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From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: "J. Bruce Fields" <bfields@redhat.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Cc: "J. Bruce Fields" <bfields@fieldses.org>,
	Chuck Lever <chuck.lever@oracle.com>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Andy Shevchenko <andy@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: [PATCH v3 05/15] lib/string_helpers: Introduce ESCAPE_NAP to escape non-ASCII and non-printable
Date: Tue,  4 May 2021 21:08:09 +0300
Message-ID: <20210504180819.73127-6-andriy.shevchenko@linux.intel.com> (raw)
In-Reply-To: <20210504180819.73127-1-andriy.shevchenko@linux.intel.com>

Some users may want to have an ASCII based filter for printable only characters,
provided by conjunction of isascii() and isprint() functions.

Here is the addition of a such.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/string_helpers.h |  1 +
 lib/string_helpers.c           | 20 ++++++++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index d6cf6fe10f74..811c6a627620 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -53,6 +53,7 @@ static inline int string_unescape_any_inplace(char *buf)
 #define ESCAPE_ANY_NP		(ESCAPE_ANY | ESCAPE_NP)
 #define ESCAPE_HEX		BIT(5)
 #define ESCAPE_NA		BIT(6)
+#define ESCAPE_NAP		BIT(7)
 
 int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
 		unsigned int flags, const char *only);
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index a963404b8c16..ceca5fbbd92c 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -454,9 +454,11 @@ static bool escape_hex(unsigned char c, char **dst, char *end)
  *
  *	1. The character is not matched to the one from @only string and thus
  *	   must go as-is to the output.
- *	2. The character is matched to the printable or ASCII class, if asked,
+ *	2. The character is matched to the printable and ASCII classes, if asked,
  *	   and in case of match it passes through to the output.
- *	3. The character is checked if it falls into the class given by @flags.
+ *	3. The character is matched to the printable or ASCII class, if asked,
+ *	   and in case of match it passes through to the output.
+ *	4. 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.
@@ -489,11 +491,15 @@ static bool escape_hex(unsigned char c, char **dst, char *end)
  *		'\xHH' - byte with hexadecimal value HH (2 digits)
  *	%ESCAPE_NA:
  *		escape only non-ascii characters, checked by isascii()
+ *	%ESCAPE_NAP:
+ *		escape only non-printable or non-ascii characters
  *
- * One notable caveat, the %ESCAPE_NP and %ESCAPE_NA have higher priority
- * than the rest of the flags (%ESCAPE_NP is higher than %ESCAPE_NA).
+ * 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).
  * It doesn't make much sense to use either of them without %ESCAPE_OCTAL
  * or %ESCAPE_HEX, because they cover most of the other character classes.
+ * %ESCAPE_NAP can utilize %ESCAPE_SPACE or %ESCAPE_SPECIAL in addition to
+ * the above.
  *
  * Return:
  * The total size of the escaped output that would be generated for
@@ -515,6 +521,8 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
 		 * Apply rules in the following sequence:
 		 *	- the @only string is supplied and does not contain a
 		 *	  character under question
+		 *	- the character is printable and ASCII, when @flags has
+		 *	  %ESCAPE_NAP bit set
 		 *	- the character is printable, when @flags has
 		 *	  %ESCAPE_NP bit set
 		 *	- the character is ASCII, when @flags has
@@ -528,6 +536,10 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
 					  escape_passthrough(c, &p, end))
 			continue;
 
+		if (isascii(c) && isprint(c) &&
+		    flags & ESCAPE_NAP && escape_passthrough(c, &p, end))
+			continue;
+
 		if (isprint(c) &&
 		    flags & ESCAPE_NP && escape_passthrough(c, &p, end))
 			continue;
-- 
2.30.2


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-04 18:08 [PATCH v3 00/15] lib/string_helpers: get rid of ugly *_escape_mem_ascii() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 01/15] lib/string_helpers: Switch to use BIT() macro Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 02/15] lib/string_helpers: Move ESCAPE_NP check inside 'else' branch in a loop Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 03/15] lib/string_helpers: Drop indentation level in string_escape_mem() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 04/15] lib/string_helpers: Introduce ESCAPE_NA for escaping non-ASCII Andy Shevchenko
2021-05-04 18:08 ` Andy Shevchenko [this message]
2021-05-04 18:08 ` [PATCH v3 06/15] lib/string_helpers: Allow to append additional characters to be escaped Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 07/15] lib/test-string_helpers: Print flags in hexadecimal format Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 08/15] lib/test-string_helpers: Get rid of trailing comma in terminators Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 09/15] lib/test-string_helpers: Add test cases for new features Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 10/15] MAINTAINERS: Add myself as designated reviewer for generic string library Andy Shevchenko
2021-05-12  6:20   ` Joe Perches
2021-05-04 18:08 ` [PATCH v3 11/15] seq_file: Introduce seq_escape_mem() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 12/15] seq_file: Add seq_escape_str() as replica of string_escape_str() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 13/15] seq_file: Convert seq_escape() to use seq_escape_str() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 14/15] nfsd: Avoid non-flexible API in seq_quote_mem() Andy Shevchenko
2021-05-04 18:08 ` [PATCH v3 15/15] seq_file: Drop unused *_escape_mem_ascii() Andy Shevchenko
2021-05-11 18:57 ` [PATCH v3 00/15] lib/string_helpers: get rid of ugly *_escape_mem_ascii() J. Bruce Fields

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