lib / string_helpers: move documentation to c-file

The introduced function string_escape_mem() is a kind of opposite to
string_unescape. We have several users of such functionality each of
them created custom implementation. The series contains clean up of
test suite, adding new call, and switching few users to use it via %*pE
specifier.

Test suite covers all of existing and most of potential use cases.

This patch (of 11):

The documentation of API belongs to c-file. This patch moves it
accordingly.

There is no functional change.

Signed-off-by: Andy Shevchenko <[e-mail]>
Cc: "John W . Linville" <[e-mail]>
Cc: Johannes Berg <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Joe Perches <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/string_helpers.h

···
 #define UNESCAPE_ANY		\
 	(UNESCAPE_SPACE | UNESCAPE_OCTAL | UNESCAPE_HEX | UNESCAPE_SPECIAL)
 
-/**
- * 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
- *		'\n' - 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
- *
- * Returns amount of characters processed to the destination buffer excluding
- * trailing '\0'.
- *
- * 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.
- */
 int string_unescape(char *src, char *dst, size_t size, unsigned int flags);
 
 static inline int string_unescape_inplace(char *buf, unsigned int flags)

lib/string_helpers.c

···
 	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
+ *		'\n' - 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;