github.com/secoba/wails/v2@v2.6.4/internal/frontend/desktop/darwin/single_instance.go (about)

     1  //go:build darwin
     2  // +build darwin
     3  
     4  package darwin
     5  
     6  /*
     7  #cgo CFLAGS: -x objective-c
     8  #cgo LDFLAGS: -framework Foundation -framework Cocoa
     9  #import "ApDelegate.h"
    10  
    11  */
    12  import "C"
    13  
    14  import (
    15  	"encoding/json"
    16  	"fmt"
    17  	"os"
    18  	"strings"
    19  	"syscall"
    20  	"unsafe"
    21  
    22  	"github.com/secoba/wails/v2/pkg/options"
    23  )
    24  
    25  func SetupSingleInstance(uniqueID string) {
    26  	lockFilePath := getTempDir()
    27  	lockFileName := uniqueID + ".lock"
    28  	_, err := createLockFile(lockFilePath + "/" + lockFileName)
    29  	// if lockFile exist – send notification to second instance
    30  	if err != nil {
    31  		c := NewCalloc()
    32  		defer c.Free()
    33  		singleInstanceUniqueId := c.String(uniqueID)
    34  
    35  		data, err := options.NewSecondInstanceData()
    36  		if err != nil {
    37  			return
    38  		}
    39  
    40  		serialized, err := json.Marshal(data)
    41  		if err != nil {
    42  			return
    43  		}
    44  
    45  		C.SendDataToFirstInstance(singleInstanceUniqueId, c.String(string(serialized)))
    46  
    47  		os.Exit(0)
    48  	}
    49  }
    50  
    51  //export HandleSecondInstanceData
    52  func HandleSecondInstanceData(secondInstanceMessage *C.char) {
    53  	message := C.GoString(secondInstanceMessage)
    54  
    55  	var secondInstanceData options.SecondInstanceData
    56  
    57  	err := json.Unmarshal([]byte(message), &secondInstanceData)
    58  	if err == nil {
    59  		secondInstanceBuffer <- secondInstanceData
    60  	}
    61  }
    62  
    63  // CreateLockFile tries to create a file with given name and acquire an
    64  // exclusive lock on it. If the file already exists AND is still locked, it will
    65  // fail.
    66  func createLockFile(filename string) (*os.File, error) {
    67  	file, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE, 0o600)
    68  	if err != nil {
    69  		fmt.Printf("Failed to open lockfile %s: %s", filename, err)
    70  		return nil, err
    71  	}
    72  
    73  	err = syscall.Flock(int(file.Fd()), syscall.LOCK_EX|syscall.LOCK_NB)
    74  	if err != nil {
    75  		// Flock failed for some other reason than other instance already lock it. Print it in logs for possible debugging.
    76  		if !strings.Contains(err.Error(), "resource temporarily unavailable") {
    77  			fmt.Printf("Failed to lock lockfile %s: %s", filename, err)
    78  		}
    79  		file.Close()
    80  		return nil, err
    81  	}
    82  
    83  	return file, nil
    84  }
    85  
    86  // If app is sandboxed, golang os.TempDir() will return path that will not be accessible. So use native macOS temp dir function.
    87  func getTempDir() string {
    88  	cstring := C.GetMacOsNativeTempDir()
    89  	path := C.GoString(cstring)
    90  	C.free(unsafe.Pointer(cstring))
    91  
    92  	return path
    93  }