include/mbedtls/platform.h

/**
 * \file platform.h
 *
 * \brief This file contains the definitions and functions of the
 *        Mbed TLS platform abstraction layer.
 *
 *        The platform abstraction layer removes the need for the library
 *        to directly link to standard C library functions or operating
 *        system services, making the library easier to port and embed.
 *        Application developers and users of the library can provide their own
 *        implementations of these functions, or implementations specific to
 *        their platform, which can be statically linked to the library or
 *        dynamically configured at runtime.
 */
/*
 *  Copyright The Mbed TLS Contributors
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
#ifndef MBEDTLS_PLATFORM_H
#define MBEDTLS_PLATFORM_H
#include "mbedtls/private_access.h"

#include "mbedtls/build_info.h"

#if defined(MBEDTLS_HAVE_TIME)
#    include "mbedtls/platform_time.h"
#endif

#ifdef __cplusplus
extern "C" {
#endif

/**
 * \name SECTION: Module settings
 *
 * The configuration options you can set for this module are in this section.
 * Either change them in mbedtls_config.h or define them on the compiler command
 * line.
 * \{
 */

/* The older Microsoft Windows common runtime provides non-conforming
 * implementations of some standard library functions, including snprintf
 * and vsnprintf. This affects MSVC and MinGW builds.
 */
#if defined(__MINGW32__) || (defined(_MSC_VER) && _MSC_VER <= 1900)
#    define MBEDTLS_PLATFORM_HAS_NON_CONFORMING_SNPRINTF
#    define MBEDTLS_PLATFORM_HAS_NON_CONFORMING_VSNPRINTF
#endif

#if !defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS)
#    include <stdio.h>
#    include <stdlib.h>
#    include <time.h>
#    if !defined(MBEDTLS_PLATFORM_STD_SNPRINTF)
#        if defined(MBEDTLS_PLATFORM_HAS_NON_CONFORMING_SNPRINTF)
/** The default \c snprintf function to use.  */
#            define MBEDTLS_PLATFORM_STD_SNPRINTF \
                mbedtls_platform_win32_snprintf
#        else
/** The default \c snprintf function to use.  */
#            define MBEDTLS_PLATFORM_STD_SNPRINTF snprintf
#        endif
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_VSNPRINTF)
#        if defined(MBEDTLS_PLATFORM_HAS_NON_CONFORMING_VSNPRINTF)
/** The default \c vsnprintf function to use.  */
#            define MBEDTLS_PLATFORM_STD_VSNPRINTF \
                mbedtls_platform_win32_vsnprintf
#        else
/** The default \c vsnprintf function to use.  */
#            define MBEDTLS_PLATFORM_STD_VSNPRINTF vsnprintf
#        endif
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_PRINTF)
/** The default \c printf function to use. */
#        define MBEDTLS_PLATFORM_STD_PRINTF printf
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_FPRINTF)
/** The default \c fprintf function to use. */
#        define MBEDTLS_PLATFORM_STD_FPRINTF fprintf
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_CALLOC)
/** The default \c calloc function to use. */
#        define MBEDTLS_PLATFORM_STD_CALLOC calloc
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_FREE)
/** The default \c free function to use. */
#        define MBEDTLS_PLATFORM_STD_FREE free
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_EXIT)
/** The default \c exit function to use. */
#        define MBEDTLS_PLATFORM_STD_EXIT exit
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_TIME)
/** The default \c time function to use. */
#        define MBEDTLS_PLATFORM_STD_TIME time
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_EXIT_SUCCESS)
/** The default exit value to use. */
#        define MBEDTLS_PLATFORM_STD_EXIT_SUCCESS EXIT_SUCCESS
#    endif
#    if !defined(MBEDTLS_PLATFORM_STD_EXIT_FAILURE)
/** The default exit value to use. */
#        define MBEDTLS_PLATFORM_STD_EXIT_FAILURE EXIT_FAILURE
#    endif
#    if defined(MBEDTLS_FS_IO)
#        if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_READ)
#            define MBEDTLS_PLATFORM_STD_NV_SEED_READ \
                mbedtls_platform_std_nv_seed_read
#        endif
#        if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_WRITE)
#            define MBEDTLS_PLATFORM_STD_NV_SEED_WRITE \
                mbedtls_platform_std_nv_seed_write
#        endif
#        if !defined(MBEDTLS_PLATFORM_STD_NV_SEED_FILE)
#            define MBEDTLS_PLATFORM_STD_NV_SEED_FILE "seedfile"
#        endif
#    endif /* MBEDTLS_FS_IO */
#else /* MBEDTLS_PLATFORM_NO_STD_FUNCTIONS */
#    if defined(MBEDTLS_PLATFORM_STD_MEM_HDR)
#        include MBEDTLS_PLATFORM_STD_MEM_HDR
#    endif
#endif /* MBEDTLS_PLATFORM_NO_STD_FUNCTIONS */

