git-lfs support

src/libfetchers/git-lfs-fetch.hh

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+#include <array>
+#include <cstdlib>
+#include <curl/curl.h>
+#include <filesystem>
+#include <fstream>
+#include <git2.h>
+#include <iostream>
+#include <memory>
+#include <nlohmann/json.hpp>
+#include <sstream>
+#include <stdexcept>
+#include <string>
+
+namespace fs = std::filesystem;
+
+namespace lfs {
+
+// git-lfs metadata about a file
+struct Md {
+  std::string path; // fs path relative to repo root, no ./ prefix
+  std::string oid; // git-lfs managed object id. you give this to the lfs server
+                   // for downloads
+  size_t size;     // in bytes
+};
+
+std::string exec_command(const std::string &cmd) {
+  std::cout << cmd << std::endl;
+  std::string data;
+  std::array<char, 256> buffer;
+  std::string result;
+  std::unique_ptr<FILE, decltype(&pclose)> pipe(popen(cmd.c_str(), "r"),
+                                                pclose);
+  if (!pipe) {
+    throw std::runtime_error("popen() failed!");
+  }
+  while (fgets(buffer.data(), buffer.size(), pipe.get()) != nullptr) {
+    result += buffer.data();
+  }
+  if (result.back() == '\n') {
+    result.pop_back();
+  }
+  return result;
+}
+
+std::string get_lfs_api_token(const std::string &host,
+                              const std::string &path) {
+  std::string command =
+      "ssh git@" + host + " git-lfs-authenticate " + path + " download";
+  std::string output = exec_command(command);
+  std::string res;
+
+  if (!output.empty()) {
+    nlohmann::json query_resp = nlohmann::json::parse(output);
+    res = query_resp["header"]["Authorization"].get<std::string>();
+  }
+
+  return res;
+}
+
+std::tuple<std::string, std::string, std::string>
+get_lfs_endpoint_url(git_repository *repo) {
+  int err;
+  git_config *config = nullptr;
+  // using git_repository_config instead of _snapshot makes the
+  // git_config_get_string call fail why????
+  if (git_repository_config_snapshot(&config, repo) < 0) {
+    // Handle error if necessary
+    git_config_free(config);
+    std::cerr << "no config" << std::endl;
+    return {"", "", ""};
+  }
+
+  const char *url_c_str;
+  err = git_config_get_string(&url_c_str, config, "remote.origin.url");
+  if (err < 0) {
+    // Handle error if necessary
+    std::cerr << "no remote.origin.url: " << err << std::endl;
+    git_config_free(config);
+    return {"", "", ""};
+  }
+  std::string url = std::string(url_c_str);
+  std::cerr << "url_c_str: " << url_c_str << std::endl;
+
+  if (url.back() == '/') {
+    url.pop_back();
+  }
+
+  // idk what this was for man
+  // if (url.compare(url.length() - 4, 4, ".git") != 0) {
+  // url += "/info/lfs";
+  //} else {
+  //    url += ".git/info/lfs";
+  //}
+
+  // Parse the URL
+  std::string scheme, host, path;
+  if (url.find("https://") != 0) {
+    size_t at_pos = url.find('@');
+    if (at_pos != std::string::npos) {
+      host = url.substr(at_pos + 1);
+      size_t colon_pos = host.find(':');
+      path = host.substr(colon_pos + 1);
+      host = host.substr(0, colon_pos);
+      scheme = "https";
+      url = scheme + "://" + host + "/" + path;
+    }
+  }
+
+  return std::make_tuple(url, host, path);
+}
+
+std::string git_attr_value_to_string(git_attr_value_t value) {
+  switch (value) {
+  case GIT_ATTR_VALUE_UNSPECIFIED:
+    return "GIT_ATTR_VALUE_UNSPECIFIED";
+  case GIT_ATTR_VALUE_TRUE:
+    return "GIT_ATTR_VALUE_TRUE";
+  case GIT_ATTR_VALUE_FALSE:
+    return "GIT_ATTR_VALUE_FALSE";
+  case GIT_ATTR_VALUE_STRING:
+    return "GIT_ATTR_VALUE_STRING";
+  default:
+    return "Unknown value";
+  }
+}
+
+std::unique_ptr<std::vector<std::string>> find_lfs_files(git_repository *repo) {
+  git_index *index;
+  int error;
+  error = git_repository_index(&index, repo);
+  if (error < 0) {
+    const git_error *e = git_error_last();
+    std::cerr << "Error reading index: " << e->message << std::endl;
+    git_repository_free(repo);
+    return nullptr;
+  }
+
+  std::unique_ptr<std::vector<std::string>> out =
+      std::make_unique<std::vector<std::string>>();
+  size_t entry_count = git_index_entrycount(index);
+  for (size_t i = 0; i < entry_count; ++i) {
+    const git_index_entry *entry = git_index_get_byindex(index, i);
+    if (entry) {
+      const char *value;
