Make opening/closing/releasing resources available from signal handler.

diff --git a/src/process1.c b/src/process1.c
index b5004830f5c9c43e4aebc60df07a0cf1828e83ea..ad4b9111984c64b4079a78e32a41f912fcf965de 100644 (file)
--- a/src/process1.c
+++ b/src/process1.c
@@ -11,22 +11,44 @@
 /** If buffer is too small to hold entire string, it is incremented by this value */
 #define BUFFER_STEP 16
 
+/** Buffer used to store line of characters */
+char * buffer = NULL;
+
+/** Named pipe used to communnicate with process2 */
+char * write_pipe = "/tmp/process1pipe";
+
+/** File descriptor of pipe */
+int file_descriptor;
+
 /**
  * Handler for signals.
  */
 void sig_handler(int signo)
 {
        if (signo == SIGUSR1) {
-               fprintf(stderr, "[%s] SIGUSR1!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGUSR1!\n", "process1");
        }
-       else if (signo == SIGUSR2) {
-               fprintf(stderr, "[%s] SIGUSR2!\n", "process1");
+       else if (signo == SIGQUIT) {
+               fprintf(stderr, "[%s] Received SIGQUIT!\n", "process1");
+               fprintf(stderr, "[%s] > Releasing resources\n", "process1");
+               close(write_pipe);
+               unlink(write_pipe);
+
+               if (buffer) {
+                       free(buffer);
+                       buffer = NULL;
+               }
+               exit(0);
        }
        else if (signo == SIGINT) {
-               fprintf(stderr, "[%s] SIGINT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGINT!\n", "process1");
+               fprintf(stderr, "[%s] > Closing pipe\n", "process1");
+               close(write_pipe);
        }
        else if (signo == SIGCONT) {
-               fprintf(stderr, "[%s] SIGCONT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGCONT!\n", "process1");
+               fprintf(stderr, "[%s] > Opening pipe\n", "process1");
+               file_descriptor = open(write_pipe, O_WRONLY);
        }
 }
 
@@ -38,9 +60,6 @@ int main(void) {
        /** Currently fetched from stdin character */
        int c;
 
-       /** Buffer used to store line of characters */
-       char * buffer = NULL;
-
        /** Current buffer length*/
        int buffer_length = 0;
 
@@ -53,12 +72,6 @@ int main(void) {
         */
        char * tmp = NULL;
 
-       /** Named pipe used to communnicate with process2 */
-       char * write_pipe = "/tmp/process1pipe";
-
-       /** File descriptor of pipe */
-       int file_descriptor;
-
        fprintf(stderr, "[%s] Init!\n", "process1");
 
        /**
@@ -67,8 +80,8 @@ int main(void) {
        if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGUSR1\n");
        }
-       if (signal(SIGUSR2, sig_handler) == SIG_ERR) {
-               fprintf(stderr, "can't catch SIGUSR2\n");
+       if (signal(SIGQUIT, sig_handler) == SIG_ERR) {
+               fprintf(stderr, "can't catch SIGQUIT\n");
        }
        if (signal(SIGINT, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGINT\n");
@@ -137,6 +150,7 @@ int main(void) {
                }
        } while(c != EOF);
 
+       /* Release resources in normal program flow exit. */
        close(write_pipe);
        unlink(write_pipe);
 

diff --git a/src/process2.c b/src/process2.c
index 7ae70ffc4a056bfd4dfaaa21278c3537f89438ba..2b9a6f31feaf9c50d4d0135d08e1e7427cdf0f7b 100644 (file)
--- a/src/process2.c
+++ b/src/process2.c
@@ -1,4 +1,6 @@
 #include <stdio.h>
+/* exit.. */
+#include <stdlib.h>
 
 /* open/read/write/close */
 #include <fcntl.h>
@@ -9,22 +11,45 @@
 /** If buffer is too small to hold entire string, it is incremented by this value */
 #define BUFFER_STEP 16
 
+/** Named pipe used to communicate with process1 */
+char * read_pipe = "/tmp/process1pipe";
+
+/** Named pipe used to communicate with process3 */
+char * write_pipe = "/tmp/process2pipe";
+
+/** Descriptor of input pipe */
+int read_descriptor;
+
+/** Descriptor of output pipe */
+int write_descriptor;
+
 /**
  * Handler for signals.
  */
 void sig_handler(int signo)
 {
        if (signo == SIGUSR1) {
-               fprintf(stderr, "[%s] SIGUSR1!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGUSR1!\n", "process2");
        }
-       else if (signo == SIGUSR2) {
-               fprintf(stderr, "[%s] SIGUSR2!\n", "process1");
+       else if (signo == SIGQUIT) {
+               fprintf(stderr, "[%s] Received SIGQUIT!\n", "process2");
+               fprintf(stderr, "[%s] > Releasing resources\n", "process2");
+               close(read_descriptor);
+               close(write_descriptor);
+               unlink(write_descriptor);
+               exit(0);
        }
        else if (signo == SIGINT) {
-               fprintf(stderr, "[%s] SIGINT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGINT!\n", "process2");
+               fprintf(stderr, "[%s] > Closing pipes\n", "process2");
+               close(read_descriptor);
+               close(write_descriptor);
        }
        else if (signo == SIGCONT) {
-               fprintf(stderr, "[%s] SIGCONT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGCONT!\n", "process2");
+               fprintf(stderr, "[%s] > Opening pipes\n", "process2");
+               read_descriptor = open(read_pipe, O_RDONLY);
+               write_descriptor = open(write_pipe, O_WRONLY);
        }
 }
 
