vasnprintf.c

经典的C语言MP3编码解码实现,可以在linux/unix平台下编译运行.

		      else
# endif
			tmp_length = 1;
		      break;

		    case 's':
# ifdef HAVE_WCHAR_T
		      if (type == TYPE_WIDE_STRING)
			{
			  tmp_length =
			    local_wcslen (a.arg[dp->arg_index].a.a_wide_string);

#  if !WIDE_CHAR_VERSION
			  tmp_length = xtimes (tmp_length, MB_CUR_MAX);
#  endif
			}
		      else
# endif
			tmp_length = strlen (a.arg[dp->arg_index].a.a_string);
		      break;

		    case 'p':
		      tmp_length =
			(unsigned int) (sizeof (void *) * CHAR_BIT
					* 0.25 /* binary -> hexadecimal */
				       )
			  + 1 /* turn floor into ceil */
			  + 2; /* account for leading 0x */
		      break;

		    default:
		      abort ();
		    }

		  if (tmp_length < width)
		    tmp_length = width;

		  tmp_length = xsum (tmp_length, 1); /* account for trailing NUL */
		}

		if (tmp_length <= sizeof (tmpbuf) / sizeof (CHAR_T))
		  tmp = tmpbuf;
		else
		  {
		    size_t tmp_memsize = xtimes (tmp_length, sizeof (CHAR_T));

		    if (size_overflow_p (tmp_memsize))
		      /* Overflow, would lead to out of memory.  */
		      goto out_of_memory;
		    tmp = (CHAR_T *) malloc (tmp_memsize);
		    if (tmp == NULL)
		      /* Out of memory.  */
		      goto out_of_memory;
		  }
#endif

		/* Construct the format string for calling snprintf or
		   sprintf.  */
		p = buf;
		*p++ = '%';
		if (dp->flags & FLAG_GROUP)
		  *p++ = '\'';
		if (dp->flags & FLAG_LEFT)
		  *p++ = '-';
		if (dp->flags & FLAG_SHOWSIGN)
		  *p++ = '+';
		if (dp->flags & FLAG_SPACE)
		  *p++ = ' ';
		if (dp->flags & FLAG_ALT)
		  *p++ = '#';
		if (dp->flags & FLAG_ZERO)
		  *p++ = '0';
		if (dp->width_start != dp->width_end)
		  {
		    size_t n = dp->width_end - dp->width_start;
		    memcpy (p, dp->width_start, n * sizeof (CHAR_T));
		    p += n;
		  }
		if (dp->precision_start != dp->precision_end)
		  {
		    size_t n = dp->precision_end - dp->precision_start;
		    memcpy (p, dp->precision_start, n * sizeof (CHAR_T));
		    p += n;
		  }

		switch (type)
		  {
#ifdef HAVE_LONG_LONG
		  case TYPE_LONGLONGINT:
		  case TYPE_ULONGLONGINT:
		    *p++ = 'l';
		    /*FALLTHROUGH*/
#endif
		  case TYPE_LONGINT:
		  case TYPE_ULONGINT:
#ifdef HAVE_WINT_T
		  case TYPE_WIDE_CHAR:
#endif
#ifdef HAVE_WCHAR_T
		  case TYPE_WIDE_STRING:
#endif
		    *p++ = 'l';
		    break;
#ifdef HAVE_LONG_DOUBLE
		  case TYPE_LONGDOUBLE:
		    *p++ = 'L';
		    break;
#endif
		  default:
		    break;
		  }
		*p = dp->conversion;
#if USE_SNPRINTF
		p[1] = '%';
		p[2] = 'n';
		p[3] = '\0';
#else
		p[1] = '\0';
#endif

		/* Construct the arguments for calling snprintf or sprintf.  */
		prefix_count = 0;
		if (dp->width_arg_index != ARG_NONE)
		  {
		    if (!(a.arg[dp->width_arg_index].type == TYPE_INT))
		      abort ();
		    prefixes[prefix_count++] = a.arg[dp->width_arg_index].a.a_int;
		  }
		if (dp->precision_arg_index != ARG_NONE)
		  {
		    if (!(a.arg[dp->precision_arg_index].type == TYPE_INT))
		      abort ();
		    prefixes[prefix_count++] = a.arg[dp->precision_arg_index].a.a_int;
		  }