+      if (git_attr_get(&value, repo, GIT_ATTR_CHECK_INDEX_ONLY, entry->path,
+                       "filter") == 0) {
+        auto value_type = git_attr_value(value);
+        if (value_type == GIT_ATTR_VALUE_STRING && strcmp(value, "lfs") == 0) {
+          out->push_back(entry->path);
+        }
+      }
+    }
+  }
+  return out;
+}
+
+std::string get_obj_content(git_repository *repo, std::string path) {
+  // Get the HEAD commit
+  git_object *obj = nullptr;
+  if (git_revparse_single(&obj, repo, "HEAD^{commit}") != 0) {
+    std::cerr << "Failed to find HEAD" << std::endl;
+    return "";
+  }
+
+  git_commit *commit = nullptr;
+  git_commit_lookup(&commit, repo, git_object_id(obj));
+  git_object_free(obj);
+
+  git_tree *tree = nullptr;
+  if (git_commit_tree(&tree, commit) != 0) {
+    std::cerr << "Failed to get tree from commit" << std::endl;
+    git_commit_free(commit);
+    return "";
+  }
+
+  git_tree_entry *entry;
+  if (git_tree_entry_bypath(&entry, tree, path.c_str()) != 0) {
+    std::cerr << "Failed to find " << path << " in the tree" << std::endl;
+    git_tree_free(tree);
+    git_commit_free(commit);
+    return "";
+  }
+
+  git_blob *blob = nullptr;
+  if (git_blob_lookup(&blob, repo, git_tree_entry_id(entry)) != 0) {
+    std::cerr << "Failed to lookup blob" << std::endl;
+    git_tree_entry_free(
+        const_cast<git_tree_entry *>(entry)); // Free entry after use
+    git_tree_free(tree);
+    git_commit_free(commit);
+    return "";
+  }
+
+  auto content = git_blob_rawcontent(blob);
+  git_object_free(obj);
+  git_tree_free(tree);
+  git_commit_free(commit);
+
+  // is this copy elided? i wont pretend to understand
+  // https://en.cppreference.com/w/cpp/language/copy_elision
+  return std::string(static_cast<const char *>(content));
+}
+
+std::tuple<std::string, size_t> parse_lfs_metadata(const std::string &content) {
+  std::istringstream iss(content);
+  std::string line;
+  std::string oid;
+  size_t size = 0;
+
+  while (getline(iss, line)) {
+    std::size_t pos = line.find("oid sha256:");
+    if (pos != std::string::npos) {
+      oid = line.substr(pos + 11); // Extract hash after "oid sha256:"
+      continue;
+    }
+
+    pos = line.find("size ");
+    if (pos != std::string::npos) {
+      std::string sizeStr =
+          line.substr(pos + 5); // Extract size number after "size "
+      size = std::stol(sizeStr);
+      continue;
+    }
+  }
+
+  return std::make_tuple(oid, size);
+}
+
+// path, oid, size
+std::vector<Md> parse_lfs_files(git_repository *repo) {
+  const auto files = find_lfs_files(repo);
+  std::vector<Md> out;
+  for (const auto &file : *files) {
+    std::cerr << file;
+    auto content = get_obj_content(repo, file);
+    auto [oid, size] = parse_lfs_metadata(content);
+    out.push_back(Md{file, oid, size});
+  }
+
+  return out;
+}
+
+static size_t WriteCallback(void *contents, size_t size, size_t nmemb,
+                            std::string *s) {
+  size_t newLength = size * nmemb;
+  try {
+    s->append((char *)contents, newLength);
+  } catch (std::bad_alloc &e) {
+    // Handle memory bad_alloc error
+    return 0;
+  }
+  return newLength;
+}
+
+nlohmann::json oids_to_payload(const std::vector<Md> &items) {
+  nlohmann::json j_array = nlohmann::json::array();
+  for (const auto &md : items) {
+    j_array.push_back({{"oid", md.oid}, {"size", md.size}});
+  }
+  return j_array;
+}
+
+std::vector<nlohmann::json> fetch_urls(const std::string &lfs_url,
+                                       const std::string &token,
+                                       const std::vector<Md> &metadatas) {
+  std::vector<nlohmann::json> objects;
+
+  nlohmann::json oid_list = oids_to_payload(metadatas);
+  nlohmann::json data = {
+      {"operation", "download"},
+  };
+  data["objects"] = oid_list;
+  auto data_str = data.dump();
+  std::cerr << "data_str: " + data_str << std::endl;
+
+  CURL *curl = curl_easy_init();
+  std::string response_string;
+  std::string header_string;
+  auto lfs_url_batch = lfs_url + "/info/lfs/objects/batch";
+  curl_easy_setopt(curl, CURLOPT_URL, lfs_url_batch.c_str());
+  curl_easy_setopt(curl, CURLOPT_POSTFIELDS, data_str.c_str());
+
+  // Set headers
+  struct curl_slist *headers = NULL;
+  auto auth_header = "Authorization: " + token;
+  headers = curl_slist_append(headers, auth_header.c_str());
+  headers =
