void main() // no need of given args, use self pid as semaphore key
{
int c_row, c_col, r_row, r_col;
int the_pipe[2]; // 1 pipe for both children
sem_t *sem_video, *sem_c, *sem_r;
char str[20]; // str for common usage
char row_str[3], col_str[3], pipe_str[3], symbol_str[3]; // child's argv
// prep video semaphore, start value 1, make it like a mutex
sprintf( str, "%d", getpid() ); // build key str out of pid
sem_video = sem_open( str, O_CREAT, 0600, 1 );
// prep Chaser semaphore, start value 0
sprintf( str, "%d", 'C'+getpid() ); // key str out of pid + 'C'
sem_c = sem_open( str, O_CREAT, 0600, 1 );
// prep Runner semaphore, start value 0
sprintf( str, "%d", 'R'+getpid() ); // key str out of pid + 'R'
sem_r = sem_open( str, O_CREAT, 0600, 1 );
if(sem_video == SEM_FAILED) // erred in sys call sem_open
{
perror("Error opening semaphore: ");
return;
}
if( -1 == pipe(the_pipe) ) // 1 pipe for both children
{
perror("Error making pipe: ");
return;
}
InitScr( sem_video ); // starting screen
// prep argv for Chaser, starts at upper-left corner
sprintf(row_str, "%d", 0); // starting row pos, packing info into str
sprintf(col_str, "%d", 0); // starting col pos, packing info into str
sprintf(pipe_str, "%d", the_pipe[1]); // pipe end for it to write back
sprintf(symbol_str, "%c", 'C'); // Chaser's char symbol
switch( fork() ) // launch Chaser child
{
case -1:
perror("fork C: ");
return; // error in fork
case 0:
execl( "./child", "./child", // start child proc with argv
row_str, col_str, pipe_str, symbol_str, 0 );
}
// prep argv for Runner, starts at lower-right corner
sprintf(row_str, "%d", MAX_ROW);
sprintf(col_str, "%d", MAX_COL);
// sprintf(pipe_str, "%d", ...); // same pipe_str as above
sprintf(symbol_str, "%c", 'R');
switch( fork() ) // launch Runner child
{
case -1:
perror("fork R: ");
return;
case 0:
execl( "./child", "./child",
row_str, col_str, pipe_str, symbol_str, 0 );
}
while(1) // let them play forever
{
sem_post( sem_c ); // allow Chaser 1 play move (loop once, see child.c)
read( the_pipe[0], &c_row, sizeof(int) ); // read pos info row from Chaser
read( the_pipe[0], &c_col, sizeof(int) ); // read pos info col from Chaser
if(c_row == r_row && c_col == r_col) break; // collision occurred?
sem_post( sem_r ); // allow Runner 1 play move (loop once, see child.c)
read( the_pipe[0], &r_row, sizeof(int) ); // read pos info from Runner
read( the_pipe[0], &r_col, sizeof(int) ); // read pos info from Runner
if(c_row == r_row && c_col == r_col) break; // collision occurred?
}
sem_wait(sem_video); // since children are still running, hold till end
Flash(); // flash screen, restore cursor
sprintf(str, "%c[%d;%dH", 27, MAX_ROW+3, 1); // move cursor to bottom
write(1, str, strlen(str));
printf("\n*** Chaser got Runner! *** \n"); // OK to use printf since
printf("Chaser at row %d col %d\n", c_row, c_col); // we're all done with
printf("Runner at row %d col %d\n", r_row, r_col); // moving around symbols
// if not removed, same filename remains in /dev/shm/sem.<pid>
sprintf( str, "%d", getpid() ); // build key str out of pid
sem_unlink( str );
sprintf( str, "%d", 'C'+getpid() ); // build key str out of pid+'C'
sem_unlink( str );
sprintf( str, "%d", 'R'+getpid() ); // build key str out of pid+'R'
sem_unlink( str );
kill(0, SIGHUP); // shutdown all processes, include this
}
int main( int argc, char* argv[] )
{
