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Diffstat (limited to 'ext/dynmanifest.lv2/dynmanifest.h')
| -rw-r--r-- | ext/dynmanifest.lv2/dynmanifest.h | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/ext/dynmanifest.lv2/dynmanifest.h b/ext/dynmanifest.lv2/dynmanifest.h new file mode 100644 index 0000000..204e18b --- /dev/null +++ b/ext/dynmanifest.lv2/dynmanifest.h @@ -0,0 +1,247 @@ +/* Dynamic manifest specification for LV2 + * Revision 1.1 + * + * Copyright (C) 2008-2011 Stefano D'Angelo <zanga.mail@gmail.com> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. The name of the author may not be used to endorse or promote products + * derived from this software without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef LV2_DYN_MANIFEST_H_INCLUDED +#define LV2_DYN_MANIFEST_H_INCLUDED + +#include <stdio.h> +#include "lv2.h" + +#define LV2_DYN_MANIFEST_URI "http://lv2plug.in/ns/ext/dynmanifest" + +#ifdef __cplusplus +extern "C" { +#endif + + +/* ************************************************************************* */ + + +/** @file + * C header for the LV2 Dynamic Manifest extension + * <http://lv2plug.in/ns/ext/dynmanifest>. + * Revision: 1.1 + * + * == Overview == + * + * The LV2 API, on its own, cannot be used to write plugin libraries where + * data is dynamically generated at runtime (e.g. API wrappers), since LV2 + * requires needed information to be provided in one or more static data (RDF) + * files. This API addresses this limitation by extending the LV2 API. + * + * A host implementing support for this API should first detect that the plugin + * library implements a dynamic manifest generator by examining its static + * manifest file, then fetch data from the shared object file by accessing it as + * usual (e.g., dlopen() and family) and using this API. + * + * The host is allowed to request regeneration of the dynamic manifest multiple + * times, and the plugin library is expected to provide updated data if/when + * possible. All data and references provided via this API before the last + * regeneration of the dynamic manifest is to be considered invalid by the + * host, including plugin descriptors whose URIs were discovered using this API. + * + * This API is extensible in a similar fashion as the LV2 API. + * + * == Threading rules == + * + * This specification defines threading rule classes, similarly to the LV2 + * specification. + * + * The functions defined by this API belong to: + * + * - Dynamic manifest open class: lv2_dyn_manifest_open() + * - Dynamic manifest close class: lv2_dyn_manifest_close() + * - Dynamic manifest file class: lv2_dyn_manifest_get_subjects(), + * lv2_dyn_manifest_get_data() + * + * The rules that hosts must follow are these: + * + * - When a function from the Dynamic manifest open or the Dynamic manifest + * close class is running, no other functions in the same shared object file + * may run. + * - When a function from the Dynamic manifest file class is called, no other + * functions from the same class may run if they are given at least one + * FILE * argument with the same value. + * - A function from the Dynamic manifest open class may not run after a + * successful call to a function from the same class, in case a function from + * the Dynamic manifest close class was not successfully called in the + * meanwhile. + * - A function from the Dynamic manifest close class may only run after a + * successful call to a function from the Dynamic manifest open class. + * - A function from the Dynamic manifest file class may only run beetween a + * successful call to a function from the Dynamic manifest open class and the + * following successful call to a function from the Dynamic manifest close + * class. + * + * Extensions to this specification which add new functions MUST declare in + * which of these classes the functions belong, or define new classes for them; + * furthermore, classes defined by such extensions MUST only allow calls after + * a successful call to a function from the Dynamic manifest open class and + * before the following successful call to a function from the Dynamic manifest + * close class. + * + * Any simultaneous calls that are not explicitly forbidden by these rules are + * allowed. + */ + + +/* ************************************************************************* */ + + +/** Dynamic manifest generator handle. + * + * This handle indicates a particular status of a dynamic manifest generator. + * The host MUST NOT attempt to interpret it and, unlikely LV2_Handle, it is NOT + * even valid to compare this to NULL. The dynamic manifest generator may use it + * to reference internal data. */ +typedef void * LV2_Dyn_Manifest_Handle; + + +/* ************************************************************************* */ + + +/** Accessing data. + * + * Whenever a host wants to access data using this API, it could: + * + * 1. Call lv2_dyn_manifest_open(); + * 