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diff --git a/src/in.h b/src/in.h new file mode 100644 index 0000000..62f5aae --- /dev/null +++ b/src/in.h @@ -0,0 +1,252 @@ +/** + * @file in.h + * @author Radek Krejci <rkrejci@cesnet.cz> + * @brief libyang input structures and functions + * + * Copyright (c) 2020 CESNET, z.s.p.o. + * + * This source code is licensed under BSD 3-Clause License (the "License"). + * You may not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * https://opensource.org/licenses/BSD-3-Clause + */ + +#ifndef LY_IN_H_ +#define LY_IN_H_ + +#include <stdio.h> + +#include "log.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @page howtoInput Input Processing + * + * libyang provides a mechanism to generalize work with the inputs (and [outputs](@ref howtoOutput)) of + * the different types. The ::ly_in handler can be created providing necessary information connected with the specific + * input type and then used throughout the parser functions processing the input data. Using a generic input handler avoids + * need to have a set of functions for each parser functionality and results in simpler API. + * + * The API allows to alter the source of the data behind the handler by another source. Also resetting a seekable source + * input is possible with ::ly_in_reset() to re-read the input. + * + * @note + * Currently, libyang supports only reading data from standard (disk) file, not from sockets, pipes, etc. The reason is + * that the parsers expects all the data to be present in the file (input data are complete). In future, we would like + * to change the internal mechanism and support sequential processing of the input data. In XML wording - we have DOM + * parser, but in future we would like to move to something like a SAX parser. + * + * @note + * This mechanism was introduced in libyang 2.0. To simplify transition from libyang 1.0 to version 2.0 and also for + * some simple use case where using the input handler would be an overkill, there are some basic parsers functions + * that do not require input handler. But remember, that functionality of these function can be limited in particular cases + * in contrast to the functions using input handlers. + * + * Functions List + * -------------- + * - ::ly_in_new_fd() + * - ::ly_in_new_file() + * - ::ly_in_new_filepath() + * - ::ly_in_new_memory() + * + * - ::ly_in_fd() + * - ::ly_in_file() + * - ::ly_in_filepath() + * - ::ly_in_memory() + * + * - ::ly_in_type() + * - ::ly_in_parsed() + * + * - ::ly_in_reset() + * - ::ly_in_free() + * + * libyang Parsers List + * -------------------- + * - @subpage howtoSchemaParsers + * - @subpage howtoDataParsers + */ + +/** + * @struct ly_in + * @brief Parser input structure specifying where the data are read. + */ +struct ly_in; + +/** + * @brief Types of the parser's inputs + */ +typedef enum LY_IN_TYPE { + LY_IN_ERROR = -1, /**< error value to indicate failure of the functions returning LY_IN_TYPE */ + LY_IN_FD, /**< file descriptor printer */ + LY_IN_FILE, /**< FILE stream parser */ + LY_IN_FILEPATH, /**< filepath parser */ + LY_IN_MEMORY /**< memory parser */ +} LY_IN_TYPE; + +/** + * @brief Get input type of the input handler. + * + * @param[in] in Input handler. + * @return Type of the parser's input. + */ +LIBYANG_API_DECL LY_IN_TYPE ly_in_type(const struct ly_in *in); + +/** + * @brief Reset the input medium to read from its beginning, so the following parser function will read from the object's beginning. + * + * Note that in case the underlying output is not seekable (stream referring a pipe/FIFO/socket or the callback output type), + * nothing actually happens despite the function succeeds. Also note that the medium is not returned to the state it was when + * the handler was created. For example, file is seeked into the offset zero, not to the offset where it was opened when + * ::ly_in_new_file() was called. + * + * @param[in] in Input handler. + * @return LY_SUCCESS in case of success + * @return LY_ESYS in case of failure + */ +LIBYANG_API_DECL LY_ERR ly_in_reset(struct ly_in *in); + +/** + * @brief Create input handler using file descriptor. + * + * @param[in] fd File descriptor to use. + * @param[out] in Created input handler supposed to be passed to different ly*_parse() functions. + * @return LY_SUCCESS in case of success + * @return LY_ERR value in case of failure. + */ +LIBYANG_API_DECL LY_ERR ly_in_new_fd(int fd, struct ly_in **in); + +/** + * @brief Get or reset file descriptor input handler. + * + * @param[in] in Input handler. + * @param[in] fd Optional value of a new file descriptor for the handler. If -1, only the current file descriptor value is returned. + * @return Previous value of the file descriptor. Note that caller is responsible for closing the returned file descriptor in case of setting new descriptor @p fd. + * @return -1 in case of error when setting up the new file descriptor. + */ +LIBYANG_API_DECL int ly_in_fd(struct ly_in *in, int fd); + +/** + * @brief Create input handler using file stream. + * + * @param[in] f File stream to use. + * @param[out] in