src/posix/platform/config_file.hpp

/*
 *  Copyright (c) 2022, The OpenThread Authors.
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 *  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. Neither the name of the copyright holder nor the
 *     names of its contributors may be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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 */

#ifndef OT_POSIX_PLATFORM_CONFIG_FILE_HPP_
#define OT_POSIX_PLATFORM_CONFIG_FILE_HPP_

#include <assert.h>
#include <stdint.h>
#include <openthread/error.h>

namespace ot {
namespace Posix {

/**
 * Provides read/write/clear methods for key/value configuration files.
 *
 */
class ConfigFile
{
public:
    /**
     * Initializes the configuration file path.
     *
     * @param[in]  aFilePath  A pointer to the null-terminated file path.
     *
     */
    explicit ConfigFile(const char *aFilePath);

    /**
     * Gets a configuration from the configuration file.
     *
     * @param[in]      aKey          The key string associated with the requested configuration.
     * @param[in,out]  aIterator     A reference to an iterator. MUST be initialized to 0 or the behavior is undefined.
     * @param[out]     aValue        A pointer to where the new value string of the configuration should be read from.
     *                               The @p aValue string will be terminated with `\0` if this method returns success.
     *                               May be `nullptr` if performing a presence check.
     * @param[in]      aValueLength  The max length of the data pointed to by @p aValue.
     *
     * @retval OT_ERROR_NONE          The given configuration was found and fetched successfully.
     * @retval OT_ERROR_NOT_FOUND     The given key or iterator was not found in the configuration file.
     * @retval OT_ERROR_INVALID_ARGS  If @p aKey was NULL.
     *
     */
    otError Get(const char *aKey, int &aIterator, char *aValue, int aValueLength) const;

    /**
     * Adds a configuration to the configuration file.
     *
     * @param[in]  aKey    The key string associated with the requested configuration.
     * @param[in]  aValue  A pointer to where the new value string of the configuration should be written.
     *
     * @retval OT_ERROR_NONE          The given key was found and removed successfully.
     * @retval OT_ERROR_INVALID_ARGS  If @p aKey or @p aValue was NULL.
     *
     */
    otError Add(const char *aKey, const char *aValue);

    /**
     * Removes all configurations with the same key string from the configuration file.
     *
     * @param[in]  aKey  The key string associated with the requested configuration.
     *
     * @retval OT_ERROR_NONE          The given key was found and removed successfully.
     * @retval OT_ERROR_INVALID_ARGS  If @p aKey was NULL.
     *
     */
    otError Clear(const char *aKey);

    /**
     * Indicates whether the given key exists.
     *
     * @param[in]  aKey  The key string associated with the requested configuration.
     *
     * @retval TRUE  If the key exists in the configuration file.
     * @retval FALSE If the key does not exist in the configuration file.
     *
     */
    bool HasKey(const char *aKey) const;

    /**
     * Indicates whether the configuration file exists.
     *
     * @retval TRUE  If the configuration file exists.
     * @retval FALSE If the configuration file does not exist.
     *
     */
    bool DoesExist(void) const;

private:
    const char               *kCommentDelimiter = "#";
    const char               *kSwapSuffix       = ".swap";
    static constexpr uint16_t kLineMaxSize      = 512;
    static constexpr uint16_t kFileNameMaxSize  = 255;

    void Strip(char *aString) const;

    const char *mFilePath;
};

} // namespace Posix
} // namespace ot

#endif // OT_POSIX_PLATFORM_CONFIG_FILE_HPP_