feat: libraries lab complete

В задании просят починить файлы, но фактически они даются нам уже рабочими, поэтому мне нужно только разобраться с тем, что происходит внутри

OSs/lab-libs/Makefile

@@ -0,0 +1,22 @@
+all: dynamic static
+
+dynamic: main.o lib.so
+	gcc $^ -o $@ $(CFLAGS) -lm
+
+static: main.o lib.a
+	gcc $^ -o $@ $(CFLAGS) -lm
+
+lib.so: lib.o
+	gcc -shared $^ -o $@ $(CFLAGS)
+
+lib.a: lib.o
+	ar r $@ $^
+
+main.o: main.c
+	gcc -c $^ -o $@ $(CFLAGS)
+
+lib.o: lib.c
+	gcc -c -o $@ -fPIC $^ $(CFLAGS)
+
+clean:
+	rm -f dynamic static *.so *.o

OSs/lab-libs/lib.c

@@ -0,0 +1,45 @@
+#include "lib.h"
+
+#include <math.h>
+
+#define ZEROIN_MAX_ITERATIONS 1000
+
+size_t fibo(size_t n)
+{
+    size_t prev = 0, cur = 1, tmp = 0;
+    for (size_t i = 0; i < n; i++) {
+        tmp = cur;
+        cur = cur + prev;
+        prev = tmp;
+    }
+    return cur;
+}
+
+double zeroin(double (*f)(double), double err, double a, double b)
+{
+    double left = f(a);
+    if (fabs(left) < err) return left;
+    double right = f(b);
+    if (fabs(right) < err) return right;
+    if (left * right > 0) {
+        return NAN;
+    }
+
+    double x = NAN;
+    double cur = NAN;
+    size_t n = 0;
+    do {
+        x = (a + b) / 2;
+        cur = f(x);
+        if (cur * left > 0) {
+            left = cur;
+            a = x;
+        }
+        else {
+            right = cur;
+            b = x;
+        }
+        n++;
+    } while (fabs(cur) > err || n < ZEROIN_MAX_ITERATIONS);
+    return x;
+}

OSs/lab-libs/lib.h

@@ -0,0 +1,21 @@
+#ifndef LIB_H_
+#define LIB_H_
+
+#include <stdlib.h>
+
+/**
+ * Это будет просто какая-то не очень умная библиотечка с двумя функциями,
+ * просто чтобы их типа собрать
+ */
+
+/**
+ * Считает n-ное число фибоначи
+ */
+size_t fibo(size_t n);
+
+/**
+ * Считает ноль функции на интервале с указанной погрешностью
+ */
+double zeroin(double (*f)(double), double err, double a, double b);
+
+#endif

OSs/lab-libs/main.c

@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include <math.h>
+#include "lib.h"
+
+#define FIBO_NUM 15
+
+#define SIN_A 1.6
+#define SIN_B 3.7
+#define ZEROIN_ERR 0.001
+
+int main()
+{
+    printf("fibonachi number under index %u: %zu\n", FIBO_NUM, fibo(FIBO_NUM));
+    printf("zero of sin(x) in interval (%lf %lf) is %lf\n",
+            SIN_A, SIN_B, zeroin(sin, ZEROIN_ERR, SIN_A, SIN_B));
+    return 0;
+}

OSs/lab4/part-1/Makefile

@@ -0,0 +1,12 @@
+targets = main
+all: $(targets)
+
+main: main.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab4/part-1/main.c

