/***************************************************************
  MPU-ERROR.C

       This file contains error-message conversion and
       diagnostic output functions.

       PART OF : MPUIO - library .

       USAGE   : Internal and external .

       NOTE    : libc error messages are converted from the
                 current LC_CTYPE multibyte encoding to strict
                 UCS-2 before LIBMPUIO output.

       Copyright (C) 2000 - 2026  by Andrey V.Kosteltsev.
       All Rights Reserved.
 ***************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <libmpuio.h>
#include <mpu-symbols.h>
#include <mpu-libio.h>


static pthread_mutex_t  __mpu_IO_strerror_lock = PTHREAD_MUTEX_INITIALIZER;


/***************************************************************
  Copy libc's error message for ERRNUM while serializing access
  to implementations whose strerror() storage is not reentrant.
 ***************************************************************/
static char *__mpu_IO_error_message_copy( int errnum )
{
  const char *message;
  char       *copy;
  char        fallback[64];
  size_t      length;

  pthread_mutex_lock( &__mpu_IO_strerror_lock );

  message = strerror( errnum );
  if( message == (const char *)0 )
  {
    (void)snprintf( fallback, sizeof(fallback), "Unknown error %d", errnum );
    message = fallback;
  }

  length = strlen( message );
  copy = (char *)malloc( length + 1 );
  if( copy != (char *)0 )
    memcpy( copy, message, length + 1 );

  pthread_mutex_unlock( &__mpu_IO_strerror_lock );

  return( copy );

} /* End of __mpu_IO_error_message_copy() */


/***************************************************************
  Count strict UCS-2 code units required for the current-locale
  multibyte string SOURCE, excluding the terminating NUL.
 ***************************************************************/
static int __mpu_IO_mbs_ucs2_length( const char *source, size_t *length )
{
  mbstate_t    state;
  const char  *p;
  size_t       count = 0;

  if( source == (const char *)0 || length == (size_t *)0 )
  {
    errno = EINVAL;
    return( -1 );
  }

  memset( &state, 0, sizeof(state) );
  p = source;

  while( *p != '\0' )
  {
    char16_t  wc;
    size_t    n;

    n = mbrtoc16( &wc, p, MB_CUR_MAX, &state );
    if( n == (size_t)-1 || n == (size_t)-2 || n == (size_t)-3 )
    {
      errno = EILSEQ;
      return( -1 );
    }

    if( n == 0 )
      break;

    if( ((unsigned int)wc >= 0xd800U && (unsigned int)wc <= 0xdfffU) ||
        count == SIZE_MAX )
    {
      errno = ((unsigned int)wc >= 0xd800U &&
               (unsigned int)wc <= 0xdfffU) ? EILSEQ : EOVERFLOW;
      return( -1 );
    }

    ++count;
    p += n;
  }

  *length = count;
  return( 0 );

} /* End of __mpu_IO_mbs_ucs2_length() */


/***************************************************************
  Convert SOURCE from the current locale's multibyte encoding to
  strict UCS-2 and terminate DESTINATION with a UCS-2 NUL.
 ***************************************************************/
static int __mpu_IO_mbs_to_ucs2( __mpu_char16_t *destination, size_t size,
                                 const char *source )
{
  mbstate_t    state;
  const char  *p;
  size_t       used = 0;

  if( destination == (__mpu_char16_t *)0 || size == 0 ||
      source == (const char *)0 )
  {
     errno = EINVAL;
     return( -1 );
  }

  memset( &state, 0, sizeof(state) );
  p = source;

  while( *p != '\0' )
  {
    char16_t  wc;
    size_t    n;

    n = mbrtoc16( &wc, p, MB_CUR_MAX, &state );
    if( n == (size_t)-1 || n == (size_t)-2 || n == (size_t)-3 )
    {
      errno = EILSEQ;
      destination[0] = 0;
      return( -1 );
    }

    if( n == 0 )
      break;

    if( (unsigned int)wc >= 0xd800U && (unsigned int)wc <= 0xdfffU )
    {
      errno = EILSEQ;
      destination[0] = 0;
      return( -1 );
    }

    if( used + 1 >= size )
    {
      errno = ERANGE;
      destination[0] = 0;
      return( -1 );
    }

    destination[used++] = (__mpu_char16_t)wc;
    p += n;
  }

  destination[used] = 0;
  return( 0 );

