lib/string_helpers: introduce ESCAPE_NA for escaping non-ASCII
Some users may want to have an ASCII based filter, provided by isascii()
function. Here is the addition of a such.
Link: https://lkml.kernel.org/r/20210504180819.73127-5-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>
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index e3ef9f8..a963404 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -454,8 +454,8 @@ 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 class, if asked, and in
- * case of match it passes through to the output.
+ * 2. The character is matched to the printable or ASCII class, 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.
* %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
* character. Note that they actually can't go together, otherwise
@@ -463,7 +463,7 @@ static bool escape_hex(unsigned char c, char **dst, char *end)
*
* 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. The supported flags are::
+ * it if needs. The supported flags are::
*
* %ESCAPE_SPACE: (special white space, not space itself)
* '\f' - form feed
@@ -482,11 +482,18 @@ static bool escape_hex(unsigned char c, char **dst, char *end)
* %ESCAPE_ANY:
* all previous together
* %ESCAPE_NP:
- * escape only non-printable characters (checked by isprint)
+ * escape only non-printable characters, checked by isprint()
* %ESCAPE_ANY_NP:
* all previous together
* %ESCAPE_HEX:
* '\xHH' - byte with hexadecimal value HH (2 digits)
+ * %ESCAPE_NA:
+ * escape only non-ascii characters, checked by isascii()
+ *
+ * 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).
+ * 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.
*
* Return:
* The total size of the escaped output that would be generated for
@@ -510,6 +517,8 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
* character under question
* - the character is printable, when @flags has
* %ESCAPE_NP bit set
+ * - the character is ASCII, when @flags has
+ * %ESCAPE_NA bit set
* - 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
@@ -523,6 +532,10 @@ int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
flags & ESCAPE_NP && escape_passthrough(c, &p, end))
continue;
+ if (isascii(c) &&
+ flags & ESCAPE_NA && escape_passthrough(c, &p, end))
+ continue;
+
if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
continue;
