[Bug other/50277] New: strndup should use strnlen instead of strlen

[Bug other/50277] New: strndup should use strnlen instead of strlen

[ivan.tubert at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50277

             Bug #: 50277
           Summary: strndup should use strnlen instead of strlen
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ivan.tubert@gmail.com


Regarding strndup (const char *s, size_t n):

strndup is using strlen to get the length of s, in order to decide whether to
allocate n+1 characters or strlen(s)+1.

This is inefficient. Imagine that s is one googol characters long, and I call
strndup(s,3) because I want a duplicate of up to the first three characters.
Yet strlen will go all the way to the end of s, just to find that it is longer
than 3 characters!

I suggest using strnlen instead.

[Bug other/50277] strndup should use strnlen instead of strlen

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50277

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-09-02 16:45:15 UTC ---
strndup is part of the libc that comes from your OS and not part of GCC.  Most
likely you wanted to file this as a glibc bug.

[Bug other/50277] strndup should use strnlen instead of strlen

[ivan.tubert at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50277

--- Comment #2 from Ivan Tubert-Brohman <ivan.tubert at gmail dot com> 2011-09-02 16:51:42 UTC ---
On Fri, Sep 2, 2011 at 12:45 PM, pinskia at gcc dot gnu.org
<gcc-bugzilla@gcc.gnu.org> wrote:
> --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-09-02 16:45:15 UTC ---
> strndup is part of the libc that comes from your OS and not part of GCC.  Most
> likely you wanted to file this as a glibc bug.

Thanks, I got confused because I found the code in the gcc repository.
(I was looking at
http://gcc.gnu.org/viewcvs/trunk/libiberty/strndup.c?view=markup )

[Bug other/50277] strndup should use strnlen instead of strlen

[ivan.tubert at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50277

--- Comment #3 from Ivan Tubert-Brohman <ivan.tubert at gmail dot com> 2011-09-02 16:55:07 UTC ---
And the code in glibc already uses strnlen.

Sorry about that. Please close the ticket unless you deem necessary to modify
the version in libiberty/strndup.c

[Bug other/50277] strndup should use strnlen instead of strlen

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50277

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> 2011-09-02 16:58:48 UTC ---
Well that is the portable version of strndup, GCC uses it only once but it is
only will ever be called with a string which has a null char.  Also strnlen is
not portable either.