Re: Postinstall failure: file not found

Re: Postinstall failure: file not found

[Pierre A. Humblet]

OK, I've got it:

/> sh -c sayhi
hi
/> sh -c /sayhi
/sayhi: not found

With strace I saw that sh uses stat (which won't show rxw rights
in this case) and it behaves differently for absolute paths.

Possible fixes:
1) cd to /etc/postinstall before running the scripts and use relative paths
2) Put my 2nd ntsec patch in setup (I have asked Rudiyanto to test it)
3) Run the postinstall scripts with CYGWIN=nontsec, for boostrap.
   Note that scripts that rely on ntsec (chmod or chown) will need to turn 
   ntsec on.
4) patch sh.exe
5) ???

Pierre

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Re: Postinstall failure: file not found

[Pierre A. Humblet]

On Fri, Apr 04, 2003 at 10:18:40AM -0500, Pierre A. Humblet wrote:
> OK, I've got it:
> 
> /> sh -c sayhi
> hi
> /> sh -c /sayhi
> /sayhi: not found
> 
> With strace I saw that sh uses stat (which won't show rxw rights
> in this case) and it behaves differently for absolute paths.
> 
> Possible fixes:
> 1) cd to /etc/postinstall before running the scripts and use relative paths
> 2) Put my 2nd ntsec patch in setup (I have asked Rudiyanto to test it)
> 3) Run the postinstall scripts with CYGWIN=nontsec, for boostrap.
>    Note that scripts that rely on ntsec (chmod or chown) will need to turn 
>    ntsec on.
> 4) patch sh.exe
> 5) ???
Use bash
/> bash -c /sayhi
hi
/> bash -c sayhi
hi
6) ???

Pierre



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Re: Postinstall failure: file not found

[Pierre A. Humblet]

On Fri, Apr 04, 2003 at 10:17:41AM -0500, Pierre A. Humblet wrote:
> > Possible fixes:
> > 1) cd to /etc/postinstall before running the scripts and use relative paths
> > 2) Put my 2nd ntsec patch in setup (I have asked Rudiyanto to test it)
> > 3) Run the postinstall scripts with CYGWIN=nontsec, for boostrap.
> >    Note that scripts that rely on ntsec (chmod or chown) will need to turn 
> >    ntsec on.
> > 4) patch sh.exe
> > 5) ???
> Use bash
> /> bash -c /sayhi
> hi
> /> bash -c sayhi
> hi
> 6) ???
Don't use -c
/> sh -c /sayhi
/sayhi: not found
/> sh /sayhi
hi
7) ???

Pierre


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Ash ntsec woes [was: Re: Postinstall failure: file not found]

[Pierre A. Humblet]

Here is how sh behaves when executing a script with strange permissions
/> cat sayhi
echo hi
/> getfacl sayhi
# file: sayhi
# owner: AdministratorS
# group: Users
user::---
user:PHumblet:rwx
group::---
mask:rwx
other:---
/> sh -c sayhi    <== OK
hi                
/> sh -c /sayhi   <== Does not realize file is executable
/sayhi: not found 
/> setfacl -s u::---,g::---,o:--- sayhi
/> sh -c sayhi    <== Goes ahead even though file is unreadable
/> echo $?
255

The reason why ash is inconsistent is that when it searches 
a command on PATH it does NOT check for executable or even
readable files.
There is code that used to do that on line 558 of exec.c,
but it is "#ifdef notdef".
On the other hand, absolute paths are checked with stat on lines
459 and 472 (partly in Cygwin specific code).

So ash is always too permissive or too strict when looking up
commands, although its builtin "test" is fine. 
The "just right" way in Cygwin is to use access(X_OK) on all
3 lines listed above.

Pierre

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