char character; // current character
char str[40]; // general purpose string
pid_t pids[26]; // child alphabet pids
info_t *info_c; // info_t for client
info_t *info_c_m; // info_t for client monitor
info_t* infos[26]; // info_t for all alphabets
sem_t *sem_video; // video semaphore
int finishing_place = 1; // starting finish place
char termination_cond = '<'; // the termination condition
sprintf( video_key_str, "%d", getpid() );
// create video semaphore
sem_video = sem_open( video_key_str, O_CREAT, 0666, 1 );
if ( sem_video == SEM_FAILED ) {
perror( "server semaphore" );
exit(1);
}
// request/allocate shared memory for client
if( ( shmid_c = shmget( getpid()+32766,
sizeof( info_t ), IPC_CREAT|0666 ) ) < 0 ) {
perror( "server shmget" );
exit(1);
}
if( ( shmid_c_m = shmget( getpid()+32767,
sizeof( info_t ), IPC_CREAT|0666 ) ) < 0 ) {
perror( "server shmget" );
exit(1);
}
// attach to shared memory for client
if( ( info_c = (info_t *)shmat( shmid_c, 0, 0 ) ) == (info_t *) -1 ) {
perror( "server shmat" );
exit(1);
}
if( ( info_c_m = (info_t *)shmat( shmid_c_m, 0, 0 ) ) == (info_t *) -1 ) {
perror( "server shmat" );
exit(1);
}
// set default alphabet character in client shared memory
// we'll use this to notice a change, signaling the client
// has made their choice and is ready to race
info_c->alphabet = '*';
info_c->row = shmid_c_m; // give the client the monitoring shmid num
info_c->col = -1;
info_c->o_col = -1;
info_c->start = 0;
info_c->finishing_place = -1;
info_c->points = -1;
strcpy( info_c->sem_video_str, video_key_str );
// more defaults
info_c_m->alphabet = '*';
info_c_m->row = -1;
info_c_m->col = -1;
info_c_m->o_col = -1;
info_c_m->start = 0;
info_c_m->finishing_place = -1;
info_c_m->points = -1;
strcpy( info_c_m->sem_video_str, video_key_str );
ClearScr( sem_video );
// display client shared memory id so user can
// attach to the server
printf( "From another shell, run client and pick winner.\n" );
printf( "Syntax: './client %d'\n", shmid_c );
// now setup the children alphabet process while waiting for client
int i = 0;
for ( character = 'A'; character <= 'Z'; character++ ) {
if( ( shmids[i] = shmget( getpid()+32767+i,
sizeof( info_t ), IPC_CREAT|0666 ) ) < 0 ) {
perror( "server shmget alphabet" );
exit(1);
}
// attach to shared memory
if ( ( infos[i] = (info_t *)shmat( shmids[i], 0, 0 ) )
== (info_t *) -1 ) {
perror( "server shmat alphabet" );
exit(1);
}
// set defaults
infos[i]->alphabet = character;
infos[i]->row = ((int)character - 64);
infos[i]->col = 1; // default starting column
infos[i]->o_col = -1; // there is no old column yet
infos[i]->start = 0; // don't start the race yet
infos[i]->finishing_place = -1; // race has not started yet
infos[i]->points = -1; // no points yet
strcpy( infos[i]->sem_video_str, video_key_str );
i++;
}
for ( i = 0; i < 26; i++ ) {
sprintf( str, "%d", shmids[i] );
pids[i] = fork();
if ( pids[i] == -1 ) {
perror( "server fork alphabet" );
exit(1);
}
else if ( pids[i] == 0 ) { // in child process
execl( "./alphabet", "alphabet", str, NULL );
}
i++;
usleep( USEC );
}
// ensure we always cleanup
atexit( exit_handler );
while( info_c->alphabet == '*' ) {
usleep( USEC );
}
printf( "\n >>>>>> Client picked '%c' <<<<<<\n", info_c->alphabet );
usleep( USEC * 6 );
ClearScr( sem_video );
InitScr( sem_video );
// On your marks!
usleep( USEC * 3 );
// Get Set!
usleep( USEC * 3 );
// Go!
