[PATCH] implement /proc/sysvipc/*

Corinna Vinschen corinna-cygwin@cygwin.com
Fri Apr 1 10:06:00 GMT 2011


On Apr  1 04:30, Yaakov (Cygwin/X) wrote:
> These patches implement /proc/sysvipc/*, as found on Linux[1]:
> 
> $ ls -l /proc
> [...]
> dr-xr-xr-x 2 Yaakov         None           0 Apr  1 04:12 sysvipc/
> [...]
> 
> $ ls -l /proc/sysvipc
> total 0
> -r--r--r-- 1 Yaakov None 0 Apr  1 04:12 msg
> -r--r--r-- 1 Yaakov None 0 Apr  1 04:12 sem
> -r--r--r-- 1 Yaakov None 0 Apr  1 04:12 shm
> 
> # yes, these lines are very long
> $ cat /proc/sysvipc/shm 
>        key      shmid perms       size  cpid  lpid nattch   uid   gid cuid   cgid      atime      dtime      ctime
>          0     196608  6600     393216  4960  4996      2  1001   513  1001   513 1301639749          0 1301639749
>          0      65537  6600     393216  4916  4996      2  1001   513  1001   513 1301639750          0 1301639750
> [...]
> 
> If cygserver is not running, then the /proc/sysvipc directory still
> exists but readdir()s as empty, and the files therein are nonexistent:
> 
> $ ls /proc/sysvipc/
> 
> $ ls /proc/sysvipc/shm
> ls: cannot access /proc/sysvipc/sem: No such file or directory
> 
> $ cat /proc/sysvipc/shm
> cat: /proc/sysvipc/shm: No such file or directory
> 
> The code uses some hints from the Cygwin modifications to ipcs(1).
> 
> Patch and new file for winsup/cygwin, and patch for winsup/doc attached.
> 
> 
> Yaakov
> 
> 
> [1] http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/4/html/Reference_Guide/s2-proc-dir-sysvipc.html
> 

> 2011-04-01  Yaakov Selkowitz  <...>
> 
> 	* new-features.sgml (ov-new1.7.10): Document /proc/sysvipc/.
> 

> 2011-04-01  Yaakov Selkowitz  <...<
> 
> 	Implement /proc/sysvipc/*
> 	* devices.in (dev_procsysvipc_storage): Add.
> 	* devices.cc: Regenerate.
> 	* devices.h (fh_devices): Add FH_PROCSYSVIPC.
> 	* dtable.cc (build_fh_pc): Add case FH_PROCSYSVIPC.
> 	* fhandler.h (class fhandler_procsysvipc): Declare.
> 	(fhandler_union): Add __procsysvipc.
> 	* fhandler_proc.cc (proc_tab): Add sysvipc virt_directory.
> 	* fhandler_procsysvipc.cc: New file.
> 	* Makefile.in (DLL_OFILES): Add fhandler_procsysvipc.o.
> 	* path.h (isproc_dev): Add FH_PROCSYSVIPC to conditional.

Cool stuff.  Thanks for this patch.  However, your patch shows a
problem:

> Index: path.h
> ===================================================================
> RCS file: /cvs/src/src/winsup/cygwin/path.h,v
> retrieving revision 1.154
> diff -u -r1.154 path.h
> --- path.h	17 Jan 2011 14:19:39 -0000	1.154
> +++ path.h	20 Feb 2011 08:24:53 -0000
> @@ -19,7 +19,7 @@
>  
>  #define isproc_dev(devn) \
>    (devn == FH_PROC || devn == FH_REGISTRY || devn == FH_PROCESS || \
> -   devn == FH_PROCNET || devn == FH_PROCSYS)
> +   devn == FH_PROCNET || devn == FH_PROCSYS || devn == FH_PROCSYSVIPC)

The definition of isproc_dev starts to get on my nerves.  We have to
check for six distinct values now.  I think we should really change
the definition.  Here's what we have in devices.h right now:

  FH_PROC    = FHDEV (0, 250),
  FH_REGISTRY= FHDEV (0, 249),
  FH_PROCESS = FHDEV (0, 248),

  FH_FS      = FHDEV (0, 247),  /* filesystem based device */
    
  FH_NETDRIVE= FHDEV (0, 246),
  FH_DEV     = FHDEV (0, 245),
  FH_PROCNET = FHDEV (0, 244),
  FH_PROCESSFD = FHDEV (0, 243),
  FH_PROCSYS = FHDEV (0, 242),
  FH_PROCSYSVIPC = FHDEV (0, 241),

Chris, do you think there's anything speaking against rearranging this
so that the FH_FS and FH_NETDRIVE definitions are separate from the
stuff under /proc?  Or, hang on, we should change all PROC values,
along these lines:

  FH_FS      = FHDEV (0, 247),  /* filesystem based device */
  FH_NETDRIVE= FHDEV (0, 246),
  FH_DEV     = FHDEV (0, 245),

  FH_PROC    = FHDEV (0, 244),
  FH_REGISTRY= FHDEV (0, 243),
  FH_PROCESS = FHDEV (0, 242),
  FH_PROCNET = FHDEV (0, 241),
  FH_PROCESSFD = FHDEV (0, 240),
  FH_PROCSYS = FHDEV (0, 239),
  FH_PROCSYSVIPC = FHDEV (0, 238),

  FH_PROC_MIN_MINOR = FHDEV (0, 200),	/* Arbitrary value */

Then we can simplify the isproc_dev definition like this:

#define isproc_dev(devn) \
	(devn >= FH_PROC_MIN_MINOR && devn <= FH_PROC)

Does that sound ok?


Corinna

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



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