/* \} name SECTION: Module settings */

/*
 * The function pointers for calloc and free.
 */
#if defined(MBEDTLS_PLATFORM_MEMORY)
#    if defined(MBEDTLS_PLATFORM_FREE_MACRO) && \
        defined(MBEDTLS_PLATFORM_CALLOC_MACRO)
#        define mbedtls_free   MBEDTLS_PLATFORM_FREE_MACRO
#        define mbedtls_calloc MBEDTLS_PLATFORM_CALLOC_MACRO
#    else
/* For size_t */
#        include <stddef.h>
extern void *mbedtls_calloc(size_t n, size_t size);
extern void mbedtls_free(void *ptr);

/**
 * \brief               This function dynamically sets the memory-management
 *                      functions used by the library, during runtime.
 *
 * \param calloc_func   The \c calloc function implementation.
 * \param free_func     The \c free function implementation.
 *
 * \return              \c 0.
 */
int mbedtls_platform_set_calloc_free(void *(*calloc_func)(size_t, size_t),
                                     void (*free_func)(void *));
#    endif /* MBEDTLS_PLATFORM_FREE_MACRO && MBEDTLS_PLATFORM_CALLOC_MACRO */
#else /* !MBEDTLS_PLATFORM_MEMORY */
#    define mbedtls_free   free
#    define mbedtls_calloc calloc
#endif /* MBEDTLS_PLATFORM_MEMORY && !MBEDTLS_PLATFORM_{FREE,CALLOC}_MACRO */

/*
 * The function pointers for fprintf
 */
#if defined(MBEDTLS_PLATFORM_FPRINTF_ALT)
/* We need FILE * */
#    include <stdio.h>
extern int (*mbedtls_fprintf)(FILE *stream, const char *format, ...);

/**
 * \brief                This function dynamically configures the fprintf
 *                       function that is called when the
 *                       mbedtls_fprintf() function is invoked by the library.
 *
 * \param fprintf_func   The \c fprintf function implementation.
 *
 * \return               \c 0.
 */
int mbedtls_platform_set_fprintf(int (*fprintf_func)(FILE *stream,
                                                     const char *,
                                                     ...));
#else
#    if defined(MBEDTLS_PLATFORM_FPRINTF_MACRO)
#        define mbedtls_fprintf MBEDTLS_PLATFORM_FPRINTF_MACRO
#    else
#        define mbedtls_fprintf fprintf
#    endif /* MBEDTLS_PLATFORM_FPRINTF_MACRO */
#endif /* MBEDTLS_PLATFORM_FPRINTF_ALT */

/*
 * The function pointers for printf
 */
#if defined(MBEDTLS_PLATFORM_PRINTF_ALT)
extern int (*mbedtls_printf)(const char *format, ...);

/**
 * \brief               This function dynamically configures the snprintf
 *                      function that is called when the mbedtls_snprintf()
 *                      function is invoked by the library.
 *
 * \param printf_func   The \c printf function implementation.
 *
 * \return              \c 0 on success.
 */
int mbedtls_platform_set_printf(int (*printf_func)(const char *, ...));
#else /* !MBEDTLS_PLATFORM_PRINTF_ALT */
#    if defined(MBEDTLS_PLATFORM_PRINTF_MACRO)
#        define mbedtls_printf MBEDTLS_PLATFORM_PRINTF_MACRO
#    else
#        define mbedtls_printf printf
#    endif /* MBEDTLS_PLATFORM_PRINTF_MACRO */
#endif /* MBEDTLS_PLATFORM_PRINTF_ALT */

