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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: Andy 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andy Shevchenko 2021-06-30 18:55:20 -07:00 committed by Linus Torvalds
parent 0362c27fb3
commit aec0d0966f
2 changed files with 16 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/string_helpers.h
View File

@ -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);

19
lib/string_helpers.c
View File

@ -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;