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/**
 * slibc — Yet another C library
 * Copyright © 2015, 2016  Mattias Andrée (maandree@member.fsf.org)
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef _STDIO_H
#define _STDIO_H
#include <slibc/version.h>
#include <slibc/features.h>



#define __NEED_fpos_t /* TODO not implemented */
#define __NEED_off_t
#define __NEED_size_t
#define __NEED_ssize_t
#define __NEED_wchar_t
#define __NEED_va_list
#if defined(__C11__)
# define __NEED_max_align_t
#endif
#define FILE void /* TODO temporary */

#include <bits/types.h>



/* TODO implement I/O */
int fflush(FILE*);
#define stdin ((void*)1) /* TODO temporary */
#define stdout ((void*)2) /* TODO temporary */
#define stderr ((void*)3) /* TODO temporary */


/**
 * This function is identical to `fprintf` with
 * `stdout` as the first argument.
 * 
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int printf(const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1), __format__(__slibc_printf__, 1, 2))));

/**
 * Print a formatted string to a stream.
 * 
 * TODO list format rules for fprintf
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int fprintf(FILE* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2), __format__(__slibc_printf__, 2, 3))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fprintf`,
 * except it does not lock the stream.
 * 
 * This is a slibc extension.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite_unlocked`.
 * 
 * @since  Always.
 */
int fprintf_unlocked(FILE* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2), __format__(__slibc_printf__, 2, 3))));
#endif

/**
 * This function is identical to `fprintf`,
 * except it is limited to file descriptor-backed
 * streams, and uses the file descriptor as the
 * first argument rather than the stream.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int dprintf(int, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(2), __format__(__slibc_printf__, 2, 3))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `dprintf`,
 * except it uses `send` instead of `write`
 * and supports transmissions flags.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   flags   Flags to pass to `send`, see `send`
 *                  for more information.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int sockprintf(int, int, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(3), __format__(__slibc_printf__, 3, 4))));
#endif

/**
 * This function is identical to `fprintf`,
 * it prints to a buffer rather than a stream.
 * 
 * This is identical to `snprintf` with
 * `SIZE_MAX` as the second argument.
 * 
 * `sprintf` is(!) safe to use. As long as you allocate
 * the a large enough buffer. One way to do this is
 * by measuring the length of the result first.
 * 
 *     ssize_t n;
 *     char* buffer = NULL;
 *     snprintf(NULL, 0, "%zu%zn", your_value, &n);
 *     buffer = malloc((size_t)n * sizeof(char));
 *     if (buffer == NULL) goto fail;
 *     sprintf(buffer, "%zu", your_value);
 * 
 * If you don't care about portability, you can use
 * `asprintf`, `asprintfa` or `bprintf`. However, you
 * often do not need to measure the result with `snprintf`.
 * A maximum possible length can often be determined
 * at compile-time or only using `strlen'.
 * 
 *     char buffer[3 * sizeof(ssize_t) + 2]; // A very poor, but still safe,
 *                                           // approximation to log₁₀.
 *     spritnf(buffer, "%zi", your_signed_value);
 * 
 * These techniques guarantees that all of the string is
 * written, and is therefore preferable over replacing
 * `sprintf` with `snprintf`. Because of this, slibc
 * does not consider `sprintf` unsafe like some of the
 * more hokey C standard library implementations. This
 * is C damn it!
 * 
 *   “Almost anything can be unsafe if you don't use it properly.”
 * 
 * @param   buffer  The output buffer.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int sprintf(char* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2), __format__(__slibc_printf__, 2, 3))));

/**
 * This function is identical to `sprintf`,
 * expect it truncates the output.
 * 
 * @param   buffer  The output buffer.
 * @param   size    The allocation size of `buffer`.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte, that would have been written
 *                  if `size` was ignored. On error, a negative
 *                  value (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes would have been written; in slibc,
 *                  `INT_MAX` is returned if more would have
 *                  been written, you can use "%zn" to find the
 *                  actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int snprintf(char* restrict, size_t, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(3), __format__(__slibc_printf__, 3, 4))));

/* TODO plan9: char* seprintf(char* start, char* end, const char* restrict format, ...)
            ~= start + snprintf(start, end - start, format, ...)
   TODO plan9: char* smprintf(const char* restrict format, ...)
            ~= asprintf(&r, format, ...), r;
 */

