vsprintf.c

 */
static int format_decode(const char *fmt, struct printf_spec *spec)
{
	const char *start = fmt;

	/* we finished early by reading the field width */
	if (spec->type == FORMAT_TYPE_WIDTH) {
		if (spec->field_width < 0) {
			spec->field_width = -spec->field_width;
			spec->flags |= LEFT;
		}
		spec->type = FORMAT_TYPE_NONE;
		goto precision;
	}

	/* we finished early by reading the precision */
	if (spec->type == FORMAT_TYPE_PRECISION) {
		if (spec->precision < 0)
			spec->precision = 0;

		spec->type = FORMAT_TYPE_NONE;
		goto qualifier;
	}

	/* By default */
	spec->type = FORMAT_TYPE_NONE;

	for (; *fmt ; ++fmt) {
		if (*fmt == '%')
			break;
	}

	/* Return the current non-format string */
	if (fmt != start || !*fmt)
		return fmt - start;

	/* Process flags */
	spec->flags = 0;

	while (1) { /* this also skips first '%' */
		bool found = true;

		++fmt;

		switch (*fmt) {
		case '-': spec->flags |= LEFT;    break;
		case '+': spec->flags |= PLUS;    break;
		case ' ': spec->flags |= SPACE;   break;
		case '#': spec->flags |= SPECIAL; break;
		case '0': spec->flags |= ZEROPAD; break;
		default:  found = false;
		}

		if (!found)
			break;
	}

	/* get field width */
	spec->field_width = -1;

	if (isdigit(*fmt))
		spec->field_width = skip_atoi(&fmt);
	else if (*fmt == '*') {
		/* it's the next argument */
		spec->type = FORMAT_TYPE_WIDTH;
		return ++fmt - start;
	}

precision:
	/* get the precision */
	spec->precision = -1;
	if (*fmt == '.') {
		++fmt;
		if (isdigit(*fmt)) {
			spec->precision = skip_atoi(&fmt);
			if (spec->precision < 0)
				spec->precision = 0;
		} else if (*fmt == '*') {
			/* it's the next argument */
			spec->type = FORMAT_TYPE_PRECISION;
			return ++fmt - start;
		}
	}

qualifier:
	/* get the conversion qualifier */
	spec->qualifier = -1;
	if (*fmt == 'h' || TOLOWER(*fmt) == 'l' ||
	    TOLOWER(*fmt) == 'z' || *fmt == 't') {
		spec->qualifier = *fmt++;
		if (unlikely(spec->qualifier == *fmt)) {
			if (spec->qualifier == 'l') {
				spec->qualifier = 'L';
				++fmt;
			} else if (spec->qualifier == 'h') {
				spec->qualifier = 'H';
				++fmt;
			}
		}
	}

	/* default base */
	spec->base = 10;
	switch (*fmt) {
	case 'c':
		spec->type = FORMAT_TYPE_CHAR;
		return ++fmt - start;

	case 's':
		spec->type = FORMAT_TYPE_STR;
		return ++fmt - start;

	case 'p':
		spec->type = FORMAT_TYPE_PTR;
		return fmt - start;
		/* skip alnum */

	case 'n':
		spec->type = FORMAT_TYPE_NRCHARS;
		return ++fmt - start;

	case '%':
		spec->type = FORMAT_TYPE_PERCENT_CHAR;
		return ++fmt - start;

	/* integer number formats - set up the flags and "break" */
	case 'o':
		spec->base = 8;
		break;

	case 'x':
		spec->flags |= SMALL;

	case 'X':
		spec->base = 16;
		break;

	case 'd':
	case 'i':
		spec->flags |= SIGN;
	case 'u':
		break;

