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rdwr.h
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/* * Copyright (c) 2014 by Farsight Security, Inc. * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * */ #ifndef FSTRM_RDWR_H #define FSTRM_RDWR_H /** * \defgroup fstrm_rdwr fstrm_rdwr * * `fstrm_rdwr` is an interface for abstracting the process of reading and * writing data to byte streams. It allows extending the `fstrm` library to * support reading and writing Frame Streams data to new kinds of byte stream * transports. (It also allows building mock interfaces for testing the correct * functioning of the library.) * * `fstrm_rdwr` is a low-level interface that is used in conjunction with the * higher level \ref fstrm_reader and \ref fstrm_writer interfaces. The * following methods need to be defined for `fstrm_rdwr` implementations: * * Method name | Method type | Method description * ------------ | ----------------------------- | ------------------ * `destroy` | #fstrm_rdwr_destroy_func | Destroys the instance. * `open` | #fstrm_rdwr_open_func | Opens the stream. * `close` | #fstrm_rdwr_close_func | Closes the stream. * `read` | #fstrm_rdwr_read_func | Reads bytes from the stream. * `write` | #fstrm_rdwr_write_func | Writes bytes to the stream. * * The `destroy` method is optional. It cleans up any remaining resources * associated with the instance. * * The `open` method is required. It should perform the actual opening of the * byte stream and prepare it to read or write data. * * The `close` method is required. It should perform the actual closing of the * byte stream. * * If the `fstrm_rdwr` object is to be used in an `fstrm_reader` object, it must * have a `read` method. If the `fstrm_rdwr` object embedded in an * `fstrm_reader` object also has a `write` method, the stream will be * considered bi-directional (that is, it supports both reading and writing) and * handshaking will be performed. If a `read` method is supplied but a `write` * method is not, the reader's stream will instead be considered * uni-directional. See \ref fstrm_reader for details. * * If the `fstrm_rdwr` object is to be used in an `fstrm_writer` object, it must * have a `write` method. If the `fstrm_rdwr` object embedded in an * `fstrm_writer` object also has a `read` method, the stream will be considered * bi-directional and shaking will be performed. If a `write` method is supplied * but a `read` method is not, the writer's stream will instead be considered * uni-directional. See \ref fstrm_writer for details. * * An `fstrm_rdwr` instance is created with a call to `fstrm_rdwr_init()`, * optionally passing a pointer to some state object associated with the * instance. This pointer will be passed as the first argument to each of the * methods described above. Then, the various `fstrm_rdwr_set_*()` functions * should be used to configure the functions to be used to invoke the methods * required for the `fstrm_rdwr` object. * * @{ */ /** * `destroy` method function type. This method is invoked to deallocate any * per-stream resources used by an `fstrm_rdwr` implementation. * * \see fstrm_rdwr_set_destroy() * * \param obj * The `obj` value passed to `fstrm_rdwr_init()`. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ typedef fstrm_res (*fstrm_rdwr_destroy_func)(void *obj); /** * `open` method function type. This method is invoked to open the stream and * prepare it for reading or writing. For example, if an `fstrm_rdwr` * implementation is backed by file I/O, this method might be responsible for * opening a file descriptor. * * \see fstrm_rdwr_set_open() * * \param obj * The `obj` value passed to `fstrm_rdwr_init()`. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ typedef fstrm_res (*fstrm_rdwr_open_func)(void *obj); /** * `close` method function type. This method is invoked to close the stream. For * example, if an `fstrm_rdwr` implementation is backed by file I/O, this method * might be responsible for closing a file descriptor. * * \see fstrm_rdwr_set_close() * * \param obj * The `obj` value passed to `fstrm_rdwr_init()`. * * \retval #fstrm_res_success * \retval #fstrm_res_failure */ typedef fstrm_res (*fstrm_rdwr_close_func)(void *obj); /** * `read` method function type. This method is used to read data from a stream. * It must satisfy the full amount of data requested, unless the stream has * ended. * * \see fstrm_rdwr_set_read() * * \param obj * The `obj` value passed to `fstrm_rdwr_init()`. * \param data * The buffer in which to place the data read. * \param count * The number of bytes requested. * * \retval #fstrm_res_success * The data was read successfully. * \retval #fstrm_res_failure * An unexpected failure occurred. * \retval #fstrm_res_stop * The end of the stream has occurred. */ typedef fstrm_res (*fstrm_rdwr_read_func)(void *obj, void *data, size_t count); /** * `write` method function type. This method is used to write data to a stream. * It must perform the full write of all data, unless an error has occurred. * * \see fstrm_rdwr_set_write() * * \param obj * The `obj` value passed to `fstrm_rdwr_init()`. * \param iov * Array of `struct iovec` objects. * \param iovcnt * Number of `struct iovec` objects in `iov`. * * \return #fstrm_res_success * \return #fstrm_res_failure */ typedef fstrm_res (*fstrm_rdwr_write_func)(void *obj, const struct iovec *iov, int iovcnt); /** * Initialize a new `fstrm_rdwr` object. * * \param obj * Per-object state. * * \return * `fstrm_rdwr` object. * \retval * NULL on failure. */ struct fstrm_rdwr * fstrm_rdwr_init(void *obj); /** * Destroy an `fstrm_rdwr` object. This invokes the underlying `destroy` method * as well. * * \param rdwr * Pointer to an `fstrm_rdwr` object. * * \return #fstrm_res_success * \return #fstrm_res_failure */ fstrm_res fstrm_rdwr_destroy(struct fstrm_rdwr **rdwr); /** * Invoke the `open` method on an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * * \return #fstrm_res_success * \return #fstrm_res_failure */ fstrm_res fstrm_rdwr_open(struct fstrm_rdwr *rdwr); /** * Invoke the `close` method on an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * * \return #fstrm_res_success * \return #fstrm_res_failure */ fstrm_res fstrm_rdwr_close(struct fstrm_rdwr *rdwr); /** * Invoke the `read` method on an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param data * The buffer in which to place the data read. * \param count * The number of bytes to read. * * \return #fstrm_res_success * \return #fstrm_res_failure * \return #fstrm_res_stop */ fstrm_res fstrm_rdwr_read(struct fstrm_rdwr *rdwr, void *data, size_t count); /** * Invoke the `write` method on an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param iov * Array of `struct iovec` objects. * \param iovcnt * Number of `struct iovec` objects in `iov`. * * \return #fstrm_res_success * \return #fstrm_res_failure */ fstrm_res fstrm_rdwr_write(struct fstrm_rdwr *rdwr, const struct iovec *iov, int iovcnt); /** * Set the `destroy` method for an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param fn * Function to use. */ void fstrm_rdwr_set_destroy( struct fstrm_rdwr *rdwr, fstrm_rdwr_destroy_func fn); /** * Set the `open` method for an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param fn * Function to use. */ void fstrm_rdwr_set_open( struct fstrm_rdwr *rdwr, fstrm_rdwr_open_func fn); /** * Set the `close` method for an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param fn * Function to use. */ void fstrm_rdwr_set_close( struct fstrm_rdwr *rdwr, fstrm_rdwr_close_func fn); /** * Set the `read` method for an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param fn * Function to use. */ void fstrm_rdwr_set_read( struct fstrm_rdwr *rdwr, fstrm_rdwr_read_func fn); /** * Set the `write` method for an `fstrm_rdwr` object. * * \param rdwr * The `fstrm_rdwr` object. * \param fn * Function to use. */ void fstrm_rdwr_set_write( struct fstrm_rdwr *rdwr, fstrm_rdwr_write_func fn); /**@}*/ #endif /* FSTRM_RDWR_H */