Bugs involving returning strings from API functions

[Uwe Bonnes]

>>>>> "Justin" == Justin Santa Barbara <justinsb at hotmail.com> writes:

    Justin> Thanks for the quick reply Uwe.  You're absolutely correct in
    Justin> that what I stated in my email wasn't right.  I'm pretty sure
...

    Justin> The problem is that MultiByteToWideChar does count the null
    Justin> terminator, if param 4 (the multibyte string length) is -1
    Justin> indicating a null-terminated string.

I didn't consider MultiByteToWideChar.

    Justin> Hence this code needs to be changed to return instead: if (len
    Justin> <= count) return len - 1; else return len;

    Justin> Then I had a look at GetSystemDirectoryA:

    Justin> UINT WINAPI GetSystemDirectoryA( LPSTR path, UINT count ) { if
    Justin> (path) lstrcpynA( path, DIR_System.short_name, count ); return
    Justin> strlen( DIR_System.short_name ); }

You're right too.

    Justin> You're right that strlen doesn't count the terminating null, but
    Justin> the problem now is that the terminating null does need to be
    Justin> counted if the buffer is too small (it should return the size of
    Justin> the buffer required to hold the path).  Sorry I didn't explain
    Justin> that correctly. So I think we need: len = strlen() if (len <
    Justin> count) return len; else return len+1;

    Justin> ...

    Justin> As I see it, the advantage of a helper function is that for
    Justin> about the same amount of work of fixing GetSystemDirectory and
    Justin> GetCurrentDirectory, all the functions should work the same way
    Justin> meaning any bugs would quickly be found.  It might also be
    Justin> possible to optimize the case where buflen=0, while this isn't
    Justin> practical per-function.  Should I offer a patch only for
    Justin> wine/files/* ?

I think that everybody feared to write a general helper function and break a
lot ofr special cases. But if done right and tested well, its a good thing.

Write it first for wine/files/*, if it proved usefull, it will find more
uses.

    >> >>>>> "Justin" == Justin Santa Barbara <justinsb at hotmail.com> writes:
    >> 
    Justin> There are a group of functions in the kernel that appear to be

Another hint: It is well known habit to cite first, editing away unneeded
parts and then to put one own text. If the whole message gets attached
unattended, it will blew up the text length.

Bye


-- 
Uwe Bonnes                bon at elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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