	default:
		spec->type = FORMAT_TYPE_INVALID;
		return fmt - start;
	}

	if (spec->qualifier == 'L')
		spec->type = FORMAT_TYPE_LONG_LONG;
	else if (spec->qualifier == 'l') {
		if (spec->flags & SIGN)
			spec->type = FORMAT_TYPE_LONG;
		else
			spec->type = FORMAT_TYPE_ULONG;
	} else if (TOLOWER(spec->qualifier) == 'z') {
		spec->type = FORMAT_TYPE_SIZE_T;
	} else if (spec->qualifier == 't') {
		spec->type = FORMAT_TYPE_PTRDIFF;
	} else if (spec->qualifier == 'H') {
		if (spec->flags & SIGN)
			spec->type = FORMAT_TYPE_BYTE;
		else
			spec->type = FORMAT_TYPE_UBYTE;
	} else if (spec->qualifier == 'h') {
		if (spec->flags & SIGN)
			spec->type = FORMAT_TYPE_SHORT;
		else
			spec->type = FORMAT_TYPE_USHORT;
	} else {
		if (spec->flags & SIGN)
			spec->type = FORMAT_TYPE_INT;
		else
			spec->type = FORMAT_TYPE_UINT;
	}

	return ++fmt - start;
}

/**
 * vsnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * This function follows C99 vsnprintf, but has some extensions:
 * %pS output the name of a text symbol with offset
 * %ps output the name of a text symbol without offset
 * %pF output the name of a function pointer with its offset
 * %pf output the name of a function pointer without its offset
 * %pR output the address range in a struct resource with decoded flags
 * %pr output the address range in a struct resource with raw flags
 * %pM output a 6-byte MAC address with colons
 * %pm output a 6-byte MAC address without colons
 * %pI4 print an IPv4 address without leading zeros
 * %pi4 print an IPv4 address with leading zeros
 * %pI6 print an IPv6 address with colons
 * %pi6 print an IPv6 address without colons
 * %pI6c print an IPv6 address as specified by
 *   http://www.ietf.org/id/draft-kawamura-ipv6-text-representation-03.txt
 * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
 *   case.
 * %n is ignored
 *
 * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99. If you want to have the exact
 * number of characters written into @buf as return value
 * (not including the trailing '\0'), use vscnprintf(). If the
 * return is greater than or equal to @size, the resulting
 * string is truncated.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want snprintf() instead.
 */
int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	unsigned long long num;
	char *str, *end;
	struct printf_spec spec = {0};

	/* Reject out-of-range values early.  Large positive sizes are
	   used for unknown buffer sizes. */
	if (WARN_ON_ONCE((int) size < 0))
		return 0;

	str = buf;
	end = buf + size;

	/* Make sure end is always >= buf */
	if (end < buf) {
		end = ((void *)-1);
		size = end - buf;
	}

	while (*fmt) {
		const char *old_fmt = fmt;
		int read = format_decode(fmt, &spec);

		fmt += read;

		switch (spec.type) {
		case FORMAT_TYPE_NONE: {
			int copy = read;
			if (str < end) {
				if (copy > end - str)
					copy = end - str;
				memcpy(str, old_fmt, copy);
			}
			str += read;
			break;
		}

		case FORMAT_TYPE_WIDTH:
			spec.field_width = va_arg(args, int);
			break;

		case FORMAT_TYPE_PRECISION:
			spec.precision = va_arg(args, int);
			break;

		case FORMAT_TYPE_CHAR: {
			char c;

			if (!(spec.flags & LEFT)) {
				while (--spec.field_width > 0) {
					if (str < end)
						*str = ' ';
					++str;

				}
			}
			c = (unsigned char) va_arg(args, int);
			if (str < end)
				*str = c;
			++str;
			while (--spec.field_width > 0) {
				if (str < end)
					*str = ' ';
				++str;
			}
			break;
		}

		case FORMAT_TYPE_STR:
			str = string(str, end, va_arg(args, char *), spec);
			break;

		case FORMAT_TYPE_PTR:
			str = pointer(fmt+1, str, end, va_arg(args, void *),
				      spec);
			while (isalnum(*fmt))
				fmt++;
			break;

		case FORMAT_TYPE_PERCENT_CHAR:
			if (str < end)
				*str = '%';
			++str;
			break;

		case FORMAT_TYPE_INVALID:
			if (str < end)
				*str = '%';
			++str;
			break;

		case FORMAT_TYPE_NRCHARS: {
			int qualifier = spec.qualifier;

			if (qualifier == 'l') {
				long *ip = va_arg(args, long *);
				*ip = (str - buf);
			} else if (TOLOWER(qualifier) == 'z') {
				size_t *ip = va_arg(args, size_t *);
				*ip = (str - buf);
			} else {
				int *ip = va_arg(args, int *);
				*ip = (str - buf);
			}
			break;
		}

