERT_EQ(buf.capacity, 8);
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    int ret = cxBufferShiftRight(&buf, 6);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 10);
    EXPECT_EQ(buf.size, 10);
    EXPECT_GE(buf.capacity, 10);
    EXPECT_TRUE(memcmp(buf.space, "test__test__", 8) == 0);
}

TEST_F(BufferShiftRight, OffsetInterface) {
    buf.pos = 3;
    ASSERT_EQ(buf.size, 4);
    int ret = cxBufferShift(&buf, 2);
    EXPECT_EQ(ret, 0);
    EXPECT_EQ(buf.pos, 5);
    EXPECT_EQ(buf.size, 6);
    EXPECT_TRUE(memcmp(buf.space, "tetest______", 8) == 0);
}

TEST(BufferMinimumCapacity, Sufficient) {
    CxTestingAllocator alloc;
    auto space = cxMalloc(&alloc, 8);
    CxBuffer buf;
    cxBufferInit(&buf, space, 8, &alloc, CX_BUFFER_FREE_CONTENTS);
    memcpy(space, "Testing", 8);
    buf.size = 8;
    cxBufferMinimumCapacity(&buf, 6);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(buf.size, 8);
    EXPECT_TRUE(memcmp(buf.space, "Testing", 8) == 0);
    cxBufferDestroy(&buf);
    EXPECT_TRUE(alloc.verify());
}

TEST(BufferMinimumCapacity, Extend) {
    CxTestingAllocator alloc;
    auto space = cxMalloc(&alloc, 8);
    CxBuffer buf;
    cxBufferInit(&buf, space, 8, &alloc, CX_BUFFER_FREE_CONTENTS); // NO auto extend!
    memcpy(space, "Testing", 8);
    buf.size = 8;
    cxBufferMinimumCapacity(&buf, 16);
    EXPECT_EQ(buf.capacity, 16);
    EXPECT_EQ(buf.size, 8);
    EXPECT_TRUE(memcmp(buf.space, "Testing", 8) == 0);
    cxBufferDestroy(&buf);
    EXPECT_TRUE(alloc.verify());
}

TEST(BufferClear, Test) {
    char space[16];
    strcpy(space, "clear test");
    CxBuffer buf;
    cxBufferInit(&buf, space, 16, cxDefaultAllocator, CX_BUFFER_DEFAULT);
    ASSERT_EQ(buf.size, 0);
    // only clear the used part of the buffer
    cxBufferClear(&buf);
    EXPECT_EQ(memcmp(space, "clear test", 10), 0);
    buf.size = 5;
    buf.pos = 3;
    cxBufferClear(&buf);
    EXPECT_EQ(memcmp(space, "\0\0\0\0\0 test", 10), 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.pos, 0);
    cxBufferDestroy(&buf);
}

class BufferWrite : public ::testing::Test {
protected:
    CxBuffer buf{}, target{};

    void SetUp() override {
        cxBufferInit(&target, nullptr, 16, cxDefaultAllocator, CX_BUFFER_AUTO_EXTEND);
        cxBufferInit(&buf, nullptr, 16, cxDefaultAllocator, CX_BUFFER_DEFAULT);
        buf.capacity = 8; // artificially reduce capacity to check OOB writes
        memset(buf.space, 0, 16);
        memcpy(buf.space, "prep", 4);
        buf.size = buf.pos = 4;
    }

    void TearDown() override {
        cxBufferDestroy(&buf);
        cxBufferDestroy(&target);
    }

    void enableFlushing() {
        buf.flush_target = &target;
        buf.flush_func = reinterpret_cast<cx_write_func>(cxBufferWrite);
        buf.flush_blkmax = 1;
    }
};

static size_t mock_write_limited_rate(
        void const *ptr,
        size_t size,
        __attribute__((unused)) size_t nitems,
        CxBuffer *buffer
) {
    // simulate limited target drain capacity
    static bool full = false;
    if (full) {
        full = false;
        return 0;
    } else {
        full = true;
        return cxBufferWrite(ptr, size, nitems > 2 ? 2 : nitems, buffer);
    }
}

TEST_F(BufferWrite, SizeOneFit) {
    const char *data = "test";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 1, 4, &buf);
    EXPECT_EQ(written, 4);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "preptest", 8), 0);
}