@@ -33,18 +58,6 @@ void sig_handler(int signo)
  * and pass the value to process3.
  */
 int main(void) {
-       /** Named pipe used to communicate with process1 */
-       char * read_pipe = "/tmp/process1pipe";
-
-       /** Named pipe used to communicate with process3 */
-       char * write_pipe = "/tmp/process2pipe";
-
-       /** Descriptor of input pipe */
-       int read_descriptor;
-
-       /** Descriptor of output pipe */
-       int write_descriptor;
-
        /**
         * Buffer used for storing data from input pipe.
         * Data is stored in chunks of BUFFER_STEP size.
@@ -59,13 +72,6 @@ int main(void) {
        /** Stores number of bytes read from input pipe in current iteration */
        ssize_t count = 0;
 
-       /* Reading from process1 */
-       read_descriptor = open(read_pipe, O_RDONLY);
-
-       /* Writing to process2 */
-       mkfifo(write_pipe, 0666);
-       write_descriptor = open(write_pipe, O_WRONLY);
-
        int number_of_characters = 0;
 
        fprintf(stderr, "[%s] Init!\n", "process2");
@@ -76,8 +82,8 @@ int main(void) {
        if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGUSR1\n");
        }
-       if (signal(SIGUSR2, sig_handler) == SIG_ERR) {
-               fprintf(stderr, "can't catch SIGUSR2\n");
+       if (signal(SIGQUIT, sig_handler) == SIG_ERR) {
+               fprintf(stderr, "can't catch SIGQUIT\n");
        }
        if (signal(SIGINT, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGINT\n");
@@ -86,6 +92,13 @@ int main(void) {
                fprintf(stderr, "can't catch SIGCONT\n");
        }
 
+       /* Reading from process1 */
+       read_descriptor = open(read_pipe, O_RDONLY);
+
+       /* Writing to process2 */
+       mkfifo(write_pipe, 0666);
+       write_descriptor = open(write_pipe, O_WRONLY);
+
        while(1) {
                /* Read data from input pipe */
                count = read(read_descriptor, buffer, BUFFER_STEP);
@@ -107,6 +120,7 @@ int main(void) {
                }
        }
 
+       /* Release resources in normal program flow exit. */
        close(read_descriptor);
        close(write_descriptor);
        unlink(write_descriptor);

diff --git a/src/process3.c b/src/process3.c
index 8b4f8264f39a3621f6dc0f267b6f53e8339e0f63..e75a4fb610d66bae33e895d8271178a8280fe1e7 100644 (file)
--- a/src/process3.c
+++ b/src/process3.c
@@ -1,27 +1,43 @@
 #include <stdio.h>
 
+/* exit.. */
+#include <stdlib.h>
+
 /* open/read/write/close */
 #include <fcntl.h>
 
 /* Signals handling.. */
 #include <signal.h>
 
+/** Named pipe used to communicate with process2 */
+char * read_pipe = "/tmp/process2pipe";
+
+/** Descriptor of input pipe */
+int read_descriptor;
+
 /**
  * Handler for signals.
  */
 void sig_handler(int signo)
 {
        if (signo == SIGUSR1) {
-               fprintf(stderr, "[%s] SIGUSR1!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGUSR1!\n", "process3");
        }
-       else if (signo == SIGUSR2) {
-               fprintf(stderr, "[%s] SIGUSR2!\n", "process1");
+       else if (signo == SIGQUIT) {
+               fprintf(stderr, "[%s] Received SIGQUIT!\n", "process3");
+               fprintf(stderr, "[%s] > Releasing resources\n", "process3");
+               close(read_descriptor);
+               exit(0);
        }
        else if (signo == SIGINT) {
-               fprintf(stderr, "[%s] SIGINT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGINT!\n", "process3");
+               fprintf(stderr, "[%s] > Closing pipe\n", "process2");
+               close(read_descriptor);
        }
        else if (signo == SIGCONT) {
-               fprintf(stderr, "[%s] SIGCONT!\n", "process1");
+               fprintf(stderr, "[%s] Received SIGCONT!\n", "process3");
+               fprintf(stderr, "[%s] > Opening pipe\n", "process2");
+               read_descriptor = open(read_pipe, O_RDONLY);
        }
 }
 
@@ -30,12 +46,6 @@ void sig_handler(int signo)
  * grabbed data to the standard output.
  */
 int main(void) {
-       /** Named pipe used to communicate with process2 */
-       char * read_pipe = "/tmp/process2pipe";
-
-       /** Descriptor of input pipe */
-       int read_descriptor;
-
        /** Buffer used for storing data from input pipe */
        int buffer = 0;
        
@@ -50,8 +60,8 @@ int main(void) {
        if (signal(SIGUSR1, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGUSR1\n");
        }
-       if (signal(SIGUSR2, sig_handler) == SIG_ERR) {
-               fprintf(stderr, "can't catch SIGUSR2\n");
+       if (signal(SIGQUIT, sig_handler) == SIG_ERR) {
+               fprintf(stderr, "can't catch SIGQUIT\n");
        }
        if (signal(SIGINT, sig_handler) == SIG_ERR) {
                fprintf(stderr, "can't catch SIGINT\n");
@@ -77,6 +87,7 @@ int main(void) {
                }
        }
 
+       /* Release resources in normal program flow exit. */
        close(read_descriptor);
 
        return 0;