2. Create an empty resource identified by a FILE *; + * 3. Get a "list" of exposed subject URIs using + * lv2_dyn_manifest_get_subjects(); + * 4. Call lv2_dyn_manifest_get_data() for each URI of interest, in order to + * get data related to that URI (either by calling the function subsequently + * with the same FILE * resource, or by creating more FILE * resources to + * perform parallel calls); + * 5. Call lv2_dyn_manifest_close(); + * 6. Parse the content of the FILE * resource(s). + * 7. Free/delete/unlink the FILE * resource(s). + * + * The content of the FILE * resources has to be interpreted by the host as a + * regular file in Turtle syntax. This also means that each FILE * resource + * should also contain needed prefix definitions, in case any are used. + * + * Each call to lv2_dyn_manifest_open() automatically implies the (re)generation + * of the dynamic manifest on the library side. + * + * When such calls are made, data fetched from the involved library using this + * API before such call is to be considered no more valid. + * + * In case the library uses this same API to access other dynamic manifests, it + * MUST implement some mechanism to avoid potentially endless loops (such as A + * loads B, B loads A, etc.) in functions from the Dynamic manifest open class + * (the open-like operation MUST fail). For this purpose, use of a static + * boolean flag is suggested. + */ + +/** Function that (re)generates the dynamic manifest. + * + * handle is a pointer to an uninitialized dynamic manifest generator handle. + * + * features is a NULL terminated array of LV2_Feature structs which + * represent the features the host supports. The dynamic manifest geenrator may + * refuse to (re)generate the dynamic manifest if required features are not + * found here (however hosts SHOULD NOT use this as a discovery mechanism, + * instead of reading the static manifest file). This array must always exist; + * if a host has no features, it MUST pass a single element array containing + * NULL. + * + * This function MUST return 0 on success, otherwise a non-zero error code, and + * the host SHOULD evaluate the result of the operation by examining the + * returned value, rather than try to interpret the value of handle. + */ +int lv2_dyn_manifest_open(LV2_Dyn_Manifest_Handle * handle, + const LV2_Feature *const * features); + +/** Function that fetches a "list" of subject URIs exposed by the dynamic + * manifest generator. + * + * handle is the dynamic manifest generator handle. + * + * fp is the FILE * identifying the resource the host has to set up for the + * dynamic manifest generator. The host MUST pass a writable, empty resource to + * this function, and the dynamic manifest generator MUST ONLY perform write + * operations on it at the end of the stream (e.g. use only fprintf(), fwrite() + * and similar). + * + * The dynamic manifest generator has to fill the resource only with the needed + * triples to make the host aware of the "objects" it wants to expose. For + * example, if the library exposes a regular LV2 plugin, it should output only a + * triple like the following: + * + * <http://www.example.com/plugin/uri> a lv2:Plugin . + * + * This function MUST return 0 on success, otherwise a non-zero error code. + */ +int lv2_dyn_manifest_get_subjects(LV2_Dyn_Manifest_Handle handle, + FILE * fp); + +/** Function that fetches data related to a specific URI. + * + * handle is the dynamic manifest generator handle. + * + * fp is the FILE * identifying the resource the host has to set up for the + * dynamic manifest generator. The host MUST pass a writable resource to this + * function, and the dynamic manifest generator MUST ONLY perform write + * operations on it at the current position of the stream (e.g. use only + * fprintf(), fwrite() and similar). + * + * uri is the URI to get data about (in the "plain" form, a.k.a. without RDF + * prefixes). + * + * The dynamic manifest generator has to fill the resource with data related to + * the URI. For example, if the library exposes a regular LV2 plugin whose URI, + * as retrieved by the host using lv2_dyn_manifest_get_subjects() is + * http://www.example.com/plugin/uri, it should output something like: + * + * <http://www.example.com/plugin/uri> a lv2:Plugin; + * lv2:binary <mylib.so>; + * doap:name "My Plugin"; + * ... etc... + * + * This function MUST return 0 on success, otherwise a non-zero error code. + */ +int lv2_dyn_manifest_get_data(LV2_Dyn_Manifest_Handle handle, + FILE * fp, + const char * uri); + +/** Function that ends the operations on the dynamic manifest generator. + * + * handle is the dynamic manifest generator handle. + * + * This function should be used by the dynamic manifest generator to perform + * cleanup operations, etc. + */ +void lv2_dyn_manifest_close(LV2_Dyn_Manifest_Handle handle); + +#ifdef __cplusplus +} +#endif + +#endif /* LV2_DYN_MANIFEST_H_INCLUDED */ + |