TEST_F(BufferWrite, SizeOneDiscard) {
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 1, 7, &buf);
    EXPECT_EQ(written, 4);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "preptest\0", 9), 0);
}

TEST_F(BufferWrite, SizeOneExtend) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 1, 7, &buf);
    EXPECT_EQ(written, 7);
    EXPECT_EQ(buf.size, 11);
    EXPECT_EQ(buf.pos, 11);
    EXPECT_GE(buf.capacity, 11);
    EXPECT_EQ(memcmp(buf.space, "preptesting", 11), 0);
}

TEST_F(BufferWrite, MultibyteFit) {
    const char *data = "test";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 2, 2, &buf);
    EXPECT_EQ(written, 2);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "preptest", 8), 0);
}

TEST_F(BufferWrite, MultibyteDiscard) {
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.size, 4);
    buf.pos = 3;
    size_t written = cxBufferWrite(data, 2, 4, &buf);
    // remember: whole elements are discarded if they do not fit
    EXPECT_EQ(written, 2);
    EXPECT_EQ(buf.size, 7);
    EXPECT_EQ(buf.pos, 7);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "pretest\0", 8), 0);
}

TEST_F(BufferWrite, MultibyteExtend) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    const char *data = "tester";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.size, 4);
    buf.pos = 3;
    size_t written = cxBufferWrite(data, 2, 3, &buf);
    // remember: whole elements are discarded if they do not fit
    EXPECT_EQ(written, 3);
    EXPECT_EQ(buf.size, 9);
    EXPECT_EQ(buf.pos, 9);
    EXPECT_GE(buf.capacity, 9);
    EXPECT_EQ(memcmp(buf.space, "pretester", 9), 0);
}

TEST_F(BufferWrite, PutcWrapperFit) {
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    int c = cxBufferPut(&buf, 0x200 | 'a');
    EXPECT_EQ(c, 'a');
    EXPECT_EQ(buf.size, 5);
    EXPECT_EQ(buf.pos, 5);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "prepa\0", 6), 0);
}

TEST_F(BufferWrite, PutcWrapperDiscard) {
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.size, 4);
    buf.pos = 8;
    int c = cxBufferPut(&buf, 0x200 | 'a');
    EXPECT_EQ(c, EOF);
    EXPECT_EQ(buf.size, 4);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "prep\0\0\0\0\0", 9), 0);
}

TEST_F(BufferWrite, PutcWrapperExtend) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.size, 4);
    buf.pos = 8;
    int c = cxBufferPut(&buf, 0x200 | 'a');
    EXPECT_EQ(c, 'a');
    EXPECT_EQ(buf.size, 9);
    EXPECT_EQ(buf.pos, 9);
    EXPECT_GE(buf.capacity, 9);
    EXPECT_EQ(memcmp(buf.space, "prep\0\0\0\0a", 9), 0);
}

TEST_F(BufferWrite, PutStringWrapperFit) {
    const char *data = "test";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferPutString(&buf, data);
    EXPECT_EQ(written, 4);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "preptest", 8), 0);
}

TEST_F(BufferWrite, PutStringWrapperDiscard) {
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferPutString(&buf, data);
    EXPECT_EQ(written, 4);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 8);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, "preptest\0", 9), 0);
}

TEST_F(BufferWrite, PutStringWrapperExtend) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferPutString(&buf, data);
    EXPECT_EQ(written, 7);
    EXPECT_EQ(buf.size, 11);
    EXPECT_EQ(buf.pos, 11);
    EXPECT_GE(buf.capacity, 11);
    EXPECT_EQ(memcmp(buf.space, "preptesting", 11), 0);
}

TEST_F(BufferWrite, MultOverflow) {
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 8, SIZE_MAX / 4, &buf);
    EXPECT_EQ(written, 0);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_EQ(memcmp(buf.space, "prep\0", 5), 0);
}

TEST_F(BufferWrite, MaxCapaOverflow) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    const char *data = "testing";
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    ASSERT_EQ(buf.size, 4);
    size_t written = cxBufferWrite(data, 1, SIZE_MAX - 2, &buf);
    EXPECT_EQ(written, 0);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(buf.pos, 4);
    EXPECT_EQ(buf.size, 4);
    EXPECT_EQ(memcmp(buf.space, "prep\0", 5), 0);
}

