vsprintf.c

		}
	}
	if (longest == 1)		/* don't compress a single 0 */
		colonpos = -1;

	/* emit address */
	for (i = 0; i < range; i++) {
		if (i == colonpos) {
			if (needcolon || i == 0)
				*p++ = ':';
			*p++ = ':';
			needcolon = false;
			i += longest - 1;
			continue;
		}
		if (needcolon) {
			*p++ = ':';
			needcolon = false;
		}
		/* hex u16 without leading 0s */
		word = ntohs(in6.s6_addr16[i]);
		hi = word >> 8;
		lo = word & 0xff;
		if (hi) {
			if (hi > 0x0f)
				p = hex_byte_pack(p, hi);
			else
				*p++ = hex_asc_lo(hi);
			p = hex_byte_pack(p, lo);
		}
		else if (lo > 0x0f)
			p = hex_byte_pack(p, lo);
		else
			*p++ = hex_asc_lo(lo);
		needcolon = true;
	}

	if (useIPv4) {
		if (needcolon)
			*p++ = ':';
		p = ip4_string(p, &in6.s6_addr[12], "I4");
	}
	*p = '\0';

	return p;
}

static noinline_for_stack
char *ip6_string(char *p, const char *addr, const char *fmt)
{
	int i;

	for (i = 0; i < 8; i++) {
		p = hex_byte_pack(p, *addr++);
		p = hex_byte_pack(p, *addr++);
		if (fmt[0] == 'I' && i != 7)
			*p++ = ':';
	}
	*p = '\0';

	return p;
}

static noinline_for_stack
char *ip6_addr_string(char *buf, char *end, const u8 *addr,
		      struct printf_spec spec, const char *fmt)
{
	char ip6_addr[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255")];

	if (fmt[0] == 'I' && fmt[2] == 'c')
		ip6_compressed_string(ip6_addr, addr);
	else
		ip6_string(ip6_addr, addr, fmt);

	return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string(char *buf, char *end, const u8 *addr,
		      struct printf_spec spec, const char *fmt)
{
	char ip4_addr[sizeof("255.255.255.255")];

	ip4_string(ip4_addr, addr, fmt);

	return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa,
			 struct printf_spec spec, const char *fmt)
{
	bool have_p = false, have_s = false, have_f = false, have_c = false;
	char ip6_addr[sizeof("[xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255]") +
		      sizeof(":12345") + sizeof("/123456789") +
		      sizeof("%1234567890")];
	char *p = ip6_addr, *pend = ip6_addr + sizeof(ip6_addr);
	const u8 *addr = (const u8 *) &sa->sin6_addr;
	char fmt6[2] = { fmt[0], '6' };
	u8 off = 0;

	fmt++;
	while (isalpha(*++fmt)) {
		switch (*fmt) {
		case 'p':
			have_p = true;
			break;
		case 'f':
			have_f = true;
			break;
		case 's':
			have_s = true;
			break;
		case 'c':
			have_c = true;
			break;
		}
	}

	if (have_p || have_s || have_f) {
		*p = '[';
		off = 1;
	}

	if (fmt6[0] == 'I' && have_c)
		p = ip6_compressed_string(ip6_addr + off, addr);
	else
		p = ip6_string(ip6_addr + off, addr, fmt6);

	if (have_p || have_s || have_f)
		*p++ = ']';

	if (have_p) {
		*p++ = ':';
		p = number(p, pend, ntohs(sa->sin6_port), spec);
	}
	if (have_f) {
		*p++ = '/';
		p = number(p, pend, ntohl(sa->sin6_flowinfo &
					  IPV6_FLOWINFO_MASK), spec);
	}
	if (have_s) {
		*p++ = '%';
		p = number(p, pend, sa->sin6_scope_id, spec);
	}
	*p = '\0';

