Merge pull request #318 from saschagrunert/dlopen

sdjournal: use internal dlopen package

Gopkg.toml

@@ -1,7 +1,3 @@
-[[constraint]]
-  name = "github.com/coreos/pkg"
-  version = "4.0.0"
-
 [[constraint]]
   name = "github.com/godbus/dbus"
   version = "5.0"

internal/dlopen/dlopen.go

@@ -0,0 +1,82 @@
+// Copyright 2016 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package dlopen provides some convenience functions to dlopen a library and
+// get its symbols.
+package dlopen
+
+// #cgo LDFLAGS: -ldl
+// #include <stdlib.h>
+// #include <dlfcn.h>
+import "C"
+import (
+	"errors"
+	"fmt"
+	"unsafe"
+)
+
+var ErrSoNotFound = errors.New("unable to open a handle to the library")
+
+// LibHandle represents an open handle to a library (.so)
+type LibHandle struct {
+	Handle  unsafe.Pointer
+	Libname string
+}
+
+// GetHandle tries to get a handle to a library (.so), attempting to access it
+// by the names specified in libs and returning the first that is successfully
+// opened. Callers are responsible for closing the handler. If no library can
+// be successfully opened, an error is returned.
+func GetHandle(libs []string) (*LibHandle, error) {
+	for _, name := range libs {
+		libname := C.CString(name)
+		defer C.free(unsafe.Pointer(libname))
+		handle := C.dlopen(libname, C.RTLD_LAZY)
+		if handle != nil {
+			h := &LibHandle{
+				Handle:  handle,
+				Libname: name,
+			}
+			return h, nil
+		}
+	}
+	return nil, ErrSoNotFound
+}
+
+// GetSymbolPointer takes a symbol name and returns a pointer to the symbol.
+func (l *LibHandle) GetSymbolPointer(symbol string) (unsafe.Pointer, error) {
+	sym := C.CString(symbol)
+	defer C.free(unsafe.Pointer(sym))
+
+	C.dlerror()
+	p := C.dlsym(l.Handle, sym)
+	e := C.dlerror()
+	if e != nil {
+		return nil, fmt.Errorf("error resolving symbol %q: %v", symbol, errors.New(C.GoString(e)))
+	}
+
+	return p, nil
+}
+
+// Close closes a LibHandle.
+func (l *LibHandle) Close() error {
+	C.dlerror()
+	C.dlclose(l.Handle)
+	e := C.dlerror()
+	if e != nil {
+		return fmt.Errorf("error closing %v: %v", l.Libname, errors.New(C.GoString(e)))
+	}
+
+	return nil
+}

internal/dlopen/dlopen_test.go

@@ -0,0 +1,63 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package dlopen
+
+import (
+	"fmt"
+	"testing"
+)
+
+func checkFailure(shouldSucceed bool, err error) (rErr error) {
+	switch {
+	case err != nil && shouldSucceed:
+		rErr = fmt.Errorf("expected test to succeed, failed unexpectedly: %v", err)
+	case err == nil && !shouldSucceed:
+		rErr = fmt.Errorf("expected test to fail, succeeded unexpectedly")
+	}
+
+	return
+}
+
+func TestDlopen(t *testing.T) {
+	tests := []struct {
+		libs          []string
+		shouldSucceed bool
+	}{
+		{
+			libs: []string{
+				"libc.so.6",
+				"libc.so",
+			},
+			shouldSucceed: true,
+		},
+		{
+			libs: []string{
+				"libstrange.so",
+			},
+			shouldSucceed: false,
+		},
+	}
+
+	for i, tt := range tests {
+		expLen := 4
+		len, err := strlen(tt.libs, "test")
+		if checkFailure(tt.shouldSucceed, err) != nil {
+			t.Errorf("case %d: %v", i, err)
+		}
+
+		if tt.shouldSucceed && len != expLen {
+			t.Errorf("case %d: expected length %d, got %d", i, expLen, len)
+		}
+	}
+}

scripts/jenkins/periodic-go-systemd-builder.sh

@@ -19,6 +19,5 @@ if [ ! -h gopath/src/github.com/coreos/go-systemd ]; then
 fi
 export GOPATH=${PWD}/gopath
 go get -u github.com/godbus/dbus
-go get github.com/coreos/pkg/dlopen
 
 sudo -E ./test

sdjournal/functions.go

@@ -16,7 +16,7 @@
 package sdjournal
 
 import (
-	"github.com/coreos/pkg/dlopen"
+	"github.com/coreos/go-systemd/internal/dlopen"
 	"sync"
 	"unsafe"
 )

test

@@ -24,7 +24,6 @@ if [ -z "$GOPATH" ]; then
 	fi
 	export GOPATH=${PWD}/gopath
 	go get -u github.com/godbus/dbus
-	go get -u github.com/coreos/pkg/dlopen
 fi
 
 TESTABLE="activation daemon journal login1 unit"

util/util_cgo.go

@@ -58,7 +58,7 @@ import (
 	"syscall"
 	"unsafe"
 
-	"github.com/coreos/pkg/dlopen"
+	"github.com/coreos/go-systemd/internal/dlopen"
 )
 
 var libsystemdNames = []string{