* /proc/<pid>/{cwd,root} links to <defunct> for cygrunsrv, daemons, and shells
@ 2024-04-07 19:34 Brian Inglis
2024-04-09 13:08 ` /proc/<pid>/{cwd, root} " Corinna Vinschen
0 siblings, 1 reply; 4+ messages in thread
From: Brian Inglis @ 2024-04-07 19:34 UTC (permalink / raw)
To: Cygwin Patches
ISTM anomalous that for cygrunsrv, daemons, cron processes, and shells
/proc/<pid>/{cwd,root} have bad symlinks to "<defunct>", normally a process or
exe status:
/proc/732/exe -> /usr/bin/cygrunsrv
/proc/732/root -> <defunct>
/proc/732/cwd -> <defunct>
| /proc/733/exe -> /usr/sbin/cygserver
->/proc/733/root -> <defunct>
/proc/733/cwd -> <defunct>
/proc/740/exe -> /usr/bin/cygrunsrv
/proc/740/root -> <defunct>
/proc/740/cwd -> <defunct>
| /proc/741/exe -> /usr/sbin/syslog-ng
->/proc/741/root -> <defunct>
/proc/741/cwd -> <defunct>
/proc/748/exe -> /usr/bin/cygrunsrv
/proc/748/root -> <defunct>
/proc/748/cwd -> <defunct>
| /proc/749/exe -> /usr/sbin/cron
->/proc/749/root -> <defunct>
/proc/749/cwd -> <defunct>
| /proc/2080/exe -> /usr/sbin/cron
->/proc/2080/root -> <defunct>
/proc/2080/cwd -> <defunct>
| /proc/2082/exe -> /usr/bin/bash
->/proc/2082/root -> <defunct>
/proc/2082/cwd -> <defunct>
Should we consider changing that to root "/", or nothing, null, or something
meaningful?
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut
-- Antoine de Saint-Exupéry
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: /proc/<pid>/{cwd, root} links to <defunct> for cygrunsrv, daemons, and shells
2024-04-07 19:34 /proc/<pid>/{cwd,root} links to <defunct> for cygrunsrv, daemons, and shells Brian Inglis
@ 2024-04-09 13:08 ` Corinna Vinschen
2024-04-09 16:38 ` Brian Inglis
0 siblings, 1 reply; 4+ messages in thread
From: Corinna Vinschen @ 2024-04-09 13:08 UTC (permalink / raw)
To: cygwin-patches
On Apr 7 13:34, Brian Inglis wrote:
> ISTM anomalous that for cygrunsrv, daemons, cron processes, and shells
> /proc/<pid>/{cwd,root} have bad symlinks to "<defunct>", normally a process
> or exe status:
>
> /proc/732/exe -> /usr/bin/cygrunsrv
> /proc/732/root -> <defunct>
> /proc/732/cwd -> <defunct>
> | /proc/733/exe -> /usr/sbin/cygserver
> ->/proc/733/root -> <defunct>
> /proc/733/cwd -> <defunct>
> /proc/740/exe -> /usr/bin/cygrunsrv
> /proc/740/root -> <defunct>
> /proc/740/cwd -> <defunct>
> | /proc/741/exe -> /usr/sbin/syslog-ng
> ->/proc/741/root -> <defunct>
> /proc/741/cwd -> <defunct>
> /proc/748/exe -> /usr/bin/cygrunsrv
> /proc/748/root -> <defunct>
> /proc/748/cwd -> <defunct>
> | /proc/749/exe -> /usr/sbin/cron
> ->/proc/749/root -> <defunct>
> /proc/749/cwd -> <defunct>
> | /proc/2080/exe -> /usr/sbin/cron
> ->/proc/2080/root -> <defunct>
> /proc/2080/cwd -> <defunct>
> | /proc/2082/exe -> /usr/bin/bash
> ->/proc/2082/root -> <defunct>
> /proc/2082/cwd -> <defunct>
>
> Should we consider changing that to root "/", or nothing, null, or something
> meaningful?
