pkg/html: split off URL helpers

The existing pkg/html package transitively takes too many dependencies,
which complicates the reuse of some of its methods.

Split off a pkg/html/urlutil package.

4 files changed, 69 insertions, 56 deletions

diff --git a/dashboard/app/main.go b/dashboard/app/main.go
index 93ee73c00..2f04e7152 100644
--- a/dashboard/app/main.go
+++ b/dashboard/app/main.go
@@ -25,6 +25,7 @@ import (
 	"github.com/google/syzkaller/pkg/email"
 	"github.com/google/syzkaller/pkg/hash"
 	"github.com/google/syzkaller/pkg/html"
+	"github.com/google/syzkaller/pkg/html/urlutil"
 	"github.com/google/syzkaller/pkg/subsystem"
 	"github.com/google/syzkaller/pkg/vcs"
 	"golang.org/x/sync/errgroup"
@@ -113,7 +114,7 @@ func makeUIBugFilter(c context.Context, filter *userBugFilter) *uiBugFilter {
 	return &uiBugFilter{
 		Filter: filter,
 		DropURL: func(name, value string) string {
-			return html.DropParam(url, name, value)
+			return urlutil.DropParam(url, name, value)
 		},
 	}
 }
@@ -1028,11 +1029,11 @@ func handleAdmin(c context.Context, w http.ResponseWriter, r *http.Request) erro
 		MemcacheStats:  memcacheStats,
 		Stopped:        alreadyStopped,
 		MoreStopClicks: 2,
-		StopLink:       html.AmendURL("/admin", "stop_clicked", "1"),
+		StopLink:       urlutil.SetParam("/admin", "stop_clicked", "1"),
 	}
 	if r.FormValue("stop_clicked") != "" {
 		data.MoreStopClicks = 1
-		data.StopLink = html.AmendURL("/admin", "action", "emergency_stop")
+		data.StopLink = urlutil.SetParam("/admin", "action", "emergency_stop")
 	}
 	if r.FormValue("job_type") != "" {
 		data.TypeJobs = &uiJobList{Title: "Last jobs:", Jobs: typeJobs}
@@ -1041,8 +1042,8 @@ func handleAdmin(c context.Context, w http.ResponseWriter, r *http.Request) erro
 		data.RecentJobs = &uiJobList{Title: "Recent jobs:", Jobs: recentJobs}
 		data.RunningJobs = &uiJobList{Title: "Running jobs:", Jobs: runningJobs}
 		data.PendingJobs = &uiJobList{Title: "Pending jobs:", Jobs: pendingJobs}
-		data.FixBisectionsLink = html.AmendURL("/admin", "job_type", fmt.Sprintf("%d", JobBisectFix))
-		data.CauseBisectionsLink = html.AmendURL("/admin", "job_type", fmt.Sprintf("%d", JobBisectCause))
+		data.FixBisectionsLink = urlutil.SetParam("/admin", "job_type", fmt.Sprintf("%d", JobBisectFix))
+		data.CauseBisectionsLink = urlutil.SetParam("/admin", "job_type", fmt.Sprintf("%d", JobBisectCause))
 	}
 	return serveTemplate(w, "admin.html", data)
 }
@@ -1211,7 +1212,7 @@ func handleBug(c context.Context, w http.ResponseWriter, r *http.Request) error
 		LabelGroups:  getLabelGroups(c, bug),
 	}
 	if accessLevel == AccessAdmin && !bug.hasUserSubsystems() {
-		data.DebugSubsystems = html.AmendURL(data.Bug.Link, "debug_subsystems", "1")
+		data.DebugSubsystems = urlutil.SetParam(data.Bug.Link, "debug_subsystems", "1")
 	}
 	// bug.BisectFix is set to BisectNot in three cases :
 	// - no fix bisections have been performed on the bug
@@ -1326,7 +1327,7 @@ func makeBugLabelUI(c context.Context, bug *Bug, entry BugLabel) *uiBugLabel {
 	if !strings.HasPrefix(url, "/"+bug.Namespace) {
 		link = fmt.Sprintf("/%s", bug.Namespace)
 	}
-	link = html.TransformURL(link, "label", func(oldLabels []string) []string {
+	link = urlutil.TransformParam(link, "label", func(oldLabels []string) []string {
 		return mergeLabelSet(oldLabels, entry.String())
 	})
 	ret := &uiBugLabel{
@@ -1458,11 +1459,11 @@ func handleSubsystemsList(c context.Context, w http.ResponseWriter, r *http.Requ
 		Name: "",
 		Open: uiSubsystemStats{
 			Count: cached.NoSubsystem.Open,
-			Link:  html.AmendURL("/"+hdr.Namespace, "no_subsystem", "true"),
+			Link:  urlutil.SetParam("/"+hdr.Namespace, "no_subsystem", "true"),
 		},
 		Fixed: uiSubsystemStats{
 			Count: cached.NoSubsystem.Fixed,
-			Link:  html.AmendURL("/"+hdr.Namespace+"/fixed", "no_subsystem", "true"),
+			Link:  urlutil.SetParam("/"+hdr.Namespace+"/fixed", "no_subsystem", "true"),
 		},
 	}
 	sort.Slice(list, func(i, j int) bool { return list[i].Name < list[j].Name })
@@ -1471,7 +1472,7 @@ func handleSubsystemsList(c context.Context, w http.ResponseWriter, r *http.Requ
 		List:         list,
 		Unclassified: unclassified,
 		SomeHidden:   someHidden,
-		ShowAllURL:   html.AmendURL(getCurrentURL(c), "all", "true"),
+		ShowAllURL:   urlutil.SetParam(getCurrentURL(c), "all", "true"),
 	})
 }
 