} /* End of __mpu_IO_mbs_to_ucs2() */


/***************************************************************
  Convert the libc diagnostic for ERRNUM into caller-owned UCS-2
  storage.  SIZE is measured in __mpu_char16_t code units.
 ***************************************************************/
int mpu_strerror_r( int errnum, __mpu_char16_t *buffer, size_t size )
{
  char    *message;
  size_t   length;
  int      saved_errno = errno;

  if( buffer == (__mpu_char16_t *)0 || size == 0 )
  {
    errno = EINVAL;
    return( -1 );
  }

  buffer[0] = 0;

  message = __mpu_IO_error_message_copy( errnum );
  if( message == (char *)0 )
  {
    errno = ENOMEM;
    return( -1 );
  }

  if( __mpu_IO_mbs_ucs2_length( message, &length ) < 0 )
  {
    int error = errno;
    free( message );
    errno = error;
    return( -1 );
  }

  if( length == SIZE_MAX || length + 1 > size )
  {
    free( message );
    errno = ERANGE;
    return( -1 );
  }

  if( __mpu_IO_mbs_to_ucs2( buffer, size, message ) < 0 )
  {
    int error = errno;
    free( message );
    errno = error;
    return( -1 );
  }

  free( message );
  errno = saved_errno;
  return( 0 );

} /* End of mpu_strerror_r() */


/***************************************************************
  Print the current errno diagnostic to mpu_stderr.  PREFIX is a
  UCS-2 string; a nonempty prefix is followed by colon and space.
 ***************************************************************/
void mpu_perror( const __mpu_char16_t *prefix )
{
  __mpu_char16_t  stack_buffer[256];
  __mpu_char16_t *message = stack_buffer;
  size_t          size = sizeof(stack_buffer) / sizeof(stack_buffer[0]);
  int             errnum = errno;
  int             error;

  if( mpu_strerror_r( errnum, message, size ) < 0 )
  {
    size_t  capacity = size * 2;

    error = errno;
    while( error == ERANGE && capacity <= 65536U )
    {
      __mpu_char16_t  *tmp = (__mpu_char16_t *)malloc( capacity * sizeof(*tmp) );

      if( tmp == (__mpu_char16_t *)0 )
         break;

      if( mpu_strerror_r( errnum, tmp, capacity ) == 0 )
      {
         message = tmp;
         error = 0;
         break;
      }

      error = errno;
      free( tmp );
      if( capacity > 32768U )
        break;
      capacity *= 2;
    }

    if( error != 0 )
    {
      char  fallback[64];

      (void)snprintf( fallback, sizeof(fallback), "Error %d", errnum );
      for( size = 0; fallback[size] != '\0' && size + 1 < 256; ++size )
        stack_buffer[size] = (__mpu_char16_t)(unsigned char)fallback[size];
      stack_buffer[size] = 0;
      message = stack_buffer;
    }
  }

  mpu_flockfile( mpu_stderr );

  if( prefix != (const __mpu_char16_t *)0 && *prefix != 0 )
  {
    (void)mpu_fputs_unlocked( prefix, mpu_stderr );
    (void)mpu_fputc_unlocked( (__mpu_char16_t)':', mpu_stderr );
    (void)mpu_fputc_unlocked( (__mpu_char16_t)' ', mpu_stderr );
  }

  (void)mpu_fputs_unlocked( message, mpu_stderr );
  (void)mpu_fputc_unlocked( (__mpu_char16_t)'\n', mpu_stderr );

  mpu_funlockfile( mpu_stderr );

  if( message != stack_buffer )
    free( message );

  errno = errnum;
  return;

} /* End of mpu_perror() */


/* End of mpu-error.c */