/*
   * Helpers for formatting and printing strings
   *
   * Copyright 31 August 2008 James Bottomley

   * Copyright (C) 2013, Intel Corporation

   */

  #include <linux/bug.h>

  #include <linux/kernel.h>
  #include <linux/math64.h>

  #include <linux/export.h>

  #include <linux/ctype.h>

  #include <linux/errno.h>
  #include <linux/string.h>

  #include <linux/string_helpers.h>
  
  /**
   * string_get_size - get the size in the specified units

   * @size:	The size to be converted in blocks
   * @blk_size:	Size of the block (use 1 for size in bytes)

   * @units:	units to use (powers of 1000 or 1024)
   * @buf:	buffer to format to
   * @len:	length of buffer
   *
   * This function returns a string formatted to 3 significant figures

   * giving the size in the required units.  @buf should have room for
   * at least 9 bytes and will always be zero terminated.

   *
   */

  void string_get_size(u64 size, u64 blk_size, const enum string_size_units units,

  		     char *buf, int len)

  {

  	static const char *const units_10[] = {

  		"B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB"

  	};
  	static const char *const units_2[] = {

  		"B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB"

  	};
  	static const char *const *const units_str[] = {
  		[STRING_UNITS_10] = units_10,

  		[STRING_UNITS_2] = units_2,
  	};

  	static const unsigned int divisor[] = {

  		[STRING_UNITS_10] = 1000,
  		[STRING_UNITS_2] = 1024,
  	};
  	int i, j;

  	u32 remainder = 0, sf_cap, exp;

  	char tmp[8];

  	const char *unit;

  
  	tmp[0] = '\0';

  	i = 0;

  	if (!size)
  		goto out;

  	while (blk_size >= divisor[units]) {
  		remainder = do_div(blk_size, divisor[units]);
  		i++;
  	}
  
  	exp = divisor[units] / (u32)blk_size;
  	if (size >= exp) {
  		remainder = do_div(size, divisor[units]);
  		remainder *= blk_size;
  		i++;
  	} else {
  		remainder *= size;
  	}
  
  	size *= blk_size;
  	size += remainder / divisor[units];
  	remainder %= divisor[units];

  	while (size >= divisor[units]) {
  		remainder = do_div(size, divisor[units]);
  		i++;

  	}

  	sf_cap = size;
  	for (j = 0; sf_cap*10 < 1000; j++)
  		sf_cap *= 10;
  
  	if (j) {
  		remainder *= 1000;
  		remainder /= divisor[units];
  		snprintf(tmp, sizeof(tmp), ".%03u", remainder);
  		tmp[j+1] = '\0';
  	}
  
   out:
  	if (i >= ARRAY_SIZE(units_2))
  		unit = "UNK";
  	else
  		unit = units_str[units][i];

  	snprintf(buf, len, "%u%s %s", (u32)size,

  		 tmp, unit);

  }
  EXPORT_SYMBOL(string_get_size);

  
  static bool unescape_space(char **src, char **dst)
  {
  	char *p = *dst, *q = *src;
  
  	switch (*q) {
  	case 'n':
  		*p = '
  ';
  		break;
  	case 'r':
  		*p = '\r';
  		break;
  	case 't':
  		*p = '\t';
  		break;
  	case 'v':
  		*p = '\v';
  		break;
  	case 'f':
  		*p = '\f';
  		break;
  	default:
  		return false;
  	}
  	*dst += 1;
  	*src += 1;
  	return true;
  }
  
  static bool unescape_octal(char **src, char **dst)
  {
  	char *p = *dst, *q = *src;
  	u8 num;
  
  	if (isodigit(*q) == 0)
  		return false;
  
  	num = (*q++) & 7;
  	while (num < 32 && isodigit(*q) && (q - *src < 3)) {
  		num <<= 3;
  		num += (*q++) & 7;
  	}
  	*p = num;
  	*dst += 1;
  	*src = q;
  	return true;
  }
  
  static bool unescape_hex(char **src, char **dst)
  {
  	char *p = *dst, *q = *src;
  	int digit;
  	u8 num;
  
  	if (*q++ != 'x')
  		return false;
  
  	num = digit = hex_to_bin(*q++);
  	if (digit < 0)
  		return false;
  
  	digit = hex_to_bin(*q);
  	if (digit >= 0) {
  		q++;
  		num = (num << 4) | digit;
  	}
  	*p = num;
  	*dst += 1;
  	*src = q;
  	return true;
  }
  
  static bool unescape_special(char **src, char **dst)
  {
  	char *p = *dst, *q = *src;
  
  	switch (*q) {
  	case '\"':
  		*p = '\"';
  		break;
  	case '\\':
  		*p = '\\';
  		break;
  	case 'a':
  		*p = '\a';
  		break;
  	case 'e':
  		*p = '\e';
  		break;
  	default:
  		return false;
  	}
  	*dst += 1;
  	*src += 1;
  	return true;
  }

