nslcd_{server,systemd}: BREAKING CHANGE: use contexts

4 files changed, 76 insertions, 12 deletions

diff --git a/nslcd_server/ctx.go b/nslcd_server/ctx.go
new file mode 100644
index 0000000..5214adc
--- /dev/null
+++ b/nslcd_server/ctx.go
@@ -0,0 +1,46 @@
+// Copyright (C) 2017 Luke Shumaker <lukeshu@sbcglobal.net>
+//
+// This library is free software; you can redistribute it and/or
+// modify it under the terms of the GNU Lesser General Public
+// License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+// 02110-1301 USA
+
+package nslcd_server
+
+import (
+	"context"
+
+	"golang.org/x/sys/unix"
+)
+
+// contextKey is a value for use with context.WithValue.  It's used as
+// a pointer so it fits in an interface{} without allocation.
+type contextKey struct {
+	name string
+}
+
+var (
+	// PeerCredKey is a context key.  It can be used in backend
+	// methods to access the credentials of the client process.
+	// The associated value will be of type
+	// "golang.org/x/sys/unix".Ucred
+	PeerCredKey = &contextKey{"peercred"}
+)
+
+// PeerCredFromContext is a convenience function for
+//
+//     cred, ok := ctx.Value(nslcd_server.PeerCredKey).(unix.Ucred)
+func PeerCredFromContext(ctx context.Context) (unix.Ucred, bool) {
+	cred, ok := ctx.Value(PeerCredKey).(unix.Ucred)
+	return cred, ok
+}
diff --git a/nslcd_server/func_handlerequest.go.gen b/nslcd_server/func_handlerequest.go.gen
index 00e9663..750a7b0 100755
--- a/nslcd_server/func_handlerequest.go.gen
+++ b/nslcd_server/func_handlerequest.go.gen
@@ -25,12 +25,12 @@ cat <<EOF | gofmt
 package nslcd_server
 
 import (
+	"context"
 	"fmt"
 	"io"
 	"os"
 	"time"
 
-	"golang.org/x/sys/unix"
 	p "git.lukeshu.com/go/libnslcd/nslcd_proto"
 )
 