@@ -0,0 +1,99 @@
+#include <stdio.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <pthread.h>
+#include <time.h>
+#include <signal.h>
+#include <semaphore.h>
+#include <errno.h>
+
+enum events{
+    EVENT_VICTIM_THREAD_READY,
+    EVENT_PRINT_BUFFER_UPDATED,
+    EVENTS_NR
+};
+
+enum threads_roles {
+    ROLE_VICTIM,
+    ROLE_KILLER,
+    ROLE_PRINTER,
+    ROLES_NR
+};
+
+#define ERR_PTR(ret) ((void*)(long)ret)
+#define PRINTER_TIMEOUT_SECS 2
+
+#define PRINT_BUFF_SIZE 256
+static sem_t sems[EVENTS_NR];
+static pthread_t threads[ROLES_NR];
+static char print_buffer[PRINT_BUFF_SIZE];
+static volatile bool run = true;
+
+void sig_handler(int signal)
+{
+    snprintf(print_buffer, PRINT_BUFF_SIZE, "signal %d recieved", signal);
+    pthread_exit(ERR_PTR(sem_post(&sems[EVENT_PRINT_BUFFER_UPDATED])));
+}
+
+void *killer_thread(void* _)
+{
+    sigset_t ss;
+    sigemptyset(&ss);
+    sigaddset(&ss, SIGUSR1);
+    if (pthread_sigmask(SIG_BLOCK, &ss, NULL))
+        pthread_exit(ERR_PTR(-EFAULT));
+    int ret = sem_wait(&sems[EVENT_VICTIM_THREAD_READY]);
+    if (ret) pthread_exit(ERR_PTR(ret));
+    pthread_exit(ERR_PTR(pthread_kill(threads[ROLE_VICTIM], SIGUSR1)));
+}
+
+void *victim_thread(void* _)
+{
+    int ret = sem_post(&sems[EVENT_VICTIM_THREAD_READY]);
+    if (ret) pthread_exit(ERR_PTR(ret));
+    volatile int x = 0; // for compiler not to optimize infinite loop
+    while (run) {
+        x++;
+    }
+    pthread_exit(NULL);
+}
+
+void *printer_thread(void* _)
+{
+    sigset_t ss;
+    sigemptyset(&ss);
+    sigaddset(&ss, SIGUSR1);
+    if (pthread_sigmask(SIG_BLOCK, &ss, NULL)) pthread_exit(ERR_PTR(-EFAULT));
+    while (run) {
+        struct timespec ts = {0};
+        int ret = timespec_get(&ts, TIME_UTC);
+        if (ret != TIME_UTC) pthread_exit(ERR_PTR(-EFAULT));
+        ts.tv_sec += PRINTER_TIMEOUT_SECS;
+        if (sem_timedwait(&sems[EVENT_PRINT_BUFFER_UPDATED], &ts))
+            pthread_exit(ERR_PTR(-EFAULT));
+        puts(print_buffer);
+        memset(print_buffer, 0, PRINT_BUFF_SIZE);
+    }
+    pthread_exit(NULL);
+}
+
+#define DO_OR_FAIL(cond) if (cond) return EXIT_FAILURE
+
+int main()
+{
+    struct sigaction sa = {
+        .sa_handler = sig_handler,
+    };
+    DO_OR_FAIL(sigaction(SIGUSR1, &sa, NULL));
+    DO_OR_FAIL(sem_init(&sems[EVENT_VICTIM_THREAD_READY], 0, 0));
+    DO_OR_FAIL(sem_init(&sems[EVENT_PRINT_BUFFER_UPDATED], 0, 0));
+    DO_OR_FAIL(pthread_create(&threads[ROLE_KILLER], NULL, killer_thread, NULL));
+    DO_OR_FAIL(pthread_create(&threads[ROLE_PRINTER], NULL, printer_thread, NULL));
+    DO_OR_FAIL(pthread_create(&threads[ROLE_VICTIM], NULL, victim_thread, NULL));
+
+    for (size_t i = 0; i < ROLES_NR; i++) {
+        DO_OR_FAIL(pthread_join(threads[i], NULL));
+    }
+    return EXIT_SUCCESS;
+}

OSs/lab4/part-2/Makefile

@@ -0,0 +1,12 @@
+targets = main
+all: $(targets)
+
+main: main.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab4/part-2/main.c

@@ -0,0 +1,43 @@
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdbool.h>
+
+#define SLEEP_TIME 1
+
+volatile int x;
+
+void sigint_handler(int signal)
+{
+    puts("sigint handler");
+    sleep(SLEEP_TIME);
+}
+
+void sigusr1_handler(int signal)
+{
+    puts("sigusr1 handler");
+    kill(getpid(), SIGINT);
+}
+
+#define DO_OR_FAIL(cond) if (cond) return EXIT_FAILURE
+int main()
+{
+    struct sigaction sa_int = {
+        .sa_handler = sigint_handler
+    };
+    struct sigaction sa_usr1 = {
+        .sa_handler = sigusr1_handler
+    };
+    struct sigaction old_sa = {0};
+    DO_OR_FAIL(sigemptyset(&sa_int.sa_mask));
+    DO_OR_FAIL(sigemptyset(&sa_usr1.sa_mask));
+    DO_OR_FAIL(sigaddset(&sa_int.sa_mask, SIGINT));
+    DO_OR_FAIL(sigaddset(&sa_usr1.sa_mask, SIGUSR1));
+    DO_OR_FAIL(sigaction(SIGINT, &sa_int, &old_sa));
+    DO_OR_FAIL(sigaction(SIGUSR1, &sa_usr1, NULL));
+    while (true) {
+        x++; // чтобы не соптимизировался
+    }
+    return EXIT_SUCCESS;
+}

