Finita la conversione dei listati in file separati. Passato anche alla nuova

[gapil.git] / listati / MemShared.c

diff --git a/listati/MemShared.c b/listati/MemShared.c
new file mode 100644 (file)
index 0000000..dfeea8d
--- /dev/null
+++ b/listati/MemShared.c
@@ -0,0 +1,45 @@
+/* Function CreateShm: Create a shared memory segment mapping it */
+void * CreateShm(char * shm_name, off_t shm_size, mode_t perm, int fill) 
+{
+    void * shm_ptr;
+    int fd;
+    int flag;
+    /* first open the object, creating it if not existent */
+    flag = O_CREAT|O_EXCL|O_RDWR;
+    fd = shm_open(shm_name, flag, perm);    /* get object file descriptor */
+    if (fd < 0) { 
+        return NULL;
+    }
+    /* set the object size */
+    if (ftruncate(fd, shm_size)) {
+        return NULL;
+    }
+    /* map it in the process address space */
+    shm_ptr = mmap(NULL, shm_size, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
+    if (shm_ptr == MAP_FAILED) {
+        return NULL;
+    }
+    memset((void *) shm_ptr, fill, shm_size);                /* fill segment */
+    return shm_ptr;
+}
+/* Function FindShm: Find a POSIX shared memory segment  */
+void * FindShm(char * shm_name, off_t shm_size) 
+{
+    void * shm_ptr;
+    int fd;                           /* ID of the IPC shared memory segment */
+    /* find shared memory ID */
+    if ((fd = shm_open(shm_name, O_RDWR|O_EXCL, 0)) < 0) {
+        return NULL;
+    }
+    /* take the pointer to it */
+    shm_ptr = mmap(NULL, shm_size, PROT_WRITE|PROT_READ, MAP_SHARED, fd, 0);
+    if (shm_ptr == MAP_FAILED) {
+        return NULL;
+    }
+    return shm_ptr;
+}
+/* Function RemoveShm: Remove a POSIX shared memory segment */
+int RemoveShm(char * shm_name)
+{
+    return shm_unlink(shm_name);
+}