Merge branch 'master' of github.com:Maxxquoi/Introduction-to-Operating-Systems

Author: Emmanuel Massaquoi

p1/Makefile

@@ -1,6 +1,6 @@
 
 ReadWrite: ReadWrite.c
-gcc -o ReadWrite ReadWrite.c -pthread
+gcc -std=c99 -o ReadWrite ReadWrite.c -pthread
 
 Clean:
 rm ReadWrite

p1/ReadWrite.c

@@ -1,13 +1,20 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <pthread.h>
 
+#define NUM_THREADS 10
+
 //
 // Created by Emmanuel Massaquoi on 6/19/17.
 //
 
 int shared_var = 0;
-int resource_use = 0;
+int resource_use;
+int num_reader = 0;
+
+int reading = 0;
+int writing = 1;
 
 pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
 pthread_cond_t read_phase = PTHREAD_COND_INITIALIZER;
@@ -19,7 +26,29 @@ void *writer (void *param);
 
 int main(int argc, char *argv[]) {
 
- printf("Hello World/m");
+ pthread_t tid[NUM_THREADS];
+
+ for (int i = 0; i < 5; i++) {
+
+ printf("Create Reader\n");
+ if(pthread_create(&tid[i], NULL, reader, NULL) != 0) {
+ fprintf(stderr, "Unable to create reader thread");
+ exit(1);
+ }
+
+ printf("Create Writer\n");
+ if(pthread_create(&tid[i+5], NULL, writer, NULL) != 0) {
+ fprintf(stderr, "Unable to create writer thread");
+ exit(1);
+ }
+ }
+
+ for (int j = 0; j < NUM_THREADS; ++j) {
+ pthread_join(tid[j], NULL);
+ }
+
+ printf("Parent quiting\n");
+
  return 0;
 }
 
@@ -29,10 +58,39 @@ void *reader(void *param) {
 
  pthread_mutex_lock(&m);
 
- while (resource_use == 1) {
+ while (resource_use == writing) {
  pthread_cond_wait(&read_phase, &m);
  }
 
+ printf("Reader Value: %d\n", shared_var);
+ printf("Number of Readers Present: %d\n", num_reader);
+
+ resource_use = reading;
+ pthread_cond_broadcast(&write_phase);
+
+ pthread_mutex_unlock(&m);
+ }
+
+ return 0;
+}
+
+void *writer(void *param) {
+
+ for (int i = 1; i <= 20; ++i) {
+ pthread_mutex_lock(&m);
+
+ while (resource_use == reading || num_reader != 0) {
+ pthread_cond_wait(&write_phase, &m);
+ }
+
+ shared_var = i;
+ printf("Written Value: %d\n", shared_var);
+ printf("Number of Readers Present: %d\n", num_reader);
+
+ resource_use = writing;
+ pthread_cond_broadcast(&read_phase);
+
  pthread_mutex_unlock(&m);
  }
+
 }

p1Solutions/echo-client.c

@@ -0,0 +1,75 @@
+/* ============================================================================
+ * Introduction to Operating Systems
+ * CS 8803, GT OMSCS
+ *
+ * Unauthorized copying of this file, via any medium is strictly prohibited.
+ * 
+ * "echo-client.c"
+ * Implements the client for "The Echo Protocol" in Problem Set 1.
+============================================================================ */
+#include <netdb.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <strings.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+/* CONSTANTS =============================================================== */
+#define SERVER_ADDR "localhost"
+#define SERVER_PORT 8888
+#define BUFFER_SIZE 1024
+#define MESSAGE "ramblin wreck"
+
+int main(int argc, char **argv) {
+
+ int socket_fd = 0;
+ struct sockaddr_in server_socket_addr;
+ char buffer[BUFFER_SIZE];
+
+ // Converts localhost into 0.0.0.0
+ struct hostent *he = gethostbyname(SERVER_ADDR);
+ unsigned long server_addr_nbo = *(unsigned long *)(he->h_addr_list[0]);
+
+ // Create socket (IPv4, stream-based, protocol likely set to TCP)
+ if (0 > (socket_fd = socket(AF_INET, SOCK_STREAM, 0))) {
+ fprintf(stderr, "client failed to create socket\n");
+ exit(1);
+ }
+
+ // Configure server socket address structure (init to zero, IPv4,
+ // network byte order for port and address) 
+ bzero(&server_socket_addr, sizeof(server_socket_addr));
+ server_socket_addr.sin_family = AF_INET;
+ server_socket_addr.sin_port = htons(SERVER_PORT);
+ server_socket_addr.sin_addr.s_addr = server_addr_nbo;
+
+ // Connect socket to server
+ if (0 > connect(socket_fd, (struct sockaddr *)&server_socket_addr, sizeof(server_socket_addr))) {
+ fprintf(stderr, "client failed to connect to %s:%d!\n", SERVER_ADDR, SERVER_PORT);
+ close(socket_fd);
+ exit(1);
+ } else {
+ fprintf(stdout, "client connected to to %s:%d!\n", SERVER_ADDR, SERVER_PORT);
+ }
+
+ // Send echo message
+ if (0 > send(socket_fd, MESSAGE, strlen(MESSAGE), 0)) {
+ fprintf(stderr, "client failed to send echo message");
+ close(socket_fd);
+ exit(1);
+ }
+
+ // Process response from server
+ bzero(buffer, BUFFER_SIZE);
+ if(0 > read(socket_fd, buffer, BUFFER_SIZE)) {
+ fprintf(stderr, "client could not read response from server\n");
+ close(socket_fd);
+ exit(1);
+ } else {
+ fprintf(stdout, "echo from server: %s\n", buffer);
+ }
+
+ // Close the socket and return the response length (in bytes)
+ close(socket_fd);
+ return 0; 
+}