for ( i = 0; i < 26; i++ ) {
infos[i]->start = 1;
}
info_c->start = 1;
// loop and display children updates
// also update client with new positions
while ( 1 ) {
int i;
for ( i = 0; i < 26; i++ ) {
PutChar( infos[i]->row, infos[i]->o_col, ' ', sem_video );
PutChar( infos[i]->row, infos[i]->col,
infos[i]->alphabet, sem_video );
// update client monitor
info_c_m->alphabet = infos[i]->alphabet;
info_c_m->row = infos[i]->row;
info_c_m->col = infos[i]->col;
info_c_m->o_col = infos[i]->o_col;
if ( infos[i]->col == MAX_COL ) {
sem_wait( sem_video );
sprintf( str, "\033[%d;%dH", infos[i]->alphabet - 64, 62 );
write( OUT, str, strlen(str) );
sprintf( str, "<-- %d", finishing_place );
write( OUT, str, strlen(str) );
if ( finishing_place <= 5 ) {
sprintf( str, "\033[%d;%dH", infos[i]->alphabet - 64, 68 );
write( OUT, str, strlen(str) );
sprintf( str, "%s", "***" );
write( OUT, str, strlen(str) );
}
sem_post( sem_video );
infos[i]->finishing_place = finishing_place;
infos[i]->points = 26 - finishing_place;
// update client monitor
info_c_m->finishing_place = infos[i]->finishing_place;
info_c_m->points = infos[i]->points;
finishing_place++;
}
}
if ( finishing_place > 26 ) break;
}
// inform client race is over
info_c_m->alphabet = termination_cond;
// assign client their points
info_c->points = infos[info_c->alphabet - 64]->points;
FlashScr( sem_video );
CursorOn( sem_video );
printf( "Client points: %d\n", info_c->points );
if ( info_c->points < 21 ) {
printf( "Better luck next time!\n" );
} else {
printf( "Nice!\n" );
}
return 0; // normal return
}
int main( int argc, char* argv[] )
{
int pipes[2];
char write_pipe_str[8];
int c_pos[2];
int r_pos[2];
sem_t *sem_video, *sem_c, *sem_r;
char video_key_str[8];
char c_key_str[8];
char r_key_str[8];
pid_t video_key = getpid();
pid_t pids[2];
// create pipes for comms
if ( -1 == pipe( pipes ) ) {
perror( "pipe: ");
exit(1);
}
sprintf( write_pipe_str, "%d", pipes[1] );
sprintf( video_key_str, "%d", video_key );
sprintf( c_key_str, "c_%d", video_key );
sprintf( r_key_str, "r_%d", video_key );
// create semaphores
sem_video = sem_open( video_key_str, O_CREAT, 0600, 1 );
sem_c = sem_open( c_key_str, O_CREAT, 0600, 1 );
sem_r = sem_open( r_key_str, O_CREAT, 0600, 1 );
// check for semaphore creation errors
if ( sem_video == SEM_FAILED ) {
perror( "video sem: " );
exit(1);
}
if ( sem_c == SEM_FAILED ) {
perror( "c sem: " );
exit(1);
}
if ( sem_r == SEM_FAILED ) {
perror( "r sem: " );
exit(1);
}
// block semaphores so children don't start playing early
sem_wait( sem_c );
sem_wait( sem_r );
// init screen
sem_wait( sem_video );
InitScr();
sem_post( sem_video );
// create childres (C and R)
int i;
for ( i = 0; i < 2; i++ ) {
pids[i] = fork();
if ( pids[i] == -1 ) {
perror( "fork: " );
exit(1);
}
else if ( pids[i] == 0 ) { // in child process
if ( i == 0 ) { // chaser
execl( "./child", "child", "C", write_pipe_str, c_key_str, video_key_str, NULL );
} else if ( i == 1 ) { // runner
execl( "./child", "child", "R", write_pipe_str, r_key_str, video_key_str, NULL );
}
}
}
// round robin children until C catches R
while( 1 ) {
usleep( USEC );
sem_post( sem_r );
read( pipes[0], &r_pos[0], sizeof(int) );
read( pipes[0], &r_pos[1], sizeof(int) );
usleep( USEC );
sem_post( sem_c );
read( pipes[0], &c_pos[0], sizeof(int) );
read( pipes[0], &c_pos[1], sizeof(int) );
if ( c_pos[0] == r_pos[0] && c_pos[1] == r_pos[1] ) {
// Chaser caught Runner
for ( i = 0; i < 2; i++ ) {
kill( pids[i], SIGTERM );
}
FlashScr();
printf( "*** Chaser got Runner! ***\n" );
printf( "row # %d == %d\n", c_pos[0], r_pos[0] );
printf( "col # %d == %d\n", c_pos[1], r_pos[1] );
break;
}
}
// cleanup
close( pipes[0] );
close( pipes[1] );
sem_unlink( video_key_str );
sem_unlink( c_key_str );
sem_unlink( r_key_str );
return 0;
}
