From: Rafał Długołęcki <rafal@dlugolecki.net.pl>
Date: Sat, 21 Jun 2014 05:21:49 +0000 (+0200)
Subject: Make opening/closing/releasing resources available from signal handler.
X-Git-Url: https://git.dlugolecki.net.pl/?a=commitdiff_plain;h=08dc9bf01302aa7d9a75efca24de1a9b19ec5c9e;p=wsti_so.git

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

diff --git a/src/process1.c b/src/process1.c
index b500483..ad4b911 100644
--- 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 7ae70ff..2b9a6f3 100644
--- 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 8b4f826..e75a4fb 100644
--- 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;