execlp/execvp needs case-correct PATH

execlp/execvp needs case-correct PATH

[Thomas Wolff]

With a Windows case sensitive file system (and according mount flags
for /cygdrive), the PATH does not properly reflect casing of the actual
directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
However, the shell finds programs anyway, like e.g. notepad.
The exec*p system calls, on the other hand, do not find a program in this
case as demonstrated by the attached test program.
This is in contrast to the Linux (and POSIX?) manual page which claims
„The execlp(), execvp(), and execvpe() functions duplicate the actions
of the shell in searching for an executable file …“

Thomas

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Re: execlp/execvp needs case-correct PATH

[Thomas Wolff]

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Am 09.02.2015 um 00:04 schrieb Thomas Wolff:
> ... as demonstrated by the attached test program.


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#include <unistd.h>
#include <string.h>
#include <errno.h>

#include <stdio.h>

int
main (int argc, char * * argv)
{
	char * prog = argc > 1 ? argv [1] : "notepad";
	int res;

	printf ("Calling exec %s\n", prog);

/*	res = execlp (prog, "-", 0);	*/
	res = execvp (prog, & argv [1]);
	if (res < 0) {
		fprintf (stderr, "errno %d - ", errno);
		perror ("exec");
	}
}

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Re: execlp/execvp needs case-correct PATH

[Andrey Repin]

Greetings, Thomas Wolff!

> With a Windows case sensitive file system (and according mount flags
> for /cygdrive), the PATH does not properly reflect casing of the actual
> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).

NTFS is a case-insensitive, but case-preserving file system.
I'll leave it up to you to google the implications.

> However, the shell finds programs anyway, like e.g. notepad.
> The exec*p system calls, on the other hand, do not find a program in this
> case as demonstrated by the attached test program.
> This is in contrast to the Linux (and POSIX?) manual page which claims
> „The execlp(), execvp(), and execvpe() functions duplicate the actions
> of the shell in searching for an executable file …“


--
WBR,
Andrey Repin (anrdaemon@yandex.ru) 09.02.2015, <07:20>

Sorry for my terrible english...

Re: execlp/execvp needs case-correct PATH

[Thomas Wolff]

Am 09.02.2015 um 05:21 schrieb Andrey Repin:
> Greetings, Thomas Wolff!
>
>> With a Windows case sensitive file system (and according mount flags
>> for /cygdrive), the PATH does not properly reflect casing of the actual
>> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
> NTFS is a case-insensitive, but case-preserving file system.
> I'll leave it up to you to google the implications.
Not quite, there is an optional feature (well-hidden) to switch to 
complete case sensitiveness.
It's also referred somewhere in the Cygwin user guide.

>
>> However, the shell finds programs anyway, like e.g. notepad.
>> The exec*p system calls, on the other hand, do not find a program in this
>> case as demonstrated by the attached test program.
>> This is in contrast to the Linux (and POSIX?) manual page which claims
>> „The execlp(), execvp(), and execvpe() functions duplicate the actions
>> of the shell in searching for an executable file …“
>
> --
> WBR,
> Andrey Repin (anrdaemon@yandex.ru) 09.02.2015, <07:20>
>
> Sorry for my terrible english...


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Re: execlp/execvp needs case-correct PATH

[Corinna Vinschen]

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On Feb  9 00:04, Thomas Wolff wrote:
> With a Windows case sensitive file system (and according mount flags
> for /cygdrive), the PATH does not properly reflect casing of the actual
> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
> However, the shell finds programs anyway, like e.g. notepad.
> The exec*p system calls, on the other hand, do not find a program in this
> case as demonstrated by the attached test program.
> This is in contrast to the Linux (and POSIX?) manual page which claims
> „The execlp(), execvp(), and execvpe() functions duplicate the actions
> of the shell in searching for an executable file …“

I can't reproduce this.  If I change my cygdrive mounts to
case-sensitive, my shell doesn't start notepad anymore:

  $ cat /etc/fstab
  none /mnt cygdrive binary,posix=1,user 0 0
  $ echo $SHELL
  /bin/tcsh
  $ echo $path
  /usr/bin /mnt/c/WINDOWS/system32 /mnt/c/WINDOWS /mnt/c/WINDOWS/System32/Wbem /mnt/c/WINDOWS/System32/WindowsPowerShell/v1.0 /usr/lib/lapack
  $ notepad
  notepad: Command not found.
  $ /mnt/c/Windows/notepad
  <works>
  $