p1Solutions/echo-server.c

@@ -0,0 +1,125 @@
+/* ============================================================================
+ * Introduction to Operating Systems
+ * CS 8803, GT OMSCS
+ *
+ * Unauthorized copying of this file, via any medium is strictly prohibited.
+ * 
+ * "echo-server.c"
+ * Implements the server for "The Echo Protocol" in Problem Set 1.
+============================================================================ */
+#include <arpa/inet.h>
+#include <ctype.h>
+#include <netdb.h>
+#include <netinet/in.h> 
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+/* CONSTANTS =============================================================== */
+#define SERVER_PORT 8888
+#define BUFFER_SIZE 1024
+
+void capitalizeBuffer(char *buffer) {
+ do {
+ *buffer = toupper((unsigned char) *buffer);
+ } while (*buffer++);
+}
+
+int main(int argc, char **argv) {
+
+ int socket_fd = 0;
+ int client_socket_fd = 0;
+ 
+ char buffer[BUFFER_SIZE];
+ int num_bytes = 0;
+
+ int set_reuse_addr = 1; // ON == 1 
+ int max_pending_connections = 1;
+
+ struct sockaddr_in server;
+ struct sockaddr_in client;
+ struct hostent *client_host_info;
+ char *client_host_ip;
+ socklen_t client_addr_len; 
+
+ // Create socket (IPv4, stream-based, protocol likely set to TCP)
+ if (0 > (socket_fd = socket(AF_INET, SOCK_STREAM, 0))) {
+ fprintf(stderr, "server failed to create the listening socket\n");
+ exit(1);
+ }
+
+ // Set socket to use wildcards - i.e. 0.0.0.0:21 and 192.168.0.1:21
+ // can be bound separately (helps to avoid conflicts) 
+ if (0 != setsockopt(socket_fd, SOL_SOCKET, SO_REUSEADDR, &set_reuse_addr, sizeof(set_reuse_addr))) {
+ fprintf(stderr, "server failed to set SO_REUSEADDR socket option (not fatal)\n");
+ }
+
+ // Configure server socket address structure (init to zero, IPv4,
+ // network byte order for port and address)
+ // Address uses local wildcard 0.0.0.0.0 (will connect to any local addr)
+ bzero(&server, sizeof(server));
+ server.sin_family = AF_INET;
+ server.sin_addr.s_addr = htonl(INADDR_ANY);
+ server.sin_port = htons(SERVER_PORT);
+
+ // Bind the socket
+ if (0 > bind(socket_fd, (struct sockaddr *)&server, sizeof(server))) {
+ fprintf(stderr, "server failed to bind\n");
+ exit(1);
+ }
+
+ // Listen on the socket for up to some maximum pending connections
+ if (0 > listen(socket_fd, max_pending_connections)) {
+ fprintf(stderr, "server failed to listen\n");
+ exit(1);
+ } else {
+ fprintf(stdout, "server listening for a connection on port %d\n", SERVER_PORT);
+ }
+
+ // Get the size client's address structure
+ client_addr_len = sizeof(client);
+
+ // Accept a new client
+ if (0 > (client_socket_fd = accept(socket_fd, (struct sockaddr *)&client, &client_addr_len))) 
+ {
+ fprintf(stderr, "server accept failed\n");
+ } else {
+ fprintf(stdout, "server accepted a client!\n"); 
+ }
+
+ // Determine who sent the echo so that we can respond
+ client_host_info = gethostbyaddr((const char *)&client.sin_addr.s_addr, sizeof(client.sin_addr.s_addr), AF_INET);
+ if (client_host_info == NULL) {
+ fprintf(stderr, "server could not determine client host address\n");
+ } 
+ client_host_ip = inet_ntoa(client.sin_addr);
+ if (client_host_ip == NULL) {
+ fprintf(stderr, "server could not determine client host ip\n");
+ }
+ fprintf(stdout, "server established connection with %s (%s)\n", client_host_info->h_name, client_host_ip);
+ 
+ // Read echo from the client
+ bzero(buffer, BUFFER_SIZE);
+ num_bytes = read(client_socket_fd, buffer, BUFFER_SIZE);
+ if (num_bytes == 0) {
+ fprintf(stderr, "server could not read from socket\n");
+ } else {
+ fprintf(stdout, "server received %d bytes: %s\n", num_bytes, buffer);
+ }
+ 
+ // Optional: Modifying client message before echo'ing (correctness test)
+ capitalizeBuffer(buffer);
+
+ // Echo back to the client
+ if (0 > write(client_socket_fd, buffer, strlen(buffer))) {
+ fprintf(stderr, "server could not write back to socket\n");
+ } else {
+ fprintf(stdout, "server sending message back to client\n");
+ }
+
+ // Close the socket and return 
+ close(socket_fd);
+ return 0;
+}