NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
FILE *fp = NULL, *cmdFP = NULL;
BOOL error = YES;
@try {
  NSString *archivePath = [archiveURL path];

  // Get the file size.
  NSNumber *fs = [[[NSFileManager defaultManager] fileAttributesAtPath:archivePath traverseLink:NO] objectForKey:NSFileSize];
  if (fs == nil) return;

  fp = fopen([archivePath fileSystemRepresentation], "r");
  if (fp == nil) return;

  setenv("DESTINATION", [[archivePath stringByDeletingLastPathComponent] UTF8String], 1);
  cmdFP = popen([command fileSystemRepresentation], "w");
  if (cmdFP == nil) return;

  char buf[32*1024];
  size_t len;
  while((len = fread(buf, 1, sizeof buf, fp))) {
    fwrite(buf, 1, len, cmdFP);
    [self performSelectorOnMainThread: @selector(_notifyDelegateOfExtractedLength:) withObject:[NSNumber numberWithLong:len] waitUntilDone:NO];
  }

  error = NO;
}
@finally {
  if(fp) fclose(fp);
  if(cmdFP) pclose(cmdFP);

  if(error) {
    [self performSelectorOnMainThread:@selector(_notifyDelegateOfSuccess) withObject:nil waitUntilDone:NO];
  } else {
    [self performSelectorOnMainThread:@selector(_notifyDelegateOfFailure) withObject:nil waitUntilDone:NO];
  }

  [pool drain];
}