		default:
			switch (spec.type) {
			case FORMAT_TYPE_LONG_LONG:
				num = va_arg(args, long long);
				break;
			case FORMAT_TYPE_ULONG:
				num = va_arg(args, unsigned long);
				break;
			case FORMAT_TYPE_LONG:
				num = va_arg(args, long);
				break;
			case FORMAT_TYPE_SIZE_T:
				num = va_arg(args, size_t);
				break;
			case FORMAT_TYPE_PTRDIFF:
				num = va_arg(args, ptrdiff_t);
				break;
			case FORMAT_TYPE_UBYTE:
				num = (unsigned char) va_arg(args, int);
				break;
			case FORMAT_TYPE_BYTE:
				num = (signed char) va_arg(args, int);
				break;
			case FORMAT_TYPE_USHORT:
				num = (unsigned short) va_arg(args, int);
				break;
			case FORMAT_TYPE_SHORT:
				num = (short) va_arg(args, int);
				break;
			case FORMAT_TYPE_INT:
				num = (int) va_arg(args, int);
				break;
			default:
				num = va_arg(args, unsigned int);
			}

			str = number(str, end, num, spec);
		}
	}

	if (size > 0) {
		if (str < end)
			*str = '\0';
		else
			end[-1] = '\0';
	}

	/* the trailing null byte doesn't count towards the total */
	return str-buf;

}
EXPORT_SYMBOL(vsnprintf);

/**
 * vscnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The return value is the number of characters which have been written into
 * the @buf not including the trailing '\0'. If @size is <= 0 the function
 * returns 0.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want scnprintf() instead.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
	int i;

	i = vsnprintf(buf, size, fmt, args);

	return (i >= size) ? (size - 1) : i;
}
EXPORT_SYMBOL(vscnprintf);

/**
 * snprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters which would be
 * generated for the given input, excluding the trailing null,
 * as per ISO C99.  If the return is greater than or equal to
 * @size, the resulting string is truncated.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int snprintf(char *buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	i = vsnprintf(buf, size, fmt, args);
	va_end(args);

	return i;
}
EXPORT_SYMBOL(snprintf);

/**
 * scnprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The return value is the number of characters written into @buf not including
 * the trailing '\0'. If @size is <= 0 the function returns 0.
 */

int scnprintf(char *buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	i = vsnprintf(buf, size, fmt, args);
	va_end(args);

	return (i >= size) ? (size - 1) : i;
}
EXPORT_SYMBOL(scnprintf);

/**
 * vsprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use vsnprintf() or vscnprintf() in order to avoid
 * buffer overflows.
 *
 * Call this function if you are already dealing with a va_list.
 * You probably want sprintf() instead.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int vsprintf(char *buf, const char *fmt, va_list args)
{
	return vsnprintf(buf, INT_MAX, fmt, args);
}
EXPORT_SYMBOL(vsprintf);

/**
 * sprintf - Format a string and place it in a buffer
 * @buf: The buffer to place the result into
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of characters written
 * into @buf. Use snprintf() or scnprintf() in order to avoid
 * buffer overflows.
 *
 * See the vsnprintf() documentation for format string extensions over C99.
 */
int sprintf(char *buf, const char *fmt, ...)
{
	va_list args;
	int i;

	va_start(args, fmt);
	i = vsnprintf(buf, INT_MAX, fmt, args);
	va_end(args);

	return i;
}
EXPORT_SYMBOL(sprintf);

#ifdef CONFIG_BINARY_PRINTF
/*
 * bprintf service:
 * vbin_printf() - VA arguments to binary data
 * bstr_printf() - Binary data to text string
 */

/**
 * vbin_printf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @args: Arguments for the format string
 *
 * The format follows C99 vsnprintf, except %n is ignored, and its argument
 * is skiped.
 *
 * The return value is the number of words(32bits) which would be generated for
 * the given input.
 *
 * NOTE:
 * If the return value is greater than @size, the resulting bin_buf is NOT
 * valid for bstr_printf().
 */
int vbin_printf(u32 *bin_buf, size_t size, const char *fmt, va_list args)
{
	struct printf_spec spec = {0};
	char *str, *end;

	str = (char *)bin_buf;
	end = (char *)(bin_buf + size);

