tasks call-with-output-string segv

tasks call-with-output-string segv

[Kevin Ryde]

I added to the todo list under 1.6 from what Nic Ferrier reported on
guile-user,

  - call-with-output-string seg faults if its port is closed, eg.
       (call-with-output-string close-port)
    What should happen?  Should this be an error, or should it be
    possible to get the string out of a closed string port?
    [Same situation in the cvs head.]


I don't know what call-with-output-string ought to do in this case,
but a segv is certainly not it :-).


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Re: tasks call-with-output-string segv

[Rob Browning]

Kevin Ryde <user42@zip.com.au> writes:

> I added to the todo list under 1.6 from what Nic Ferrier reported on
> guile-user,
>
>   - call-with-output-string seg faults if its port is closed, eg.
>        (call-with-output-string close-port)
>     What should happen?  Should this be an error, or should it be
>     possible to get the string out of a closed string port?
>     [Same situation in the cvs head.]
>
>
> I don't know what call-with-output-string ought to do in this case,
> but a segv is certainly not it :-).

Offhand, I'd guess some kind of exception would be in order.

-- 
Rob Browning
rlb @defaultvalue.org and @debian.org; previously @cs.utexas.edu
GPG starting 2002-11-03 = 14DD 432F AE39 534D B592  F9A0 25C8 D377 8C7E 73A4


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Re: tasks call-with-output-string segv

[Kevin Ryde]

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Rob Browning <rlb@defaultvalue.org> writes:
>
> Offhand, I'd guess some kind of exception would be in order.

        * strports.c (scm_call_with_output_string): scm_get_output_string
        rather than scm_strport_to_string, so as to guard against the port
        having been closed by the called procedure.

        * tests/ports.test (call-with-output-string): Test proc closing port.

        * scheme-io.texi (String Ports): In call-with-output-string, note proc
        should not close the port.  In get-output-string, note string must be
        gotten before closing the port.

This would be a candidate for the 1.6 branch too, if the solution
seems ok.


[-- Attachment #2: strports.c.call-out.diff --]
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--- strports.c.~1.98.~	1970-01-01 10:00:01.000000000 +1000
+++ strports.c	2003-09-22 13:39:47.000000000 +1000
@@ -333,7 +333,7 @@
                      FUNC_NAME);
   scm_call_1 (proc, p);
 
-  return scm_strport_to_string (p);
+  return scm_get_output_string (p);
 }
 #undef FUNC_NAME
 

[-- Attachment #3: ports.test.csc.diff --]
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--- ports.test.~1.28.~	1970-01-01 10:00:01.000000000 +1000
+++ ports.test	2003-09-22 13:49:23.000000000 +1000
@@ -301,6 +301,14 @@
     (pass-if "output check"
 	     (string=? text result))))
 
+(with-test-prefix "call-with-output-string"
+
+  ;; In Guile 1.6.4, closing the port resulted in a segv, check that doesn't
+  ;; occur.
+  (pass-if-exception "proc closes port" exception:wrong-type-arg
+    (call-with-output-string close-port)))
+
+
 
 \f
 ;;;; Soft ports.  No tests implemented yet.

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--- scheme-io.texi.~1.15.~	1970-01-01 10:00:01.000000000 +1000
+++ scheme-io.texi	2003-09-22 14:56:31.000000000 +1000
@@ -798,7 +798,7 @@
 @deffnx {C Function} scm_call_with_output_string (proc)
 Calls the one-argument procedure @var{proc} with a newly created output
 port.  When the function returns, the string composed of the characters
-written into the port is returned.
+written into the port is returned.  @var{proc} should not close the port.
 @end deffn
 
 @deffn {Scheme Procedure} call-with-input-string string proc
@@ -842,6 +842,9 @@
 Given an output port created by @code{open-output-string},
 return a string consisting of the characters that have been
 output to the port so far.
+
+@code{get-output-string} must be used before closing @var{port}, once
+closed the string cannot be obtained.
 @end deffn
 
 A string port can be used in many procedures which accept a port

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Re: tasks call-with-output-string segv

[Rob Browning]

Kevin Ryde <user42@zip.com.au> writes:

> This would be a candidate for the 1.6 branch too, if the solution
> seems ok.

Yes, that looks good.  Please commit it if you have time.

-- 
Rob Browning
rlb @defaultvalue.org and @debian.org; previously @cs.utexas.edu
GPG starting 2002-11-03 = 14DD 432F AE39 534D B592  F9A0 25C8 D377 8C7E 73A4


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Re: tasks call-with-output-string segv

[Kevin Ryde]

Rob Browning <rlb@defaultvalue.org> writes:
>
> Yes, that looks good.  Please commit it if you have time.

Done.


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Re: tasks call-with-output-string segv

[Rob Browning]

Kevin Ryde <user42@zip.com.au> writes:

> Done.

Thanks.  After I hear back about the cygwin patch, and we do
whatever's needed, I'll start working on the release.

-- 
Rob Browning
rlb @defaultvalue.org and @debian.org; previously @cs.utexas.edu
GPG starting 2002-11-03 = 14DD 432F AE39 534D B592  F9A0 25C8 D377 8C7E 73A4


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