From f0a7f7a71896b25cc524598e5472c821f987a71c Mon Sep 17 00:00:00 2001 From: =?utf8?q?Rafa=C5=82=20D=C5=82ugo=C5=82=C4=99cki?= Date: Sat, 21 Jun 2014 11:43:53 +0200 Subject: [PATCH] Added initial inter-process communication: Sharing pids between processes. --- src/process1.c | 39 +++++++++++++++++++++++++++++++++++++++ src/process2.c | 40 ++++++++++++++++++++++++++++++++++++++++ src/process3.c | 39 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 118 insertions(+) diff --git a/src/process1.c b/src/process1.c index 9fdee30..b28563f 100644 --- a/src/process1.c +++ b/src/process1.c @@ -8,6 +8,9 @@ /* Signals handling.. */ #include +#include + + /** If buffer is too small to hold entire string, it is incremented by this value */ #define BUFFER_STEP 16 @@ -20,6 +23,29 @@ char * write_pipe = "/tmp/process1pipe"; /** File descriptor of pipe */ int file_descriptor; + +/** + * Shared memory variables + */ +/** + * Memory key for processes. Must be same between all processes to properly + * communicate. + */ +key_t shmkey = 18912; +/** + * Id of the shared memory + */ +int shmid; + +/** + * Message shared by processes. Contains array of process IDs + */ +struct message { + pid_t pids[3]; +}; + +struct message * processes = NULL; + /** * Handler for signals. */ @@ -29,6 +55,7 @@ void sig_handler(int signo) if (signo == SIGUSR1) { } else if (signo == SIGTERM) { + int i = 0; fprintf(stderr, "[%s] > Releasing resources\n", "process1"); close(write_pipe); unlink(write_pipe); @@ -37,6 +64,9 @@ void sig_handler(int signo) free(buffer); buffer = NULL; } + for (; i < 3; i++) { + fprintf(stderr, "[%s] Process %d, PID: %d\n", "process3", i, processes->pids[i]); + } exit(0); } else if (signo == SIGTSTP) { @@ -88,6 +118,15 @@ int main(void) { fprintf(stderr, "can't catch SIGCONT\n"); } + /* + * Register memory to share with other processes, and pass current + * process id to the array. + */ + shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666); + + processes = (struct message *)shmat(shmid, NULL, 0); + processes->pids[0] = getpid(); + mkfifo(write_pipe, 0666); file_descriptor = open(write_pipe, O_WRONLY); diff --git a/src/process2.c b/src/process2.c index 4908173..2417fe8 100644 --- a/src/process2.c +++ b/src/process2.c @@ -8,6 +8,8 @@ /* Signals handling.. */ #include +#include + /** If buffer is too small to hold entire string, it is incremented by this value */ #define BUFFER_STEP 16 @@ -23,6 +25,31 @@ int read_descriptor; /** Descriptor of output pipe */ int write_descriptor; + +/** + * Shared memory variables + */ + +/** + * Memory key for processes. Must be same between all processes to properly + * communicate. + */ +key_t shmkey = 18912; +/** + * Id of the shared memory + */ +int shmid; + +/** + * Message shared by processes. Contains array of process IDs + */ +struct message { + pid_t pids[3]; +}; + +struct message * processes = NULL; + + /** * Handler for signals. */ @@ -32,10 +59,14 @@ void sig_handler(int signo) if (signo == SIGUSR1) { } else if (signo == SIGTERM) { + int i = 0; fprintf(stderr, "[%s] > Releasing resources\n", "process2"); close(read_descriptor); close(write_descriptor); unlink(write_descriptor); + for (; i < 3; i++) { + fprintf(stderr, "[%s] Process %d, PID: %d\n", "process3", i, processes->pids[i]); + } exit(0); } else if (signo == SIGTSTP) { @@ -90,6 +121,15 @@ int main(void) { fprintf(stderr, "can't catch SIGCONT\n"); } + /* + * Register memory to share with other processes, and pass current + * process id to the array. + */ + shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666); + + processes = (struct message *)shmat(shmid, NULL, 0); + processes->pids[1] = getpid(); + /* Reading from process1 */ read_descriptor = open(read_pipe, O_RDONLY); diff --git a/src/process3.c b/src/process3.c index 12efd40..b1b9972 100644 --- a/src/process3.c +++ b/src/process3.c @@ -9,12 +9,38 @@ /* Signals handling.. */ #include +#include + /** Named pipe used to communicate with process2 */ char * read_pipe = "/tmp/process2pipe"; /** Descriptor of input pipe */ int read_descriptor; + +/** + * Shared memory variables + */ +/** + * Memory key for processes. Must be same between all processes to properly + * communicate. + */ +key_t shmkey = 18912; +/** + * Id of the shared memory + */ +int shmid; + +/** + * Message shared by processes. Contains array of process IDs + */ +struct message { + pid_t pids[3]; +}; + +struct message * processes = NULL; + + /** * Handler for signals. */ @@ -24,8 +50,12 @@ void sig_handler(int signo) if (signo == SIGUSR1) { } else if (signo == SIGTERM) { + int i = 0; fprintf(stderr, "[%s] > Releasing resources\n", "process3"); close(read_descriptor); + for (; i < 3; i++) { + fprintf(stderr, "[%s] Process %d, PID: %d\n", "process3", i, processes->pids[i]); + } exit(0); } else if (signo == SIGTSTP) { @@ -68,6 +98,15 @@ int main(void) { fprintf(stderr, "can't catch SIGCONT\n"); } + /* + * Register memory to share with other processes, and pass current + * process id to the array. + */ + shmid = shmget(shmkey, sizeof(struct message), IPC_CREAT | 0666); + + processes = (struct message *)shmat(shmid, NULL, 0); + processes->pids[2] = getpid(); + /* Reading from process2 */ read_descriptor = open(read_pipe, O_RDONLY); -- 2.30.2