+      curl_slist_append(headers, "Content-Type: application/vnd.git-lfs+json");
+  headers = curl_slist_append(headers, "Accept: application/vnd.git-lfs+json");
+  curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+  curl_easy_setopt(curl, CURLOPT_POST, 1L);
+  curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);
+  curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteCallback);
+  curl_easy_setopt(curl, CURLOPT_WRITEDATA, &response_string);
+
+  CURLcode res = curl_easy_perform(curl);
+  // Check for errors
+  if (res != CURLE_OK)
+    fprintf(stderr, "curl_easy_perform() failed: %s\n",
+            curl_easy_strerror(res));
+
+  curl_easy_cleanup(curl);
+  curl_slist_free_all(headers);
+
+  try {
+    std::cerr << "resp: " << response_string << std::endl;
+    // example resp here:
+    // {"objects":[{"oid":"f5e02aa71e67f41d79023a128ca35bad86cf7b6656967bfe0884b3a3c4325eaf","size":10000000,"actions":{"download":{"href":"https://gitlab.com/b-camacho/test-lfs.git/gitlab-lfs/objects/f5e02aa71e67f41d79023a128ca35bad86cf7b6656967bfe0884b3a3c4325eaf","header":{"Authorization":"Basic
+    // Yi1jYW1hY2hvOmV5SjBlWEFpT2lKS1YxUWlMQ0poYkdjaU9pSklVekkxTmlKOS5leUprWVhSaElqcDdJbUZqZEc5eUlqb2lZaTFqWVcxaFkyaHZJbjBzSW1wMGFTSTZJbUptTURZNFpXVTFMVEprWmpVdE5HWm1ZUzFpWWpRMExUSXpNVEV3WVRReU1qWmtaaUlzSW1saGRDSTZNVGN4TkRZeE16ZzBOU3dpYm1KbUlqb3hOekUwTmpFek9EUXdMQ0psZUhBaU9qRTNNVFEyTWpFd05EVjkuZk9yMDNkYjBWSTFXQzFZaTBKRmJUNnJTTHJPZlBwVW9lYllkT0NQZlJ4QQ=="}}},"authenticated":true}]}
+    auto resp = nlohmann::json::parse(response_string);
+    if (resp.contains("objects")) {
+      objects.insert(objects.end(), resp["objects"].begin(),
+                     resp["objects"].end());
+    } else {
+      throw std::runtime_error("Response does not contain 'objects'");
+    }
+  } catch (std::exception &e) {
+    std::cerr << "Failed to parse JSON or invalid response: " << e.what()
+              << std::endl;
+  }
+
+  return objects;
+}
+
+static size_t WriteData(void *ptr, size_t size, size_t nmemb, void *stream) {
+  size_t written = fwrite(ptr, size, nmemb, (FILE *)stream);
+  return written;
+}
+
+void download_file(const std::string &url, const std::string &auth_header,
+                   const std::string &output_filename) {
+  CURL *curl;
+  FILE *fp;
+  CURLcode res;
+
+  curl = curl_easy_init();
+  if (curl) {
+    fp = fopen(output_filename.c_str(), "wb");
+    if (fp == nullptr) {
+      std::cerr << "Failed to open file for writing: " << output_filename
+                << std::endl;
+      return;
+    }
+
+    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, WriteData);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
+    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
+
+    struct curl_slist *headers = nullptr;
+    const std::string auth_header_prepend = "Authorization: " + auth_header;
+    headers = curl_slist_append(headers, auth_header_prepend.c_str());
+    curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
+
+    res = curl_easy_perform(curl);
+    if (res != CURLE_OK) {
+      std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res)
+                << std::endl;
+    }
+
+    curl_slist_free_all(headers);
+    curl_easy_cleanup(curl);
+    fclose(fp);
+  }
+}
+
+void download_files(nlohmann::json objects, std::string dir) {
+  for (auto &obj : objects) {
+    std::string oid = obj["oid"];
+    std::string url = obj["actions"]["download"]["href"];
+    std::string auth_header =
+        obj["actions"]["download"]["header"]["Authorization"];
+    download_file(url, auth_header, dir + "/" + oid);
+  }
+}
+
+// moves files from temporary download dir to final location
+void move_files(const std::vector<Md> &metadata,
+                const std::string &sourceDir, const std::string &repoRoot) {
+  namespace fs = std::filesystem;
+
+  for (const auto &md : metadata) {
+    fs::path srcFile =
+        fs::path(sourceDir) / md.oid; // Construct the source file path
+    fs::path destFile =
+        fs::path(repoRoot) / md.path; // Construct the destination file path
+
+    // Move the file
+    try {
+      fs::rename(srcFile, destFile);
+    } catch (const fs::filesystem_error &e) {
+      std::cerr << "Error moving file " << srcFile << " to " << destFile << ": "
+                << e.what() << std::endl;
+    }
+  }
+}
+
+} // namespace lfs