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Subject[PATCH] Fix isspace() and other ctype.h functions to ignore chars 128-255
Date
Originally isspace() and other similar functions in ctype.h ignored  
any character with the high bit set; however this was changed during
the linux 2.1 days to map Latin-1. As following Latin-1 will most
likely break UTF-8 any any *other* encoding that is backwards-
compatible with 7-bit-ASCII, change ctype.c to ignore such characters
completely (the way they were before). Linus seems to think this is
a good thing, and he's the one that wrote the code in the first place.

Signed-off-by: Kyle Moffett <mrlinuxman@mac.com>

---

On Nov 06, 2007, at 10:53:08, Linus Torvalds wrote:
> On Tue, 6 Nov 2007, Kyle Moffett wrote:
>> Personally I think that isspace() accepting character 0xA0 is a bug
>
> I think I agree with you. As far as the kernel is concerned,
> "isspace()" should just accept the obvious spaces (hardspace, tab,
> newline), and *perhaps* the VT/FF kind of things.
>
> You should realize that the kernel <ctype.h> thing is *ancient*.
> It's basically there from v0.01, and while the really original one
> (I just checked) had all the non-ascii characters not trigger
> anything, it was converted to be latin1 in the 2.1.x timeframe.
>
> That's a *loong* time ago. Way before UTF-8 and other things were
> really common.
>
> So we should probably just make all the upper 128 bytes go back to
> "don't trigger anything in ctype.h" - they'd not be spaces, but
> they'd not be control characters or anything else either.

lib/ctype.c | 17 +++++++++++------
1 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib/ctype.c b/lib/ctype.c
index d02ace1..ce2807a 100644
--- a/lib/ctype.c
+++ b/lib/ctype.c
@@ -24,13 +24,18 @@ _P,_L|_X,_L|_X,_L|_X,_L|_X,_L|_X,_L|_X,_L, /* 96-103 */
_L,_L,_L,_L,_L,_L,_L,_L, /* 104-111 */
_L,_L,_L,_L,_L,_L,_L,_L, /* 112-119 */
_L,_L,_L,_P,_P,_P,_P,_C, /* 120-127 */
+
+/*
+ * None of these match any type bits to avoid screwing up UTF-8 or any other
+ * 7-bit-ASCII-compatible encoding.
+ */
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 128-143 */
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 144-159 */
-_S|_SP,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P, /* 160-175 */
-_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P,_P, /* 176-191 */
-_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U,_U, /* 192-207 */
-_U,_U,_U,_U,_U,_U,_U,_P,_U,_U,_U,_U,_U,_U,_U,_L, /* 208-223 */
-_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L,_L, /* 224-239 */
-_L,_L,_L,_L,_L,_L,_L,_P,_L,_L,_L,_L,_L,_L,_L,_L}; /* 240-255 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 160-175 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 176-191 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 192-207 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 208-223 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, /* 224-239 */
+0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}; /* 240-255 */

EXPORT_SYMBOL(_ctype);
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