OSs/lab5/part-A/Makefile

@@ -0,0 +1,12 @@
+targets = main
+all: $(targets)
+
+main: main.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab5/part-A/main.c

@@ -0,0 +1,132 @@
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <string.h>
+#include <ctype.h>
+
+#define PIPE_READ_IDX   0
+#define PIPE_WRITE_IDX  1
+
+int client(int fd_read, int fd_write);
+int server(int fd_read, int fd_write);
+
+#define DO_OR_FAIL(cond) if (cond) return EXIT_FAILURE
+int main()
+{
+    int pipe_to_server[2], pipe_to_client[2];
+    DO_OR_FAIL(pipe(pipe_to_server) < 0);
+    DO_OR_FAIL(pipe(pipe_to_client) < 0);
+
+    pid_t client_pid;
+    if ((client_pid = fork()) == 0) { // server
+        DO_OR_FAIL(close(pipe_to_server[PIPE_WRITE_IDX]));
+        DO_OR_FAIL(close(pipe_to_client[PIPE_READ_IDX]));
+
+        DO_OR_FAIL(
+                server(
+                    pipe_to_server[PIPE_READ_IDX],
+                    pipe_to_client[PIPE_WRITE_IDX]
+                    )
+                );
+    }
+    // client
+    DO_OR_FAIL(close(pipe_to_server[PIPE_READ_IDX]));
+    DO_OR_FAIL(close(pipe_to_client[PIPE_WRITE_IDX]));
+
+    DO_OR_FAIL(
+            client(
+                pipe_to_client[PIPE_READ_IDX],
+                pipe_to_server[PIPE_WRITE_IDX]
+                )
+            );
+
+    return 0;
+}
+
+char *ltrim(char *s)
+{
+    while(isspace(*s)) s++;
+    return s;
+}
+
+char *rtrim(char *s)
+{
+    char* back = s + strlen(s);
+    while(isspace(*--back));
+    *(back+1) = '\0';
+    return s;
+}
+
+char *trim(char *s)
+{
+    return rtrim(ltrim(s)); 
+}
+
+#define BUF_SIZE 256
+
+#define DO_OR_PROPAGATE(call, expected, tmp_var) \
+    if ((tmp_var = (call)) != expected)) return tmp_var
+
+/**
+ * Performs client actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write t\no
+ * 
+ * returns 0 on success or -errno on fail
+ */
+int client(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    if (!fgets(buf, BUF_SIZE, stdin)) return -EFAULT;
+    const char *s = trim(buf);
+    size_t len = strlen(s);
+    ssize_t n_written = write(fd_write, s, len);
+    if (n_written < 0 || n_written < len) {
+        return -EFAULT;
+    }
+    memset(buf, 0, BUF_SIZE);
+    size_t n;
+    while ((n = read(fd_read, buf, BUF_SIZE)) > 0) {
+        len = strlen(buf);
+        n_written = fwrite(buf, sizeof(buf[0]), strlen(buf), stdout);
+        if (n_written < 0 || n_written < len) {
+            return -EFAULT;
+        }
+        memset(buf, 0, sizeof(buf));
+    }
+    return 0;
+}
+
+/**
+ * Performs server actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write to
+ *
+ * returns 0 on success or -errno on fail
+ */
+int server(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    size_t n = read(fd_read, buf, BUF_SIZE);
+    if (n == 0) return -EFAULT;
+    FILE *f = fopen(buf, "r");
+    // не 100% правильно, но наиболее вероятно
+    if (f == NULL) {
+        const char error_msg[] = "Can't open requested file\n";
+        write(fd_write, error_msg, sizeof(error_msg));
+        goto epilog;
+    }
+
+    while ((n = fread(buf, sizeof(buf[0]), BUF_SIZE, f)) > 0) {
+        write(fd_write, buf, n);
+        memset(buf, 0, sizeof(buf));
+    }
+
+epilog:
+    fclose(f);
+    return 0;
+}

