CSingleCheck::CSingleCheck()
{
m_pid = 0;
m_old = false;
FILE *fp;
std::string temp;
GetTempDir( temp );
temp += "/single.lock";
fp = fopen( temp.c_str(), "r" );
if ( fp == NULL )
{
fp = fopen( temp.c_str(), "w" );
if ( fp == NULL )
return ; //some error
fprintf( fp, "%ld", long( getpid() ) );
fclose( fp );
//make pipe
if ( !MakePipe() )
{
DBGOUT( "error to make fifo" );
}
}
else
{ //old exists,check if prog exists
//read pid and check pid;
long pid = 0;
fscanf( fp, "%ld", &pid );
char buf[ 20 ];
sprintf( buf, "/proc/%ld", pid );
FILE *fp2;
fp2 = fopen( buf, "r" );
if ( fp2 == NULL )
{ //prog quit;
fclose( fp );
Clean();
fp = fopen( temp.c_str(), "w" );
if ( fp == NULL )
return ; //some error
fprintf( fp, "%ld", ( long ) getpid() );
fclose( fp );
if ( !MakePipe() )
{
DBGOUT( "error to make fifo" );
}
}
else
{ //prog exists
fclose( fp2 );
fclose( fp );
m_old = true;
m_pid = pid;
}
}
}
WinNamedPipeServer::WinNamedPipeServer( char *server_name)
{
_listeningPipe = MakePipe( server_name);
// Error handling needed
}
int main(int argc, char *argv[]) {
int i,
status,
parent,
child[3],
exitStatus,
parentToChild1[2],
child1ToChild2[2],
child2ToChild3[2],
child1ToParent[2],
parentToChild2[2],
child2ToParent[2],
parentToChild3[2],
child3ToParent[2];
char command[100],
token[] = "GO_AHEAD";
/* Error handling */
if (argc != 2) {
fprintf(stderr, "Usage: ./a.out <file name>\n");
exit(99);
}
/* Create pipes */
MakePipe(parentToChild1);
MakePipe(child1ToChild2);
MakePipe(child2ToChild3);
MakePipe(child1ToParent);
MakePipe(parentToChild2);
MakePipe(child2ToParent);
MakePipe(parentToChild3);
MakePipe(child3ToParent);
/* Set all I/O operations to non-buffered
Stderr is unbuffered by default, so we
can have this under the error handling */
setvbuf(stdin, NULL, _IONBF, 0);
setvbuf(stdout, NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild1[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild1[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(child1ToChild2[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(child1ToChild2[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(child2ToParent[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(child2ToParent[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(child1ToParent[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(child1ToParent[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild2[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild2[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(child2ToChild3[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(child2ToChild3[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild3[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(parentToChild3[1], "w"), NULL, _IONBF, 0);
setvbuf(fdopen(child3ToParent[0], "r"), NULL, _IONBF, 0);
setvbuf(fdopen(child3ToParent[1], "w"), NULL, _IONBF, 0);
/* Produces 3 children */
for (i = 0; i < 3; ++i) {
if ((parent = child[i] = fork()) == error) {
fprintf(stderr, "Could not produce child #%d\n", i+1);
exit(99);
}
if (!parent)
break;
}
/* Send and receive tokens from children and then wait for them to finish */
if (parent) {
fprintf(stdout, "I am the parent of the following: %d, %d, and %d\n", child[0], child[1], child[2]);
WriteToPipe(parentToChild1, token);
ReadFromPipe(child1ToParent, command);
WriteToPipe(parentToChild2, token);
ReadFromPipe(child2ToParent, command);
WriteToPipe(parentToChild3, token);
ReadFromPipe(child3ToParent, command);
for (i = 0; i < 3; ++i) {
waitpid(child[i], &status, 0);
fprintf(stdout, "From main: child, id #%d ended with status %d\n", child[i], WEXITSTATUS(status));
}
fprintf(stdout, "Goodbye!\n");
}
else {
/* First child */
if (i == 0) {
ReadFromPipe(parentToChild1, command);
fprintf(stdout, "I am child #%d and my id is: %d\n", i+1, getpid());
/* Copies file received from argument */
sprintf(command, "cp %s newcopy.txt", argv[1]);
exitStatus = system(command);
char done[] = "child1_done";
WriteToPipe(child1ToParent, done);
WriteToPipe(child1ToChild2, done);
exit(++exitStatus);
}
/* Second child */
else if (i == 1) {
ReadFromPipe(child1ToChild2, command);
ReadFromPipe(parentToChild2, command);
fprintf(stdout, "I am child #%d and my id is: %d\n", i+1, getpid());
/* Runs ls on /bin and /sbin */
sprintf(command, "ls /bin /sbin -lR");
exitStatus = system(command);
char done[] = "child2_done";
WriteToPipe(child2ToChild3, done);
WriteToPipe(child2ToParent, done);
exit(++exitStatus);
}
/* Third child */
else {
ReadFromPipe(child2ToChild3, command);
ReadFromPipe(parentToChild3, command);
fprintf(stdout, "I am child #%d and my id is: %d\n", i+1, getpid());
/* Cats file received from argument and source code */
sprintf(command, "cat %s Assignment5.c", argv[1]);
exitStatus = system(command);
char done[] = "child3_done";
WriteToPipe(child3ToParent, done);
exit(++exitStatus);
}
}
return 0;
}