#define save_arg(type)							\
do {									\
	if (sizeof(type) == 8) {					\
		unsigned long long value;				\
		str = PTR_ALIGN(str, sizeof(u32));			\
		value = va_arg(args, unsigned long long);		\
		if (str + sizeof(type) <= end) {			\
			*(u32 *)str = *(u32 *)&value;			\
			*(u32 *)(str + 4) = *((u32 *)&value + 1);	\
		}							\
	} else {							\
		unsigned long value;					\
		str = PTR_ALIGN(str, sizeof(type));			\
		value = va_arg(args, int);				\
		if (str + sizeof(type) <= end)				\
			*(typeof(type) *)str = (type)value;		\
	}								\
	str += sizeof(type);						\
} while (0)

	while (*fmt) {
		int read = format_decode(fmt, &spec);

		fmt += read;

		switch (spec.type) {
		case FORMAT_TYPE_NONE:
		case FORMAT_TYPE_INVALID:
		case FORMAT_TYPE_PERCENT_CHAR:
			break;

		case FORMAT_TYPE_WIDTH:
		case FORMAT_TYPE_PRECISION:
			save_arg(int);
			break;

		case FORMAT_TYPE_CHAR:
			save_arg(char);
			break;

		case FORMAT_TYPE_STR: {
			const char *save_str = va_arg(args, char *);
			size_t len;

			if ((unsigned long)save_str > (unsigned long)-PAGE_SIZE
					|| (unsigned long)save_str < PAGE_SIZE)
				save_str = "(null)";
			len = strlen(save_str) + 1;
			if (str + len < end)
				memcpy(str, save_str, len);
			str += len;
			break;
		}

		case FORMAT_TYPE_PTR:
			save_arg(void *);
			/* skip all alphanumeric pointer suffixes */
			while (isalnum(*fmt))
				fmt++;
			break;

		case FORMAT_TYPE_NRCHARS: {
			/* skip %n 's argument */
			int qualifier = spec.qualifier;
			void *skip_arg;
			if (qualifier == 'l')
				skip_arg = va_arg(args, long *);
			else if (TOLOWER(qualifier) == 'z')
				skip_arg = va_arg(args, size_t *);
			else
				skip_arg = va_arg(args, int *);
			break;
		}

		default:
			switch (spec.type) {

			case FORMAT_TYPE_LONG_LONG:
				save_arg(long long);
				break;
			case FORMAT_TYPE_ULONG:
			case FORMAT_TYPE_LONG:
				save_arg(unsigned long);
				break;
			case FORMAT_TYPE_SIZE_T:
				save_arg(size_t);
				break;
			case FORMAT_TYPE_PTRDIFF:
				save_arg(ptrdiff_t);
				break;
			case FORMAT_TYPE_UBYTE:
			case FORMAT_TYPE_BYTE:
				save_arg(char);
				break;
			case FORMAT_TYPE_USHORT:
			case FORMAT_TYPE_SHORT:
				save_arg(short);
				break;
			default:
				save_arg(int);
			}
		}
	}

	return (u32 *)(PTR_ALIGN(str, sizeof(u32))) - bin_buf;
#undef save_arg
}
EXPORT_SYMBOL_GPL(vbin_printf);

/**
 * bstr_printf - Format a string from binary arguments and place it in a buffer
 * @buf: The buffer to place the result into
 * @size: The size of the buffer, including the trailing null space
 * @fmt: The format string to use
 * @bin_buf: Binary arguments for the format string
 *
 * This function like C99 vsnprintf, but the difference is that vsnprintf gets
 * arguments from stack, and bstr_printf gets arguments from @bin_buf which is
 * a binary buffer that generated by vbin_printf.
 *
 * The format follows C99 vsnprintf, but has some extensions:
 *  see vsnprintf comment for details.
 *
 * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99. If you want to have the exact
 * number of characters written into @buf as return value
 * (not including the trailing '\0'), use vscnprintf(). If the
 * return is greater than or equal to @size, the resulting
 * string is truncated.
 */
int bstr_printf(char *buf, size_t size, const char *fmt, const u32 *bin_buf)
{
	struct printf_spec spec = {0};
	char *str, *end;
	const char *args = (const char *)bin_buf;

	if (WARN_ON_ONCE((int) size < 0))
		return 0;

	str = buf;
	end = buf + size;

