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-rw-r--r--sync/assign.rst41
-rw-r--r--sync/makefile5
-rw-r--r--sync/reader.c86
-rw-r--r--sync/sync.c118
-rw-r--r--sync/writer.c76
5 files changed, 0 insertions, 326 deletions
diff --git a/sync/assign.rst b/sync/assign.rst
deleted file mode 100644
index ea4a566..0000000
--- a/sync/assign.rst
+++ /dev/null
@@ -1,41 +0,0 @@
-================
-Syncronization 1
-================
-
-Write a program that uses semaphores to implement a readers/writers solution. Your program should:
-
- - be written in C and use the standard kernel IPC mechanisms (semget,semop,shmget etc)
- - be written as a single top level source file compiled as: gcc –o myprog myprog.c
- - take two arguments on the command line: myprog NR NW where NR,NW are each integers specifying the number of reader/writer processes respectively
- - use fork/exec to create the readers/writers
-
-The shared memory segment should be 16k bytes in size, with all bytes initialized to 0x30
-
-Reader:
-
-.. code ::
-
- open a file (for append) named reader.N, where N is the reader number
- while (1) {
- for (i=0; i<16k; i++) {
- read the next byte of the shared memory segment
- write that byte to the file
- flush the file
- }
- sleep a random number of seconds, between 0 and N inclusive
- }
-
-Writer:
-
-.. code ::
-
- while (1) {
- for (i=0; i<16k; i++)
- shared memory segment[i] = N + 0x30;
- sleep a random number of seconds between 0 and 2*N inclusive
- }
-
-readers and writers should be mutually exclusive
-multiple concurrent readers are allowed
-writers have priority over readers
-writers are mutually exclusive relative to each other
diff --git a/sync/makefile b/sync/makefile
deleted file mode 100644
index dd9c463..0000000
--- a/sync/makefile
+++ /dev/null
@@ -1,5 +0,0 @@
-sync: sync.c reader.c writer.c
- cc -o sync sync.c
- cc -o reader reader.c
- cc -o writer writer.c
-
diff --git a/sync/reader.c b/sync/reader.c
deleted file mode 100644
index 929eba1..0000000
--- a/sync/reader.c
+++ /dev/null
@@ -1,86 +0,0 @@
-#include <errno.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/ipc.h>
-#include <sys/select.h>
-#include <sys/sem.h>
-#include <sys/shm.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#define NSEM 3
-#define KEY 52
-
-char *mem;
-
-void quit(signum)
-int signum;
-{
- shmdt(mem);
- exit(1);
-}
-
-int main(argc, argv)
-int argc;
-char **argv;
-{
- int shmid, semid, i, pid, id;
- char filename[50];
- FILE *fd;
- struct sembuf sb;
-
- if (argc < 2) {
- printf("usage: reader [id]\n");
- exit(1);
- }
-
- id = atoi(argv[1]);
-
-
- if ((shmid = shmget(52, 1<<14, IPC_CREAT | 0666)) == -1){
- perror("shmget: shmget failed");
- exit(1);
- }
-
- if ((mem = shmat(shmid, NULL, 0)) == (char *) -1) {
- perror("shmat");
- exit(1);
- }
-
- if ((semid = semget(shmid, NSEM, 0)) == -1) {
- perror("Rsemget: ");
- exit(1);
- }
-
- signal(SIGQUIT, quit);
-
- sprintf(filename, "reader.%d", id);
-
- fd = fopen(filename, "a");
-
- if (!fd) {
- perror("fopen: ");
- exit(1);
- }
- srand(time(NULL));
-
- while (1) {
- sb.sem_num = 0; sb.sem_op = -1; sb.sem_flg = 0;
- semop(semid, &sb, 1);
-
- for (i = 0; i < 1<<14; i++) {
- fprintf(fd, "%c", *(mem + i));
- fflush(fd);
- }
- fprintf(fd, "\n");
- fflush(fd);
-
- sb.sem_op = 1;
- semop(semid, &sb, 1);
-
-
- sleep(rand() % (id + 1));
- }
-}
diff --git a/sync/sync.c b/sync/sync.c
deleted file mode 100644
index 23d6ba1..0000000
--- a/sync/sync.c
+++ /dev/null
@@ -1,118 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/ipc.h>
