Add raw snippet endpoints to support files

With the addition of multiple file support, this change
allows API requests to specify a `ref` and `file_path` in
order to get the RAW content for a specific file at a specific
commit

changelogs/unreleased/vij-update-existing-raw-snippet.yml

+---
+title: Add raw snippet repository file endpoint to API
+merge_request: 36037
+author:
+type: changed

doc/api/project_snippets.md

@@ -183,6 +183,28 @@ curl "https://gitlab.com/api/v4/projects/:id/snippets/:snippet_id/raw" \
      --header "PRIVATE-TOKEN: <your_access_token>"
 ```
 
+## Snippet repository file content
+
+Returns the raw file content as plain text.
+
+```plaintext
+GET /projects/:id/snippets/:snippet_id/files/:ref/:file_path/raw
+```
+
+Parameters:
+
+- `id` (required) - The ID or [URL-encoded path of the project](README.md#namespaced-path-encoding) owned by the authenticated user
+- `snippet_id` (required) - The ID of a project's snippet
+- `ref` (required) - The name of a branch, tag or commit e.g. master
+- `file_path` (required) - The URL-encoded path to the file, e.g. snippet%2Erb
+
+Example request:
+
+```shell
+curl "https://gitlab.com/api/v4/projects/1/snippets/2/files/master/snippet%2Erb/raw" \
+     --header "PRIVATE-TOKEN: <your_access_token>"
+```
+
 ## Get user agent details
 
 > [Introduced](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/29508) in GitLab 9.4.

doc/api/snippets.md

@@ -150,6 +150,34 @@ Example response:
 Hello World snippet
 ```
 
+## Snippet repository file content
+
+Returns the raw file content as plain text.
+
+```plaintext
+GET /snippets/:id/files/:ref/:file_path/raw
+```
+
+Parameters:
+
+| Attribute   | Type    | Required | Description                                                        |
+|:------------|:--------|:---------|:-------------------------------------------------------------------|
+| `id`        | integer | yes      | ID of snippet to retrieve                                          |
+| `ref`       | string  | yes      | Reference to a tag, branch or commit                               |
+| `file_path` | string  | yes      | URL-encoded path to the file                                       |
+
+Example request:
+
+```shell
+curl --header "PRIVATE-TOKEN: <your_access_token>" "https://gitlab.example.com/api/v4/snippets/1/files/master/snippet%2Erb/raw"
+```
+
+Example response:
+
+```plaintext
+Hello World snippet
+```
+
 ## Create new snippet
 
 Create a new snippet.

lib/api/helpers/snippets_helpers.rb

@@ -3,15 +3,37 @@
 module API
   module Helpers
     module SnippetsHelpers
+      extend Grape::API::Helpers
+
+      params :raw_file_params do
+        requires :file_path, type: String, file_path: true, desc: 'The url encoded path to the file, e.g. lib%2Fclass%2Erb'
+        requires :ref, type: String, desc: 'The name of branch, tag or commit'
+      end
+
       def content_for(snippet)
         if snippet.empty_repo?
+          env['api.format'] = :txt
+          content_type 'text/plain'
+          header['Content-Disposition'] = 'attachment'
+
           snippet.content
         else
           blob = snippet.blobs.first
-          blob.load_all_data!
-          blob.data
+
+          send_git_blob(blob.repository, blob)
         end
       end
+
+      def file_content_for(snippet)
+        repo = snippet.repository
+        commit = repo.commit(params[:ref])
+        not_found!('Reference') unless commit
+
+        blob = repo.blob_at(commit.sha, params[:file_path])
+        not_found!('File') unless blob
+
+        send_git_blob(repo, blob)
+      end
     end
   end
 end

lib/api/project_snippets.rb

@@ -147,10 +147,19 @@ module API
         snippet = snippets_for_current_user.find_by(id: params[:snippet_id])
         not_found!('Snippet') unless snippet
 
-        env['api.format'] = :txt
-        content_type 'text/plain'
         present content_for(snippet)
       end
+
+      desc 'Get raw project snippet file contents from the repository'
+      params do
+        use :raw_file_params
+      end
+      get ":id/snippets/:snippet_id/files/:ref/:file_path/raw", requirements: { file_path: API::NO_SLASH_URL_PART_REGEX } do
+        snippet = snippets_for_current_user.find_by(id: params[:snippet_id])
+        not_found!('Snippet') unless snippet&.repo_exists?
+
+        present file_content_for(snippet)
+      end
       # rubocop: enable CodeReuse/ActiveRecord
 
       desc 'Get the user agent details for a project snippet' do

lib/api/snippets.rb

@@ -155,14 +155,22 @@ module API
       end
       get ":id/raw" do
         snippet = snippets.find_by_id(params.delete(:id))
-        break not_found!('Snippet') unless snippet
+        not_found!('Snippet') unless snippet
 
-        env['api.format'] = :txt
-        content_type 'text/plain'
-        header['Content-Disposition'] = 'attachment'
         present content_for(snippet)
       end
 
