net/http/cgi: allow CGI host to configure where child's stderr goes

Patch originally from Steven Hartland. Tweaked a bit & added a test.

Fixes #7197

Change-Id: I09012b4674e7c641dba31a24e9758cedb898d3ee
Reviewed-on: https://go-review.googlesource.com/21196
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/http/cgi/host.go b/src/net/http/cgi/host.go
index b2657b13a82ea72acceb8ed3d6c8641fb81da904..2eea64334b63c14328d2db658dd21aae4fe76dcc 100644 (file)
--- a/src/net/http/cgi/host.go
+++ b/src/net/http/cgi/host.go
@@ -58,6 +58,7 @@ type Handler struct {
        InheritEnv []string    // environment variables to inherit from host, as "key"
        Logger     *log.Logger // optional log for errors or nil to use log.Print
        Args       []string    // optional arguments to pass to child process
+       Stderr     io.Writer   // optional stderr for the child process; nil means os.Stderr
 
        // PathLocationHandler specifies the root http Handler that
        // should handle internal redirects when the CGI process
@@ -70,6 +71,13 @@ type Handler struct {
        PathLocationHandler http.Handler
 }
 
+func (h *Handler) stderr() io.Writer {
+       if h.Stderr != nil {
+               return h.Stderr
+       }
+       return os.Stderr
+}
+
 // removeLeadingDuplicates remove leading duplicate in environments.
 // It's possible to override environment like following.
 //    cgi.Handler{
@@ -204,7 +212,7 @@ func (h *Handler) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
                Args:   append([]string{h.Path}, h.Args...),
                Dir:    cwd,
                Env:    env,
-               Stderr: os.Stderr, // for now
+               Stderr: h.stderr(),
        }
        if req.ContentLength != 0 {
                cmd.Stdin = req.Body

diff --git a/src/net/http/cgi/host_test.go b/src/net/http/cgi/host_test.go
index 33277640ea54caa05bd319e6d275bbd9e07cbe7c..70c5aff5e29932912461edf0101552c481d8577f 100644 (file)
--- a/src/net/http/cgi/host_test.go
+++ b/src/net/http/cgi/host_test.go
@@ -8,6 +8,7 @@ package cgi
 
 import (
        "bufio"
+       "bytes"
        "fmt"
        "io"
        "net"
@@ -500,6 +501,23 @@ func TestEnvOverride(t *testing.T) {
        runCgiTest(t, h, "GET /test.cgi HTTP/1.0\nHost: example.com\n\n", expectedMap)
 }
 
+func TestHandlerStderr(t *testing.T) {
+       check(t)
+       var stderr bytes.Buffer
+       h := &Handler{
+               Path:   "testdata/test.cgi",
+               Root:   "/test.cgi",
+               Stderr: &stderr,
+       }
+
+       rw := httptest.NewRecorder()
+       req := newRequest("GET /test.cgi?writestderr=1 HTTP/1.0\nHost: example.com\n\n")
+       h.ServeHTTP(rw, req)
+       if got, want := stderr.String(), "Hello, stderr!\n"; got != want {
+               t.Errorf("Stderr = %q; want %q", got, want)
+       }
+}
+
 func TestRemoveLeadingDuplicates(t *testing.T) {
        tests := []struct {
                env  []string

diff --git a/src/net/http/cgi/testdata/test.cgi b/src/net/http/cgi/testdata/test.cgi
index ec7ee6f38641cdf55a6e937bf1e80b4116f12b39..667fce217ea649066b8b7af28075d487923658eb 100755 (executable)
--- a/src/net/http/cgi/testdata/test.cgi
+++ b/src/net/http/cgi/testdata/test.cgi
@@ -23,6 +23,10 @@ print "X-CGI-Pid: $$\r\n";
 print "X-Test-Header: X-Test-Value\r\n";
 print "\r\n";
 
+if ($params->{"writestderr"}) {
+    print STDERR "Hello, stderr!\n";
+}
+
 if ($params->{"bigresponse"}) {
     # 17 MB, for OS X: golang.org/issue/4958
     for (1..(17 * 1024)) {