#if defined(__GNU_SOURCE)
/**
 * This function is identical to `sprintf`,
 * except it allocates a sufficiently large
 * buffer.
 * 
 * This is a GNU extension.
 * 
 * @param   buffer  Output parameter for the output buffer.
 *                  On error the content of this pointer is undefined.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int asprintf(char** restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2), __format__(__slibc_printf__, 2, 3), __warn_unused_result__)));
#endif

#if defined(__SLIBC_SOURCE)
# if defined(__GNUC__)
/**
 * This function is identical to `sprintf`,
 * except it allocates a sufficiently large
 * buffer to the stack (using `alloca`.)
 * 
 * This is a slibc extension. It is only available
 * if compiling with GCC.
 * 
 * There is no `vasprintfa` function.
 * 
 * @param   buffer:char**  Output parameter for the output buffer,
 *                         must not be `NULL`. On error the content
 *                         of this pointer is either `NULL` or a
 *                         pointer to memory allocated with `alloca`.
 * @param   format:char*   The formatting-string, must not have
 *                         side-effects or be `NULL`.
 * @param   ...            The formatting-arguments, must not have
 *                         side-effects.
 * @return  :int           The number of written bytes, excluding
 *                         the NUL byte. On error, a negative value
 *                         (namely -1 in this implementation) is
 *                         returned. It is unspecified what shall
 *                         happen if more than `INT_MAX` non-NUL
 *                         bytes are written; in slibc, `INT_MAX`
 *                         is returned if more is written, you can
 *                         use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
#define asprintfa(buffer, format, ...)					\
  ({									\
    ssize_t __size;							\
    int __r;								\
    __r = snprintf(NULL, 0, format "%zn", ##__VA_ARGS__, &__size);	\
    if (*buffer = NULL, __size += 1, __r >= 0)				\
      *buffer = __builtin_alloca((size_t)__size * sizeof(char)),	\
	__r = sprintf(*buffer, format, ##__VA_ARGS__);			\
    __r;							\
  })
# endif

/**
 * This function is identical to `asprintf`,
 * except it can reuse allocated buffers.
 * 
 * This is a slibc extension.
 * 
 * @param   buffer  Reference parameter for the output buffer.
 *                  It should point to the buffer than shall
 *                  be used, or point to `NULL` if a new buffer
 *                  shall be allocated. It will be updated with
 *                  a new buffer if it points to `NULL`, or the
 *                  new pointer if `buffer` needed to be reallocated.
 *                  On error, this pointer will only have been
 *                  updated if the buffer was reallocated during
 *                  the call; if it pointed to `NULL`, it will
 *                  still point to `NULL`.
 * @param   size    Reference parameter for the buffer size.
 *                  It shall point to a variable whose value is
 *                  the allocation size of `*buffer`, or point to
 *                  a variable whose value is zero if `*buffer`
 *                  is `NULL`.
 * @param   offset  The offset in the buffer where the function
 *                  shall start the printing.
 * @param   secure  Non-zero if the function must override the
 *                  buffer with zero before freeing it if it
 *                  creates a new allocation.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int bprintf(char** restrict, size_t* restrict, size_t, int, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2, 5), __format__(__slibc_printf__, 5, 6), __warn_unused_result__)));
#endif


/**
 * This function is identical to `printf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int vprintf(const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1))));

/**
 * This function is identical to `fprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int vfprintf(FILE* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fprintf_unlocked`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite_unlocked`.
 * 
 * @since  Always.
 */
int vfprintf_unlocked(FILE* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));
#endif

/**
 * This function is identical to `dprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `write`.
 * 
 * @since  Always.
 */
int vdprintf(int, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(2))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `sockprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   flags   Flags to pass to `send`, see `send`
 *                  for more information.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int vsockprintf(int, int, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(3))));
#endif

/**
 * This function is identical to `sprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   buffer  The output buffer.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int vsprintf(char* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

/**
 * This function is identical to `snprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   buffer  The output buffer.
 * @param   size    The allocation size of `buffer`.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte, that would have been written
 *                  if `size` was ignored. On error, a negative
 *                  value (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes would have been written; in slibc,
 *                  `INT_MAX` is returned if more would have
 *                  been written, you can use "%zn" to find the
 *                  actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int vsnprintf(char* restrict, size_t, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(3))));