-#include <sys/sem.h>
-#include <sys/shm.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <unistd.h>
-
-#define NSEM 3
-
-union semun {
- int val;
- struct semid_ds *buf;
- ushort *array;
-};
-
-
-int shmid, semid;
-
-void quit(signum)
-int signum;
-{
- shmctl(shmid, IPC_RMID, NULL);
- semctl(semid, IPC_RMID, 0);
-}
-
-
-int main(argc, argv)
-int argc;
-char **argv;
-{
- int i, pid, n_read, n_write, w;
- char *mem, **arg_r, **arg_w;
- union semun semarg;
-
- if (argc < 2) {
- printf("usage: sync [number readers] [number writers]\n");
- exit(1);
- }
- n_read = atoi(argv[1]);
- n_write = atoi(argv[2]);
-
- if ((shmid = shmget(52, 1<<14, IPC_CREAT | 0666)) == -1){
- perror("shmget: shmget failed");
- exit(1);
- }
-
- if ((mem = shmat(shmid, NULL, 0)) == (char *) -1) {
- perror("shmat");
- exit(1);
- }
-printf("Sshmid: %x\n", shmid);
- signal(SIGQUIT, quit);
-
- for (i = 0; i < 1<<14; i++) {
- *(mem + i) = 0x30;
- }
-
- if ((semid = semget(shmid, NSEM, 0666 | IPC_CREAT)) == -1) {
- perror("Ssemget: ");
- exit(1);
- }
-
- semarg.val = 1;
- for (i = 0; i < NSEM; i++) {
- if ((semctl(semid, i, SETVAL, semarg)) == -1) {
- perror("semctl: ");
- exit(1);
- }
- }
-
-
- arg_r = malloc(sizeof(char*) * 3);
- arg_w = malloc(sizeof(char*) * 3);
- *arg_r = malloc(sizeof(char) * 10);
- *arg_w = malloc(sizeof(char) * 10);
-
- *(arg_r + 1) = malloc(sizeof(char) * 50);
- *(arg_w + 1) = malloc(sizeof(char) * 50);
-
- *arg_r = "reader";
- *arg_w = "writer";
-
- *(arg_r + 2) = NULL;
- *(arg_w + 2) = NULL;
-
- for (i = 0; i < n_read; i++){
- sprintf(*(arg_r + 1), "%d", i);
- if (pid = fork()) {
- /* printf("starting reader %d...\n", i); */
- } else {
- int ret = execv("./reader", arg_r);
- printf("exec retern %d", ret);
- }
- }
-
- for (i = 0; i < n_write; i++) {
- sprintf(*(arg_w + 1), "%d", i);
- if (pid = fork()) {
- /* printf("starting writer %d...\n", i); */
- } else {
- execvp("./writer", arg_w);
- }
-
- }
-
- shmdt(mem);
-printf("sync done...\n");
-/* TODO
- * why is this returning 8
- */
- for (i = 0; i < (n_write + n_read); i++) {
- wait(&w);
- printf("\nReturned with code:%d\n", WEXITSTATUS(w));
- }
- quit();
-}
diff --git a/sync/writer.c b/sync/writer.c
deleted file mode 100644
index d38dd70..0000000
--- a/sync/writer.c
+++ /dev/null
@@ -1,76 +0,0 @@
-#include <errno.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/ipc.h>
-#include <sys/select.h>
-#include <sys/sem.h>
-#include <sys/shm.h>
-#include <sys/types.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#define NSEM 3
-
-char *mem;
-
-void quit(signum)
-int signum;
-{
- shmdt(mem);
- exit(1);
-}
-
-int main(argc, argv)
-int argc;
-char **argv;
-{
- int shmid, semid, i, pid, id;
- char *mem;
- struct sembuf sb;
-
- if (argc < 2) {
- printf("usage: writer [id]\n");
- exit(1);
- }
-
- id = atoi(argv[1]);
-
-
- if ((shmid = shmget(52, 1<<14, IPC_CREAT | 0666)) == -1){
- perror("shmget: shmget failed");
- exit(1);
- }
-
- if ((mem = shmat(shmid, NULL, 0)) == (char *) -1) {
- perror("shmat");
- exit(1);
- }
-printf("Wshmid: %x\n", shmid);
-
- if ((semid = semget(shmid, NSEM, 0)) == -1) {
- perror("Wsemget: ");
- exit(1);
- }
-
- signal(SIGQUIT, quit);
-
- srand(time(NULL));
-
- while (1) {
- rand() % id;
-
- sb.sem_num = 0; sb.sem_op = -1; sb.sem_flg = 0;
- semop(semid, &sb, 1);
-
- for (i = 0; i < 1<<14; i++) {
- mem[i]= 0x30 + id;
- }
-
- sb.sem_op = 1;
- semop(semid, &sb, 1);
-
- sleep(rand() % ((id * 2) + 1));
- }
-}
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