TEST_F(BufferWrite, OnlyOverwrite) {
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    ASSERT_EQ(buf.capacity, 8);
    memcpy(buf.space, "preptest", 8);
    buf.pos = 3;
    buf.size = 8;
    size_t written = cxBufferWrite("XXX", 2, 2, &buf);
    EXPECT_EQ(written, 2);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(buf.size, 8);
    EXPECT_EQ(buf.pos, 7);
    EXPECT_EQ(memcmp(buf.space, "preXXX\0t", 8), 0);
}

TEST_F(BufferWrite, FlushAtCapacity) {
    enableFlushing();
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    size_t written = cxBufferWrite("foo", 1, 3, &buf);
    EXPECT_EQ(written, 3);
    ASSERT_EQ(buf.pos, 7);
    ASSERT_EQ(buf.size, 7);
    ASSERT_EQ(target.pos, 0);
    ASSERT_EQ(target.size, 0);
    written = cxBufferWrite("hello", 1, 5, &buf);
    EXPECT_EQ(written, 5);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(target.pos, 12);
    ASSERT_EQ(target.size, 12);
    EXPECT_EQ(memcmp(target.space, "prepfoohello", 12), 0);
}

TEST_F(BufferWrite, FlushAtThreshold) {
    enableFlushing();
    buf.flush_threshold = 12;
    buf.flags |= CX_BUFFER_AUTO_EXTEND;
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    size_t written = cxBufferWrite("foobar", 1, 6, &buf);
    EXPECT_EQ(written, 6);
    ASSERT_EQ(buf.pos, 10);
    ASSERT_EQ(buf.size, 10);
    ASSERT_GE(buf.capacity, 10);
    ASSERT_LE(buf.capacity, 12);
    ASSERT_EQ(target.pos, 0);
    ASSERT_EQ(target.size, 0);
    written = cxBufferWrite("hello", 1, 5, &buf);
    EXPECT_EQ(written, 5);
    EXPECT_EQ(buf.pos, 0);
    EXPECT_EQ(buf.size, 0);
    EXPECT_LE(buf.capacity, 12);
    EXPECT_EQ(target.pos, 15);
    ASSERT_EQ(target.size, 15);
    EXPECT_EQ(memcmp(target.space, "prepfoobarhello", 15), 0);
}

TEST_F(BufferWrite, FlushRateLimited) {
    enableFlushing();
    // limit the rate of the flush function and the capacity of the target
    target.capacity = 16;
    target.flags &= ~CX_BUFFER_AUTO_EXTEND;
    buf.flush_func = (cx_write_func) mock_write_limited_rate;
    ASSERT_EQ(buf.capacity, 8);
    ASSERT_EQ(buf.pos, 4);
    size_t written = cxBufferWrite("foo", 1, 3, &buf);
    EXPECT_EQ(written, 3);
    ASSERT_EQ(buf.pos, 7);
    ASSERT_EQ(buf.size, 7);
    ASSERT_EQ(target.pos, 0);
    ASSERT_EQ(target.size, 0);
    written = cxBufferWrite("hello, world!", 1, 13, &buf);
    // " world!" fits into this buffer, the remaining stuff is flushed out
    EXPECT_EQ(written, 13);
    EXPECT_EQ(buf.pos, 7);
    EXPECT_EQ(buf.size, 7);
    EXPECT_EQ(buf.capacity, 8);
    EXPECT_EQ(memcmp(buf.space, " world!", 7), 0);
    EXPECT_EQ(target.pos, 13);
    ASSERT_EQ(target.size, 13);
    EXPECT_EQ(target.capacity, 16);
    EXPECT_EQ(memcmp(target.space, "prepfoohello,", 13), 0);
}

class BufferSeek : public BufferFixture {
};

TEST_F(BufferSeek, SetZero) {
    int result = cxBufferSeek(&buf, 0, SEEK_SET);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 0);
}

TEST_F(BufferSeek, SetValid) {
    int result = cxBufferSeek(&buf, 5, SEEK_SET);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 5);
}

TEST_F(BufferSeek, SetInvalid) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, 6, SEEK_SET);
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, CurZero) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, 0, SEEK_CUR);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, CurValidPositive) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, 2, SEEK_CUR);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 5);
}

TEST_F(BufferSeek, CurValidNegative) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, -3, SEEK_CUR);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 0);
}

