include/ringbuffer/iterator.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
   2  *
   3  * ringbuffer/iterator.h
   4  *
   5  * Ring buffer and channel iterators.
   6  *
   7  * Copyright (C) 2010-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #ifndef _LIB_RING_BUFFER_ITERATOR_H
  11 #define _LIB_RING_BUFFER_ITERATOR_H
  12
  13 #include <ringbuffer/backend.h>
  14 #include <ringbuffer/frontend.h>
  15 #include <ringbuffer/vfs.h>
  16
  17 /*
  18  * lib_ring_buffer_get_next_record advances the buffer read position to the next
  19  * record. It returns either the size of the next record, -EAGAIN if there is
  20  * currently no data available, or -ENODATA if no data is available and buffer
  21  * is finalized.
  22  */
  23 extern ssize_t lib_ring_buffer_get_next_record(struct channel *chan,
  24                                                struct lib_ring_buffer *buf);
  25
  26 /*
  27  * channel_get_next_record advances the buffer read position to the next record.
  28  * It returns either the size of the next record, -EAGAIN if there is currently
  29  * no data available, or -ENODATA if no data is available and buffer is
  30  * finalized.
  31  * Returns the current buffer in ret_buf.
  32  */
  33 extern ssize_t channel_get_next_record(struct channel *chan,
  34                                        struct lib_ring_buffer **ret_buf);
  35
  36 /**
  37  * read_current_record - copy the buffer current record into dest.
  38  * @buf: ring buffer
  39  * @dest: destination where the record should be copied
  40  *
  41  * dest should be large enough to contain the record. Returns the number of
  42  * bytes copied.
  43  */
  44 static inline size_t read_current_record(struct lib_ring_buffer *buf, void *dest)
  45 {
  46         return lib_ring_buffer_read(&buf->backend, buf->iter.read_offset,
  47                                     dest, buf->iter.payload_len);
  48 }
  49
  50 extern int lib_ring_buffer_iterator_open(struct lib_ring_buffer *buf);
  51 extern void lib_ring_buffer_iterator_release(struct lib_ring_buffer *buf);
  52 extern int channel_iterator_open(struct channel *chan);
  53 extern void channel_iterator_release(struct channel *chan);
  54
  55 extern const struct file_operations channel_payload_file_operations;
  56 extern const struct file_operations lib_ring_buffer_payload_file_operations;
  57
  58 /*
  59  * Used internally.
  60  */
  61 int channel_iterator_init(struct channel *chan);
  62 void channel_iterator_unregister_notifiers(struct channel *chan);
  63 void channel_iterator_free(struct channel *chan);
  64 void channel_iterator_reset(struct channel *chan);
  65 void lib_ring_buffer_iterator_reset(struct lib_ring_buffer *buf);
  66
  67 #endif /* _LIB_RING_BUFFER_ITERATOR_H */