feat(libstore): add DELETE method support to FileTransfer

src/libfetchers/git-lfs-fetch.cc

@@ -209,7 +209,7 @@ std::vector<nlohmann::json> Fetch::fetchUrls(const std::vector<Pointer> & pointe
     auto url = api.endpoint + "/objects/batch";
     const auto & authHeader = api.authHeader;
     FileTransferRequest request(parseURL(url));
-    request.post = true;
+    request.method = HttpMethod::POST;
     Headers headers;
     if (authHeader.has_value())
         headers.push_back({"Authorization", *authHeader});

src/libstore/filetransfer.cc

@@ -384,11 +384,14 @@ struct curlFileTransfer : public FileTransfer
             if (settings.downloadSpeed.get() > 0)
                 curl_easy_setopt(req, CURLOPT_MAX_RECV_SPEED_LARGE, (curl_off_t) (settings.downloadSpeed.get() * 1024));
 
-            if (request.head)
+            if (request.method == HttpMethod::HEAD)
                 curl_easy_setopt(req, CURLOPT_NOBODY, 1);
 
+            if (request.method == HttpMethod::DELETE)
+                curl_easy_setopt(req, CURLOPT_CUSTOMREQUEST, "DELETE");
+
             if (request.data) {
-                if (request.post) {
+                if (request.method == HttpMethod::POST) {
                     curl_easy_setopt(req, CURLOPT_POST, 1L);
                     curl_easy_setopt(req, CURLOPT_POSTFIELDSIZE_LARGE, (curl_off_t) request.data->length());
                 } else {
@@ -919,6 +922,11 @@ FileTransferResult FileTransfer::upload(const FileTransferRequest & request)
     return enqueueFileTransfer(request).get();
 }
 
+FileTransferResult FileTransfer::deleteResource(const FileTransferRequest & request)
+{
+    return enqueueFileTransfer(request).get();
+}
+
 void FileTransfer::download(
     FileTransferRequest && request, Sink & sink, std::function<void(FileTransferResult)> resultCallback)
 {

src/libstore/http-binary-cache-store.cc

@@ -139,7 +139,7 @@ class HttpBinaryCacheStore : public virtual BinaryCacheStore
 
         try {
             FileTransferRequest request(makeRequest(path));
-            request.head = true;
+            request.method = HttpMethod::HEAD;
             getFileTransfer()->download(request);
             return true;
         } catch (FileTransferError & e) {

src/libstore/include/nix/store/filetransfer.hh

@@ -83,6 +83,16 @@ extern FileTransferSettings fileTransferSettings;
 
 extern const unsigned int RETRY_TIME_MS_DEFAULT;
 
+/**
+ * HTTP methods supported by FileTransfer.
+ */
+enum struct HttpMethod {
+    GET,
+    HEAD,
+    POST,
+    DELETE,
+};
+
 /**
  * Username and optional password for HTTP basic authentication.
  * These are used with curl's CURLOPT_USERNAME and CURLOPT_PASSWORD options
@@ -99,8 +109,7 @@ struct FileTransferRequest
     VerbatimURL uri;
     Headers headers;
     std::string expectedETag;
-    bool head = false;
-    bool post = false;
+    HttpMethod method = HttpMethod::GET;
     size_t tries = fileTransferSettings.tries;
     unsigned int baseRetryTimeMs = RETRY_TIME_MS_DEFAULT;
     ActivityId parentAct;
@@ -127,9 +136,23 @@ struct FileTransferRequest
     {
     }
 
+    /**
+     * Returns the verb root for logging purposes.
+     * The returned string is intended to be concatenated with "ing" to form the gerund,
+     * e.g., "download" + "ing" -> "downloading", "upload" + "ing" -> "uploading".
+     */
     std::string verb() const
     {
-        return data ? "upload" : "download";
+        switch (method) {
+        case HttpMethod::HEAD:
+        case HttpMethod::GET:
+            return "download";
+        case HttpMethod::POST:
+            return "upload";
+        case HttpMethod::DELETE:
+            return "delet";
+        }
+        unreachable();
     }
 
 private:
@@ -201,6 +224,11 @@ struct FileTransfer
      */
     FileTransferResult upload(const FileTransferRequest & request);
 
+    /**
+     * Synchronously delete a resource.
+     */
+    FileTransferResult deleteResource(const FileTransferRequest & request);
+
     /**
      * Download a file, writing its data to a sink. The sink will be
      * invoked on the thread of the caller.