@@ -70,8 +70,9 @@ type Conn interface {
 	SetWriteDeadline(t time.Time) error
 }
 
-// Handle a request to nslcd
-func HandleRequest(backend Backend, limits Limits, conn Conn, cred unix.Ucred) (err error) {
+// Handle a request to nslcd.  The caller is responsible for
+// initializing the context with PeerCredKey.
+func HandleRequest(backend Backend, limits Limits, conn Conn, ctx context.Context) (err error) {
 	defer func() {
 		if r := recover(); r != nil {
 			switch r := r.(type) {
@@ -89,6 +90,11 @@ func HandleRequest(backend Backend, limits Limits, conn Conn, cred unix.Ucred) (
 	if limits.Timeout != 0 {
 		deadlineAll = now.Add(limits.Timeout)
 	}
+	if deadline, ok := ctx.Deadline(); ok {
+		if deadlineAll.IsZero() || deadline.Before(deadlineAll) {
+			deadlineAll = deadline
+		}
+	}
 	if limits.ReadTimeout != 0 {
 		deadlineRead = now.Add(limits.ReadTimeout)
 		if !deadlineAll.IsZero() && deadlineAll.Before(deadlineRead) {
@@ -149,6 +155,7 @@ while read -r request; do
 				;;
 		esac
 		)
+
 		if limits.WriteTimeout != 0 {
 			deadlineWrite = time.Now().Add(limits.WriteTimeout)
 			if !deadlineAll.IsZero() && deadlineAll.Before(deadlineWrite) {
@@ -161,9 +168,18 @@ while read -r request; do
 				return err
 			}
 		}
+
+		var cancel context.CancelFunc
+		if deadline, ok := ctx.Deadline(); !ok || (!deadlineWrite.IsZero() && deadline.After(deadlineWrite)) {
+			ctx, cancel = context.WithDeadline(ctx, deadlineWrite)
+		} else {
+			ctx, cancel = context.WithCancel(ctx)
+		}
+		defer cancel()
+
 		maybePanic(p.Write(out, p.NSLCD_VERSION))
 		maybePanic(p.Write(out, action))
-		ch := backend.${request}(cred, req)
+		ch := backend.${request}(ctx, req)
 		for result := range ch {
 			if err == nil {
 				err = p.Write(out, p.NSLCD_RESULT_BEGIN)
@@ -174,7 +190,7 @@ while read -r request; do
 		}
 		maybePanic(err)
 		maybePanic(p.Write(out, p.NSLCD_RESULT_END))
-		return nil
+		return ctx.Err() // probably nil
 EOT
 done < "$requests"
 )
diff --git a/nslcd_server/interface_backend.go.gen b/nslcd_server/interface_backend.go.gen
index 4749d0c..4ced5e7 100755
--- a/nslcd_server/interface_backend.go.gen
+++ b/nslcd_server/interface_backend.go.gen
@@ -1,5 +1,5 @@
 #!/usr/bin/env bash
-# Copyright (C) 2015 Luke Shumaker <lukeshu@sbcglobal.net>
+# Copyright (C) 2015, 2017 Luke Shumaker <lukeshu@sbcglobal.net>
 #
 # This library is free software; you can redistribute it and/or
 # modify it under the terms of the GNU Lesser General Public
@@ -24,7 +24,8 @@ cat <<EOF | gofmt
 package nslcd_server
 
 import (
-	"golang.org/x/sys/unix"
+	"context"
+
 	p "git.lukeshu.com/go/libnslcd/nslcd_proto"
 )
 
@@ -33,7 +34,7 @@ import (
 // that the nslcd server may reply to is implemented simply as a
 // method that returns a channel of the resulting values.
 type Backend interface {
-	$(sed -rn 's/([^_]+)(.*)/\1\2(unix.Ucred, p.Request_\1\2) <-chan p.\1/p' "$requests" | grep -v PAM)
-	$(sed -rn 's/(PAM)(.*)/\1\2(unix.Ucred, p.Request_\1\2) <-chan p.\1\2/p' "$requests")
+	$(sed -rn 's/([^_]+)(.*)/\1\2(context.Context, p.Request_\1\2) <-chan p.\1/p' "$requests" | grep -v PAM)
+	$(sed -rn 's/(PAM)(.*)/\1\2(context.Context, p.Request_\1\2) <-chan p.\1\2/p' "$requests")
 }
 EOF
diff --git a/nslcd_server/type_nilbackend.go.gen b/nslcd_server/type_nilbackend.go.gen
index 0c6f4b5..b7ea372 100755
--- a/nslcd_server/type_nilbackend.go.gen
+++ b/nslcd_server/type_nilbackend.go.gen
@@ -24,7 +24,8 @@ cat <<EOF | gofmt
 package nslcd_server
 
 import (
-	"golang.org/x/sys/unix"
+	"context"
+
 	p "git.lukeshu.com/go/libnslcd/nslcd_proto"
 )
 
@@ -35,8 +36,8 @@ import (
 type NilBackend struct{}
 
 $(
-	re_in='^\t([^(]+)\(unix\.Ucred, ([^)]+)\) <-chan (\S+)$'
-	re_out='func (o NilBackend) \1(unix.Ucred, \2) <-chan \3 { r := make(chan \3); close(r); return r }'
+	re_in='^\t([^(]+)\(context\.Context, ([^)]+)\) <-chan (\S+)$'
+	re_out='func (o NilBackend) \1(context.Context, \2) <-chan \3 { r := make(chan \3); close(r); return r }'
 	< "$interface" sed -rn "s/$re_in/$re_out/p"
 )