That's typically a permission problem. On Linux you get something like
ls: cannot read symbolic link '/proc/1/cwd': Permission denied
But on Cygwin the content of those links require to open the processes'
signal pipe and send/receive a message containing the information. I
didn't look into the code for a while but it seems we don't check why we
couldn't connect to a process to fetch the info. IIRC the current
fhandler_process framework doesn't have a way to communicate that
info.
If you want to change that, feel free!
Corinna
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: /proc/<pid>/{cwd, root} links to <defunct> for cygrunsrv, daemons, and shells
2024-04-09 13:08 ` /proc/<pid>/{cwd, root} " Corinna Vinschen
@ 2024-04-09 16:38 ` Brian Inglis
2024-04-09 21:24 ` Corinna Vinschen
0 siblings, 1 reply; 4+ messages in thread
From: Brian Inglis @ 2024-04-09 16:38 UTC (permalink / raw)
To: cygwin-patches
On 2024-04-09 07:08, Corinna Vinschen wrote:
> On Apr 7 13:34, Brian Inglis wrote:
>> ISTM anomalous that for cygrunsrv, daemons, cron processes, and shells
>> /proc/<pid>/{cwd,root} have bad symlinks to "<defunct>", normally a process
>> or exe status:
>>
>> /proc/732/exe -> /usr/bin/cygrunsrv
>> /proc/732/root -> <defunct>
>> /proc/732/cwd -> <defunct>
>> | /proc/733/exe -> /usr/sbin/cygserver
>> ->/proc/733/root -> <defunct>
>> /proc/733/cwd -> <defunct>
>> /proc/740/exe -> /usr/bin/cygrunsrv
>> /proc/740/root -> <defunct>
>> /proc/740/cwd -> <defunct>
>> | /proc/741/exe -> /usr/sbin/syslog-ng
>> ->/proc/741/root -> <defunct>
>> /proc/741/cwd -> <defunct>
>> /proc/748/exe -> /usr/bin/cygrunsrv
>> /proc/748/root -> <defunct>
>> /proc/748/cwd -> <defunct>
>> | /proc/749/exe -> /usr/sbin/cron
>> ->/proc/749/root -> <defunct>
>> /proc/749/cwd -> <defunct>
>> | /proc/2080/exe -> /usr/sbin/cron
>> ->/proc/2080/root -> <defunct>
>> /proc/2080/cwd -> <defunct>
>> | /proc/2082/exe -> /usr/bin/bash
>> ->/proc/2082/root -> <defunct>
>> /proc/2082/cwd -> <defunct>
>>
>> Should we consider changing that to root "/", or nothing, null, or something
>> meaningful?
>
> That's typically a permission problem. On Linux you get something like
>
> ls: cannot read symbolic link '/proc/1/cwd': Permission denied
Thanks Corinna,
That now makes sense, as Cygwin ps -a and btop showed the processes, although
procps and top did not, and other info is visible, I never thought about
permissions as there were links, but I see from elevated admin sh:
/proc/732/exe -> /usr/bin/cygrunsrv
/proc/732/root -> /
/proc/732/cwd -> /proc/cygdrive/c/WINDOWS/system32
| /proc/733/exe -> /usr/sbin/cygserver
->/proc/733/root -> /
/proc/733/cwd -> /proc/cygdrive/WINDOWS/system32
/proc/740/exe -> /usr/bin/cygrunsrv
/proc/740/root -> /
/proc/740/cwd -> /proc/cygdrive/WINDOWS/system32
| /proc/741/exe -> /usr/sbin/syslog-ng
->/proc/741/root -> /
/proc/741/cwd -> /proc/cygdrive/WINDOWS/system32
/proc/748/exe -> /usr/bin/cygrunsrv
/proc/748/root -> /
/proc/748/cwd -> /proc/cygdrive/WINDOWS/system32
| /proc/749/exe -> /usr/sbin/cron
->/proc/749/root -> /
/proc/749/cwd -> /var/cron
and from normal mintty bash:
$ stat -L -c%a\ %A\ %n /proc/732/*
444 -r--r--r-- /proc/732/cmdline
444 -r--r--r-- /proc/732/ctty
stat: cannot stat '/proc/732/cwd': No such file or directory
