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
59 struct queue_message {
64 void notify_other_processes(int signo) {
66 struct queue_message msg;
70 pid_t pid = processes->pids[i];
72 if (i != 0 && pid != 0) {
74 fprintf(stderr, "[%s] Sending message of type (%d) with value %d\n", "process1", msg.mtype, msg.signo[0]);
75 msgsnd(pid, &msg, sizeof(int), 0);
76 fprintf(stderr, "[%s] Sending signal %s (%d) to PID: %d\n", "process1", strsignal(SIGUSR1), SIGUSR1, pid);
83 * Handler for signals.
85 void sig_handler(int signo)
87 fprintf(stderr, "[%s] Received %s!\n", "process1", strsignal(signo));
89 if (signo == SIGUSR1) {
90 fprintf(stderr, "[%s] > Notified!\n", "process1");
91 struct queue_message msg;
92 /* Check queues from both other processes */
93 if (msgrcv(processes->pids[1], &msg, sizeof(int), 1, 0) > 0) {
94 fprintf(stderr, "[%s] > Notified with value: %s!\n", "process1", strsignal(msg.signo[0]));
98 else if (msgrcv(processes->pids[2], &msg, sizeof(int), 1, 0) > 0) {
99 fprintf(stderr, "[%s] > Notified with value: %s!\n", "process1", strsignal(msg.signo[0]));
104 else if (signo == SIGTERM) {
105 fprintf(stderr, "[%s] > Signalling other processes..\n", "process1");
106 processes->pids[1] = 0;
107 notify_other_processes(signo);
109 fprintf(stderr, "[%s] > Releasing resources\n", "process1");
119 else if (signo == SIGTSTP) {
120 fprintf(stderr, "[%s] > Closing pipe\n", "process1");
124 else if (signo == SIGCONT) {
125 fprintf(stderr, "[%s] > Opening pipe\n", "process1");
126 file_descriptor = open(write_pipe, O_WRONLY);
131 * Program reads entire lines of text from the standard input and pass them
132 * to the process2 using created pipe.
135 /** Currently fetched from stdin character */
138 /** Current buffer length*/
139 int buffer_length = 0;
141 /** Index of the current character */
145 * Temporary buffer used as a proxy between
146 * checking memory allocation and copying data to real buffer
150 fprintf(stderr, "[%s] Init!\n", "process1");
153 * Register signals handled by process
155 if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
156 fprintf(stderr, "can't catch SIGUSR1\n");
158 if (signal(SIGTERM, sig_handler) == SIG_ERR) {
159 fprintf(stderr, "can't catch SIGTERM\n");
161 if (signal(SIGTSTP, sig_handler) == SIG_ERR) {
162 fprintf(stderr, "can't catch SIGTSTP\n");
164 if (signal(SIGCONT, sig_handler) == SIG_ERR) {
165 fprintf(stderr, "can't catch SIGCONT\n");
169 * Register memory to share with other processes, and pass current
170 * process id to the array.
172 shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666);
174 processes = (struct message *)shmat(shmid, NULL, 0);
175 processes->pids[0] = getpid();
177 fprintf(stderr, "[%s] Shared pid: %d\n", "process1", getpid());
180 * Register message queue to communicate with other processes
183 qid_input = msgget(qkey, IPC_CREAT | 0666);
185 qid_output1 = msgget(processes->pids[1], IPC_CREAT | 0666);
186 qid_output2 = msgget(processes->pids[2], IPC_CREAT | 0666);
188 mkfifo(write_pipe, 0666);
190 file_descriptor = open(write_pipe, O_WRONLY);
196 * Check if current index is bigger than current buffer size.
197 * If so increment buffer size. On error release memory, and set
200 if (i >= buffer_length) {
202 buffer_length += BUFFER_STEP;
203 tmp = (char*) realloc(buffer, buffer_length);
205 fprintf(stderr, "[%s] Memory allocation problem on read!\n", "process1");
213 * If there were no errors or it was not just an empty newline:
216 if (c != EOF || ((i == 0) && (c == 10))) {
217 /* If newline has been found
218 * return entire string and release the memory
220 if (c == 10 && (i != 0)) {
222 write(file_descriptor, buffer, strlen(buffer));
223 fprintf(stderr, "[%s] buffer: %s/%d\n", "process1", buffer, strlen(buffer));
233 * Normal character, add it to the buffer
239 /* Used only for debugging..*/
241 printf("c: %c/%d, i: %d, bl: %d\n", c, c, i, buffer_length);
248 /* Release resources in normal program flow exit. */