#define get_arg(type)							\
({									\
	typeof(type) value;						\
	if (sizeof(type) == 8) {					\
		args = PTR_ALIGN(args, sizeof(u32));			\
		*(u32 *)&value = *(u32 *)args;				\
		*((u32 *)&value + 1) = *(u32 *)(args + 4);		\
	} else {							\
		args = PTR_ALIGN(args, sizeof(type));			\
		value = *(typeof(type) *)args;				\
	}								\
	args += sizeof(type);						\
	value;								\
})

	/* Make sure end is always >= buf */
	if (end < buf) {
		end = ((void *)-1);
		size = end - buf;
	}

	while (*fmt) {
		const char *old_fmt = fmt;
		int read = format_decode(fmt, &spec);

		fmt += read;

		switch (spec.type) {
		case FORMAT_TYPE_NONE: {
			int copy = read;
			if (str < end) {
				if (copy > end - str)
					copy = end - str;
				memcpy(str, old_fmt, copy);
			}
			str += read;
			break;
		}

		case FORMAT_TYPE_WIDTH:
			spec.field_width = get_arg(int);
			break;

		case FORMAT_TYPE_PRECISION:
			spec.precision = get_arg(int);
			break;

		case FORMAT_TYPE_CHAR: {
			char c;

			if (!(spec.flags & LEFT)) {
				while (--spec.field_width > 0) {
					if (str < end)
						*str = ' ';
					++str;
				}
			}
			c = (unsigned char) get_arg(char);
			if (str < end)
				*str = c;
			++str;
			while (--spec.field_width > 0) {
				if (str < end)
					*str = ' ';
				++str;
			}
			break;
		}

		case FORMAT_TYPE_STR: {
			const char *str_arg = args;
			args += strlen(str_arg) + 1;
			str = string(str, end, (char *)str_arg, spec);
			break;
		}

		case FORMAT_TYPE_PTR:
			str = pointer(fmt+1, str, end, get_arg(void *), spec);
			while (isalnum(*fmt))
				fmt++;
			break;

		case FORMAT_TYPE_PERCENT_CHAR:
		case FORMAT_TYPE_INVALID:
			if (str < end)
				*str = '%';
			++str;
			break;

		case FORMAT_TYPE_NRCHARS:
			/* skip */
			break;

		default: {
			unsigned long long num;

			switch (spec.type) {

			case FORMAT_TYPE_LONG_LONG:
				num = get_arg(long long);
				break;
			case FORMAT_TYPE_ULONG:
			case FORMAT_TYPE_LONG:
				num = get_arg(unsigned long);
				break;
			case FORMAT_TYPE_SIZE_T:
				num = get_arg(size_t);
				break;
			case FORMAT_TYPE_PTRDIFF:
				num = get_arg(ptrdiff_t);
				break;
			case FORMAT_TYPE_UBYTE:
				num = get_arg(unsigned char);
				break;
			case FORMAT_TYPE_BYTE:
				num = get_arg(signed char);
				break;
			case FORMAT_TYPE_USHORT:
				num = get_arg(unsigned short);
				break;
			case FORMAT_TYPE_SHORT:
				num = get_arg(short);
				break;
			case FORMAT_TYPE_UINT:
				num = get_arg(unsigned int);
				break;
			default:
				num = get_arg(int);
			}

			str = number(str, end, num, spec);
		} /* default: */
		} /* switch(spec.type) */
	} /* while(*fmt) */

	if (size > 0) {
		if (str < end)
			*str = '\0';
		else
			end[-1] = '\0';
	}

#undef get_arg

	/* the trailing null byte doesn't count towards the total */
	return str - buf;
}
EXPORT_SYMBOL_GPL(bstr_printf);