@@ -1487,7 +1488,7 @@ func createUISubsystem(ns string, item *subsystem.Subsystem, cached *Cached) *ui
 		},
 		Fixed: uiSubsystemStats{
 			Count: stats.Fixed,
-			Link: html.AmendURL("/"+ns+"/fixed", "label", BugLabel{
+			Link: urlutil.SetParam("/"+ns+"/fixed", "label", BugLabel{
 				Label: SubsystemLabel,
 				Value: item.Name,
 			}.String()),
diff --git a/pkg/html/html.go b/pkg/html/html.go
index 4893b8377..9d15c8777 100644
--- a/pkg/html/html.go
+++ b/pkg/html/html.go
@@ -6,7 +6,6 @@ package html
 import (
 	"fmt"
 	"html/template"
-	"net/url"
 	"path/filepath"
 	"reflect"
 	"strings"
@@ -214,46 +213,3 @@ func dereferencePointer(v interface{}) interface{} {
 func commitLink(repo, commit string) string {
 	return vcs.CommitLink(repo, commit)
 }
-
-func AmendURL(baseURL, key, value string) string {
-	return TransformURL(baseURL, key, func(_ []string) []string {
-		if value == "" {
-			return nil
-		}
-		return []string{value}
-	})
-}
-
-func DropParam(baseURL, key, value string) string {
-	return TransformURL(baseURL, key, func(oldValues []string) []string {
-		if value == "" {
-			return nil
-		}
-		var newValues []string
-		for _, iterVal := range oldValues {
-			if iterVal != value {
-				newValues = append(newValues, iterVal)
-			}
-		}
-		return newValues
-	})
-}
-
-func TransformURL(baseURL, key string, f func([]string) []string) string {
-	if baseURL == "" {
-		return ""
-	}
-	parsed, err := url.Parse(baseURL)
-	if err != nil {
-		return ""
-	}
-	values := parsed.Query()
-	ret := f(values[key])
-	if len(ret) == 0 {
-		values.Del(key)
-	} else {
-		values[key] = ret
-	}
-	parsed.RawQuery = values.Encode()
-	return parsed.String()
-}
diff --git a/pkg/html/urlutil/urls.go b/pkg/html/urlutil/urls.go
new file mode 100644
index 000000000..42ab505c8
--- /dev/null
+++ b/pkg/html/urlutil/urls.go
@@ -0,0 +1,56 @@
+// Copyright 2025 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package urlutil
+
+import "net/url"
+
+// SetParam overrides the specific key from the URL.
+// It does not take into account that there may be multiple parameters with the same name.
+func SetParam(baseURL, key, value string) string {
+	return TransformParam(baseURL, key, func(_ []string) []string {
+		if value == "" {
+			return nil
+		}
+		return []string{value}
+	})
+}
+
+// DropParam removes the specific key=value pair from the URL
+// (it's possible to have many of parameters with the same name).
+// Set value="" to remove the key regardless of the value.
+func DropParam(baseURL, key, value string) string {
+	return TransformParam(baseURL, key, func(oldValues []string) []string {
+		if value == "" {
+			return nil
+		}
+		var newValues []string
+		for _, iterVal := range oldValues {
+			if iterVal != value {
+				newValues = append(newValues, iterVal)
+			}
+		}
+		return newValues
+	})
+}
+
+// TransformParam is a generic method that transforms the set of values
+// for the specified URL parameter key.
+func TransformParam(baseURL, key string, f func([]string) []string) string {
+	if baseURL == "" {
+		return ""
+	}
+	parsed, err := url.Parse(baseURL)
+	if err != nil {
+		return ""
+	}
+	values := parsed.Query()
+	ret := f(values[key])
+	if len(ret) == 0 {
+		values.Del(key)
+	} else {
+		values[key] = ret
+	}
+	parsed.RawQuery = values.Encode()
+	return parsed.String()
+}
diff --git a/pkg/html/html_test.go b/pkg/html/urlutil/urls_test.go
index d824e0246..a8782c35e 100644
--- a/pkg/html/html_test.go
+++ b/pkg/html/urlutil/urls_test.go
@@ -1,7 +1,7 @@
 // Copyright 2023 syzkaller project authors. All rights reserved.
 // Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
 
-package html
+package urlutil
 
 import (
 	"testing"