Re: Reiser4 changes meaning of ENOENT/EACCES, breaking gcc?

[Hans Reiser <reiser@namesys.com>]

Perry Kundert wrote:

> Hello;
>
>    I am running 2.6.5 patched wtih Debian package 
> "kernel-patch-2.6-reiser4", varsion 20040326-2.  So far, my uptime is 
> 65 days, running a quite active Apache/NFS/WiFi/Shorewall server.  
> Some known problems with corruption of Mozilla's configuration and 
> mail files when it accesses them over NFS (and corruption of files 
> written by the "tee" program, oddly enough), but everything else seems 
> to work fine.  Until now...
>
>    I am attempting to build openzaurus.  Along the way it builds 
> glibc, which fails due to the following problem (see below).
>
>    Question:  has reiser4 changed the semantics of accessing 
> directories and files in such a way that we should expect similar 
> failures in other programs that use error codes to distinguish between 
> files and directories?

Well, we made files act as directories for their metafiles, so, yes.

> Is this a known/expected issue

no, I didn't know that there were many programs that did this.  It is a 
little bit too be expected though.   Is the testing code by any chance 
written by David Woodhouse?

> that is not expected to cause too many problems?
>
>    By the way, his suggested workaround was effective...

Can you talk the glibc guys into adopting it?  That would be best.

>
> -- 
>    -pjk
>
>
>
>> Situation: reiser4 filesystem, wd contains an ordinary file mode 0644 
>> named
>> 'nss'. (This is important).
>>
>> Cause: in gcc/cppfiles.c,
>> _cpp_find_file() calls find_file_in_dir() on . for nss/nsswitch.h
>> find_file_in_dir() calls open_file() on ./nss/nsswitch.h
>> open_file() calls open() on ./nss/nsswitch.h
>> Instead of failing ENOTDIR, open() fails EACCES. This is because 
>> under reiser4
>> all files are directories so ENOTDIR is unused as an error code; 
>> instead it
>> tries to read 'nss' as a directory but as 'nss' is 0644 its 
>> "directory contents"
>> are not accessible.
>> On any normal file system, open() fails ENOTDIR, open_file() returns 
>> false
>> converting ENOTDIR to ENOENT, find_file_in_dir() returns false, and
>> _cpp_find_file() continues to the next node in the include list, 
>> eventually
>> finding nss/nsswitch.h in -I..
>> On reiser4, open() fails EACCES, open_file() returns false, 
>> find_file_in_dir()
>> calls open_file_failed() and returns true, everything falls apart.
>>
>> The workaround I suggest for glibc is to make 'nss' 0755 thus causing 
>> open() to
>> fail ENOENT which causes _cpp_find_file_in_dir() to continue to the 
>> next node in
>> the include list.
>>
>> The fix I suggest for gcc is to make EACCES non-fatal: gcc should 
>> instead of
>> failing print a warning message and continue searching for an include 
>> file it
>> can access.
>> The patch is obvious and I will attach it as soon as I have tested it 
>> properly.
>>
>> -- 
>>           Summary: "Permission denied" compiling glibc 2.3.3 on reiser4:
>>                    EACCES fatal to #include
>>           Product: gcc
>>           Version: 3.4.0
>>            Status: UNCONFIRMED
>>          Severity: normal
>>          Priority: P2
>>         Component: c
>>        AssignedTo: unassigned at gcc dot gnu dot org
>>        ReportedBy: ed at catmur dot co dot uk
>>                CC: gcc-bugs at gcc dot gnu dot org
>>
>>
>> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15772
>>
>
>