/dev/clipboard corrupted
Thomas Wolff
towo@towo.net
Sun Jul 8 23:15:00 GMT 2012
Am 04.07.2012 10:15, schrieb Corinna Vinschen:
> On Jul 3 18:29, Thomas Wolff wrote:
>> ...
>> * The current (CVS) code will not work if even the first character
>> to be converted
>> needs more bytes than the buffer provides, e.g. if the
>> application calls read() with length 1 only.
>> Some extra buffering would be needed to make it work then.
> Yes, indeed. I'll have a look.
...
> No, not yet. This isn't exactly a regression from former behaviour.
> Please provide a patch or remind me in a few weeks again.
About the buffering I may send a patch when I find time.
>
>> * I assume the current code will also fail in non-UTF-8 locales;
>> if the wcs block being converted contains a non-convertible character,
>> it would abort since wcstombs returns -1
>> (assuming here that sys_wcstombs behaves alike in this respect)
> It doesn't. In fact, sys_cp_wcstombs was designed to never fail
> to convert a string. See the source code in strfunc.cc, line 447ff.
Tested meanwhile. My assumption was too speculative, sorry.
>> * I had previously observed that with a read size of n only n-1
>> bytes would be delivered
>> and thought this was on purpose because wcstombs appends a final
>> nul to its result.
>> Now n bytes are returned (if available) and in fact the byte
>> behind the read() buffer is
>> overwritten (see modified test program).
> It's not Cygwin overwriting the byte, your testcase is...
Both were, actually...
>> ...
>> n = read (fd, filebuf, filebuflen);
>> if (out_tty) {
>> filebuf [n] = 0;
> Hmm, what if n == filebuflen?
I admit my test case was bogus in this respect *BLUSH*.
However, yet the error is there, as a fixed test case reveals.
Also your own testcase does print out "OVERWRITTEN".
This complies with the comment in strfuncs.cc:sys_cp_wcstombs:
- The functions always create 0-terminated results, no matter what.
The fix is easy:
if (pos < glen)
{
len --; /* leave space for final NUL */
...
------
Thomas
More information about the Cygwin-developers
mailing list