TEST_F(BufferSeek, CurInvalidPositive) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, 3, SEEK_CUR);
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, CurInvalidNegative) {
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, -4, SEEK_CUR);
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, EndZero) {
    ASSERT_EQ(buf.size, 6);
    int result = cxBufferSeek(&buf, 0, SEEK_END);
    // the (past-the-)end position is always invalid
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, EndValid) {
    ASSERT_EQ(buf.size, 6);
    int result = cxBufferSeek(&buf, -6, SEEK_END);
    EXPECT_EQ(result, 0);
    EXPECT_EQ(buf.pos, 0);
}

TEST_F(BufferSeek, EndInvalid) {
    ASSERT_EQ(buf.size, 6);
    int result = cxBufferSeek(&buf, 1, SEEK_END);
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.pos, 3);
}

TEST_F(BufferSeek, WhenceInvalid) {
    ASSERT_EQ(buf.size, 6);
    ASSERT_EQ(buf.pos, 3);
    int result = cxBufferSeek(&buf, 2, 9000);
    EXPECT_NE(result, 0);
    EXPECT_EQ(buf.size, 6);
    EXPECT_EQ(buf.pos, 3);
}

class BufferEof : public BufferFixture {
};

TEST_F(BufferEof, Reached) {
    buf.pos = buf.size;
    EXPECT_TRUE(cxBufferEof(&buf));
    buf.pos = buf.size - 1;
    ASSERT_FALSE(cxBufferEof(&buf));
    cxBufferPut(&buf, 'a');
    EXPECT_TRUE(cxBufferEof(&buf));
}

TEST_F(BufferEof, NotReached) {
    buf.pos = buf.size - 1;
    EXPECT_FALSE(cxBufferEof(&buf));
    buf.pos = 0;
    cxBufferWrite("test", 1, 5, &buf);
    EXPECT_FALSE(cxBufferEof(&buf));
}

class BufferRead : public ::testing::Test {
protected:
    CxBuffer buf{};

    void SetUp() override {
        cxBufferInit(&buf, nullptr, 16, cxDefaultAllocator, CX_BUFFER_DEFAULT);
        buf.capacity = 8; // artificially reduce capacity to check OOB writes
        memset(buf.space, 0, 16);
        memcpy(buf.space, "some data", 9);
        buf.size = 9;
    }

    void TearDown() override {
        cxBufferDestroy(&buf);
    }
};

TEST_F(BufferRead, GetByte) {
    buf.pos = 2;
    EXPECT_EQ(cxBufferGet(&buf), 'm');
    EXPECT_EQ(cxBufferGet(&buf), 'e');
    EXPECT_EQ(cxBufferGet(&buf), ' ');
    EXPECT_EQ(cxBufferGet(&buf), 'd');
    EXPECT_EQ(buf.pos, 6);
}

TEST_F(BufferRead, GetEof) {
    buf.pos = buf.size;
    EXPECT_EQ(cxBufferGet(&buf), EOF);
}

TEST_F(BufferRead, ReadWithinBounds) {
    buf.pos = 2;
    char target[4];
    auto read = cxBufferRead(&target, 1, 4, &buf);
    ASSERT_EQ(read, 4);
    EXPECT_EQ(memcmp(&target, "me d", 4), 0);
    EXPECT_EQ(buf.pos, 6);
}

TEST_F(BufferRead, ReadOutOfBounds) {
    buf.pos = 6;
    char target[4];
    auto read = cxBufferRead(&target, 1, 4, &buf);
    ASSERT_EQ(read, 3);
    EXPECT_EQ(memcmp(&target, "ata", 3), 0);
    EXPECT_EQ(buf.pos, 9);
}

TEST_F(BufferRead, ReadOutOfBoundsMultibyte) {
    buf.pos = 6;
    char target[4];
    target[2] = '\0';
    auto read = cxBufferRead(&target, 2, 2, &buf);
    ASSERT_EQ(read, 1);
    EXPECT_EQ(memcmp(&target, "at\0", 3), 0);
    EXPECT_EQ(buf.pos, 8);
}

TEST_F(BufferRead, ReadEof) {
    buf.pos = 9;
    char target[4];
    auto read = cxBufferRead(&target, 1, 1, &buf);
    ASSERT_EQ(read, 0);
    EXPECT_EQ(buf.pos, 9);
}

mercurial