	return string(buf, end, ip6_addr, spec);
}

static noinline_for_stack
char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa,
			 struct printf_spec spec, const char *fmt)
{
	bool have_p = false;
	char *p, ip4_addr[sizeof("255.255.255.255") + sizeof(":12345")];
	char *pend = ip4_addr + sizeof(ip4_addr);
	const u8 *addr = (const u8 *) &sa->sin_addr.s_addr;
	char fmt4[3] = { fmt[0], '4', 0 };

	fmt++;
	while (isalpha(*++fmt)) {
		switch (*fmt) {
		case 'p':
			have_p = true;
			break;
		case 'h':
		case 'l':
		case 'n':
		case 'b':
			fmt4[2] = *fmt;
			break;
		}
	}

	p = ip4_string(ip4_addr, addr, fmt4);
	if (have_p) {
		*p++ = ':';
		p = number(p, pend, ntohs(sa->sin_port), spec);
	}
	*p = '\0';

	return string(buf, end, ip4_addr, spec);
}

static noinline_for_stack
char *escaped_string(char *buf, char *end, u8 *addr, struct printf_spec spec,
		     const char *fmt)
{
	bool found = true;
	int count = 1;
	unsigned int flags = 0;
	int len;

	if (spec.field_width == 0)
		return buf;				/* nothing to print */

	if (ZERO_OR_NULL_PTR(addr))
		return string(buf, end, NULL, spec);	/* NULL pointer */


	do {
		switch (fmt[count++]) {
		case 'a':
			flags |= ESCAPE_ANY;
			break;
		case 'c':
			flags |= ESCAPE_SPECIAL;
			break;
		case 'h':
			flags |= ESCAPE_HEX;
			break;
		case 'n':
			flags |= ESCAPE_NULL;
			break;
		case 'o':
			flags |= ESCAPE_OCTAL;
			break;
		case 'p':
			flags |= ESCAPE_NP;
			break;
		case 's':
			flags |= ESCAPE_SPACE;
			break;
		default:
			found = false;
			break;
		}
	} while (found);

	if (!flags)
		flags = ESCAPE_ANY_NP;

	len = spec.field_width < 0 ? 1 : spec.field_width;

	/* Ignore the error. We print as many characters as we can */
	string_escape_mem(addr, len, &buf, end - buf, flags, NULL);

	return buf;
}

static noinline_for_stack
char *uuid_string(char *buf, char *end, const u8 *addr,
		  struct printf_spec spec, const char *fmt)
{
	char uuid[sizeof("xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx")];
	char *p = uuid;
	int i;
	static const u8 be[16] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
	static const u8 le[16] = {3,2,1,0,5,4,7,6,8,9,10,11,12,13,14,15};
	const u8 *index = be;
	bool uc = false;

	switch (*(++fmt)) {
	case 'L':
		uc = true;		/* fall-through */
	case 'l':
		index = le;
		break;
	case 'B':
		uc = true;
		break;
	}

	for (i = 0; i < 16; i++) {
		p = hex_byte_pack(p, addr[index[i]]);
		switch (i) {
		case 3:
		case 5:
		case 7:
		case 9:
			*p++ = '-';
			break;
		}
	}

	*p = 0;

	if (uc) {
		p = uuid;
		do {
			*p = toupper(*p);
		} while (*(++p));
	}

	return string(buf, end, uuid, spec);
}

static
char *netdev_feature_string(char *buf, char *end, const u8 *addr,
		      struct printf_spec spec)
{
	spec.flags |= SPECIAL | SMALL | ZEROPAD;
	if (spec.field_width == -1)
		spec.field_width = 2 + 2 * sizeof(netdev_features_t);
	spec.base = 16;

	return number(buf, end, *(const netdev_features_t *)addr, spec);
}

static noinline_for_stack
char *address_val(char *buf, char *end, const void *addr,
		  struct printf_spec spec, const char *fmt)
{
	unsigned long long num;

	spec.flags |= SPECIAL | SMALL | ZEROPAD;
	spec.base = 16;

	switch (fmt[1]) {
	case 'd':
		num = *(const dma_addr_t *)addr;
		spec.field_width = sizeof(dma_addr_t) * 2 + 2;
		break;
	case 'p':
	default:
		num = *(const phys_addr_t *)addr;
		spec.field_width = sizeof(phys_addr_t) * 2 + 2;
		break;
	}

	return number(buf, end, num, spec);
}

int kptr_restrict __read_mostly;