+      desc 'Get raw snippet file contents from the repository'
+      params do
+        use :raw_file_params
+      end
+      get ":id/files/:ref/:file_path/raw", requirements: { file_path: API::NO_SLASH_URL_PART_REGEX } do
+        snippet = snippets.find_by_id(params.delete(:id))
+        not_found!('Snippet') unless snippet&.repo_exists?
+
+        present file_content_for(snippet)
+      end
+
       desc 'Get the user agent details for a snippet' do
         success Entities::UserAgentDetail
       end

spec/requests/api/project_snippets_spec.rb

@@ -474,4 +474,12 @@ RSpec.describe API::ProjectSnippets do
       subject { get api("/projects/#{snippet.project.id}/snippets/#{snippet.id}/raw", snippet.author) }
     end
   end
+
+  describe 'GET /projects/:project_id/snippets/:id/files/:ref/:file_path/raw' do
+    let_it_be(:snippet) { create(:project_snippet, :repository, author: admin, project: project) }
+
+    it_behaves_like 'raw snippet files' do
+      let(:api_path) { "/projects/#{snippet.project.id}/snippets/#{snippet_id}/files/#{ref}/#{file_path}/raw" }
+    end
+  end
 end

spec/requests/api/snippets_spec.rb

@@ -107,12 +107,7 @@ RSpec.describe API::Snippets do
 
       expect(response).to have_gitlab_http_status(:ok)
       expect(response.media_type).to eq 'text/plain'
-    end
-
-    it 'forces attachment content disposition' do
-      get api("/snippets/#{snippet.id}/raw", author)
-
-      expect(headers['Content-Disposition']).to match(/^attachment/)
+      expect(headers['Content-Disposition']).to match(/^inline/)
     end
 
     it 'returns 404 for invalid snippet id' do
@@ -145,6 +140,14 @@ RSpec.describe API::Snippets do
     end
   end
 
+  describe 'GET /snippets/:id/files/:ref/:file_path/raw' do
+    let_it_be(:snippet) { create(:personal_snippet, :repository, :private) }
+
+    it_behaves_like 'raw snippet files' do
+      let(:api_path) { "/snippets/#{snippet_id}/files/#{ref}/#{file_path}/raw" }
+    end
+  end
+
   describe 'GET /snippets/:id' do
     let_it_be(:admin) { create(:user, :admin) }
     let_it_be(:author) { create(:user) }

spec/support/shared_examples/requests/api/snippets_shared_examples.rb

+# frozen_string_literal: true
+
+RSpec.shared_examples 'raw snippet files' do
+  let_it_be(:unauthorized_user) { create(:user) }
+  let(:snippet_id) { snippet.id }
+  let(:user)       { snippet.author }
+  let(:file_path)  { '%2Egitattributes' }
+  let(:ref)        { 'master' }
+
+  context 'with no user' do
+    it 'requires authentication' do
+      get api(api_path)
+
+      expect(response).to have_gitlab_http_status(:unauthorized)
+    end
+  end
+
+  shared_examples 'not found' do
+    it 'returns 404' do
+      get api(api_path, user)
+
+      expect(response).to have_gitlab_http_status(:not_found)
+      expect(json_response['message']).to eq('404 Snippet Not Found')
+    end
+  end
+
+  context 'when not authorized' do
+    let(:user) { unauthorized_user }
+
+    it_behaves_like 'not found'
+  end
+
+  context 'with an invalid snippet ID' do
+    let(:snippet_id) { 'invalid' }
+
+    it_behaves_like 'not found'
+  end
+
+  context 'with valid params' do
+    it 'returns the raw file info' do
+      expect(Gitlab::Workhorse).to receive(:send_git_blob).and_call_original
+
+      get api(api_path, user)
+
+      aggregate_failures do
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response.media_type).to eq 'text/plain'
+        expect(response.header[Gitlab::Workhorse::DETECT_HEADER]).to eq 'true'
+        expect(response.header[Gitlab::Workhorse::SEND_DATA_HEADER]).to start_with('git-blob:')
+        expect(response.header['Content-Disposition']).to match 'filename=".gitattributes"'
+      end
+    end
+  end
+
+  context 'with invalid params' do
+    using RSpec::Parameterized::TableSyntax
+
+    where(:file_path, :ref, :status, :key, :message) do
+      '%2Egitattributes'      | 'invalid-ref' | :not_found   | 'message' | '404 Reference Not Found'
+      '%2Egitattributes'      | nil           | :not_found   | 'error'   | '404 Not Found'
+      '%2Egitattributes'      | ''            | :not_found   | 'error'   | '404 Not Found'
+
+      'doesnotexist.rb'       | 'master'      | :not_found   | 'message' | '404 File Not Found'
+      '/does/not/exist.rb'    | 'master'      | :not_found   | 'error'   | '404 Not Found'
+      '%2E%2E%2Fetc%2Fpasswd' | 'master'      | :bad_request | 'error'   | 'file_path should be a valid file path'
+      '%2Fetc%2Fpasswd'       | 'master'      | :bad_request | 'error'   | 'file_path should be a valid file path'
+      '../../etc/passwd'      | 'master'      | :not_found   | 'error'   | '404 Not Found'
+    end
+
+    with_them do
+      before do
+        get api(api_path, user)
+      end
+
+      it { expect(response).to have_gitlab_http_status(status) }
+      it { expect(json_response[key]).to eq(message) }
+    end
+  end
+end

spec/support/shared_examples/requests/snippet_shared_examples.rb

@@ -76,9 +76,12 @@ end
 
 RSpec.shared_examples 'snippet blob content' do
   it 'returns content from repository' do
+    expect(Gitlab::Workhorse).to receive(:send_git_blob).and_call_original
+
     subject
 
-    expect(response.body).to eq(snippet.blobs.first.data)
+    expect(response.header[Gitlab::Workhorse::DETECT_HEADER]).to eq 'true'
+    expect(response.header[Gitlab::Workhorse::SEND_DATA_HEADER]).to start_with('git-blob:')
   end
 
   context 'when snippet repository is empty' do