Added task 3.1

.gitignore

@@ -3,3 +3,6 @@ cmake-build-debug
 CMakeLists.txt
 .idea
 *.o
+
+# Apple
+.DS_Store

Topic-2/child_functions.c

@@ -1,5 +1,5 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 void child_task() {

Topic-2/child_functions.h

@@ -1,5 +1,5 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 #ifndef AAE_CNAS_LABS_CHILD_FUNCTIONS_H

Topic-2/task_2_1.c

@@ -1,5 +1,5 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 #include <stdio.h>

Topic-2/task_2_2.c

@@ -1,5 +1,5 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 #include <stdio.h>

Topic-2/task_2_3.c

@@ -1,5 +1,5 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 #include <stdio.h>

Topic-2/task_2_4.c

@@ -1,57 +1,82 @@
 //
-// Wrote for Computer Networks and Systems lab classes
+// Written for Computer Networks and Systems lab classes
 // AUTHOR : Sergiusz Warga
 
 #include <stdio.h>
 #include <sys/types.h>
+#include <sys/time.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <signal.h>
+#include <time.h>
+
+const char * get_timestamp() {
+    struct timeval now;
+    gettimeofday(&now, NULL);
+    char buff[127];
+    sprintf(&buff, "us : %d", now.tv_usec);
+    return buff;
+}
 
 void parent_before_child() {
     pid_t pid;
-    printf("parent_before_child()\n");
+    printf("\nparent_before_child()\n");
     pid = fork();
     if (pid == -1) {    // If something went wrong.
         perror("Fork: ");
         exit(EXIT_FAILURE);
     }
     if (pid != 0) {     // If this is a parent process.
-        printf("I am a parent.\n");
-        kill(getpid(), SIGKILL);
-    } else {
+        printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", get_timestamp(), getpid());
         sleep(1);
-        printf("I am a child\n");   // This line will not be printed, as (usually) parent process will finish
-        // its execution in less than 1 second.
+        kill(getpid(), SIGTERM);
+    } else {
+        printf("===\n%s\nI am a child.\nMy PID is: %d\nMy PPID is: %d\n===", get_timestamp(), getpid(), getppid());
+        sleep(1);
+        printf("===\n%s\nI am a child.\nMy PID is: %d\nMy PPID is: %d\n===", get_timestamp(), getpid(), getppid());
+        sleep(1);
+        printf("===\n%s\nI am a child.\nMy PID is: %d\nMy PPID is: %d\n===", get_timestamp(), getpid(), getppid());
+        // When parent is killed PPID of its child process becomes 1 (and so the init process becomes a new parent).
     }
 }
 
 void child_before_parent() {
     pid_t pid;
-    printf("child_before_parent()\n");
+    printf("\nchild_before_parent()\n");
+    printf("PID before fork: %d\n", getpid());
     pid = fork();
     if (pid == -1) {    // If something went wrong.
         perror("Fork: ");
         exit(EXIT_FAILURE);
     }
     if (pid == 0) {     // If this is a parent process.
-        printf("I am a child.\n");
-        kill(getpid(), SIGKILL);
-    } else {
+        printf("===\n%s\nI am a child.\nMy PID is: %d\nMy PPID is: %d\n===", get_timestamp(), getpid(), getppid());
         sleep(1);
-        printf("I am a parent.\n");
+        kill(getpid(), SIGTERM);
+    } else {
+        printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", get_timestamp(), getpid());
+        sleep(1);
+        printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", get_timestamp(), getpid());
+        sleep(1);
+        printf("===\n%s\nI am a parent.\nMy PID is: %d\n===", get_timestamp(), getpid());
     }
 }
 
+
 int main() {
+    int status;
     pid_t pid;
+    printf("%s: Grandparent process has PID: %d\n", get_timestamp(), getpid());
     pid = fork();
-    if (pid == 0) {
+    if (pid == 0) { // If child process
+        printf("%s: Process with PID %d will execute funs.\n", get_timestamp(), getpid());
         child_before_parent();
-        sleep(1);
-        parent_before_child();
-        sleep(1);
-    }
         sleep(5);
+        parent_before_child();
+        sleep(5);
+    } else {        // If parent process
+        printf("%s: Grandparent's child process has PID: %d\n", get_timestamp(), pid);
+        sleep(12);
+    }
     return 0;
 }

Topic-3/task_3_1.c

@@ -0,0 +1,36 @@
+//
+// Written for Computer Networks and Systems lab classes
+// AUTHOR : Sergiusz Warga
+
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void child_task() {
+    for (int i = 1; i <= 10; ++i) {
+        printf("%d\n", i);
+        fflush(stdout);
+        if (i < 10) sleep(1);
+    }
+}
+
+int main() {
+    pid_t pid;
+
+    pid = fork();
+
+    if (pid == -1) {    // If something went wrong.
+        perror("Fork: ");
+        exit(EXIT_FAILURE);
+    }
+
+    if (pid == 0) {     // If this is a child process.
+        child_task();
+        exit(EXIT_SUCCESS);
+    }
+
+    wait();
+    printf("END OF WORK\n");
+    return 0;
+}