/*
 * Show a '%p' thing.  A kernel extension is that the '%p' is followed
 * by an extra set of alphanumeric characters that are extended format
 * specifiers.
 *
 * Right now we handle:
 *
 * - 'F' For symbolic function descriptor pointers with offset
 * - 'f' For simple symbolic function names without offset
 * - 'S' For symbolic direct pointers with offset
 * - 's' For symbolic direct pointers without offset
 * - '[FfSs]R' as above with __builtin_extract_return_addr() translation
 * - 'B' For backtraced symbolic direct pointers with offset
 * - 'R' For decoded struct resource, e.g., [mem 0x0-0x1f 64bit pref]
 * - 'r' For raw struct resource, e.g., [mem 0x0-0x1f flags 0x201]
 * - 'b[l]' For a bitmap, the number of bits is determined by the field
 *       width which must be explicitly specified either as part of the
 *       format string '%32b[l]' or through '%*b[l]', [l] selects
 *       range-list format instead of hex format
 * - 'M' For a 6-byte MAC address, it prints the address in the
 *       usual colon-separated hex notation
 * - 'm' For a 6-byte MAC address, it prints the hex address without colons
 * - 'MF' For a 6-byte MAC FDDI address, it prints the address
 *       with a dash-separated hex notation
 * - '[mM]R' For a 6-byte MAC address, Reverse order (Bluetooth)
 * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
 *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
 *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - 'i' [46] for 'raw' IPv4/IPv6 addresses
 *       IPv6 omits the colons (01020304...0f)
 *       IPv4 uses dot-separated decimal with leading 0's (010.123.045.006)
 *       [S][pfs]
 *       Generic IPv4/IPv6 address (struct sockaddr *) that falls back to
 *       [4] or [6] and is able to print port [p], flowinfo [f], scope [s]
 * - '[Ii][4S][hnbl]' IPv4 addresses in host, network, big or little endian order
 * - 'I[6S]c' for IPv6 addresses printed as specified by
 *       http://tools.ietf.org/html/rfc5952
 * - 'E[achnops]' For an escaped buffer, where rules are defined by combination
 *                of the following flags (see string_escape_mem() for the
 *                details):
 *                  a - ESCAPE_ANY
 *                  c - ESCAPE_SPECIAL
 *                  h - ESCAPE_HEX
 *                  n - ESCAPE_NULL
 *                  o - ESCAPE_OCTAL
 *                  p - ESCAPE_NP
 *                  s - ESCAPE_SPACE
 *                By default ESCAPE_ANY_NP is used.
 * - 'U' For a 16 byte UUID/GUID, it prints the UUID/GUID in the form
 *       "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx"
 *       Options for %pU are:
 *         b big endian lower case hex (default)
 *         B big endian UPPER case hex
 *         l little endian lower case hex
 *         L little endian UPPER case hex
 *           big endian output byte order is:
 *             [0][1][2][3]-[4][5]-[6][7]-[8][9]-[10][11][12][13][14][15]
 *           little endian output byte order is:
 *             [3][2][1][0]-[5][4]-[7][6]-[8][9]-[10][11][12][13][14][15]
 * - 'V' For a struct va_format which contains a format string * and va_list *,
 *       call vsnprintf(->format, *->va_list).
 *       Implements a "recursive vsnprintf".
 *       Do not use this feature without some mechanism to verify the
 *       correctness of the format string and va_list arguments.
 * - 'K' For a kernel pointer that should be hidden from unprivileged users
 * - 'NF' For a netdev_features_t
 * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
 *            a certain separator (' ' by default):
 *              C colon
 *              D dash
 *              N no separator
 *            The maximum supported length is 64 bytes of the input. Consider
 *            to use print_hex_dump() for the larger input.
 * - 'a[pd]' For address types [p] phys_addr_t, [d] dma_addr_t and derivatives
 *           (default assumed to be phys_addr_t, passed by reference)
 * - 'd[234]' For a dentry name (optionally 2-4 last components)
 * - 'D[234]' Same as 'd' but for a struct file
 *
 * Note: The difference between 'S' and 'F' is that on ia64 and ppc64
 * function pointers are really function descriptors, which contain a
 * pointer to the real address.
 */
static noinline_for_stack
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
	      struct printf_spec spec)
{
	int default_width = 2 * sizeof(void *) + (spec.flags & SPECIAL ? 2 : 0);

