void
ring_buffer_free (struct ring_buffer *buffer)
{
int status;
status = munmap (buffer->address, buffer->count_bytes << 1);
if (status)
report_exceptional_condition ();
}
void
ring_buffer_create (struct ring_buffer *buffer, unsigned long order)
{
char path[] = "/dev/shm/ring-buffer-XXXXXX";
int file_descriptor;
void *address;
int status;
file_descriptor = mkstemp (path);
if (file_descriptor < 0)
report_exceptional_condition ();
status = unlink (path);
if (status)
report_exceptional_condition ();
buffer->count_bytes = 1UL << order;
buffer->write_offset_bytes = 0;
buffer->read_offset_bytes = 0;
status = ftruncate (file_descriptor, buffer->count_bytes);
if (status)
report_exceptional_condition ();
buffer->address = mmap (NULL, buffer->count_bytes << 1, PROT_NONE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (buffer->address == MAP_FAILED)
report_exceptional_condition ();
address =
mmap (buffer->address, buffer->count_bytes, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, file_descriptor, 0);
if (address != buffer->address)
report_exceptional_condition ();
address = mmap (buffer->address + buffer->count_bytes,
buffer->count_bytes, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, file_descriptor, 0);
if (address != buffer->address + buffer->count_bytes)
report_exceptional_condition ();
status = close (file_descriptor);
if (status)
report_exceptional_condition ();
}
void
buffer_free (buffer_t *buffer)
{
if (munmap (buffer->address, buffer->length << 1))
report_exceptional_condition("Could not unmap memory.");
}
void
buffer_create(buffer_t *buffer, int size, const char *buffer_name)
{
/* The size of the buffer (in bytes). Note that for some buffers
* such as the memory-mirrored ring buffer the actual buffer size
* may be larger.
*/
/* TODO: Make this configurable. */
static unsigned long default_buffer_size = 1024 * 512;
unsigned long buffer_size = 1024 * size;
int name_length = strlen (buffer_name);
char *path = malloc (sizeof (char) * (name_length + 29));
memcpy (path, "/dev/shm/ring-buffer-", 21);
memcpy (path + 21, buffer_name, name_length);
memcpy (path + 21 + name_length, "-XXXXXX", 7);
path[name_length+28] = 0;
if (buffer_size < default_buffer_size)
buffer_size = default_buffer_size;
//char path[] = "/dev/shm/ring-buffer-XXXXXX";
int file_descriptor;
void *address;
int status;
file_descriptor = mkstemp (path);
if (file_descriptor < 0) {
free (path);
report_exceptional_condition("Could not get a file descriptor.");
return;
}
status = unlink(path);
if (status)
report_exceptional_condition("Could not unlink.");
// Round up the length to the nearest page boundary.
long page_size = sysconf(_SC_PAGESIZE);
buffer->length = ((buffer_size + page_size - 1) / page_size) * page_size;
buffer->fill_count = 0;
buffer->head = buffer->tail = 0;
status = ftruncate(file_descriptor, buffer->length);
if (status)
report_exceptional_condition("Could not truncate.");
buffer->address = mmap (NULL, buffer->length << 1, PROT_NONE,
MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
if (buffer->address == MAP_FAILED)
report_exceptional_condition("Failed to map full memory.");
address =
mmap (buffer->address, buffer->length, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, file_descriptor, 0);
if (address != buffer->address)
report_exceptional_condition("Failed to map initial memory.");
address = mmap (buffer->address + buffer->length,
buffer->length, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, file_descriptor, 0);
if (address != buffer->address + buffer->length)
report_exceptional_condition("Failed to map mirror memory.");
status = close(file_descriptor);
if (status)
report_exceptional_condition("Could not close file descriptor.");
buffer->last_token = 0;
free (path);
}
