[pacman-dev] [PATCH 5/7] fix off-by-one error in _alpm_filelist_resolve

[Andrew Gregory]

On Thu, 14 Feb 2013 22:12:59 +1000
Allan McRae <allan at archlinux.org> wrote:

> On 14/02/13 09:54, Andrew Gregory wrote:
> > Signed-off-by: Andrew Gregory <andrew.gregory.8 at gmail.com>
> > ---
> 
> OK...   I'm tired, so feel free to point out where I am wring here...
> 
> AFAIK, realpath will not return a trailing "/".  So what is being fixed
> here?  If I take out the unneeded if statement, if am failing to see the
> off-by-one error...
> 

Realpath does include a "trailing" '/' when root == "/".  That's why
this was passing the test suite.  You can see the error by building a
package with a file in /lib and then updating it with the file
in /usr/lib.

> >  lib/libalpm/filelist.c | 11 +++++++----
> >  1 file changed, 7 insertions(+), 4 deletions(-)
> > 
> > diff --git a/lib/libalpm/filelist.c b/lib/libalpm/filelist.c
> > index f29bb7c..c2ca1ca 100644
> > --- a/lib/libalpm/filelist.c
> > +++ b/lib/libalpm/filelist.c
> > @@ -198,12 +198,15 @@ int _alpm_filelist_resolve(alpm_handle_t *handle, alpm_filelist_t *files)
> >  	if(realpath(handle->root, path) == NULL){
> >  		return -1;
> >  	}
> > -	root_len = strlen(path) + 1;
> > -	if(root_len >= PATH_MAX) {
> > +	root_len = strlen(path);
> > +	if(root_len + 1 >= PATH_MAX) {
> >  		return -1;
> >  	}
> > -	path[root_len - 1] = '/';
> > -	path[root_len] = '\0';
> > +	if(path[root_len - 1] != '/') {
> > +		path[root_len] = '/';
> > +		root_len++;
> > +		path[root_len] = '\0';
> > +	}
> >  
> >  	ret = _alpm_filelist_resolve_link(files, &i, path, root_len, 0);
> >  
> > 
> 
>