src/input_stream.h

   1 /*
   2  * Copyright (C) 2003-2010 The Music Player Daemon Project
   3  * http://www.musicpd.org
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #ifndef MPD_INPUT_STREAM_H
  21 #define MPD_INPUT_STREAM_H
  22
  23 #include "check.h"
  24
  25 #include <glib.h>
  26
  27 #include <stddef.h>
  28 #include <stdbool.h>
  29 #include <sys/types.h>
  30
  31 #if !GLIB_CHECK_VERSION(2,14,0)
  32 typedef gint64 goffset;
  33 #endif
  34
  35 struct input_stream {
  36         /**
  37          * the plugin which implements this input stream
  38          */
  39         const struct input_plugin *plugin;
  40
  41         /**
  42          * The absolute URI which was used to open this stream.  May
  43          * be NULL if this is unknown.
  44          */
  45         char *uri;
  46
  47         /**
  48          * indicates whether the stream is ready for reading and
  49          * whether the other attributes in this struct are valid
  50          */
  51         bool ready;
  52
  53         /**
  54          * if true, then the stream is fully seekable
  55          */
  56         bool seekable;
  57
  58         /**
  59          * the size of the resource, or -1 if unknown
  60          */
  61         goffset size;
  62
  63         /**
  64          * the current offset within the stream
  65          */
  66         goffset offset;
  67
  68         /**
  69          * the MIME content type of the resource, or NULL if unknown
  70          */
  71         char *mime;
  72 };
  73
  74 static inline void
  75 input_stream_init(struct input_stream *is, const struct input_plugin *plugin,
  76                   const char *uri)
  77 {
  78         is->plugin = plugin;
  79         is->uri = g_strdup(uri);
  80         is->ready = false;
  81         is->seekable = false;
  82         is->size = -1;
  83         is->offset = 0;
  84         is->mime = NULL;
  85 }
  86
  87 static inline void
  88 input_stream_deinit(struct input_stream *is)
  89 {
  90         g_free(is->uri);
  91         g_free(is->mime);
  92 }
  93
  94 /**
  95  * Opens a new input stream.  You may not access it until the "ready"
  96  * flag is set.
  97  *
  98  * @return an #input_stream object on success, NULL on error
  99  */
 100 struct input_stream *
 101 input_stream_open(const char *uri, GError **error_r);
 102
 103 /**
 104  * Close the input stream and free resources.
 105  */
 106 void
 107 input_stream_close(struct input_stream *is);
 108
 109 /**
 110  * Seeks to the specified position in the stream.  This will most
 111  * likely fail if the "seekable" flag is false.
 112  *
 113  * @param is the input_stream object
 114  * @param offset the relative offset
 115  * @param whence the base of the seek, one of SEEK_SET, SEEK_CUR, SEEK_END
 116  */
 117 bool
 118 input_stream_seek(struct input_stream *is, goffset offset, int whence,
 119                   GError **error_r);
 120
 121 /**
 122  * Returns true if the stream has reached end-of-file.
 123  */
 124 bool input_stream_eof(struct input_stream *is);
 125
 126 /**
 127  * Reads the tag from the stream.
 128  *
 129  * @return a tag object which must be freed with tag_free(), or NULL
 130  * if the tag has not changed since the last call
 131  */
 132 struct tag *
 133 input_stream_tag(struct input_stream *is);
 134
 135 /**
 136  * Reads some of the stream into its buffer.  The following return
 137  * codes are defined: -1 = error, 1 = something was buffered, 0 =
 138  * nothing was buffered.
 139  *
 140  * The semantics of this function are not well-defined, and it will
 141  * eventually be removed.
 142  */
 143 int input_stream_buffer(struct input_stream *is, GError **error_r);
 144
 145 /**
 146  * Reads data from the stream into the caller-supplied buffer.
 147  * Returns 0 on error or eof (check with input_stream_eof()).
 148  *
 149  * @param is the input_stream object
 150  * @param ptr the buffer to read into
 151  * @param size the maximum number of bytes to read
 152  * @return the number of bytes read
 153  */
 154 size_t
 155 input_stream_read(struct input_stream *is, void *ptr, size_t size,
 156                   GError **error_r);
 157
 158 #endif