  /**
   * string_unescape - unquote characters in the given string
   * @src:	source buffer (escaped)
   * @dst:	destination buffer (unescaped)
   * @size:	size of the destination buffer (0 to unlimit)
   * @flags:	combination of the flags (bitwise OR):
   *	%UNESCAPE_SPACE:
   *		'\f' - form feed
   *		'
  ' - new line
   *		'\r' - carriage return
   *		'\t' - horizontal tab
   *		'\v' - vertical tab
   *	%UNESCAPE_OCTAL:
   *		'\NNN' - byte with octal value NNN (1 to 3 digits)
   *	%UNESCAPE_HEX:
   *		'\xHH' - byte with hexadecimal value HH (1 to 2 digits)
   *	%UNESCAPE_SPECIAL:
   *		'\"' - double quote
   *		'\\' - backslash
   *		'\a' - alert (BEL)
   *		'\e' - escape
   *	%UNESCAPE_ANY:
   *		all previous together
   *
   * Description:
   * The function unquotes characters in the given string.
   *
   * Because the size of the output will be the same as or less than the size of
   * the input, the transformation may be performed in place.
   *
   * Caller must provide valid source and destination pointers. Be aware that
   * destination buffer will always be NULL-terminated. Source string must be
   * NULL-terminated as well.
   *
   * Return:
   * The amount of the characters processed to the destination buffer excluding
   * trailing '\0' is returned.
   */

  int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
  {
  	char *out = dst;
  
  	while (*src && --size) {
  		if (src[0] == '\\' && src[1] != '\0' && size > 1) {
  			src++;
  			size--;
  
  			if (flags & UNESCAPE_SPACE &&
  					unescape_space(&src, &out))
  				continue;
  
  			if (flags & UNESCAPE_OCTAL &&
  					unescape_octal(&src, &out))
  				continue;
  
  			if (flags & UNESCAPE_HEX &&
  					unescape_hex(&src, &out))
  				continue;
  
  			if (flags & UNESCAPE_SPECIAL &&
  					unescape_special(&src, &out))
  				continue;
  
  			*out++ = '\\';
  		}
  		*out++ = *src++;
  	}
  	*out = '\0';
  
  	return out - dst;
  }
  EXPORT_SYMBOL(string_unescape);

  static bool escape_passthrough(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;

  	if (out < end)
  		*out = c;
  	*dst = out + 1;
  	return true;

  }

  static bool escape_space(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;
  	unsigned char to;

  	switch (c) {
  	case '
  ':
  		to = 'n';
  		break;
  	case '\r':
  		to = 'r';
  		break;
  	case '\t':
  		to = 't';
  		break;
  	case '\v':
  		to = 'v';
  		break;
  	case '\f':
  		to = 'f';
  		break;
  	default:

  		return false;

  	}

  	if (out < end)
  		*out = '\\';
  	++out;
  	if (out < end)
  		*out = to;
  	++out;

  	*dst = out;
  	return true;

  }

  static bool escape_special(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;
  	unsigned char to;

  	switch (c) {
  	case '\\':
  		to = '\\';
  		break;
  	case '\a':
  		to = 'a';
  		break;
  	case '\e':
  		to = 'e';
  		break;
  	default:

  		return false;

  	}

  	if (out < end)
  		*out = '\\';
  	++out;
  	if (out < end)
  		*out = to;
  	++out;

  	*dst = out;
  	return true;

  }

  static bool escape_null(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;

  	if (c)

  		return false;

  	if (out < end)
  		*out = '\\';
  	++out;
  	if (out < end)
  		*out = '0';
  	++out;

  	*dst = out;
  	return true;

