2 * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file write.h Writer-related structures. */
9 /** The list of supported writers. */
10 enum writer_enum {WRITER_ENUM};
13 * Describes one running instance of a writer.
16 /** The number of this writer. */
18 /** Writer-specific data. */
20 /** The writer-specific configuration of this node. */
22 struct btr_node *btrn;
27 /** Describes one supported writer. */
30 * The init function of the writer.
32 * It must fill in all other function pointers of the given
35 void (*init)(struct writer *w);
37 * The command line parser of the writer.
39 * It should check whether the command line options given by \a options are
40 * valid. On success, it should return a pointer to the writer-specific
41 * configuration data determined by \a options. Note that this might be called
42 * more than once with different values of \a options.
44 void *(*parse_config)(const char *options);
45 void (*free_config)(void *conf);
47 * Open one instance of this writer.
49 * This function should perform any work necessary to write the incoming
50 * stream. To this aim, it may allocate its private data structure and store
51 * a pointer to that structure via the given writer_node parameter.
53 int (*open)(struct writer_node *);
55 * Prepare the fd sets for select.
57 * This is called from the writer node group task's pre_select(). It
58 * may use the sched pointer to add any file descriptors or to decrease
59 * the select timeout. It must return positive on success and negative
62 int (*pre_select)(struct sched *s, struct writer_node *wn);
63 void (*pre_select_btr)(struct sched *s, struct task *t);
67 * Called from the post_select function of the wng task. It must keep
68 * track of the number of bytes consumed from the wng's buffer via
69 * the \p wn->written variable (which may be modified by the wng handling
70 * functions). This function must return positive on success and
73 int (*post_select)(struct sched *s, struct writer_node *wn);
74 void (*post_select_btr)(struct sched *s, struct task *t);
76 * Close one instance of the writer.
78 * This function is assumed to succeed.
80 void (*close)(struct writer_node *);
84 * This is a optional function pointer used for cleaning up.
86 void (*shutdown)(struct writer_node *);
88 btr_command_handler execute;
91 /** Loop over each supported writer. */
92 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
94 /** Declare the init functions of all supported writers. */
97 /** Array containing the name of each writer. */
98 extern const char *writer_names[];
100 /** The writer structure for each supported writer. */
101 extern struct writer writers[NUM_SUPPORTED_WRITERS];