Commit aec0d096 authored by Andy Shevchenko's avatar Andy Shevchenko Committed by Linus Torvalds
Browse files

lib/string_helpers: allow to append additional characters to be escaped 

Introduce a new flag to append additional characters, passed in 'only'
parameter, to be escaped if they fall in the corresponding class.

Link: https://lkml.kernel.org/r/20210504180819.73127-7-andriy.shevchenko@linux.intel.com


Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0362c27f

include/linux/string_helpers.h

+1 −0
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ static inline int string_unescape_any_inplace(char *buf) 
#define ESCAPE_HEX		BIT(5)

#define ESCAPE_NA		BIT(6)

#define ESCAPE_NAP		BIT(7)

#define ESCAPE_APPEND		BIT(8)



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

		unsigned int flags, const char *only);

lib/string_helpers.c

+15 −4
Original line number Diff line number Diff line
@@ -493,6 +493,11 @@ static bool escape_hex(unsigned char c, char **dst, char *end) 
 *		escape only non-ascii characters, checked by isascii()

 *	%ESCAPE_NAP:

 *		escape only non-printable or non-ascii characters

 *	%ESCAPE_APPEND:

 *		append characters from @only to be escaped by the given classes

 *

 * %ESCAPE_APPEND would help to pass additional characters to the escaped, when

 * one of %ESCAPE_NP, %ESCAPE_NA, or %ESCAPE_NAP is provided.

 *

 * One notable caveat, the %ESCAPE_NAP, %ESCAPE_NP and %ESCAPE_NA have the

 * higher priority than the rest of the flags (%ESCAPE_NAP is the highest).
@@ -513,9 +518,11 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz, 
	char *p = dst;

	char *end = p + osz;

	bool is_dict = only && *only;

	bool is_append = flags & ESCAPE_APPEND;



	while (isz--) {

		unsigned char c = *src++;

		bool in_dict = is_dict && strchr(only, c);



		/*

		 * Apply rules in the following sequence:
@@ -531,20 +538,24 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz, 
		 *	  defined by given @flags

		 * In these cases we just pass through a character to the

		 * output buffer.

		 *

		 * When %ESCAPE_APPEND is passed, the characters from @only

		 * have been excluded from the %ESCAPE_NAP, %ESCAPE_NP, and

		 * %ESCAPE_NA cases.

		 */

		if (is_dict && !strchr(only, c) &&

		if (!(is_append || in_dict) && is_dict &&

					  escape_passthrough(c, &p, end))

			continue;



		if (isascii(c) && isprint(c) &&

		if (!(is_append && in_dict) && isascii(c) && isprint(c) &&

		    flags & ESCAPE_NAP && escape_passthrough(c, &p, end))

			continue;



		if (isprint(c) &&

		if (!(is_append && in_dict) && isprint(c) &&

		    flags & ESCAPE_NP && escape_passthrough(c, &p, end))

			continue;



		if (isascii(c) &&

		if (!(is_append && in_dict) && isascii(c) &&

		    flags & ESCAPE_NA && escape_passthrough(c, &p, end))

			continue;