444 -r--r--r-- /proc/732/environ
755 -rwxr-xr-x /proc/732/exe
444 -r--r--r-- /proc/732/exename
555 dr-xr-xr-x /proc/732/fd
444 -r--r--r-- /proc/732/gid
444 -r--r--r-- /proc/732/maps
444 -r--r--r-- /proc/732/mountinfo
444 -r--r--r-- /proc/732/mounts
444 -r--r--r-- /proc/732/pgid
444 -r--r--r-- /proc/732/ppid
stat: cannot stat '/proc/732/root': No such file or directory
444 -r--r--r-- /proc/732/sid
444 -r--r--r-- /proc/732/stat
444 -r--r--r-- /proc/732/statm
444 -r--r--r-- /proc/732/status
444 -r--r--r-- /proc/732/uid
444 -r--r--r-- /proc/732/winexename
444 -r--r--r-- /proc/732/winpid
$ more /proc/732/* > /dev/null
more: cannot open /proc/732/cwd: No such file or directory
more: cannot open /proc/732/maps: Permission denied
more: cannot open /proc/732/root: No such file or directory
more: cannot open /proc/732/stat: Permission denied
more: cannot open /proc/732/statm: Permission denied
so I think perms on these should be 440 or 550 not 444 or 555, but that may
involve a lot of work to decide that for each entry?
> But on Cygwin the content of those links require to open the processes'
> signal pipe and send/receive a message containing the information. I
> didn't look into the code for a while but it seems we don't check why we
> couldn't connect to a process to fetch the info. IIRC the current
> fhandler_process framework doesn't have a way to communicate that
> info.
>
> If you want to change that, feel free!
I will take a look sometime but no promises of any patch(es) ;^>
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer but when there is no more to cut
-- Antoine de Saint-Exupéry
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: /proc/<pid>/{cwd, root} links to <defunct> for cygrunsrv, daemons, and shells
2024-04-09 16:38 ` Brian Inglis
@ 2024-04-09 21:24 ` Corinna Vinschen
0 siblings, 0 replies; 4+ messages in thread
From: Corinna Vinschen @ 2024-04-09 21:24 UTC (permalink / raw)
To: cygwin-patches
On Apr 9 10:38, Brian Inglis wrote:
> On 2024-04-09 07:08, Corinna Vinschen wrote:
> > That's typically a permission problem. On Linux you get something like
> >
> > ls: cannot read symbolic link '/proc/1/cwd': Permission denied
>
> Thanks Corinna,
>
> That now makes sense, as Cygwin ps -a and btop showed the processes,
> although procps and top did not, and other info is visible, I never thought
> about permissions as there were links, but I see from elevated admin sh:
> [...]
> so I think perms on these should be 440 or 550 not 444 or 555, but that may
> involve a lot of work to decide that for each entry?
Not really. Have a look into fhandler/proc.cc, fhandler/process.cc,
etc. We can add a permisions member to struct virt_tab_t and add
this as static info to every member in the list. Doesn't sound overly
complicated to me (*nudge, nudge*).
Changing <defunct> to a "Permission denied" when trying to open a
virtual symlink may be a bit more involved, but maybe not very much.
Corinna
^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-04-07 19:34 /proc/<pid>/{cwd,root} links to <defunct> for cygrunsrv, daemons, and shells Brian Inglis
2024-04-09 13:08 ` /proc/<pid>/{cwd, root} " Corinna Vinschen
2024-04-09 16:38 ` Brian Inglis
2024-04-09 21:24 ` Corinna Vinschen
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