OSs/lab5/part-B/Makefile

@@ -0,0 +1,15 @@
+targets = server client
+all: $(targets)
+
+server: server.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+client: client.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab5/part-B/client.c

@@ -0,0 +1,80 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <ctype.h>
+#include <fcntl.h>
+
+#include "common.h"
+
+int client(int fd_read, int fd_write);
+
+int main()
+{
+    int read_fd, write_fd;
+    FAIL_ON((write_fd=open(FIFO_SERVER_PATH, O_WRONLY)) < 0);
+    FAIL_ON((read_fd=open(FIFO_CLIENT_PATH, O_RDONLY)) < 0);
+
+    FAIL_ON(client(read_fd, write_fd));
+
+    FAIL_ON(unlink(FIFO_SERVER_PATH) < 0);
+    printf("unlinked %s\n", FIFO_SERVER_PATH);
+    FAIL_ON(unlink(FIFO_CLIENT_PATH) < 0);
+    printf("unlinked %s\n", FIFO_CLIENT_PATH);
+
+    return EXIT_SUCCESS;
+}
+
+#define BUF_SIZE 256
+
+char *ltrim(char *s)
+{
+    while(isspace(*s)) s++;
+    return s;
+}
+
+char *rtrim(char *s)
+{
+    char* back = s + strlen(s);
+    while(isspace(*--back));
+    *(back+1) = '\0';
+    return s;
+}
+
+char *trim(char *s)
+{
+    return rtrim(ltrim(s)); 
+}
+
+/**
+ * Performs client actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write t\no
+ * 
+ * returns 0 on success or -errno on fail
+ */
+int client(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    if (!fgets(buf, BUF_SIZE, stdin)) return -EFAULT;
+    const char *s = trim(buf);
+    size_t len = strlen(s);
+    ssize_t n_written = write(fd_write, s, len);
+    if (n_written < 0 || n_written < len) {
+        return -EFAULT;
+    }
+    memset(buf, 0, BUF_SIZE);
+    size_t n;
+    struct custom_ds ds;
+    while ((n = recv_msg(fd_read, &ds)) > 0) {
+        len = ds.hdr.len;
+        n_written = fwrite(ds.msg, sizeof(ds.msg[0]), len, stdout);
+        if (n_written < 0 || n_written < len) {
+            return -EFAULT;
+        }
+        memset(buf, 0, sizeof(buf));
+    }
+    return 0;
+}

OSs/lab5/part-B/common.h

@@ -0,0 +1,45 @@
+#ifndef COMMON_H_
+#define COMMON_H_
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+
+#define FIFO_SERVER_PATH "/tmp/fifo.to_server" // server reads this file
+#define FIFO_CLIENT_PATH "/tmp/fifo.to_client" // client reads this file
+
+#define __DATA_STRUCT_MSG_LEN 4096
+
+enum ds_types {
+    DS_MESSAGE,
+    DS_FAIL
+};
+
+struct custom_ds {
+    struct {
+        long len;
+        long type;
+    } hdr;
+    char msg[__DATA_STRUCT_MSG_LEN];
+};
+
+static inline ssize_t send_msg(int fd, const struct custom_ds *ds)
+{
+    return write(fd, ds, sizeof(ds->hdr) + ds->hdr.len);
+}
+
+static inline ssize_t recv_msg(int fd, struct custom_ds *reciever)
+{
+    size_t n_hdr = read(fd, reciever, sizeof(reciever->hdr));
+    if (n_hdr == 0) return 0; // eof reached
+    if (n_hdr != sizeof(reciever->hdr)) return -ENOMSG;
+    if (reciever->hdr.len == 0) return 0;
+
+    size_t n_payload = read(fd, &reciever->msg, reciever->hdr.len);
+    if (n_payload != reciever->hdr.len) return -EFAULT;
+    return n_hdr + n_payload;
+}
+
+#define FAIL_ON(cond) if (cond) return EXIT_FAILURE
+
+#endif