/* TODO plan9: char* vseprintf(char* start, char* end, const char* restrict format, va_list args)
            ~= start + vsnprintf(start, end - start, format, args)
   TODO plan9: char* vsmprintf(const char* restrict format, va_list args)
            ~= vasprintf(&r, format, args), r;
 */

#if defined(__GNU_SOURCE)
/**
 * This function is identical to `asprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a GNU extension.
 * 
 * @param   buffer  Output parameter for the output buffer.
 *                  On error the content of this pointer is undefined.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int vasprintf(char** restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2), __warn_unused_result__)));
#endif

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `bprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension.
 * 
 * @param   buffer  Reference parameter for the output buffer.
 *                  It should point to the buffer than shall
 *                  be used, or point to `NULL` if a new buffer
 *                  shall be allocated. It will be updated with
 *                  a new buffer if it points to `NULL`, or the
 *                  new pointer if `buffer` needed to be reallocated.
 *                  On error, this pointer will only have been
 *                  updated if the buffer was reallocated during
 *                  the call; if it pointed to `NULL`, it will
 *                  still point to `NULL`.
 * @param   size    Reference parameter for the buffer size.
 *                  It shall point to a variable whose value is
 *                  the allocation size of `*buffer`, or point to
 *                  a variable whose value is zero if `*buffer`
 *                  is `NULL`.
 * @param   offset  The offset in the buffer where the function
 *                  shall start the printing.
 * @param   secure  Non-zero if the function must override the
 *                  buffer with zero before freeing it if it
 *                  creates a new allocation.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes, excluding
 *                  the NUL byte. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  bytes are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int vbprintf(char** restrict, size_t* restrict, size_t, int, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2, 5), __warn_unused_result__)));
#endif


#if !defined(__PORTABLE) /* wchar_t is not portable. */
/**
 * This function is identical to `printf` except
 * it uses wide characters.
 * 
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int wprintf(const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1))));

/**
 * This function is identical to `fprintf` except
 * it uses wide characters.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int fwprintf(FILE* restrict, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

# if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fprintf_unlocked` except
 * it uses wide characters.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite_unlocked`.
 * 
 * @since  Always.
 */
int fwprintf_unlocked(FILE* restrict, const wchar_t* restrict, ...)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

/**
 * This function is identical to `dprintf` except
 * it uses wide characters.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int dwprintf(int, const wchar_t* restrict, ...)
 __GCC_ONLY(__attribute__((__nonnull__(2))));

/**
 * This function is identical to `sockprintf`
 * except it uses wide characters.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   flags   Flags to pass to `send`, see `send`
 *                  for more information.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int sockwprintf(int, int, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__nonnull__(3))));
# endif

/**
 * This function is identical to `snprintf`
 * (not `sprintf`) except it uses wide characters.
 * 
 * @param   buffer  The output buffer.
 * @param   size    The allocation size of `buffer`.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character, that would have been written
 *                  if `size` was ignored. On error, a negative
 *                  value (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters would have been written; in slibc,
 *                  `INT_MAX` is returned if more would have
 *                  been written, you can use "%zn" to find the
 *                  actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int swprintf(wchar_t* restrict, size_t, const wchar_t* restrict, ...)
 __GCC_ONLY(__attribute__((__nonnull__(3))));

/* TODO plan9 derived: char* sewprintf(wchar_t* start, wchar_t* end, const wchar_t* restrict format, ...)
                    ~= start + swprintf(start, end - start, format, ...)
   TODO plan9 derived: char* smwprintf(const wchar_t* restrict format, ...)
                    ~= aswprintf(&r, format, ...), r;
 */

# if defined(__GNU_SOURCE) && defined(__SLIBC_SOURCE)
/**
 * This function is identical to `aswprintf` except
 * it uses wide characters.
 * 
 * This is a slibc extension added for completeness.
 * This is only available if GNU extensions are enabled.
 * 
 * @param   buffer  Output parameter for the output buffer.
 *                  On error the content of this pointer is undefined.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int aswprintf(wchar_t** restrict, const wchar_t* restrict, ...)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2), __warn_unused_result__)));
# endif