	if (!ptr && *fmt != 'K') {
		/*
		 * Print (null) with the same width as a pointer so it makes
		 * tabular output look nice.
		 */
		if (spec.field_width == -1)
			spec.field_width = default_width;
		return string(buf, end, "(null)", spec);
	}

	switch (*fmt) {
	case 'F':
	case 'f':
		ptr = dereference_function_descriptor(ptr);
		/* Fallthrough */
	case 'S':
	case 's':
	case 'B':
		return symbol_string(buf, end, ptr, spec, fmt);
	case 'R':
	case 'r':
		return resource_string(buf, end, ptr, spec, fmt);
	case 'h':
		return hex_string(buf, end, ptr, spec, fmt);
	case 'b':
		switch (fmt[1]) {
		case 'l':
			return bitmap_list_string(buf, end, ptr, spec, fmt);
		default:
			return bitmap_string(buf, end, ptr, spec, fmt);
		}
	case 'M':			/* Colon separated: 00:01:02:03:04:05 */
	case 'm':			/* Contiguous: 000102030405 */
					/* [mM]F (FDDI) */
					/* [mM]R (Reverse order; Bluetooth) */
		return mac_address_string(buf, end, ptr, spec, fmt);
	case 'I':			/* Formatted IP supported
					 * 4:	1.2.3.4
					 * 6:	0001:0203:...:0708
					 * 6c:	1::708 or 1::1.2.3.4
					 */
	case 'i':			/* Contiguous:
					 * 4:	001.002.003.004
					 * 6:   000102...0f
					 */
		switch (fmt[1]) {
		case '6':
			return ip6_addr_string(buf, end, ptr, spec, fmt);
		case '4':
			return ip4_addr_string(buf, end, ptr, spec, fmt);
		case 'S': {
			const union {
				struct sockaddr		raw;
				struct sockaddr_in	v4;
				struct sockaddr_in6	v6;
			} *sa = ptr;

			switch (sa->raw.sa_family) {
			case AF_INET:
				return ip4_addr_string_sa(buf, end, &sa->v4, spec, fmt);
			case AF_INET6:
				return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt);
			default:
				return string(buf, end, "(invalid address)", spec);
			}}
		}
		break;
	case 'E':
		return escaped_string(buf, end, ptr, spec, fmt);
	case 'U':
		return uuid_string(buf, end, ptr, spec, fmt);
	case 'V':
		{
			va_list va;

			va_copy(va, *((struct va_format *)ptr)->va);
			buf += vsnprintf(buf, end > buf ? end - buf : 0,
					 ((struct va_format *)ptr)->fmt, va);
			va_end(va);
			return buf;
		}
	case 'K':
		/*
		 * %pK cannot be used in IRQ context because its test
		 * for CAP_SYSLOG would be meaningless.
		 */
		if (kptr_restrict && (in_irq() || in_serving_softirq() ||
				      in_nmi())) {
			if (spec.field_width == -1)
				spec.field_width = default_width;
			return string(buf, end, "pK-error", spec);
		}

