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dl.go
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dl.go
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// Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
//
// 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 dl
import (
"errors"
"fmt"
"runtime"
"unsafe"
)
// #cgo LDFLAGS: -ldl
// #include <dlfcn.h>
// #include <stdlib.h>
import "C"
const (
RTLD_LAZY = C.RTLD_LAZY
RTLD_NOW = C.RTLD_NOW
RTLD_GLOBAL = C.RTLD_GLOBAL
RTLD_LOCAL = C.RTLD_LOCAL
RTLD_NODELETE = C.RTLD_NODELETE
RTLD_NOLOAD = C.RTLD_NOLOAD
)
type DynamicLibrary struct {
Name string
Flags int
handle unsafe.Pointer
}
func New(name string, flags int) *DynamicLibrary {
return &DynamicLibrary{
Name: name,
Flags: flags,
handle: nil,
}
}
func withOSLock(action func() error) error {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
return action()
}
func dlError() error {
lastErr := C.dlerror()
if lastErr == nil {
return nil
}
return errors.New(C.GoString(lastErr))
}
func (dl *DynamicLibrary) Open() error {
name := C.CString(dl.Name)
defer C.free(unsafe.Pointer(name))
if err := withOSLock(func() error {
handle := C.dlopen(name, C.int(dl.Flags))
if handle == nil {
return dlError()
}
dl.handle = handle
return nil
}); err != nil {
return err
}
return nil
}
func (dl *DynamicLibrary) Close() error {
if dl.handle == nil {
return nil
}
if err := withOSLock(func() error {
if C.dlclose(dl.handle) != 0 {
return dlError()
}
dl.handle = nil
return nil
}); err != nil {
return err
}
return nil
}
func (dl *DynamicLibrary) Lookup(symbol string) error {
sym := C.CString(symbol)
defer C.free(unsafe.Pointer(sym))
var pointer unsafe.Pointer
if err := withOSLock(func() error {
// Call dlError() to clear out any previous errors.
_ = dlError()
pointer = C.dlsym(dl.handle, sym)
if pointer == nil {
return fmt.Errorf("symbol %q not found: %w", symbol, dlError())
}
return nil
}); err != nil {
return err
}
return nil
}