# if defined(__SLIBC_SOURCE)
#  if defined(__GNUC__)
/**
 * This function is identical to `swprintf`,
 * except it allocates a sufficiently large
 * buffer to the stack (using `alloca`.)
 * 
 * This is a slibc extension. It is only available
 * if compiling with GCC.
 * 
 * There is no `vaswprintfa` function.
 * 
 * @param   buffer:char**  Output parameter for the output buffer,
 *                         must not be `NULL`. On error the content
 *                         of this pointer is either `NULL` or a
 *                         pointer to memory allocated with `alloca`.
 * @param   format:char*   The formatting-string, must not have
 *                         side-effects or be `NULL`.
 * @param   ...            The formatting-arguments, must not have
 *                         side-effects.
 * @return  :int           The number of written bytes, excluding
 *                         the NUL byte. On error, a negative value
 *                         (namely -1 in this implementation) is
 *                         returned. It is unspecified what shall
 *                         happen if more than `INT_MAX` non-NUL
 *                         bytes are written; in slibc, `INT_MAX`
 *                         is returned if more is written, you can
 *                         use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
#define aswprintfa(buffer, format, ...)						\
  ({										\
    ssize_t __size;								\
    int __r;									\
    __r = swprintf(NULL, 0, format "%zn", ##__VA_ARGS__, &__size);		\
    if (*buffer = NULL, __size += 1, __r >= 0)					\
      *buffer = __builtin_alloca((size_t)__size * sizeof(wchar_t)),		\
	__r = swprintf(*buffer, (size_t)__size, format, ##__VA_ARGS__);		\
    __r;									\
  })
#  endif

/**
 * This function is identical to `bprintf` except
 * it uses wide characters.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   buffer  Reference parameter for the output buffer.
 *                  It should point to the buffer than shall
 *                  be used, or point to `NULL` if a new buffer
 *                  shall be allocated. It will be updated with
 *                  a new buffer if it points to `NULL`, or the
 *                  new pointer if `buffer` needed to be reallocated.
 *                  On error, this pointer will only have been
 *                  updated if the buffer was reallocated during
 *                  the call; if it pointed to `NULL`, it will
 *                  still point to `NULL`.
 * @param   size    Reference parameter for the buffer size,
 *                  in `wchar_t`.
 *                  It shall point to a variable whose value is
 *                  the allocation size of `*buffer`, or point to
 *                  a variable whose value is zero if `*buffer`
 *                  is `NULL`.
 * @param   offset  The offset in the buffer where the function
 *                  shall start the printing.
 * @param   secure  Non-zero if the function must override the
 *                  buffer with zero before freeing it if it
 *                  creates a new allocation.
 * @param   format  The formatting-string.
 * @param   ...     The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int bwprintf(wchar_t** restrict, size_t* restrict, size_t, int, const wchar_t* restrict, ...)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2, 5), __warn_unused_result__)));
# endif


/**
 * This function is identical to `wprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int vwprintf(const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(1))));

/**
 * This function is identical to `fwprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite`.
 * 
 * @since  Always.
 */
int vfwprintf(FILE* restrict, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

# if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fwprintf_unlocked`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   stream  The output stream.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws          Any error specified for `fwrite_unlocked`.
 * 
 * @since  Always.
 */
int vfwprintf_unlocked(FILE* restrict, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2))));

/**
 * This function is identical to `dwprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` characters are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int vdwprintf(int, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(2))));

/**
 * This function is identical to `sockwprintf`
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   flags   Flags to pass to `send`, see `send`
 *                  for more information.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written bytes.
 *                  On error, a negative value (namely -1
 *                  in this implementation) is returned.
 *                  It is unspecified what shall happen if
 *                  more than `INT_MAX` bytes are written;
 *                  in slibc, `INT_MAX` is returned if more
 *                  is written, you can use "%zn" to find
 *                  the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws           Any error specified for `write`.
 * 
 * @since  Always.
 */
int vsockwprintf(int, int, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__nonnull__(3))));
# endif

/**
 * This function is identical to `swprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * @param   buffer  The output buffer.
 * @param   size    The allocation size of `buffer`.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character, that would have been written
 *                  if `size` was ignored. On error, a negative
 *                  value (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters would have been written; in slibc,
 *                  `INT_MAX` is returned if more would have
 *                  been written, you can use "%zn" to find the
 *                  actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * 
 * @since  Always.
 */
int vswprintf(wchar_t* restrict, size_t, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(3))));

/* TODO plan9 derived: char* vsewprintf(wchar_t* start, wchar_t* end, const wchar_t* restrict format, va_list args)
                    ~= start + vswprintf(start, end - start, format, args)
   TODO plan9 derived: char* vsmwprintf(const wchar_t* restrict format, va_list args)
                    ~= vaswprintf(&r, format, args), r;
 */

