From 08d6167988a0bbec72d84ff12f8857f0b4d0b42a Mon Sep 17 00:00:00 2001
From: Stefan Zabka <zabkaste@hu-berlin.de>
Date: Wed, 13 May 2020 20:38:21 +0200
Subject: Changing dirs kinda works

---
 02_exercise/beispiele/pipe_bidirect/pingpong.c | 205 +++++++++++++------------
 1 file changed, 103 insertions(+), 102 deletions(-)

(limited to '02_exercise/beispiele/pipe_bidirect')

diff --git a/02_exercise/beispiele/pipe_bidirect/pingpong.c b/02_exercise/beispiele/pipe_bidirect/pingpong.c
index ac5eb1c..f38394f 100644
--- a/02_exercise/beispiele/pipe_bidirect/pingpong.c
+++ b/02_exercise/beispiele/pipe_bidirect/pingpong.c
@@ -1,124 +1,125 @@
+#include <fcntl.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <fcntl.h>
 #include <unistd.h>
 
 static int split(int fd[2]);
-static int redir(int fd, const char* file);
+static int redir(int fd, const char *file);
 static void sig_handler(int sig);
 
 static int parent;
 
 int main(void) {
-	ssize_t bytes;
-	char buf[256];
-	int fd[2];
-	
-	// disable buffering for stdout
-	setvbuf(stdout, NULL, _IONBF, 0);
-	
-	// redirect stdout to write into a file
-	if (redir(1, "log.txt") < 0) {
-		perror("redir()");
-		exit(-1);
-	}
-	
-	// install the signal handler for Ctrl+C
-	if (signal(SIGINT, sig_handler) == SIG_ERR) {
-		perror("signal()");
-		exit(-1);
-	}
-	
-	// split processes and assign file descriptors for communication
-	switch (split(fd)) {
-	case -1: // error
-		exit(-1);
-		
-	case 0:  // child
-		while ((bytes = read(fd[0], buf, sizeof(buf))) > 0) {
-			printf("[%u]: %s\n", getpid(), buf);
-			sleep(1);
-			write(fd[1], "pong", 5);
-		}
-		break;
-		
-	case 1:  // parent
-		parent = 1;
-		write(fd[1], "ping", 5);
-		while ((bytes = read(fd[0], buf, sizeof(buf))) > 0) {
-			printf("[%u]: %s\n", getpid(), buf);
-			sleep(1);
-			write(fd[1], "ping", 5);
-		}
-		break;
-	}
-	
-	// close the file descriptors
-	close(fd[0]);
-	close(fd[1]);
-	
-	return 0;
+    ssize_t bytes;
+    char buf[256];
+    int fd[2];
+
+    // disable buffering for stdout
+    setvbuf(stdout, NULL, _IONBF, 0);
+
+    // redirect stdout to write into a file
+    if (redir(1, "log.txt") < 0) {
+        perror("redir()");
+        exit(-1);
+    }
+
+    // install the signal handler for Ctrl+C
+    if (signal(SIGINT, sig_handler) == SIG_ERR) {
+        perror("signal()");
+        exit(-1);
+    }
+
+    // split processes and assign file descriptors for communication
+    switch (split(fd)) {
+    case -1: // error
+        exit(-1);
+
+    case 0: // child
+        while ((bytes = read(fd[0], buf, sizeof(buf))) > 0) {
+            printf("[%u]: %s\n", getpid(), buf);
+            sleep(1);
+            write(fd[1], "pong", 5);
+        }
+        break;
+
+    case 1: // parent
+        parent = 1;
+        write(fd[1], "ping", 5);
+        while ((bytes = read(fd[0], buf, sizeof(buf))) > 0) {
+            printf("[%u]: %s\n", getpid(), buf);
+            sleep(1);
+            write(fd[1], "ping", 5);
+        }
+        break;
+    }
+
+    // close the file descriptors
+    close(fd[0]);
+    close(fd[1]);
+
+    return 0;
 }
 
 int split(int fd[2]) {
-	int pfd[2][2];
-	
-	if (pipe(pfd[0]) < 0) {
-		perror("pipe()");
-		goto err_pipe1;
-	}
-	
-	if (pipe(pfd[1]) < 0) {
-		perror("pipe()");
-		goto err_pipe2;
-	}
-	
-	switch (fork()) {
-	case -1:
-		perror("fork()");
-		goto err_fork;
-		
-	case 0:  // child process
-		close(pfd[0][1]);  // close write for child
-		close(pfd[1][0]);  // close read for parent
-		fd[0] = pfd[0][0]; // keep read for child
-		fd[1] = pfd[1][1]; // keep write for parent
-		return 0;
-		
-	default: // parent process
-		close(pfd[1][1]);  // close write for parent
-		close(pfd[0][0]);  // close read for child
-		fd[0] = pfd[1][0]; // keep read for parent
-		fd[1] = pfd[0][1]; // keep write for child
-		return 1;
-	}
-	
+    int pfd[2][2];
+
+    if (pipe(pfd[0]) < 0) {
+        perror("pipe()");
+        goto err_pipe1;
+    }
+
+    if (pipe(pfd[1]) < 0) {
+        perror("pipe()");
+        goto err_pipe2;
+    }
+
+    switch (fork()) {
+    case -1:
+        perror("fork()");
+        goto err_fork;
+
+    case 0:                // child process
+        close(pfd[0][1]);  // close write for child
+        close(pfd[1][0]);  // close read for parent
+        fd[0] = pfd[0][0]; // keep read for child
+        fd[1] = pfd[1][1]; // keep write for parent
+        return 0;
+
+    default:               // parent process
+        close(pfd[1][1]);  // close write for parent
+        close(pfd[0][0]);  // close read for child
+        fd[0] = pfd[1][0]; // keep read for parent
+        fd[1] = pfd[0][1]; // keep write for child
+        return 1;
+    }
+
 err_fork:
-	close(pfd[1][0]);
-	close(pfd[1][1]);
+    close(pfd[1][0]);
+    close(pfd[1][1]);
 err_pipe2:
-	close(pfd[0][0]);
-	close(pfd[0][1]);
+    close(pfd[0][0]);
+    close(pfd[0][1]);
 err_pipe1:
-	return -1;
+    return -1;
 }
 
-int redir(int fd, const char* file) {
-	int fd2 = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-	
-	if (fd2 < 0)
-		return -1;
-	
-	dup2(fd2, fd);
-	close(fd2);
-	
-	return 0;
+int redir(int fd, const char *file) {
+    int fd2 = open(file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
+
+    if (fd2 < 0)
+        return -1;
+
+    dup2(fd2, fd);
+    close(fd2);
+
+    return 0;
 }
 
 void sig_handler(int sig) {
-	if (parent) {
-		const char msg[] = "Programmabbruch durch Nutzer\n";
-		write(1, msg, sizeof(msg) - 1);
-	}
-	exit(0);
+    if (parent) {
+        const char msg[] = "Programmabbruch durch Nutzer\n";
+        write(1, msg, sizeof(msg) - 1);
+    }
+    exit(0);
 }
-- 
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