net/http/cgi: optimize internal function removeLeadingDuplicates a bit

Change-Id: I0255f24f5c5925ea4daa28a28d23606df35d4373
Reviewed-on: https://go-review.googlesource.com/15824
Reviewed-by: Andrew Gerrand <adg@golang.org>

diff --git a/src/net/http/cgi/host.go b/src/net/http/cgi/host.go
index 1ae66e097ce5835b300de20e3a2533b955fa939e..9b4d8754183247661e339a104bd6a1d2738323b2 100644 (file)
--- a/src/net/http/cgi/host.go
+++ b/src/net/http/cgi/host.go
@@ -77,15 +77,15 @@ type Handler struct {
 //      Env: []string{"SCRIPT_FILENAME=foo.php"},
 //    }
 func removeLeadingDuplicates(env []string) (ret []string) {
-       n := len(env)
-       for i := 0; i < n; i++ {
-               e := env[i]
-               s := strings.SplitN(e, "=", 2)[0]
+       for i, e := range env {
                found := false
-               for j := i + 1; j < n; j++ {
-                       if s == strings.SplitN(env[j], "=", 2)[0] {
-                               found = true
-                               break
+               if eq := strings.IndexByte(e, '='); eq != -1 {
+                       keq := e[:eq+1] // "key="
+                       for _, e2 := range env[i+1:] {
+                               if strings.HasPrefix(e2, keq) {
+                                       found = true
+                                       break
+                               }
                        }
                }
                if !found {

diff --git a/src/net/http/cgi/host_test.go b/src/net/http/cgi/host_test.go
index 8a82789fd34eeae36c8cb2dae85e442bbb36a103..33277640ea54caa05bd319e6d275bbd9e07cbe7c 100644 (file)
--- a/src/net/http/cgi/host_test.go
+++ b/src/net/http/cgi/host_test.go
@@ -16,6 +16,7 @@ import (
        "os"
        "os/exec"
        "path/filepath"
+       "reflect"
        "runtime"
        "strconv"
        "strings"
@@ -498,3 +499,25 @@ func TestEnvOverride(t *testing.T) {
        }
        runCgiTest(t, h, "GET /test.cgi HTTP/1.0\nHost: example.com\n\n", expectedMap)
 }
+
+func TestRemoveLeadingDuplicates(t *testing.T) {
+       tests := []struct {
+               env  []string
+               want []string
+       }{
+               {
+                       env:  []string{"a=b", "b=c", "a=b2"},
+                       want: []string{"b=c", "a=b2"},
+               },
+               {
+                       env:  []string{"a=b", "b=c", "d", "e=f"},
+                       want: []string{"a=b", "b=c", "d", "e=f"},
+               },
+       }
+       for _, tt := range tests {
+               got := removeLeadingDuplicates(tt.env)
+               if !reflect.DeepEqual(got, tt.want) {
+                       t.Errorf("removeLeadingDuplicates(%q) = %q; want %q", tt.env, got, tt.want)
+               }
+       }
+}