Created input handler supposed to be passed to different ly*_parse() functions. + * @return LY_SUCCESS in case of success + * @return LY_ERR value in case of failure. + */ +LIBYANG_API_DECL LY_ERR ly_in_new_file(FILE *f, struct ly_in **in); + +/** + * @brief Get or reset file stream input handler. + * + * @param[in] in Input handler. + * @param[in] f Optional new file stream for the handler. If NULL, only the current file stream is returned. + * @return NULL in case of invalid argument or an error when setting up the new input file, original input handler @p in is untouched in this case. + * @return Previous file stream of the handler. Note that caller is responsible for closing the returned stream in case of setting new stream @p f. + */ +LIBYANG_API_DECL FILE *ly_in_file(struct ly_in *in, FILE *f); + +/** + * @brief Create input handler using memory to read data. + * + * @param[in] str Pointer where to start reading data. The input data are expected to be NULL-terminated. + * Note that in case the destroy argument of ::ly_in_free() is used, the input string is passed to free(), + * so if it is really a static string, do not use the destroy argument! + * @param[out] in Created input handler supposed to be passed to different ly*_parse() functions. + * @return LY_SUCCESS in case of success + * @return LY_ERR value in case of failure. + */ +LIBYANG_API_DECL LY_ERR ly_in_new_memory(const char *str, struct ly_in **in); + +/** + * @brief Get or change memory where the data are read from. + * + * @param[in] in Input handler. + * @param[in] str String containing the data to read. The input data are expected to be NULL-terminated. + * Note that in case the destroy argument of ::ly_in_free() is used, the input string is passed to free(), + * so if it is really a static string, do not use the destroy argument! + * @return Previous starting address to read data from. Note that the caller is responsible to free + * the data in case of changing string pointer @p str. + */ +LIBYANG_API_DECL const char *ly_in_memory(struct ly_in *in, const char *str); + +/** + * @brief Create input handler file of the given filename. + * + * @param[in] filepath Path of the file where to read data. + * @param[in] len Optional number of bytes to use from @p filepath. If 0, the @p filepath is considered to be NULL-terminated and + * the whole string is taken into account. + * @param[out] in Created input handler supposed to be passed to different ly*_parse() functions. + * @return LY_SUCCESS in case of success + * @return LY_ERR value in case of failure. + */ +LIBYANG_API_DECL LY_ERR ly_in_new_filepath(const char *filepath, size_t len, struct ly_in **in); + +/** + * @brief Get or change the filepath of the file where the parser reads the data. + * + * Note that in case of changing the filepath, the current file is closed and a new one is + * created/opened instead of renaming the previous file. Also note that the previous filepath + * string is returned only in case of not changing it's value. + * + * @param[in] in Input handler. + * @param[in] filepath Optional new filepath for the handler. If and only if NULL, the current filepath string is returned. + * @param[in] len Optional number of bytes to use from @p filepath. If 0, the @p filepath is considered to be NULL-terminated and + * the whole string is taken into account. + * @return Previous filepath string in case the @p filepath argument is NULL. + * @return NULL if changing filepath succeedes and ((void *)-1) otherwise. + */ +LIBYANG_API_DECL const char *ly_in_filepath(struct ly_in *in, const char *filepath, size_t len); + +/** + * @brief Get the number of parsed bytes by the last function. + * + * @param[in] in In structure used. + * @return Number of parsed bytes. + */ +LIBYANG_API_DECL size_t ly_in_parsed(const struct ly_in *in); + +/** + * @brief Free the input handler. + * + * @param[in] in Input handler to free. + * @param[in] destroy Flag to free the input data buffer (for LY_IN_MEMORY) or to + * close stream/file descriptor (for LY_IN_FD and LY_IN_FILE) + */ +LIBYANG_API_DECL void ly_in_free(struct ly_in *in, ly_bool destroy); + +/** + * @brief Read bytes from an input. + * + * Does not count new lines, which is expected from the caller who has better idea about + * the content of the read data and can better optimize counting. + * + * @param[in] in Input structure. + * @param[in] buf Destination buffer. + * @param[in] count Number of bytes to read. + * @return LY_SUCCESS on success, + * @return LY_EDENIED on EOF. + */ +LIBYANG_API_DECL LY_ERR ly_in_read(struct ly_in *in, void *buf, size_t count); + +/** + * @brief Just skip bytes in an input. + * + * Does not count new lines, which is expected from the caller who has better idea about + * the content of the skipped data and can better optimize counting. + * + * @param[in] in Input structure. + * @param[in] count Number of bytes to skip. + * @return LY_SUCCESS on success, + * @return LY_EDENIED on EOF. + */ +LIBYANG_API_DECL LY_ERR ly_in_skip(struct ly_in *in, size_t count); + +#ifdef __cplusplus +} +#endif + +#endif /* LY_IN_H_ */ |