5 /* open/read/write/close */
8 /* Signals handling.. */
15 /** If buffer is too small to hold entire string, it is incremented by this value */
16 #define BUFFER_STEP 16
18 /** Buffer used to store line of characters */
21 /** Named pipe used to communnicate with process2 */
22 char * write_pipe = "/tmp/process1pipe";
24 /** File descriptor of pipe */
29 * Shared memory variables
32 * Memory key for processes. Must be same between all processes to properly
37 * Id of the shared memory
42 * Message shared by processes. Contains array of process IDs
48 struct message * processes = NULL;
51 * Message Queue variables
55 * Unique key of message queue.
65 * Structure holding queue message data.
66 * Parameter mtype describes process to whom message is sent.
67 * Parameter signo is a signal to raise after getting message.
69 struct queue_message {
74 void notify_other_processes(int signo) {
76 struct queue_message msg;
80 pid_t pid = processes->pids[i];
82 if (i != 0 && pid != 0) {
84 fprintf(stderr, "[%s] Sending message of type (%d) with value %d\n", "process1", msg.mtype, msg.signo[0]);
85 msgsnd(qid, &msg, sizeof(int), 0);
86 fprintf(stderr, "[%s] Sending signal %s (%d) to PID: %d\n", "process1", strsignal(SIGUSR1), SIGUSR1, pid);
93 * Handler for signals.
95 void sig_handler(int signo)
97 fprintf(stderr, "[%s] Received %s!\n", "process1", strsignal(signo));
98 if (signo == SIGUSR1) {
99 fprintf(stderr, "[%s] > Notified!\n", "process1");
100 struct queue_message msg;
101 /* Check queues from both other processes */
102 if (msgrcv(qid, &msg, sizeof(int), 1, 0) > 0) {
103 fprintf(stderr, "[%s] > Notified with value: %s!\n", "process1", strsignal(msg.signo[0]));
107 else if (signo == SIGTERM) {
108 fprintf(stderr, "[%s] > Signalling other processes..\n", "process1");
109 processes->pids[0] = 0;
110 notify_other_processes(signo);
112 fprintf(stderr, "[%s] > Releasing resources\n", "process1");
122 else if (signo == SIGTSTP) {
123 fprintf(stderr, "[%s] > Signalling other processes..\n", "process1");
124 processes->pids[0] = 0;
125 notify_other_processes(signo);
127 processes->pids[0] = getpid();
129 fprintf(stderr, "[%s] > Closing pipe\n", "process1");
133 else if (signo == SIGCONT) {
134 fprintf(stderr, "[%s] > Opening pipe\n", "process1");
135 file_descriptor = open(write_pipe, O_WRONLY);
136 processes->pids[0] = 0;
137 notify_other_processes(signo);
139 processes->pids[0] = getpid();
144 * Program reads entire lines of text from the standard input and pass them
145 * to the process2 using created pipe.
148 /** Currently fetched from stdin character */
151 /** Current buffer length*/
152 int buffer_length = 0;
154 /** Index of the current character */
158 * Temporary buffer used as a proxy between
159 * checking memory allocation and copying data to real buffer
163 fprintf(stderr, "[%s] Init!\n", "process1");
166 * Register signals handled by process
168 if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
169 fprintf(stderr, "can't catch SIGUSR1\n");
171 if (signal(SIGTERM, sig_handler) == SIG_ERR) {
172 fprintf(stderr, "can't catch SIGTERM\n");
174 if (signal(SIGTSTP, sig_handler) == SIG_ERR) {
175 fprintf(stderr, "can't catch SIGTSTP\n");
177 if (signal(SIGCONT, sig_handler) == SIG_ERR) {
178 fprintf(stderr, "can't catch SIGCONT\n");
182 * Register memory to share with other processes, and pass current
183 * process id to the array.
185 shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666);
187 processes = (struct message *)shmat(shmid, NULL, 0);
188 processes->pids[0] = getpid();
190 fprintf(stderr, "[%s] Shared pid: %d\n", "process1", getpid());
193 * Register message queue to communicate with other processes
195 qid = msgget(qkey, IPC_CREAT | 0666);
197 mkfifo(write_pipe, 0666);
199 file_descriptor = open(write_pipe, O_WRONLY);
205 * Check if current index is bigger than current buffer size.
206 * If so increment buffer size. On error release memory, and set
209 if (i >= buffer_length) {
211 buffer_length += BUFFER_STEP;
212 tmp = (char*) realloc(buffer, buffer_length);
214 fprintf(stderr, "[%s] Memory allocation problem on read!\n", "process1");
222 * If there were no errors or it was not just an empty newline:
225 if (c != EOF || ((i == 0) && (c == 10))) {
226 /* If newline has been found
227 * return entire string and release the memory
229 if (c == 10 && (i != 0)) {
231 write(file_descriptor, buffer, strlen(buffer));
232 fprintf(stderr, "[%s] buffer: %s/%d\n", "process1", buffer, strlen(buffer));
242 * Normal character, add it to the buffer
248 /* Used only for debugging..*/
250 printf("c: %c/%d, i: %d, bl: %d\n", c, c, i, buffer_length);
257 /* Release resources in normal program flow exit. */