/**
 * bprintf - Parse a format string and place args' binary value in a buffer
 * @bin_buf: The buffer to place args' binary value
 * @size: The size of the buffer(by words(32bits), not characters)
 * @fmt: The format string to use
 * @...: Arguments for the format string
 *
 * The function returns the number of words(u32) written
 * into @bin_buf.
 */
int bprintf(u32 *bin_buf, size_t size, const char *fmt, ...)
{
	va_list args;
	int ret;

	va_start(args, fmt);
	ret = vbin_printf(bin_buf, size, fmt, args);
	va_end(args);

	return ret;
}
EXPORT_SYMBOL_GPL(bprintf);

#endif /* CONFIG_BINARY_PRINTF */

/**
 * vsscanf - Unformat a buffer into a list of arguments
 * @buf:	input buffer
 * @fmt:	format of buffer
 * @args:	arguments
 */
int vsscanf(const char *buf, const char *fmt, va_list args)
{
	const char *str = buf;
	char *next;
	char digit;
	int num = 0;
	int qualifier, base, field_width;
	bool is_sign;

	while (*fmt && *str) {
		/* skip any white space in format */
		/* white space in format matchs any amount of
		 * white space, including none, in the input.
		 */
		if (isspace(*fmt)) {
			fmt = skip_spaces(++fmt);
			str = skip_spaces(str);
		}

		/* anything that is not a conversion must match exactly */
		if (*fmt != '%' && *fmt) {
			if (*fmt++ != *str++)
				break;
			continue;
		}

		if (!*fmt)
			break;
		++fmt;

		/* skip this conversion.
		 * advance both strings to next white space
		 */
		if (*fmt == '*') {
			while (!isspace(*fmt) && *fmt != '%' && *fmt)
				fmt++;
			while (!isspace(*str) && *str)
				str++;
			continue;
		}

		/* get field width */
		field_width = -1;
		if (isdigit(*fmt))
			field_width = skip_atoi(&fmt);

		/* get conversion qualifier */
		qualifier = -1;
		if (*fmt == 'h' || TOLOWER(*fmt) == 'l' ||
		    TOLOWER(*fmt) == 'z') {
			qualifier = *fmt++;
			if (unlikely(qualifier == *fmt)) {
				if (qualifier == 'h') {
					qualifier = 'H';
					fmt++;
				} else if (qualifier == 'l') {
					qualifier = 'L';
					fmt++;
				}
			}
		}

		if (!*fmt || !*str)
			break;

		base = 10;
		is_sign = 0;

		switch (*fmt++) {
		case 'c':
		{
			char *s = (char *)va_arg(args, char*);
			if (field_width == -1)
				field_width = 1;
			do {
				*s++ = *str++;
			} while (--field_width > 0 && *str);
			num++;
		}
		continue;
		case 's':
		{
			char *s = (char *)va_arg(args, char *);
			if (field_width == -1)
				field_width = INT_MAX;
			/* first, skip leading white space in buffer */
			str = skip_spaces(str);

			/* now copy until next white space */
			while (*str && !isspace(*str) && field_width--)
				*s++ = *str++;
			*s = '\0';
			num++;
		}
		continue;
		case 'n':
			/* return number of characters read so far */
		{
			int *i = (int *)va_arg(args, int*);
			*i = str - buf;
		}
		continue;
		case 'o':
			base = 8;
			break;
		case 'x':
		case 'X':
			base = 16;
			break;
		case 'i':
			base = 0;
		case 'd':
			is_sign = 1;
		case 'u':
			break;
		case '%':
			/* looking for '%' in str */
			if (*str++ != '%')
				return num;
			continue;
		default:
			/* invalid format; stop here */
			return num;
		}

		/* have some sort of integer conversion.
		 * first, skip white space in buffer.
		 */
		str = skip_spaces(str);

		digit = *str;
		if (is_sign && digit == '-')
			digit = *(str + 1);

		if (!digit
		    || (base == 16 && !isxdigit(digit))
		    || (base == 10 && !isdigit(digit))
		    || (base == 8 && (!isdigit(digit) || digit > '7'))
		    || (base == 0 && !isdigit(digit)))
			break;

		switch (qualifier) {
		case 'H':	/* that's 'hh' in format */
			if (is_sign) {
				signed char *s = (signed char *)va_arg(args, signed char *);