functions.go

Documentation: github.com/coreos/go-systemd/v22/sdjournal

     1  // Copyright 2015 RedHat, Inc.
     2  // Copyright 2015 CoreOS, Inc.
     3  //
     4  // Licensed under the Apache License, Version 2.0 (the "License");
     5  // you may not use this file except in compliance with the License.
     6  // You may obtain a copy of the License at
     7  //
     8  //     http://www.apache.org/licenses/LICENSE-2.0
     9  //
    10  // Unless required by applicable law or agreed to in writing, software
    11  // distributed under the License is distributed on an "AS IS" BASIS,
    12  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  // See the License for the specific language governing permissions and
    14  // limitations under the License.
    15  
    16  package sdjournal
    17  
    18  import (
    19  	"github.com/coreos/go-systemd/v22/internal/dlopen"
    20  	"sync"
    21  	"unsafe"
    22  )
    23  
    24  var (
    25  	// lazy initialized
    26  	libsystemdHandle *dlopen.LibHandle
    27  
    28  	libsystemdMutex     = &sync.Mutex{}
    29  	libsystemdFunctions = map[string]unsafe.Pointer{}
    30  	libsystemdNames     = []string{
    31  		// systemd < 209
    32  		"libsystemd-journal.so.0",
    33  		"libsystemd-journal.so",
    34  
    35  		// systemd >= 209 merged libsystemd-journal into libsystemd proper
    36  		"libsystemd.so.0",
    37  		"libsystemd.so",
    38  	}
    39  )
    40  
    41  func getFunction(name string) (unsafe.Pointer, error) {
    42  	libsystemdMutex.Lock()
    43  	defer libsystemdMutex.Unlock()
    44  
    45  	if libsystemdHandle == nil {
    46  		h, err := dlopen.GetHandle(libsystemdNames)
    47  		if err != nil {
    48  			return nil, err
    49  		}
    50  
    51  		libsystemdHandle = h
    52  	}
    53  
    54  	f, ok := libsystemdFunctions[name]
    55  	if !ok {
    56  		var err error
    57  		f, err = libsystemdHandle.GetSymbolPointer(name)
    58  		if err != nil {
    59  			return nil, err
    60  		}
    61  
    62  		libsystemdFunctions[name] = f
    63  	}
    64  
    65  	return f, nil
    66  }
    67
View as plain text