[M3devel] symlink grief?

[Olaf Wagner]

Quoting Jay K <jay.krell at cornell.edu>:

> No they were in a very central place m3-libs/libm3/src/os/POSIX/FSPosix.m3.
> How about:
>
> PROCEDURE CStatus(s: Ctypes.char_star; VAR status: File.Status): INTEGER =
>   VAR statBuf: Ustat.struct_stat;
>   BEGIN
>     IF Ustat.stat(s, ADR(statBuf)) < 0 AND Ustat.lstat(s,   
> ADR(statBuf)) < 0 THEN
>       RETURN -1;
>     END;
>     status.type := FilePosix.FileTypeFromStatbuf(statBuf);
>     (* Could make following assignments conditional on type: *)
>     status.modificationTime := FLOAT(statBuf.st_mtime, LONGREAL);
>     status.size := statBuf.st_size;
>     IF status.size < 0L THEN RETURN -1 END;
>     RETURN 0
>   END CStatus;

Could be worth a try,

Olaf

>
> I can look again, *maybe* rmrec can avoid calling here.
> Though probably the best way to achieve that is by writing two   
> independent versions in C.
> I think the Modula-3 file system libraries are just too keen on   
> calling stat, which fails
> for dangling symlinks.
>
>  - Jay
>
> ----------------------------------------
>> Date: Fri, 3 Sep 2010 13:10:51 +0200
>> From: wagner at elegosoft.com
>> To: m3devel at elegosoft.com
>> Subject: Re: [M3devel] symlink grief?
>>
>> Symbolic links usually `just work'.
>> If you have changed stat to lstat for all use cases, that will of
>> course cause problems. I thought your changes were local to the
>> rmrec implementation for quake. Aren't they?
>>
>> If not, it will be better to revert them.
>>
>> Olaf
>>
>> PS: Windows NTFS does support symbolic links, too, though I've probably
>> never used them: http://en.wikipedia.org/wiki/NTFS_symbolic_link
>>
>> Quoting Jay K :
>>
>> >  +++ /cm3/bin/cm3  -ship -DROOT=/home/jay/dev2/cm3 +++
>> > --- shipping from I386_LINUX ---
>> >
>> > "/home/jay/dev2/cm3/m3-libs/m3core/I386_LINUX/.M3SHIP", line 1:
>> > quake runtime error: unable to create directory "/cm3": errno=17
>> >
>> > --procedure--  -line-  -file---
>> > make_dir           --
>> >                     1    
>> /home/jay/dev2/cm3/m3-libs/m3core/I386_LINUX/.M3SHIP
>> >
>> > Fatal Error: package build failed
>> >  *** execution of [,
>> >
>> >
>> >
>> > /cm3 is a symlink to /home/jay/cm3
>> > They both exist.
>> > /home/jay/cm3 is a directory.
>> >
>> > I predict no good answers here.
>> >  - a code base that historically used stat, that I changed to lstat.
>> >
>> > I think maybe I should put it back to stat.
>> > And maybe come up with new functions for fs_rmrec to use.
>> >
>> > Wild guess... we have code like:
>> >
>> >
>> > PROCEDURE IsDirectory (path: TEXT): BOOLEAN =
>> >   VAR s: File.Status;
>> >   BEGIN
>> >     TRY
>> >       s := FS.Status (path);
>> >       RETURN (s.type = FS.DirectoryFileType);
>> >     EXCEPT OSError.E =>
>> >       RETURN FALSE;
>> >     END;
>> >   END IsDirectory;
>> >
>> >
>> > Maybe the right thing is to mimic Posix and allow code like:
>> >
>> >
>> > PROCEDURE IsDirectory (path: TEXT): BOOLEAN =
>> >   VAR s: File.Status;
>> >   BEGIN
>> >     TRY
>> >       s := FS.LinkStatus (path);
>> >       RETURN (s.type = FS.SymblicLinkFileType);
>> >     EXCEPT OSError.E =>
>> >       RETURN FALSE;
>> >     END;
>> >   END IsDirectory;
>> >
>> > or such?
>> >
>> > Not sure it is needed.
>> >
>> > Or FS.StatusNoLinkResolve? Is that clearer?
>> >
>> > There are a few basic problems here:
>> >   - The "Modula-3 code base" has been written I assume without
>> > symlinks in mind. ??
>> >   - I don't have symlinks in mind, much at all, since I'm usually
>> > not on a system with them.
>> >   I don't have a mental model of how to program with them, etc.
>> >   Maybe some short document I can read and memorize?
>> >
>> >
>> >  - Jay
>> >
>>
>>
>>
>> --
>> Olaf Wagner -- elego Software Solutions GmbH
>> Gustav-Meyer-Allee 25 / Gebäude 12, 13355 Berlin, Germany
>> phone: +49 30 23 45 86 96 mobile: +49 177 2345 869 fax: +49 30 23 45 86 95
>> http://www.elegosoft.com | Geschäftsführer: Olaf Wagner | Sitz: Berlin
>> Handelregister: Amtsgericht Charlottenburg HRB 77719 | USt-IdNr: DE163214194
>>
>



-- 
Olaf Wagner -- elego Software Solutions GmbH
                Gustav-Meyer-Allee 25 / Gebäude 12, 13355 Berlin, Germany
phone: +49 30 23 45 86 96  mobile: +49 177 2345 869  fax: +49 30 23 45 86 95
    http://www.elegosoft.com | Geschäftsführer: Olaf Wagner | Sitz: Berlin
Handelregister: Amtsgericht Charlottenburg HRB 77719 | USt-IdNr: DE163214194