  }

  static bool escape_octal(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;

  	if (out < end)
  		*out = '\\';
  	++out;
  	if (out < end)
  		*out = ((c >> 6) & 0x07) + '0';
  	++out;
  	if (out < end)
  		*out = ((c >> 3) & 0x07) + '0';
  	++out;
  	if (out < end)
  		*out = ((c >> 0) & 0x07) + '0';
  	++out;

  
  	*dst = out;

  	return true;

  }

  static bool escape_hex(unsigned char c, char **dst, char *end)

  {
  	char *out = *dst;

  	if (out < end)
  		*out = '\\';
  	++out;
  	if (out < end)
  		*out = 'x';
  	++out;
  	if (out < end)
  		*out = hex_asc_hi(c);
  	++out;
  	if (out < end)
  		*out = hex_asc_lo(c);
  	++out;

  
  	*dst = out;

  	return true;

  }
  
  /**
   * string_escape_mem - quote characters in the given memory buffer
   * @src:	source buffer (unescaped)
   * @isz:	source buffer size
   * @dst:	destination buffer (escaped)
   * @osz:	destination buffer size
   * @flags:	combination of the flags (bitwise OR):
   *	%ESCAPE_SPACE:
   *		'\f' - form feed
   *		'
  ' - new line
   *		'\r' - carriage return
   *		'\t' - horizontal tab
   *		'\v' - vertical tab
   *	%ESCAPE_SPECIAL:
   *		'\\' - backslash
   *		'\a' - alert (BEL)
   *		'\e' - escape
   *	%ESCAPE_NULL:
   *		'\0' - null
   *	%ESCAPE_OCTAL:
   *		'\NNN' - byte with octal value NNN (3 digits)
   *	%ESCAPE_ANY:
   *		all previous together
   *	%ESCAPE_NP:
   *		escape only non-printable characters (checked by isprint)
   *	%ESCAPE_ANY_NP:
   *		all previous together
   *	%ESCAPE_HEX:
   *		'\xHH' - byte with hexadecimal value HH (2 digits)
   * @esc:	NULL-terminated string of characters any of which, if found in
   *		the source, has to be escaped
   *
   * Description:
   * The process of escaping byte buffer includes several parts. They are applied
   * in the following sequence.
   *	1. The character is matched to the printable class, if asked, and in
   *	   case of match it passes through to the output.
   *	2. The character is not matched to the one from @esc string and thus
   *	   must go as is to the output.
   *	3. The character is checked if it falls into the class given by @flags.
   *	   %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
   *	   character. Note that they actually can't go together, otherwise
   *	   %ESCAPE_HEX will be ignored.
   *
   * Caller must provide valid source and destination pointers. Be aware that
   * destination buffer will not be NULL-terminated, thus caller have to append
   * it if needs.
   *
   * Return:

   * The total size of the escaped output that would be generated for
   * the given input and flags. To check whether the output was
   * truncated, compare the return value to osz. There is room left in
   * dst for a '\0' terminator if and only if ret < osz.

   */

  int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,

  		      unsigned int flags, const char *esc)
  {

  	char *p = dst;

  	char *end = p + osz;

  	bool is_dict = esc && *esc;

  
  	while (isz--) {
  		unsigned char c = *src++;
  
  		/*
  		 * Apply rules in the following sequence:
  		 *	- the character is printable, when @flags has
  		 *	  %ESCAPE_NP bit set
  		 *	- the @esc string is supplied and does not contain a
  		 *	  character under question
  		 *	- the character doesn't fall into a class of symbols
  		 *	  defined by given @flags
  		 * In these cases we just pass through a character to the
  		 * output buffer.
  		 */
  		if ((flags & ESCAPE_NP && isprint(c)) ||
  		    (is_dict && !strchr(esc, c))) {
  			/* do nothing */
  		} else {

  			if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
  				continue;
  
  			if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
  				continue;
  
  			if (flags & ESCAPE_NULL && escape_null(c, &p, end))
  				continue;

  
  			/* ESCAPE_OCTAL and ESCAPE_HEX always go last */

  			if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))

  				continue;

  
  			if (flags & ESCAPE_HEX && escape_hex(c, &p, end))

  				continue;

  		}

  		escape_passthrough(c, &p, end);

  	}

  	return p - dst;

  }
  EXPORT_SYMBOL(string_escape_mem);