102980 - too many versions of nsCRT::strncmp

Status: RESOLVED DUPLICATE of bug 124536

(Core :: XPCOM, defect)

Description

[Bradley Baetz (:bbaetz)]

We have both:

static PRInt32 strncmp(const char* s1, const char* s2,
                         PRUint32 aMaxLen)

and

static PRInt32 strncmp(const char* s1, const char* s2, PRInt32 aMaxLen)
The latter does some wierd 'optimisation' to compare the first character. Other
than that, they are identical, except that the 'optimisation' doesn't handle
aMaxLen==0.

I broke the mac yesterday when one of my calls called this with a paramater of
sizeof(foo)-1, when it complained that the call was ambiguous. I have no idea
whether it was right or not, but its silly to have two versions of this. Can we
get rid of the signed one?

Comment 1

[Doug Turner (:dougt)]

not sure what the rationale was.  The same was done to the strncmp that takes
PRUnichars.

Comment 2

[Darin Fisher]

for |const char*| let's use the native strncmp.  for |const PRUnichar*| we
should also use the native version (e.g. wcsncmp) when provided natively (win32,
linux, etc).

Comment 3

[Bradley Baetz (:bbaetz)]

We can only use native functions on platforms where the native functions accept
two byte encodings. (ie not linux)

Comment 4

[Darin Fisher]

so i'm on my redhat 7.2 box, and i look in /usr/include and i see a file called
wchar.h.  i open it and i find wcsncmp and friends.  now i suppose this is
probably a new addition or something, but shouldn't we check for it (via
autoconf) and use it when available?

Comment 5

[Bradley Baetz (:bbaetz)]

No, you can't use those. Those routines are compiled into libc, which uses a 4
byte wchar_T, which is the linux abi. We use two byte wchar_t, and so all the
libc functions wouldn't read the string correctly.

On windows, which does have a 2 byte wchar_t abi, you probably could use those.
There are still encoding issues, possibly, though.

Comment 6

[Darin Fisher]

ah interesting... ok, well we should try to at least use the win32 ones if they
prove to be compatible.

Comment 7

[Doug Turner (:dougt)]

cathleen is this something that you are cleaning up?

Comment 8

[Alfred Kayser]

The double strncmp issue is fixed with Bug 124536, attachment:
https://bugzilla.mozilla.org/attachment.cgi?id=135660
Which is not yet checked in.

The wchar discussion is not for this bug.

So dupping this bug 124536.

*** This bug has been marked as a duplicate of 124536 ***