Corinna

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Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: execlp/execvp needs case-correct PATH

[Thomas Wolff]

Am 09.02.2015 um 11:17 schrieb Corinna Vinschen:
> On Feb  9 00:04, Thomas Wolff wrote:
>> With a Windows case sensitive file system (and according mount flags
>> for /cygdrive), the PATH does not properly reflect casing of the actual
>> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
>> However, the shell finds programs anyway, like e.g. notepad.
>> The exec*p system calls, on the other hand, do not find a program in this
>> case as demonstrated by the attached test program.
>> This is in contrast to the Linux (and POSIX?) manual page which claims
>> „The execlp(), execvp(), and execvpe() functions duplicate the actions
>> of the shell in searching for an executable file …“
> I can't reproduce this.  If I change my cygdrive mounts to
> case-sensitive, my shell doesn't start notepad anymore:
>
>    $ cat /etc/fstab
>    none /mnt cygdrive binary,posix=1,user 0 0
>    $ echo $SHELL
>    /bin/tcsh
>    $ echo $path
>    /usr/bin /mnt/c/WINDOWS/system32 /mnt/c/WINDOWS /mnt/c/WINDOWS/System32/Wbem /mnt/c/WINDOWS/System32/WindowsPowerShell/v1.0 /usr/lib/lapack
>    $ notepad
>    notepad: Command not found.
>    $ /mnt/c/Windows/notepad
>    <works>
>    $
Sorry, I forgot one detail: I added /cygdrive/c/Windows/System32 to my path
so the shell will find it, but yet execlp does not find it.

#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
int main (int argc, char * * argv)
{
         char * prog = argc > 1 ? argv [1] : "notepad";
         int res;
         printf ("Calling exec %s\n", prog);

         res = execlp (prog, "-", 0);
         if (res < 0) {
                 fprintf (stderr, "errno %d - ", errno);
                 perror ("exec");
         }
}


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Re: execlp/execvp needs case-correct PATH

[Corinna Vinschen]

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On Feb  9 21:49, Thomas Wolff wrote:
> Am 09.02.2015 um 11:17 schrieb Corinna Vinschen:
> >On Feb  9 00:04, Thomas Wolff wrote:
> >>With a Windows case sensitive file system (and according mount flags
> >>for /cygdrive), the PATH does not properly reflect casing of the actual
> >>directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
> >>However, the shell finds programs anyway, like e.g. notepad.
> >>The exec*p system calls, on the other hand, do not find a program in this
> >>case as demonstrated by the attached test program.
> >>This is in contrast to the Linux (and POSIX?) manual page which claims
> >>„The execlp(), execvp(), and execvpe() functions duplicate the actions
> >>of the shell in searching for an executable file …“
> >I can't reproduce this.  If I change my cygdrive mounts to
> >case-sensitive, my shell doesn't start notepad anymore:
> >
> >   $ cat /etc/fstab
> >   none /mnt cygdrive binary,posix=1,user 0 0
> >   $ echo $SHELL
> >   /bin/tcsh
> >   $ echo $path
> >   /usr/bin /mnt/c/WINDOWS/system32 /mnt/c/WINDOWS /mnt/c/WINDOWS/System32/Wbem /mnt/c/WINDOWS/System32/WindowsPowerShell/v1.0 /usr/lib/lapack
> >   $ notepad
> >   notepad: Command not found.
> >   $ /mnt/c/Windows/notepad
> >   <works>
> >   $
> Sorry, I forgot one detail: I added /cygdrive/c/Windows/System32 to my path
> so the shell will find it, but yet execlp does not find it.

Which makes sense, given that notepad is not in C:\Windows\System32,
but in C:\Windows.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
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Red Hat

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Re: execlp/execvp needs case-correct PATH

[Thomas Wolff]

