Fix git grep search limit, add test (go-gitea#30071)

Fix go-gitea#30069

Author: wxiaoguang

modules/git/grep.go

@@ -24,6 +24,7 @@ type GrepResult struct {
 
 type GrepOptions struct {
 	RefName           string
+	MaxResultLimit    int
 	ContextLineNumber int
 	IsFuzzy           bool
 }
@@ -59,6 +60,7 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
 		cmd.AddOptionValues("-e", strings.TrimLeft(search, "-"))
 	}
 	cmd.AddDynamicArguments(util.IfZero(opts.RefName, "HEAD"))
+	opts.MaxResultLimit = util.IfZero(opts.MaxResultLimit, 50)
 	stderr := bytes.Buffer{}
 	err = cmd.Run(&RunOpts{
 		Dir:    repo.Path,
@@ -82,7 +84,7 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
 					continue
 				}
 				if line == "" {
-					if len(results) >= 50 {
+					if len(results) >= opts.MaxResultLimit {
 						cancel()
 						break
 					}
@@ -101,6 +103,10 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
 			return scanner.Err()
 		},
 	})
+	// git grep exits by cancel (killed), usually it is caused by the limit of results
+	if IsErrorExitCode(err, -1) && stderr.Len() == 0 {
+		return results, nil
+	}
 	// git grep exits with 1 if no results are found
 	if IsErrorExitCode(err, 1) && stderr.Len() == 0 {
 		return nil, nil

modules/git/grep_test.go

@@ -31,6 +31,16 @@ func TestGrepSearch(t *testing.T) {
 		},
 	}, res)
 
+	res, err = GrepSearch(context.Background(), repo, "void", GrepOptions{MaxResultLimit: 1})
+	assert.NoError(t, err)
+	assert.Equal(t, []*GrepResult{
+		{
+			Filename:    "java-hello/main.java",
+			LineNumbers: []int{3},
+			LineCodes:   []string{" public static void main(String[] args)"},
+		},
+	}, res)
+
 	res, err = GrepSearch(context.Background(), repo, "no-such-content", GrepOptions{})
 	assert.NoError(t, err)
 	assert.Len(t, res, 0)