		switch (kptr_restrict) {
		case 0:
			/* Always print %pK values */
			break;
		case 1: {
			/*
			 * Only print the real pointer value if the current
			 * process has CAP_SYSLOG and is running with the
			 * same credentials it started with. This is because
			 * access to files is checked at open() time, but %pK
			 * checks permission at read() time. We don't want to
			 * leak pointer values if a binary opens a file using
			 * %pK and then elevates privileges before reading it.
			 */
			const struct cred *cred = current_cred();

			if (!has_capability_noaudit(current, CAP_SYSLOG) ||
			    !uid_eq(cred->euid, cred->uid) ||
			    !gid_eq(cred->egid, cred->gid))
				ptr = NULL;
			break;
		}
		case 2:
		default:
			/* Always print 0's for %pK */
			ptr = NULL;
			break;
		}
		break;

	case 'N':
		switch (fmt[1]) {
		case 'F':
			return netdev_feature_string(buf, end, ptr, spec);
		}
		break;
	case 'a':
		return address_val(buf, end, ptr, spec, fmt);
	case 'd':
		return dentry_name(buf, end, ptr, spec, fmt);
	case 'D':
		return dentry_name(buf, end,
				   ((const struct file *)ptr)->f_path.dentry,
				   spec, fmt);
	}
	spec.flags |= SMALL;
	if (spec.field_width == -1) {
		spec.field_width = default_width;
		spec.flags |= ZEROPAD;
	}
	spec.base = 16;

	return number(buf, end, (unsigned long) ptr, spec);
}

/*
 * Helper function to decode printf style format.
 * Each call decode a token from the format and return the
 * number of characters read (or likely the delta where it wants
 * to go on the next call).
 * The decoded token is returned through the parameters
 *
 * 'h', 'l', or 'L' for integer fields
 * 'z' support added 23/7/1999 S.H.
 * 'z' changed to 'Z' --davidm 1/25/99
 * 't' added for ptrdiff_t
 *
 * @fmt: the format string
 * @type of the token returned
 * @flags: various flags such as +, -, # tokens..
 * @field_width: overwritten width
 * @base: base of the number (octal, hex, ...)
 * @precision: precision of a number
 * @qualifier: qualifier of a number (long, size_t, ...)
 */
static noinline_for_stack
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;

	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;

	case 'n':
		/*
		 * Since %n poses a greater security risk than utility, treat
		 * it as an invalid format specifier. Warn about its use so
		 * that new instances don't get added.
		 */
		WARN_ONCE(1, "Please remove ignored %%n in '%s'\n", fmt);
		/* Fall-through */

	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
 * %pB output the name of a backtrace symbol with 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
 * %pb output the bitmap with field width as the number of bits
 * %pbl output the bitmap as range list with field width as the number of bits
 * %pM output a 6-byte MAC address with colons
 * %pMR output a 6-byte MAC address with colons in reversed order
 * %pMF output a 6-byte MAC address with dashes
 * %pm output a 6-byte MAC address without colons
 * %pmR output a 6-byte MAC address without colons in reversed order
 * %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 RFC 5952
 * %pIS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
 * %piS depending on sa_family of 'struct sockaddr *' print IPv4/IPv6 address
 * %pU[bBlL] print a UUID/GUID in big or little endian using lower or upper
 *   case.
 * %*pE[achnops] print an escaped buffer
 * %*ph[CDN] a variable-length hex string with a separator (supports up to 64
 *           bytes of the input)
 * %n is ignored
 *
 * ** Please update Documentation/printk-formats.txt when making changes **
 *
 * 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.
 *
 * If you're not already dealing with a va_list consider using snprintf().
 */
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(size > INT_MAX))
		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, 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;

		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:
				if (spec.flags & SIGN)
					num = va_arg(args, ssize_t);
				else
					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.
 *
 * If you're not already dealing with a va_list consider using scnprintf().
 *
 * 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);

	if (likely(i < size))
		return i;
	if (size != 0)
		return size - 1;
	return 0;
}
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
 *