Am 10.02.2015 um 10:27 schrieb Corinna Vinschen:
> On Feb  9 21:49, Thomas Wolff wrote:
>> Am 09.02.2015 um 11:17 schrieb Corinna Vinschen:
>>> On Feb  9 00:04, Thomas Wolff wrote:
>>>> With a Windows case sensitive file system (and according mount flags
>>>> for /cygdrive), the PATH does not properly reflect casing of the actual
>>>> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
>>>> However, the shell finds programs anyway, like e.g. notepad.
>>>> The exec*p system calls, on the other hand, do not find a program in this
>>>> case as demonstrated by the attached test program.
>>>> This is in contrast to the Linux (and POSIX?) manual page which claims
>>>> „The execlp(), execvp(), and execvpe() functions duplicate the actions
>>>> of the shell in searching for an executable file …“
>>> ...
>> Sorry, I forgot one detail: I added /cygdrive/c/Windows/System32 to my path
>> so the shell will find it, but yet execlp does not find it.
> Which makes sense, given that notepad is not in C:\Windows\System32, but in C:\Windows.
On my systems (Windows 7 Professional/Ultimate) it’s in both C:\Windows 
and C:\Windows\System32
(otherwise the shell wouldn’t have found it after adding to the path).

However, I could resolve the issue partly by putting
/cygdrive/c/Windows (or ../System32) in the path *before* the bogus
/cygdrive/c/WINDOWS - weird, but this way exec*p works.

With the old setting (bogus first in path), apparently/assumedly exec*p 
somehow finds the file in /cygdrive/c/WINDOWS but then cannot start it 
from there because of the case mis-match.
There’s still the inconsistency with shell behaviour.

------
Thomas

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Re: execlp/execvp needs case-correct PATH

[Csaba Raduly]

On Tue, Feb 10, 2015 at 8:14 PM, Thomas Wolff  wrote:
> Am 10.02.2015 um 10:27 schrieb Corinna Vinschen:
(snip)
>>
>> Which makes sense, given that notepad is not in C:\Windows\System32, but
>> in C:\Windows.
>
> On my systems (Windows 7 Professional/Ultimate) it's in both C:\Windows and
> C:\Windows\System32

Which is what I'd expect on most (if not all) Windows systems:

http://blogs.msdn.com/b/oldnewthing/archive/2006/03/28/563008.aspx

Csaba
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Re: execlp/execvp needs case-correct PATH

[Corinna Vinschen]

[-- Attachment #1: Type: text/plain, Size: 2596 bytes --]

On Feb 10 20:14, Thomas Wolff wrote:
> Am 10.02.2015 um 10:27 schrieb Corinna Vinschen:
> >On Feb  9 21:49, Thomas Wolff wrote:
> >>Am 09.02.2015 um 11:17 schrieb Corinna Vinschen:
> >>>On Feb  9 00:04, Thomas Wolff wrote:
> >>>>With a Windows case sensitive file system (and according mount flags
> >>>>for /cygdrive), the PATH does not properly reflect casing of the actual
> >>>>directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
> >>>>However, the shell finds programs anyway, like e.g. notepad.
> >>>>The exec*p system calls, on the other hand, do not find a program in this
> >>>>case as demonstrated by the attached test program.
> >>>>This is in contrast to the Linux (and POSIX?) manual page which claims
> >>>>„The execlp(), execvp(), and execvpe() functions duplicate the actions
> >>>>of the shell in searching for an executable file …“
> >>>...
> >>Sorry, I forgot one detail: I added /cygdrive/c/Windows/System32 to my path
> >>so the shell will find it, but yet execlp does not find it.
> >Which makes sense, given that notepad is not in C:\Windows\System32, but in C:\Windows.
> On my systems (Windows 7 Professional/Ultimate) it’s in both C:\Windows and
> C:\Windows\System32
> (otherwise the shell wouldn’t have found it after adding to the path).
> 
> However, I could resolve the issue partly by putting
> /cygdrive/c/Windows (or ../System32) in the path *before* the bogus
> /cygdrive/c/WINDOWS - weird, but this way exec*p works.
> 
> With the old setting (bogus first in path), apparently/assumedly exec*p
> somehow finds the file in /cygdrive/c/WINDOWS but then cannot start it from
> there because of the case mis-match.
> There’s still the inconsistency with shell behaviour.

I found the cause.  The function searching for executables in $PATH was
searching on the Win32 PATH variable.  The underlying conversion
functionality treats Win32 paths with default flags.  I revamped the
search function to iterate over the POSIX PATH variable so the
posix=[0|1] mount flag is taken into account.  As a nice side effect,
the search function is mow much simpler and easier to understand.

I tested this new stuff in a variety of situations, but there's still
the chance that I missed something.  So this needs a good, sturdy testing.

I just uploaded new snapshots to the usual place:
https://cygwin.com/snapshots/

Please give it a try.