#if USE_SNPRINTF
		/* Prepare checking whether snprintf returns the count
		   via %n.  */
		ENSURE_ALLOCATION (xsum (length, 1));
		result[length] = '\0';
#endif

		for (;;)
		  {
		    size_t maxlen;
		    int count;
		    int retcount;

		    maxlen = allocated - length;
		    count = -1;
		    retcount = 0;

#if USE_SNPRINTF
# define SNPRINTF_BUF(arg) \
		    switch (prefix_count)				    \
		      {							    \
		      case 0:						    \
			retcount = SNPRINTF (result + length, maxlen, buf,  \
					     arg, &count);		    \
			break;						    \
		      case 1:						    \
			retcount = SNPRINTF (result + length, maxlen, buf,  \
					     prefixes[0], arg, &count);	    \
			break;						    \
		      case 2:						    \
			retcount = SNPRINTF (result + length, maxlen, buf,  \
					     prefixes[0], prefixes[1], arg, \
					     &count);			    \
			break;						    \
		      default:						    \
			abort ();					    \
		      }
#else
# define SNPRINTF_BUF(arg) \
		    switch (prefix_count)				    \
		      {							    \
		      case 0:						    \
			count = sprintf (tmp, buf, arg);		    \
			break;						    \
		      case 1:						    \
			count = sprintf (tmp, buf, prefixes[0], arg);	    \
			break;						    \
		      case 2:						    \
			count = sprintf (tmp, buf, prefixes[0], prefixes[1],\
					 arg);				    \
			break;						    \
		      default:						    \
			abort ();					    \
		      }
#endif

		    switch (type)
		      {
		      case TYPE_SCHAR:
			{
			  int arg = a.arg[dp->arg_index].a.a_schar;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_UCHAR:
			{
			  unsigned int arg = a.arg[dp->arg_index].a.a_uchar;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_SHORT:
			{
			  int arg = a.arg[dp->arg_index].a.a_short;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_USHORT:
			{
			  unsigned int arg = a.arg[dp->arg_index].a.a_ushort;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_INT:
			{
			  int arg = a.arg[dp->arg_index].a.a_int;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_UINT:
			{
			  unsigned int arg = a.arg[dp->arg_index].a.a_uint;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_LONGINT:
			{
			  long int arg = a.arg[dp->arg_index].a.a_longint;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_ULONGINT:
			{
			  unsigned long int arg = a.arg[dp->arg_index].a.a_ulongint;
			  SNPRINTF_BUF (arg);
			}
			break;
#ifdef HAVE_LONG_LONG
		      case TYPE_LONGLONGINT:
			{
			  long long int arg = a.arg[dp->arg_index].a.a_longlongint;
			  SNPRINTF_BUF (arg);
			}
			break;
		      case TYPE_ULONGLONGINT:
			{
			  unsigned long long int arg = a.arg[dp->arg_index].a.a_ulonglongint;
			  SNPRINTF_BUF (arg);
			}
			break;
#endif
		      case TYPE_DOUBLE:
			{
			  double arg = a.arg[dp->arg_index].a.a_double;
			  SNPRINTF_BUF (arg);
			}
			break;
#ifdef HAVE_LONG_DOUBLE
		      case TYPE_LONGDOUBLE:
			{
			  long double arg = a.arg[dp->arg_index].a.a_longdouble;
			  SNPRINTF_BUF (arg);
			}
			break;
#endif
		      case TYPE_CHAR:
			{
			  int arg = a.arg[dp->arg_index].a.a_char;
			  SNPRINTF_BUF (arg);
			}
			break;
#ifdef HAVE_WINT_T
		      case TYPE_WIDE_CHAR:
			{
			  wint_t arg = a.arg[dp->arg_index].a.a_wide_char;
			  SNPRINTF_BUF (arg);
			}
			break;
#endif
		      case TYPE_STRING:
			{
			  const char *arg = a.arg[dp->arg_index].a.a_string;
			  SNPRINTF_BUF (arg);
			}
			break;
#ifdef HAVE_WCHAR_T
		      case TYPE_WIDE_STRING:
			{
			  const wchar_t *arg = a.arg[dp->arg_index].a.a_wide_string;
			  SNPRINTF_BUF (arg);
			}
			break;
#endif
		      case TYPE_POINTER:
			{
			  void *arg = a.arg[dp->arg_index].a.a_pointer;
			  SNPRINTF_BUF (arg);
			}
			break;
		      default:
			abort ();
		      }

