连接到远程存储库并获取数据

Question

我想连接到远程存储库并从他那里获取数据。我包含并使用了 libgit2 库。这是我的代码：

const char* url = "http://address.to.repository";
git_libgit2_init();

git_repository* repo = nullptr;
git_remote* newremote = nullptr;
git_buf* buf;
git_strarray remotes = {0};


if (git_repository_init(&repo, "/tmp/gittest", false) != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_repository_init, error message : '" << lastError->message <<"'"<< std::endl;
}

if (git_remote_create_anonymous(&newremote, repo, url) != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_create_anonymous, error message : '" << lastError->message <<"'"<< std::endl;
}


if (git_remote_connect(newremote, GIT_DIRECTION_FETCH, nullptr, nullptr, nullptr) != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_connect, error message : '" << lastError->message <<"'"<< std::endl;
}

if (git_remote_connected(newremote) != 1)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_connected, error message : '" << lastError->message <<"'"<< std::endl;
}

git_remote_add_fetch(repo, "origin", "refs/heads/master:refs/heads/master");


if (git_remote_lookup(&newremote, repo, "origin") != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_lookup, error message : '" << lastError->message <<"'"<< std::endl;
}

if (git_remote_fetch(newremote, nullptr, nullptr, nullptr) != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_fetch, error message : '" << lastError->message <<"'"<< std::endl;
}

git_remote_free(newremote);
git_repository_free(repo);
git_libgit2_shutdown();

我不确定我是否做对了。现在，我有三个错误：

problem with git_remote_connect, error message : 'authentication required but no callback set'
problem with git_remote_connected, error message : 'authentication required but no callback set'
problem with git_remote_lookup, error message : 'remote 'origin' does not exist'
problem with git_remote_fetch, error message : 'authentication required but no callback set'

我不明白，如何正确连接到远程存储库并解决这些问题。因此，如果您就如何解决这些问题提供建议或分享链接，我将不胜感激。

更新

我阅读了文档并查看了主题，其中讨论了 libgit2 的不同问题。我创建了一个可以解决我的问题的函数（也许 :)）

int cred_acquire_cb(git_cred** out,
                    const char* url,
                    const char* username_from_url,
                    unsigned int allowed_types,
                    void* payload)
{
    return git_cred_userpass_plaintext_new(out, "user", "pass");
}

在主要代码中，我写：

git_remote_callbacks callback = GIT_REMOTE_CALLBACKS_INIT;
callback.credentials = cred_acquire_cb;

在互联网上，我找到了一些旧库版本的例子。现在我不明白如何在 git_remote_connect 函数中使用这个回调选项。

更新2

我试着用另一种方式做了这个：

git_strarray remotes = {0};
git_cred* cred = nullptr;
git_proxy_options opt = GIT_PROXY_OPTIONS_INIT;

if (git_cred_userpass_plaintext_new(&cred, "user", "pass") != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_cred_userpass_plaintext_new, error message : '" << lastError->message <<"'"<< std::endl;
}

if (git_remote_connect(newremote, GIT_DIRECTION_FETCH, git_cred_acquire_cb(&cred, url, "username@bitbucket.org", 1, nullptr), opt, remotes) != 0)
{
    const git_error *lastError = giterr_last();
    std::cerr << "problem with git_remote_connect, error message : '" << lastError->message <<"'"<< std::endl;
}

但是编译器告诉我下一个错误：

error: expression list treated as compound expression in functional cast [-fpermissive]
     if (git_remote_connect(newremote, GIT_DIRECTION_FETCH, git_cred_acquire_cb(&cred, url, "ableigdev@bitbucket.org", 1, nullptr), opt, remotes) != 0)

error: cannot convert ‘git_cred_acquire_cb {aka int (*)(git_cred**, const char*, const char*, unsigned int, void*)}’ to ‘const git_remote_callbacks*’ for argument ‘3’ to ‘int git_remote_connect(git_remote*, git_direction, const git_remote_callbacks*, const git_proxy_options*, const git_strarray*)’
     if (git_remote_connect(newremote, GIT_DIRECTION_FETCH, git_cred_acquire_cb(&cred, url, "ableigdev@bitbucket.org", 1, nullptr), opt, remotes) != 0)

如何解决？两种方式中哪一种更正确？

Answer 1

您要连接的遥控器要求您进行身份验证。您需要使用 git_remote_connect 的 callbacks 参数来传递 git_cred_acquire_cb（struct, for the callback 的文档）。

这将在请求身份验证以及您需要提供的身份验证 "type" 时被调用。有关详细信息（支持密码或 SSH 方法），请参阅文档的 cred 部分，以及用于构建回调应该 return.[=18= 的 git_cred 对象]

这是一个最小的例子（有意编译错误）：

int my_git_cred_cb(git_cred **cred, const char *url, const char *username_from_url, unsigned int allowed_types, void *payload)
{
    if ((allowed_type & GIT_CREDTYPE_USERPASS_PLAINTEXT) != 0) {
        return git_cred_userpass_plaintext_new(&cred, "user", "pass");
    } else {
        /* Some other kind of authentication was requested */
        return -1;
    }

    return 1; /* unable to provide authentication data */
}

void perform_fetch(git_remote *remote)
{
    git_fetch_options opts = GIT_FETCH_OPTIONS_INIT;

    opts.callbacks.credentials = my_git_cred_cb;
    opts.callbacks.payload = NULL; /* you'll get that pointer back as the payload parameter */

    return git_remote_fetch(remote, NULL, &opts, NULL);
}

请注意，您不需要执行所有步骤（即连接、检查连接），调用 git_remote_fetch 将导致建立连接，如果成功，将进行提取。

连接到远程存储库并获取数据

Connect to remote repository and fetch data

c

c++

git

libgit2