[SP/P5] Added solutions to some exercises from today

6 files changed, 239 insertions, 0 deletions

diff --git a/Year 3/System programming/Practicum5/ex1.c b/Year 3/System programming/Practicum5/ex1.c
new file mode 100644
index 0000000..85e86bb
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex1.c
@@ -0,0 +1,55 @@
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+	pid_t fpid = fork();
+
+	if (fpid < 0) {
+		perror("fork");
+		return 1;
+	}
+
+	int f = open("test.txt", O_CREAT | O_WRONLY | O_APPEND, 0755);
+	if (f < 0) {
+		perror("open test.txt");
+		return 2;
+	}
+
+	if (fpid == 0) { // in child
+		sleep(2);
+		int ws = write(f, "From Child 1\n", 13);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+
+		sleep(5);
+		ws = write(f, "From Child 2\n", 13);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+	}
+	else {
+		int ws = write(f, "From Parent 1\n", 14);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+
+		sleep(3);
+		ws = write(f, "From Parent 2\n", 14);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+		sleep(5);
+	}
+}
diff --git a/Year 3/System programming/Practicum5/ex2.c b/Year 3/System programming/Practicum5/ex2.c
new file mode 100644
index 0000000..88b337c
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex2.c
@@ -0,0 +1,54 @@
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int main() {
+	int f = open("test.txt", O_CREAT | O_WRONLY | O_TRUNC, 0755);
+	if (f < 0) {
+		perror("open test.txt");
+		return 2;
+	}
+
+	pid_t fpid = fork();
+
+	if (fpid < 0) {
+		perror("fork");
+		return 1;
+	}
+
+	if (fpid == 0) { // in child
+		sleep(2);
+		int ws = write(f, "From Child 1\n", 13);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+
+		sleep(5);
+		ws = write(f, "From Child 2\n", 13);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+	}
+	else {
+		int ws = write(f, "From Parent 1\n", 14);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+
+		sleep(3);
+		ws = write(f, "From Parent 2\n", 14);
+
+		if (ws < 0) {
+			perror("write from child");
+			return 3;
+		}
+	}
+}
diff --git a/Year 3/System programming/Practicum5/ex3.c b/Year 3/System programming/Practicum5/ex3.c
new file mode 100644
index 0000000..b7b33e0
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex3.c
@@ -0,0 +1,38 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+
+int main() {
+	int f1 = open("read.txt", O_RDONLY);
+	if (f1 < 0) {
+		perror("open read.txt");
+		return 1;
+	}
+
+	int f2 = open("write.txt", O_CREAT | O_WRONLY | O_TRUNC, 0755);
+	if (f2 < 0) {
+		perror("open write.txt");
+		return 1;
+	}
+
+	pid_t fpid = fork();
+	if (fpid < 0) {
+		perror("fork");
+		return 2;
+	}
+
+	if (fpid == 0) { // child
+		for (int i = 0; i < 5; i++) {
+			sleep(2);
+			write(f2, "abc", 3);
+		}
+	}
+	else {
+		char buff[3];
+		for (int i = 0; i < 5; i++) {
+			read(f1, buff, 3);
+			write(f2, buff, 3);
+			sleep(1);
+		}
+	}
+}
diff --git a/Year 3/System programming/Practicum5/ex4.c b/Year 3/System programming/Practicum5/ex4.c
new file mode 100644
index 0000000..682376d
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex4.c
@@ -0,0 +1,41 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/wait.h>
+
+int main() {
+	int f1 = open("read.txt", O_RDONLY);
+	if (f1 < 0) {
+		perror("open read.txt");
+		return 1;
+	}
+
+	int f2 = open("write.txt", O_CREAT | O_WRONLY | O_APPEND, 0755);
+	if (f2 < 0) {
+		perror("open write.txt");
+		return 1;
+	}
+
+	pid_t fpid = fork();
+	if (fpid < 0) {
+		perror("fork");
+		return 2;
+	}
+
+	if (fpid == 0) { // child
+		char buff[3];
+		for (int i = 0; i < 6; i++) {
+			read(f1, buff, 3);
+			write(f2, buff, 3);
+			sleep(1);
+		}
+	}
+	else {
+		int status = -2;
+		while (status == -2) {
+			sleep(2);
+			write(f2, "abc", 3);
+			waitpid(fpid, &status, WNOHANG);
+		}
+	}
+}
diff --git a/Year 3/System programming/Practicum5/ex5.c b/Year 3/System programming/Practicum5/ex5.c
new file mode 100644
index 0000000..49fe3e2
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex5.c
@@ -0,0 +1,21 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+	pid_t f = fork();
+	if (f < 0) {
+		perror("fork");
+		return 1;
+	}
+
+	if (f == 0) {
+		execvp(argv[1], argv + 1);
+	}
+	else {
+		int status = -2;
+		wait(&status);
+		printf("Child: %d\tExit: %d\n", f, status);
+	}
+}
diff --git a/Year 3/System programming/Practicum5/ex6.c b/Year 3/System programming/Practicum5/ex6.c
new file mode 100644
index 0000000..86e206c
--- /dev/null
+++ b/Year 3/System programming/Practicum5/ex6.c
@@ -0,0 +1,30 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/wait.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[]) {
+	pid_t f = fork();
+	if (f < 0) {
+		perror("fork");
+		return 1;
+	}
+
+	if (f == 0) {
+		char *commargs[argc];
+		commargs[0] = argv[1];
+		for (int i = 0; i < argc - 2; i++)
+			commargs[i+1] = argv[i+1];
+		commargs[argc - 1] = NULL;
+
+		int w = open(argv[argc-1], O_WRONLY | O_CREAT, 0755);
+		dup2(w, 1);
+		close(w);
+		execvp(*commargs, commargs + 1);
+	}
+	else {
+		int status = -2;
+		wait(&status);
+		printf("Exit: %d\n", status);
+	}
+}