makefile

@@ -6,7 +6,7 @@ FIND_SRC = ./scripts/find_src.sh
 OSS_TARGET = oss
 USER_TARGET = user
 
-OSS_REDQUIRED = oss.c
+OSS_REDQUIRED = oss.c new_process.c shared_memory.c logical_clock.c
 
 USER_REQUIRED = user.c
 
@@ -54,7 +54,7 @@ debug:
 
 .PHONY: help
 help:
-	@echo "makefile for project 4"
+	@echo "makefile for project 5"
 	@echo "make all - builds the project"
 	@echo "make rebuild - cleans and builds the project"
 	@echo "make clean - removes the build directory"

src/config.h

@@ -3,4 +3,7 @@
 
 #define PATH_TO_USER "./build/user"
 
+#define SHM_CLOCK_ID 0
+#define SHM_CLOCK_PATH "./build/oss"
+
 #endif
\ No newline at end of file

src/logical_clock/logical_clock.c

+#include <stdio.h>
+#include "logical_clock.h"
+#include "shared_memory.h"
+
+/* create_shared_clock
+ *
+ * Returns a pointer to a shared logical clock.
+ * If the clock does not exist, it is created.
+ * If an error occurs, prints an error message and returns NULL.
+ * 
+ * path: the path to the file to use for ftok
+ * id: the id to use for ftok
+ * 
+ * returns: a pointer to a shared logical clock
+ */
+logical_clock_t *create_shared_clock(const char *path, int id)
+{
+  static logical_clock_t *clock = NULL;
+
+  if (clock == NULL) {
+    key_t key = get_key(path, id);
+    if (key == -1) {
+      return NULL;
+    }
+    int shmid = get_shared_memory(key, sizeof(logical_clock_t), CREATE_FLAG);
+    if (shmid == -1) {
+      return NULL;
+    }
+    clock = attach_shared_memory(shmid);
+  }
+  return clock;
+
+}
\ No newline at end of file

src/logical_clock/logical_clock.h

+#ifndef LOGICAL_CLOCK_H
+#define LOGICAL_CLOCK_H
+
+typedef struct logical_clock_s {
+  unsigned int seconds;
+  unsigned int nanoseconds;
+} logical_clock_t;
+
+logical_clock_t *creat_shared_clock(const char *path, int id);
+
+#endif
\ No newline at end of file

src/oss.c

@@ -4,6 +4,11 @@
 #include <sys/types.h>
 #include "new_process/new_process.h"
 #include "config.h"
+#include "shared_memory/shared_memory.h"
+#include "logical_clock/logical_clock.h"
+
+// globals
+logical_clock_t *clock;
 
 // function prototypes
 int run_user();
@@ -11,7 +16,8 @@ int run_user();
 int main(void)
 {
     printf("Hello, world from oss!\n");
-    run_user();
+    printf("key: %d\n", get_key(SHM_CLOCK_PATH, SHM_CLOCK_ID));
+    // run_user();
 }
 
 int run_user()

src/shared_memory/shared_memory.c

+#include <stdio.h>
+#include "shared_memory.h"
+
+const int CREATE_FLAG = 0666 | IPC_CREAT; // use if shared memory does not exist
+const int EXIST_FLAG = 0; // use if shared memory already exists
+
+/* get_key
+ * 
+ * Returns a key_t for use with shared memory.
+ * If ftok fails, prints an error message and returns -1.
+ * 
+ * path: the path to the file to use for ftok
+ * id: the id to use for ftok
+ * 
+ * returns: a key_t for use with shared memory
+ */
+key_t get_key(const char *path, int id) {
+    key_t key = ftok(path, id);
+    if (key == -1) {
+        perror("ftok");
+        return -1;
+    }
+    return key;
+}
+
+/* get_shared_memory
+ * 
+ * Returns a shared memory id.
+ * If shmget fails, prints an error message and returns -1.
+ * 
+ * key: the key to use for shmget
+ * size: the size to use for shmget
+ * flags: the flags to use for shmget
+ * 
+ * returns: a shared memory id
+ */
+int get_shared_memory(key_t key, size_t size, int flags) {
+    int shmid = shmget(key, size, flags);
+    if (shmid == -1) {
+        perror("shmget");
+        return -1;
+    }
+    return shmid;
+}
+
+/* attach_shared_memory
+ * 
+ * Returns a pointer to the shared memory.
+ * If shmat fails, prints an error message and returns NULL.
+ * 
+ * shmid: the shared memory id to use for shmat
+ * 
+ * returns: a pointer to the shared memory
+ */
+void *attach_shared_memory(int shmid) {
+    void *shmaddr = shmat(shmid, NULL, 0);
+    if (shmaddr == (void *) -1) {
+        perror("shmat");
+        return NULL;
+    }
+    return shmaddr;
+}
+
+/* detach_shared_memory
+ * 
+ * Returns 0 if successful.
+ * If shmdt fails, prints an error message and returns -1.
+ * 
+ * shmaddr: the shared memory address to use for shmdt
+ * 
+ * returns: 0 if successful, -1 otherwise
+ */
+int detach_shared_memory(const void *shmaddr) {
+    int status = shmdt(shmaddr);
+    if (status == -1) {
+        perror("shmdt");
+        return -1;
+    }
+    return 0;
+}
+
+/* remove_shared_memory
+ * 
+ * Returns 0 if successful.
+ * If shmctl fails, prints an error message and returns -1.
+ * 
+ * shmid: the shared memory id to use for shmctl
+ * 
+ * returns: 0 if successful, -1 otherwise
+ */
+int remove_shared_memory(int shmid) {
+    int status = shmctl(shmid, IPC_RMID, NULL);
+    if (status == -1) {
+        perror("shmctl");
+        return -1;
+    }
+    return 0;
+}
\ No newline at end of file

src/shared_memory/shared_memory.h

+#ifndef SHARED_MEMORY_H
+#define SHARED_MEMORY_H
+
+#include <stdio.h>
+#include <sys/ipc.h>
+
+extern const int CREATE_FLAG;
+extern const int EXIST_FLAG;
+
+key_t get_key(const char *path, int id);
+int get_shared_memory(key_t key, size_t size, int flags);
+void *attach_shared_memory(int shmid);
+int detach_shared_memory(const void *shmaddr);
+int remove_shared_memory(int shmid);
+
+#endif
\ No newline at end of file