#if USE_SNPRINTF
		    /* Portability: Not all implementations of snprintf()
		       are ISO C 99 compliant.  Determine the number of
		       bytes that snprintf() has produced or would have
		       produced.  */
		    if (count >= 0)
		      {
			/* Verify that snprintf() has NUL-terminated its
			   result.  */
			if (count < maxlen && result[length + count] != '\0')
			  abort ();
			/* Portability hack.  */
			if (retcount > count)
			  count = retcount;
		      }
		    else
		      {
			/* snprintf() doesn't understand the '%n'
			   directive.  */
			if (p[1] != '\0')
			  {
			    /* Don't use the '%n' directive; instead, look
			       at the snprintf() return value.  */
			    p[1] = '\0';
			    continue;
			  }
			else
			  {
			    /* Look at the snprintf() return value.  */
			    if (retcount < 0)
			      {
				/* HP-UX 10.20 snprintf() is doubly deficient:
				   It doesn't understand the '%n' directive,
				   *and* it returns -1 (rather than the length
				   that would have been required) when the
				   buffer is too small.  */
				size_t bigger_need =
				  xsum (xtimes (allocated, 2), 12);
				ENSURE_ALLOCATION (bigger_need);
				continue;
			      }
			    else
			      count = retcount;
			  }
		      }
#endif

		    /* Attempt to handle failure.  */
		    if (count < 0)
		      {
			if (!(result == resultbuf || result == NULL))
			  free (result);
			if (buf_malloced != NULL)
			  free (buf_malloced);
			CLEANUP ();
			errno = EINVAL;
			return NULL;
		      }

#if !USE_SNPRINTF
		    if (count >= tmp_length)
		      /* tmp_length was incorrectly calculated - fix the
			 code above!  */
		      abort ();
#endif

		    /* Make room for the result.  */
		    if (count >= maxlen)
		      {
			/* Need at least count bytes.  But allocate
			   proportionally, to avoid looping eternally if
			   snprintf() reports a too small count.  */
			size_t n =
			  xmax (xsum (length, count), xtimes (allocated, 2));

			ENSURE_ALLOCATION (n);
#if USE_SNPRINTF
			continue;
#endif
		      }

#if USE_SNPRINTF
		    /* The snprintf() result did fit.  */
#else
		    /* Append the sprintf() result.  */
		    memcpy (result + length, tmp, count * sizeof (CHAR_T));
		    if (tmp != tmpbuf)
		      free (tmp);
#endif

		    length += count;
		    break;
		  }
	      }
	  }
      }

    /* Add the final NUL.  */
    ENSURE_ALLOCATION (xsum (length, 1));
    result[length] = '\0';

    if (result != resultbuf && length + 1 < allocated)
      {
	/* Shrink the allocated memory if possible.  */
	CHAR_T *memory;

	memory = (CHAR_T *) realloc (result, (length + 1) * sizeof (CHAR_T));
	if (memory != NULL)
	  result = memory;
      }

    if (buf_malloced != NULL)
      free (buf_malloced);
    CLEANUP ();
    *lengthp = length;
    return result;

  out_of_memory:
    if (!(result == resultbuf || result == NULL))
      free (result);
    if (buf_malloced != NULL)
      free (buf_malloced);
  out_of_memory_1:
    CLEANUP ();
    errno = ENOMEM;
    return NULL;
  }
}

#undef SNPRINTF
#undef USE_SNPRINTF
#undef PRINTF_PARSE
#undef DIRECTIVES
#undef DIRECTIVE
#undef CHAR_T
#undef VASNPRINTF