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From: Marius Vollmer <marius.vollmer@uni-dortmund.de>
Cc: guile-devel@gnu.org
Subject: Re: port initialization?
Date: 08 Aug 2002 19:33:52 +0200	[thread overview]
Message-ID: <ljeld9s1a7.fsf@burns.dt.e-technik.uni-dortmund.de> (raw)
In-Reply-To: <15693.15724.416839.636665@blauw.xs4all.nl>

Han-Wen <hanwen@cs.uu.nl> writes:

> what about
>   
>   z = scm_cell (scm_tc16_strport, 0);
>   SCM_DEFER_INTS;
>   pt = scm_add_to_port_table (z);
>   SCM_SET_CELL_TYPE (z, scm_tc16_strport | modes);
>   SCM_SETPTAB_ENTRY (z, pt);
>   SCM_SETSTREAM (z, SCM_UNPACK (str));
> 
> This looks like fishy code to me. When scm_add_to_port_table triggers
> GC then it will see the (scm_tc16_strport, 0) cell, which is (or
> should be) invalid.

Yes, but the GC will not notice since "z" still refers to it and
therefore the port cell wont be freed.  So we are safe.  It's a little
fishy, yes.  We could flag the port as closed until its ptab_entry is
set properly.  Closed ports do also have a NULL ptab_entry.

> Why not
> [...] 
>     {
> 	scm_t_port *newport =  scm_add_to_port_table ();
> 	SCM port = scm_cell (scm_tc16_port, newport);
> 	newport->port = port;
> 		      ..
>     }

This will leak newport when the call to scm_cell throws.

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  reply	other threads:[~2002-08-08 17:33 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-08-04 14:42 port initialization? Han-Wen
2002-08-08 17:33 ` Marius Vollmer [this message]
2002-08-08 19:35   ` Han-Wen Nienhuys
2002-08-08 20:31     ` Marius Vollmer
2002-08-08 20:54       ` Han-Wen Nienhuys
2002-08-08 21:14         ` Marius Vollmer
2002-08-08 23:17           ` Han-Wen Nienhuys
2002-08-10 13:30             ` Marius Vollmer
2002-08-16 22:06               ` Han-Wen Nienhuys
2002-08-17  0:21                 ` Marius Vollmer
2002-08-08 23:20           ` Lynn Winebarger
2002-08-09  8:06             ` Han-Wen Nienhuys
2002-08-10 13:33             ` Marius Vollmer
2002-08-10 14:12               ` Lynn Winebarger
2002-08-11 15:57                 ` Marius Vollmer
2002-08-08 19:37   ` Han-Wen Nienhuys
2002-08-08 20:32     ` Marius Vollmer
2002-08-08 23:07       ` Han-Wen Nienhuys
2002-08-10 13:09         ` Marius Vollmer
2002-08-16 22:06           ` Han-Wen Nienhuys

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