/*
 * The function pointers for snprintf
 *
 * The snprintf implementation should conform to C99:
 * - it *must* always correctly zero-terminate the buffer
 *   (except when n == 0, then it must leave the buffer untouched)
 * - however it is acceptable to return -1 instead of the required length when
 *   the destination buffer is too short.
 */
#if defined(MBEDTLS_PLATFORM_HAS_NON_CONFORMING_SNPRINTF)
/* For Windows (inc. MSYS2), we provide our own fixed implementation */
int mbedtls_platform_win32_snprintf(char *s, size_t n, const char *fmt, ...);
#endif

#if defined(MBEDTLS_PLATFORM_SNPRINTF_ALT)
extern int (*mbedtls_snprintf)(char *s, size_t n, const char *format, ...);

/**
 * \brief                 This function allows configuring a custom
 *                        \c snprintf function pointer.
 *
 * \param snprintf_func   The \c snprintf function implementation.
 *
 * \return                \c 0 on success.
 */
int mbedtls_platform_set_snprintf(
    int (*snprintf_func)(char *s, size_t n, const char *format, ...));
#else /* MBEDTLS_PLATFORM_SNPRINTF_ALT */
#    if defined(MBEDTLS_PLATFORM_SNPRINTF_MACRO)
#        define mbedtls_snprintf MBEDTLS_PLATFORM_SNPRINTF_MACRO
#    else
#        define mbedtls_snprintf MBEDTLS_PLATFORM_STD_SNPRINTF
#    endif /* MBEDTLS_PLATFORM_SNPRINTF_MACRO */
#endif /* MBEDTLS_PLATFORM_SNPRINTF_ALT */

/*
 * The function pointers for vsnprintf
 *
 * The vsnprintf implementation should conform to C99:
 * - it *must* always correctly zero-terminate the buffer
 *   (except when n == 0, then it must leave the buffer untouched)
 * - however it is acceptable to return -1 instead of the required length when
 *   the destination buffer is too short.
 */
#if defined(MBEDTLS_PLATFORM_HAS_NON_CONFORMING_VSNPRINTF)
#    include <stdarg.h>
/* For Older Windows (inc. MSYS2), we provide our own fixed implementation */
int mbedtls_platform_win32_vsnprintf(char *s,
                                     size_t n,
                                     const char *fmt,
                                     va_list arg);
#endif

#if defined(MBEDTLS_PLATFORM_VSNPRINTF_ALT)
#    include <stdarg.h>
extern int (*mbedtls_vsnprintf)(char *s,
                                size_t n,
                                const char *format,
                                va_list arg);

/**
 * \brief   Set your own snprintf function pointer
 *
 * \param   vsnprintf_func   The \c vsnprintf function implementation
 *
 * \return  \c 0
 */
int mbedtls_platform_set_vsnprintf(
    int (*vsnprintf_func)(char *s, size_t n, const char *format, va_list arg));
#else /* MBEDTLS_PLATFORM_VSNPRINTF_ALT */
#    if defined(MBEDTLS_PLATFORM_VSNPRINTF_MACRO)
#        define mbedtls_vsnprintf MBEDTLS_PLATFORM_VSNPRINTF_MACRO
#    else
#        define mbedtls_vsnprintf vsnprintf
#    endif /* MBEDTLS_PLATFORM_VSNPRINTF_MACRO */
#endif /* MBEDTLS_PLATFORM_VSNPRINTF_ALT */

/*
 * The function pointers for exit
 */
#if defined(MBEDTLS_PLATFORM_EXIT_ALT)
extern void (*mbedtls_exit)(int status);

/**
 * \brief             This function dynamically configures the exit
 *                    function that is called when the mbedtls_exit()
 *                    function is invoked by the library.
 *
 * \param exit_func   The \c exit function implementation.
 *
 * \return            \c 0 on success.
 */
int mbedtls_platform_set_exit(void (*exit_func)(int status));
#else
#    if defined(MBEDTLS_PLATFORM_EXIT_MACRO)
#        define mbedtls_exit MBEDTLS_PLATFORM_EXIT_MACRO
#    else
#        define mbedtls_exit exit
#    endif /* MBEDTLS_PLATFORM_EXIT_MACRO */
#endif /* MBEDTLS_PLATFORM_EXIT_ALT */