# if defined(__GNU_SOURCE) && defined(__SLIBC_SOURCE)
/**
 * This function is identical to `aswprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * This is only available if GNU extensions are enabled.
 * 
 * @param   buffer  Output parameter for the output buffer.
 *                  On error the content of this pointer is undefined.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int vaswprintf(wchar_t** restrict, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2), __warn_unused_result__)));
# endif

# if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `bwprintf`,
 * except it uses `va_list` instead of variadic argument.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   buffer  Reference parameter for the output buffer.
 *                  It should point to the buffer than shall
 *                  be used, or point to `NULL` if a new buffer
 *                  shall be allocated. It will be updated with
 *                  a new buffer if it points to `NULL`, or the
 *                  new pointer if `buffer` needed to be reallocated.
 *                  On error, this pointer will only have been
 *                  updated if the buffer was reallocated during
 *                  the call; if it pointed to `NULL`, it will
 *                  still point to `NULL`.
 * @param   size    Reference parameter for the buffer size,
 *                  in `wchar_t`.
 *                  It shall point to a variable whose value is
 *                  the allocation size of `*buffer`, or point to
 *                  a variable whose value is zero if `*buffer`
 *                  is `NULL`.
 * @param   offset  The offset in the buffer where the function
 *                  shall start the printing.
 * @param   secure  Non-zero if the function must override the
 *                  buffer with zero before freeing it if it
 *                  creates a new allocation.
 * @param   format  The formatting-string.
 * @param   args    The formatting-arguments.
 * @return          The number of written characters, excluding
 *                  the NUL character. On error, a negative value
 *                  (namely -1 in this implementation) is
 *                  returned. It is unspecified what shall
 *                  happen if more than `INT_MAX` non-NUL
 *                  characters are written; in slibc, `INT_MAX`
 *                  is returned if more is written, you can
 *                  use "%zn" to find the actual length.
 * 
 * @throws  EINVAL  `format` contained unsupported formatting codes.
 * @throws  ENOMEM  The process cannot allocation the
 *                  sufficient amount of memory.
 * 
 * @since  Always.
 */
int vbwprintf(wchar_t** restrict, size_t* restrict, size_t, int, const wchar_t* restrict, va_list)
 __GCC_ONLY(__attribute__((__nonnull__(1, 2, 5), __warn_unused_result__)));
# endif
#endif



/**
 * This function is identical to `fscanf` with
 * `stdout` as the first argument.
 * 
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int scanf(const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1), __format__(__slibc_scanf__, 1, 2))));

/**
 * Parse data from from a text stream.
 * 
 * TODO list format rules for fscanf
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int fscanf(FILE* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2), __format__(__slibc_scanf__, 2, 3))));

/**
 * This function is identical to `fscanf`,
 * except it reads from a string rather than
 * a file.
 * 
 * @param   input   The formatted string.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int sscanf(const char* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2), __format__(__slibc_scanf__, 2, 3))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fscanf`,
 * except it does not lock the stream.
 * 
 * This is a slibc extension.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int fscanf_unlocked(FILE* restrict, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2), __format__(__slibc_scanf__, 2, 3))));

/**
 * This function is identical to `scanf`,
 * except it will stop parsing the string
 * after a selected number of bytes, or
 * at the end of the string.
 * 
 * This is a slibc extension.
 * 
 * @param   input   The formatted string.
 * @param   length  The maximum number of bytes to read.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int snscanf(const char* restrict, size_t, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(3), __format__(__slibc_scanf__, 3, 4))));

/**
 * This function is identical to `fscanf`,
 * except it is limited to file descriptor-backed
 * streams, and uses the file descriptor as the
 * first argument rather than the stream.
 * 
 * This is a slibc extension.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int dscanf(int, const char* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(2), __format__(__slibc_scanf__, 2, 3))));
#endif


/**
 * This function is identical to `scanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vscanf(const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `fscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vfscanf(FILE* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `sscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   input   The formatted string.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vsscanf(const char* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fscanf_unlocked`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vfscanf_unlocked(FILE* restrict, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `snscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension.
 * 
 * @param   input   The formatted string.
 * @param   length  The maximum number of bytes to read.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vsnscanf(const char* restrict, size_t, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(3))));

/**
 * This function is identical to `sscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vdscanf(int, const char* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(2))));
#endif