Thanks,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Maintainer                 cygwin AT cygwin DOT com
Red Hat

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Re: execlp/execvp needs case-correct PATH

[Thomas Wolff]

On 11.02.2015 14:28, ext Corinna Vinschen wrote:
> On Feb 10 20:14, Thomas Wolff wrote:
>> Am 10.02.2015 um 10:27 schrieb Corinna Vinschen:
>>> On Feb  9 21:49, Thomas Wolff wrote:
>>>> Am 09.02.2015 um 11:17 schrieb Corinna Vinschen:
>>>>> On Feb  9 00:04, Thomas Wolff wrote:
>>>>>> With a Windows case sensitive file system (and according mount flags
>>>>>> for /cygdrive), the PATH does not properly reflect casing of the actual
>>>>>> directories (e.g. C:\WINDOWS vs. C:\Windows, thanks MS...).
>>>>>> However, the shell finds programs anyway, like e.g. notepad.
>>>>>> The exec*p system calls, on the other hand, do not find a program in this
>>>>>> case as demonstrated by the attached test program.
>>>>>> This is in contrast to the Linux (and POSIX?) manual page which claims
>>>>>> „The execlp(), execvp(), and execvpe() functions duplicate the actions
>>>>>> of the shell in searching for an executable file …“
>>>>> ...
>>>> Sorry, I forgot one detail: I added /cygdrive/c/Windows/System32 to my path
>>>> so the shell will find it, but yet execlp does not find it.
>>> Which makes sense, given that notepad is not in C:\Windows\System32, but in C:\Windows.
>> On my systems (Windows 7 Professional/Ultimate) it’s in both C:\Windows and
>> C:\Windows\System32
>> (otherwise the shell wouldn’t have found it after adding to the path).
>>
>> However, I could resolve the issue partly by putting
>> /cygdrive/c/Windows (or ../System32) in the path *before* the bogus
>> /cygdrive/c/WINDOWS - weird, but this way exec*p works.
>>
>> With the old setting (bogus first in path), apparently/assumedly exec*p
>> somehow finds the file in /cygdrive/c/WINDOWS but then cannot start it from
>> there because of the case mis-match.
>> There’s still the inconsistency with shell behaviour.
> I found the cause.  The function searching for executables in $PATH was
> searching on the Win32 PATH variable.  The underlying conversion
> functionality treats Win32 paths with default flags.  I revamped the
> search function to iterate over the POSIX PATH variable so the
> posix=[0|1] mount flag is taken into account.  As a nice side effect,
> the search function is mow much simpler and easier to understand.
>
> I tested this new stuff in a variety of situations, but there's still
> the chance that I missed something.  So this needs a good, sturdy testing.
>
> I just uploaded new snapshots to the usual place:
> https://cygwin.com/snapshots/
>
> Please give it a try.
Excellent, thank you. I also tested with ping vs. PING vs. PING.EXE and 
behaviour is consistent.
------
Thomas

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Re: execlp/execvp needs case-correct PATH

[Corinna Vinschen]

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On Feb 12 11:28, Thomas Wolff wrote:
> On 11.02.2015 14:28, ext Corinna Vinschen wrote:
> >On Feb 10 20:14, Thomas Wolff wrote:
> >>With the old setting (bogus first in path), apparently/assumedly exec*p
> >>somehow finds the file in /cygdrive/c/WINDOWS but then cannot start it from
> >>there because of the case mis-match.
> >>There’s still the inconsistency with shell behaviour.
> >I found the cause.  The function searching for executables in $PATH was
> >searching on the Win32 PATH variable.  The underlying conversion
> >functionality treats Win32 paths with default flags.  I revamped the
> >search function to iterate over the POSIX PATH variable so the
> >posix=[0|1] mount flag is taken into account.  As a nice side effect,
> >the search function is mow much simpler and easier to understand.
> >
> >I tested this new stuff in a variety of situations, but there's still
> >the chance that I missed something.  So this needs a good, sturdy testing.
> >
> >I just uploaded new snapshots to the usual place:
> >https://cygwin.com/snapshots/
> >
> >Please give it a try.
> Excellent, thank you. I also tested with ping vs. PING vs. PING.EXE and
> behaviour is consistent.

Thanks for testing.  Please continue to see if I accidentally broke
some other scenario.


Thanks,
Corinna

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