/*
 * The default exit values
 */
#if defined(MBEDTLS_PLATFORM_STD_EXIT_SUCCESS)
#    define MBEDTLS_EXIT_SUCCESS MBEDTLS_PLATFORM_STD_EXIT_SUCCESS
#else
#    define MBEDTLS_EXIT_SUCCESS 0
#endif
#if defined(MBEDTLS_PLATFORM_STD_EXIT_FAILURE)
#    define MBEDTLS_EXIT_FAILURE MBEDTLS_PLATFORM_STD_EXIT_FAILURE
#else
#    define MBEDTLS_EXIT_FAILURE 1
#endif

/*
 * The function pointers for reading from and writing a seed file to
 * Non-Volatile storage (NV) in a platform-independent way
 *
 * Only enabled when the NV seed entropy source is enabled
 */
#if defined(MBEDTLS_ENTROPY_NV_SEED)
#    if !defined(MBEDTLS_PLATFORM_NO_STD_FUNCTIONS) && defined(MBEDTLS_FS_IO)
/* Internal standard platform definitions */
int mbedtls_platform_std_nv_seed_read(unsigned char *buf, size_t buf_len);
int mbedtls_platform_std_nv_seed_write(unsigned char *buf, size_t buf_len);
#    endif

#    if defined(MBEDTLS_PLATFORM_NV_SEED_ALT)
extern int (*mbedtls_nv_seed_read)(unsigned char *buf, size_t buf_len);
extern int (*mbedtls_nv_seed_write)(unsigned char *buf, size_t buf_len);

/**
 * \brief   This function allows configuring custom seed file writing and
 *          reading functions.
 *
 * \param   nv_seed_read_func   The seed reading function implementation.
 * \param   nv_seed_write_func  The seed writing function implementation.
 *
 * \return  \c 0 on success.
 */
int mbedtls_platform_set_nv_seed(int (*nv_seed_read_func)(unsigned char *buf,
                                                          size_t buf_len),
                                 int (*nv_seed_write_func)(unsigned char *buf,
                                                           size_t buf_len));
#    else
#        if defined(MBEDTLS_PLATFORM_NV_SEED_READ_MACRO) && \
            defined(MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO)
#            define mbedtls_nv_seed_read  MBEDTLS_PLATFORM_NV_SEED_READ_MACRO
#            define mbedtls_nv_seed_write MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO
#        else
#            define mbedtls_nv_seed_read  mbedtls_platform_std_nv_seed_read
#            define mbedtls_nv_seed_write mbedtls_platform_std_nv_seed_write
#        endif
#    endif /* MBEDTLS_PLATFORM_NV_SEED_ALT */
#endif /* MBEDTLS_ENTROPY_NV_SEED */

#if !defined(MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT)

/**
 * \brief   The platform context structure.
 *
 * \note    This structure may be used to assist platform-specific
 *          setup or teardown operations.
 */
typedef struct mbedtls_platform_context {
    char MBEDTLS_PRIVATE(dummy); /**< A placeholder member, as empty structs are
                                    not portable. */
} mbedtls_platform_context;

#else
#    include "platform_alt.h"
#endif /* !MBEDTLS_PLATFORM_SETUP_TEARDOWN_ALT */

/**
 * \brief   This function performs any platform-specific initialization
 *          operations.
 *
 * \note    This function should be called before any other library functions.
 *
 *          Its implementation is platform-specific, and unless
 *          platform-specific code is provided, it does nothing.
 *
 * \note    The usage and necessity of this function is dependent on the
 * platform.
 *
 * \param   ctx     The platform context.
 *
 * \return  \c 0 on success.
 */
int mbedtls_platform_setup(mbedtls_platform_context *ctx);
/**
 * \brief   This function performs any platform teardown operations.
 *
 * \note    This function should be called after every other Mbed TLS module
 *          has been correctly freed using the appropriate free function.
 *
 *          Its implementation is platform-specific, and unless
 *          platform-specific code is provided, it does nothing.
 *
 * \note    The usage and necessity of this function is dependent on the
 * platform.
 *
 * \param   ctx     The platform context.
 *
 */
void mbedtls_platform_teardown(mbedtls_platform_context *ctx);

#ifdef __cplusplus
}
#endif

#endif /* platform.h */