OSs/lab5/part-B/server.c

@@ -0,0 +1,66 @@
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "common.h"
+
+int server(int fd_read, int fd_write);
+
+int main()
+{
+    FAIL_ON(mknod(FIFO_SERVER_PATH, S_IFIFO | 0666, 0) < 0);
+    printf("created %s\n", FIFO_SERVER_PATH);
+    FAIL_ON(mknod(FIFO_CLIENT_PATH, S_IFIFO | 0666, 0) < 0);
+    printf("created %s\n", FIFO_CLIENT_PATH);
+
+    int read_fd, write_fd;
+    FAIL_ON((read_fd=open(FIFO_SERVER_PATH, O_RDONLY)) < 0);
+    FAIL_ON((write_fd=open(FIFO_CLIENT_PATH, O_WRONLY)) < 0);
+
+    return server(read_fd, write_fd);
+}
+
+#define BUF_SIZE 256
+
+/**
+ * Performs server actions
+ *
+ * @fd_read - pipe to read from
+ * @fd_write - pipe to write to
+ *
+ * returns 0 on success or -errno on fail
+ */
+int server(int fd_read, int fd_write)
+{
+    char buf[BUF_SIZE] = {0};
+    size_t n = read(fd_read, buf, BUF_SIZE);
+    if (n == 0) return -EFAULT;
+    FILE *f = fopen(buf, "r");
+    // не 100% правильно, но наиболее вероятно
+    if (f == NULL) {
+        const char error_msg[] = "Can't open requested file\n";
+        struct custom_ds payload = {
+            .hdr.len = sizeof(error_msg),
+            .hdr.type = DS_FAIL,
+        };
+        strncpy(payload.msg, error_msg, sizeof(error_msg));
+        send_msg(fd_write, &payload);
+        goto epilog;
+    }
+
+    while ((n = fread(buf, sizeof(buf[0]), BUF_SIZE, f)) > 0) {
+        struct custom_ds payload = {
+            .hdr.len = n,
+            .hdr.type = DS_MESSAGE,
+        };
+        strncpy(payload.msg, buf, n);
+        send_msg(fd_write, &payload);
+        memset(buf, 0, sizeof(buf));
+    }
+
+epilog:
+    fclose(f);
+    return 0;
+}

OSs/lab6/Makefile

@@ -0,0 +1,15 @@
+targets = server_msg client_msg
+all: $(targets)
+
+server_msg: server_msg.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+client_msg: client_msg.o
+	$(CC) -o $@ $^ $(CFLAGS)
+
+%.o: %.c
+	$(CC) -c $^ -o $@ $(CFLAGS)
+
+clean:
+	rm -f $(targets)
+	rm -f *.o

OSs/lab6/client_msg.c

@@ -0,0 +1,99 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/msg.h>
+#define MQ_KEY1 1234L
+#define MQ_KEY2 2345L
+#define MAXMESGDATA 4096
+
+struct mymesg {
+    long mesg_len;
+    long mesg_type;
+    char mesg_data[MAXMESGDATA];
+};
+
+void client(int readid, int writeid);
+ssize_t mesg_send(int id, struct mymesg *mptr);
+ssize_t mesg_recv(int id, struct mymesg *mptr);
+
+int main(int argc,char **argv)
+{
+    int readid, writeid;
+
+    if((writeid=msgget(MQ_KEY1,0666)) < 0)
+    {
+        printf("Client: can not get writeid!\n");
+        exit(1);
+    }
+    printf("Client:writeid=%d\n",writeid);
+
+    if((readid=msgget(MQ_KEY2,0666)) < 0)
+    {
+        printf("Client: can not get readid!\n");
+        exit(1);
+    }
+    printf("Client: readid=%d\n",readid);
+
+    client(readid,writeid);
+
+    if((msgctl(readid,IPC_RMID, NULL)) < 0)
+    {
+        printf("Client: can not delete massage queue2!\n"); exit(1);
+    }
+
+    if((msgctl(writeid,IPC_RMID, NULL)) < 0)
+    {
+        printf("Client: can not delete massage queue1!\n"); exit(1);
+    }
+
+    exit(0);
+}
+
+void client(int readid, int writeid)
+{
+    size_t len;
+    ssize_t n;
+    struct mymesg ourmesg;
+
+    printf("Client:readid=%d writeid=%d\n",readid,writeid);
+    printf("Input file name, please\n");
+
+    fgets(ourmesg.mesg_data,MAXMESGDATA, stdin);
+    len=strlen(ourmesg.mesg_data);
+
+    if(ourmesg.mesg_data[len-1]=='\n') len--;
+    ourmesg.mesg_len=len;
+
+    ourmesg.mesg_type=1;
+
+    printf("Client: %s\n",ourmesg.mesg_data);
+
+    mesg_send(writeid,&ourmesg);
+
+    printf("Client: tvk before recv!\n");
+
+    while((n= mesg_recv(readid, &ourmesg))>0)
+        //n= mesg_recv(readid, &ourmesg);
+        write(1,ourmesg.mesg_data, n);
+}
+
+ssize_t mesg_send(int id, struct mymesg *mptr)
+{
+    return(msgsnd(id, &(mptr->mesg_type),mptr->mesg_len, 0));
+}
+
+ssize_t mesg_recv(int id, struct mymesg *mptr)
+{
+    ssize_t n;
+
+    n=msgrcv(id, &(mptr->mesg_type),MAXMESGDATA,mptr->mesg_type, 0);
+    mptr->mesg_len=n;
+    printf("Client: n=%d\n",n);
+
+    return(n);	
+}
+

