source: trunk/Sparkle/relaunch.m @ 1046

#import <AppKit/AppKit.h>

#include <unistd.h>

@interface TerminationListener : NSObject
{
    const char *executablePath;
    pid_t parentProcessId;
}

- (void) relaunch;

@end

@implementation TerminationListener

- (id) initWithExecutablePath:(const char *)execPath parentProcessId:(pid_t)ppid
{
    self = [super init];
    if (self != nil)
    {
        executablePath = execPath;
        parentProcessId = ppid;
        if (getppid() == 1) // ppid is launchd (1) => parent terminated already
            [self relaunch];
        [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(watchdog:) userInfo:nil repeats:YES];
    }
    return self;
}

- (void)watchdog:(NSTimer *)timer
{
    ProcessSerialNumber psn;
    if (GetProcessForPID(parentProcessId, &psn) == procNotFound)
        [self relaunch];
}

- (void) relaunch
{
    [[NSWorkspace sharedWorkspace] openFile:[[NSFileManager defaultManager] stringWithFileSystemRepresentation:executablePath length:strlen(executablePath)]];
    [[NSFileManager defaultManager] removeItemAtPath:[NSTemporaryDirectory() stringByAppendingPathComponent:@"relaunch"] error:nil];
    exit(0);
}

@end

int main (int argc, const char * argv[])
{
    if (argc != 3) return EXIT_FAILURE;
    
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    
    [NSApplication sharedApplication];
    [[[TerminationListener alloc] initWithExecutablePath:argv[1] parentProcessId:atoi(argv[2])] autorelease];
    [[NSApplication sharedApplication] run];
    
    [pool drain];
    
    return EXIT_SUCCESS;
}