Add binary to write basic COW

    cflags: ["-Werror"],

}

cc_binary {

    name: "basic_v2_cow_writer",

    host_supported: true,

    defaults: [

        "fs_mgr_defaults",

        "libsnapshot_cow_defaults",

    ],

    srcs: ["basic_v2_cow_writer.cpp"],

    static_libs: [

        "libsnapshot_cow",

    ],

    shared_libs: [

        "libbase",

        "liblog",

    ],

    cflags: ["-Werror"],

}

#include <android-base/file.h>

#include <android-base/logging.h>

#include <libsnapshot/cow_compress.h>

#include <libsnapshot/cow_format.h>

#include <libsnapshot/cow_writer.h>

#include <filesystem>

#include "android-base/unique_fd.h"

using namespace android::snapshot;

// This writes a simple cow v2 file in the current directory. This file will serve as testdata for

// ensuring our v3 cow reader will be able to read a cow file created by the v2 writer.

//

// WARNING: We should not be overriding this test file, as it will serve as historic marker for what

// a device with old writer_v2 will write as a cow.

void write_cow_v2() {

    CowOptions options;

    options.cluster_ops = 5;

    options.num_merge_ops = 1;

    std::string data = "This is some data, believe it";

    data.resize(options.block_size, '\0');

    char cwd_buffer[1024];

    size_t cwd_buffer_size = sizeof(cwd_buffer);

    // Get the current working directory path.

    char* err = getcwd(cwd_buffer, cwd_buffer_size);

    if (!err) {

        LOG(ERROR) << "Couldn't get current directory";

    }

    android::base::unique_fd fd(open(strcat(cwd_buffer, "/cow_v2"), O_CREAT | O_RDWR, 0666));

    if (fd.get() == -1) {

        LOG(FATAL) << "couldn't open tmp_cow";

    }

    std::unique_ptr<ICowWriter> writer = CreateCowWriter(2, options, std::move(fd));

    writer->AddCopy(0, 5);

    writer->AddRawBlocks(2, data.data(), data.size());

    writer->AddLabel(1);

    writer->AddXorBlocks(50, data.data(), data.size(), 24, 10);

    writer->AddZeroBlocks(5, 10);

    writer->AddLabel(2);

    writer->Finalize();

}

int main() {

    write_cow_v2();

}