OSs/lab6/server_msg.c

@@ -0,0 +1,116 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/msg.h>
+#define MQ_KEY1 1234L
+#define MQ_KEY2 2345L
+#define MAXMESGDATA 4096
+
+struct mymesg {
+    long mesg_len;
+    long mesg_type;
+    char mesg_data[MAXMESGDATA];
+};
+
+void server(int readid, int writeid);
+ssize_t mesg_send(int id, struct mymesg *mptr);
+ssize_t mesg_recv(int id, struct mymesg *mptr);
+
+int main(int argc,char **argv)
+{
+    int readid, writeid;
+    key_t key1,key2;
+
+    printf("Server: Hello tvk!\n");
+
+    /*
+       if((key1=ftok("/home/tvk/IPC/input.txt",'A'))<0)
+       {
+       printf("Server: can not get key!\n"); exit(1);
+       }
+       printf("key1=%x\n",key1);
+   */
+    if((readid=msgget(MQ_KEY1, 0666|IPC_CREAT)) < 0)
+    {
+        printf("Server: can not get readid!\n"); exit(1);
+    }
+    printf("Server: readid=%d\n",readid);
+    /*	
+        if((key2=ftok("/home/tvk/IPC/server_msg.c",'B'))<0)
+        {
+        printf("Server: can not get key!\n"); exit(1);
+        }
+        printf("key2=%x\n",key2);
+        */
+    if((writeid=msgget(MQ_KEY2, 0666|IPC_CREAT)) < 0)
+    {
+        printf("Server: can not get readid!\n"); exit(1);
+    }
+    printf("Server: writeid=%d\n",writeid);
+
+    server(readid,writeid);
+
+    exit(0);
+}
+
+void server(int readid, int writeid)
+{
+    FILE *fp;
+    ssize_t n;
+    struct mymesg ourmesg;
+
+    printf("Server:readid=%d writeid=%d\n",readid,writeid);
+
+    ourmesg.mesg_type=1;
+
+    if( (n=mesg_recv(readid, &ourmesg)) == 0)
+    {
+        printf("Server: can not read file name\n");
+        exit(1);	
+    }
+    ourmesg.mesg_data[n]='\0';
+
+    printf("Server: file name %s\n",ourmesg.mesg_data);
+
+    if( (fp=fopen(ourmesg.mesg_data,"r"))==NULL)
+    {
+        printf("Server: can not open file name\n");
+
+    }
+    else
+    {
+        printf("Server: %s is opened\n",ourmesg.mesg_data);
+
+        while(fgets(ourmesg.mesg_data, MAXMESGDATA,fp) != NULL)
+        { 
+            ourmesg.mesg_len=strlen(ourmesg.mesg_data);
+            printf("Server: %s\n",ourmesg.mesg_data);
+            mesg_send(writeid,&ourmesg);
+        }
+    }
+    fclose(fp);
+    ourmesg.mesg_len=0;
+    mesg_send(writeid,&ourmesg);
+}
+
+ssize_t mesg_send(int id, struct mymesg *mptr)
+{
+    return(msgsnd(id, &(mptr->mesg_type),mptr->mesg_len, 0));	
+}
+
+ssize_t mesg_recv(int id, struct mymesg *mptr)
+{
+    ssize_t n;
+    n=msgrcv(id, &(mptr->mesg_type),MAXMESGDATA,mptr->mesg_type, 0);
+    mptr->mesg_len=n;
+
+    return(n);	
+}
+
+
+
+