/**
 * This function is identical to `scanf`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int wscanf(const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `fscanf`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int fwscanf(FILE* restrict, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `sscanf`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * @param   input   The formatted string.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int swscanf(const wchar_t* restrict, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fscanf_unlocked`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int fwscanf_unlocked(FILE* restrict, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `snscanf`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   input   The formatted string.
 * @param   length  The maximum number of characters to read.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int snwscanf(const wchar_t* restrict, size_t, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(3))));

/**
 * This function is identical to `dscanf`,
 * except it uses `wchar_t` instead of `char`.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The format of the string.
 * @param   ...     The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int dwscanf(int, const wchar_t* restrict, ...)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(2))));
#endif


/**
 * This function is identical to `wscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vwscanf(const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `fwscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vfwscanf(FILE* restrict, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `swscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * @param   input   The formatted string.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vswscanf(const wchar_t* restrict, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

#if defined(__SLIBC_SOURCE)
/**
 * This function is identical to `fwscanf_unlocked`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   stream  The input stream.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vfwscanf_unlocked(FILE* restrict, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `snwscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   input   The formatted string.
 * @param   length  The maximum number of characters to read.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vsnwscanf(const wchar_t* restrict, size_t, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(3))));

/**
 * This function is identical to `swscanf`,
 * except it uses `va_list` instead of variadic arguments.
 * 
 * This is a slibc extension added for completeness.
 * 
 * @param   fd      The file descriptor.
 * @param   format  The format of the string.
 * @param   args    The output parameter for the encoded values.
 * @return          The number successfully converted argument
 *                  (may be less than specified.) `EOF` is returned
 *                  if the end of the input is reached before the
 *                  first argument is successfully converted, or
 *                  on error.
 * 
 * @since  Always.
 */
int vdwscanf(int, const wchar_t* restrict, va_list)
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(2))));
#endif



#if !defined(__PORTABLE)
/**
 * This function is identical to `scanf`.
 * 
 * @since  Always.
 */
int __isoc99_scanf(const char* restrict, ...)
  __deprecated("Use 'scanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1), __format__(__slibc_scanf__, 1, 2))));

/**
 * This function is identical to `fscanf`.
 * 
 * @since  Always.
 */
int __isoc99_fscanf(FILE* restrict, const char* restrict, ...)
  __deprecated("Use 'fscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2), __format__(__slibc_scanf__, 2, 3))));

/**
 * This function is identical to `sscanf`.
 * 
 * @since  Always.
 */
int __isoc99_sscanf(const char* restrict, const char* restrict, ...)
  __deprecated("Use 'sscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2), __format__(__slibc_scanf__, 2, 3))));


/**
 * This function is identical to `vscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vscanf(const char* restrict, va_list)
  __deprecated("Use 'vscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `vfscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vfscanf(FILE* restrict, const char* restrict, va_list)
  __deprecated("Use 'vfscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `vsscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vsscanf(const char* restrict, const char* restrict, va_list)
  __deprecated("Use 'vsscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));


/**
 * This function is identical to `wscanf`.
 * 
 * @since  Always.
 */
int __isoc99_wscanf(const wchar_t* restrict, ...)
  __deprecated("Use 'wscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `fwscanf`.
 * 
 * @since  Always.
 */
int __isoc99_fwscanf(FILE* restrict, const wchar_t* restrict, ...)
  __deprecated("Use 'fwscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `swscanf`.
 * 
 * @since  Always.
 */
int __isoc99_swscanf(const wchar_t* restrict, const wchar_t* restrict, ...)
  __deprecated("Use 'swscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));


/**
 * This function is identical to `vwscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vwscanf(const wchar_t* restrict, va_list)
  __deprecated("Use 'vwscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1))));

/**
 * This function is identical to `vfwscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vfwscanf(FILE* restrict, const wchar_t* restrict, va_list)
  __deprecated("Use 'vfwscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));

/**
 * This function is identical to `vswscanf`.
 * 
 * @since  Always.
 */
int __isoc99_vswscanf(const wchar_t* restrict, const wchar_t* restrict, va_list)
  __deprecated("Use 'vswscanf' instead.")
  __GCC_ONLY(__attribute__((__warn_unused_result__, __nonnull__(1, 2))));
#endif



#endif

/* TODO wprintf and wscanf belongs in <wchar.h> */