topic Re: class "std::basic_ofstream attach function in Operating System - HP-UX

class "std::basic_ofstream attach function

sushant keerti — Wed, 06 Aug 2008 12:06:10 GMT

Hi,
We are migrating our application from hp-ux 11.0 PA to 11.23 IPF. We are getting the below error while compiling.
class "std::basic_ofstream>" has no member "attach"
logDest.attach(2);
^

( note : logDest has been declared as
ofstream logDest; )
I found that the standard C++ runtime doesnot have anymore the attach member function for the class std::basic_ofstream.

Could anybody let me know the altarnative functionality, which works same as "attach"?.

Re: class "std::basic_ofstream attach function

Dennis Handly — Thu, 07 Aug 2008 01:22:30 GMT

cfront's fstream::attach & detach aren't Standard and don't exist in -AA mode.

There is a non-Standard replacement for attach, so it isn't mentioned in the porting page:
http://h21007.www2.hp.com/portal/site/dspp/menuitem.863c3e4cbcdc3f3515b49c108973a801/?ciid=eb08b3f1eee02110b3f1eee02110275d6e10RCRD

It does mention detach is missing.

To do ofstream::attach you can do following overloaded extension to open:
void open(int __fd, char_type *__buf=0,
streamsize __n=_RWSTD_DEFAULT_BUFSIZE)

Re: class "std::basic_ofstream attach function

sushant keerti — Thu, 14 Aug 2008 06:01:46 GMT

Dennis,
Just a confirmation...To attach the STDOUT to logDest, I am writing code as below. Is it rite?

ofstream logDest;
logDest.open(1, 0, _RWSTD_DEFAULT_BUFSIZE);

Re: class "std::basic_ofstream attach function

Dennis Handly — Thu, 14 Aug 2008 06:41:47 GMT

>To attach the STDOUT to logDest, I am writing code as below.

Well, I would take the defaults and just use:
#include
logDest.open(STDOUT_FILENO);

If you aren't using "<< endl" everywhere, you might want your buffer even bigger.

Re: class "std::basic_ofstream attach function

Dennis Handly — Fri, 15 Aug 2008 21:29:24 GMT

If you have gotten the answers you needed, please read the following about assigning points:
http://forums.itrc.hp.com/service/forums/helptips.do?#33

Re: class "std::basic_ofstream attach function

sushant keerti — Mon, 18 Aug 2008 12:27:35 GMT

Dennis,
Thanks for the response.
Some more question I have for you
1: After attaching with logDest.open, how do you close the same. Actually in my code depending on some condition I am attaching it to either STDOUT or STDERR. So once I am done with the work, I need to close the same. How would you know logDest is attached to what, and correspondingly close the same.?
=======================================
2 : My application is getting core dump, while I stopping it. The gdb is not showing much info. Below is the gdb back trace of the same.

HP gdb 5.7 for HP Itanium (32 or 64 bit) and target HP-UX 11.2x.
Copyright 1986 - 2001 Free Software Foundation, Inc.
Hewlett-Packard Wildebeest 5.7 (based on GDB) is covered by the
GNU General Public License. Type "show copying" to see the conditions to
change it and/or distribute copies. Type "show warranty" for warranty/support.
..
Core was generated by `SCHEDULER'.
Program terminated with signal 6, Aborted.

#0 0xc00000000029da30:0 in kill+0x30 () from /usr/lib/hpux64/libc.so.1
(gdb) bt
#0 0xc00000000029da30:0 in kill+0x30 () from /usr/lib/hpux64/libc.so.1
#1 0xc0000000001c1bf0:0 in raise+0x30 () from /usr/lib/hpux64/libc.so.1
#2 0xc00000000025f610:0 in abort+0x190 () from /usr/lib/hpux64/libc.so.1
#3 0xc0000000018c5910:0 in std::terminate()+0x50 ()
from /usr/lib/hpux64/libCsup.so.1
#4 0xc0000000018ef520:0 in __cxxTerm+0x60 () from /usr/lib/hpux64/libCsup.so.1
#5 0xc0000000002072a0:0 in __exit_handler+0xa0 ()
from /usr/lib/hpux64/libc.so.1

Re: class "std::basic_ofstream attach function

Dennis Handly — Tue, 19 Aug 2008 03:40:49 GMT

>1: After attaching with logDest.open, how do you close the same.

That's the problem. It may close it more than once. I.e. you can't ever close that file. You can just flush it.

>So once I am done with the work, I need to close the same. How would you know logDest is attached to what, and correspondingly close the same?

Unfortunately there is no provision for doing that. :-(
So you need to use dup(2) to make a copy of STDOUT or STDERR and then it can be closed:

#include
int fd_file = dup(STDOUT_FILENO);
logDest.open(fd_file);

>2: My application is getting core dump, while I stopping it.

You are doing a throw out of a destructor that isn't caught, during static destruction. This is illegal, 15.5.1(1). In gdb, you need to use "catch throw" just before you exit, so you can catch it.

I'm not sure if it is due to the problem in 1) above?

Re: class "std::basic_ofstream attach function

sushant keerti — Tue, 19 Aug 2008 08:13:12 GMT

Dennis,
1 : Our application was dumping core due to close function call. In our application we were calling close like below

logDest.close();

I commented it and we are not getting the core !.

2 : I am getting compiler error, when I try to close with 1 argument as below

error #2140: too many arguments in function call
SYSLOG::logDest.close(STDOUT_FILENO);
^

3 : Is it OK, if you donot close, if you are done with the work?.
You said
int fd_file = dup(STDOUT_FILENO);
logDest.open(fd_file);

Againg open, after dup??? ( there is no close call??)

Re: class "std::basic_ofstream attach function

Dennis Handly — Tue, 19 Aug 2008 09:00:51 GMT

>I commented it and we are not getting the core!

Ok. You can do that or call dup(2).

>2: I am getting compiler error, when I try to close with 1 argument as below
SYSLOG::logDest.close(STDOUT_FILENO);

Why would you think that works? If it was that easy, I would have mentioned it. :-)

>3: Is it OK, if you do not close, if you are done with the work?

For stderr and stdout, they are never closed. But you should flush them.

>You said
>int fd_file = dup(STDOUT_FILENO);
>logDest.open(fd_file);
>Again open, after dup??? (there is no close call??)

Basically, replace that open by dup(2) then open. If you use dup(2), you can leave that close call there.

Re: class "std::basic_ofstream attach function

Kishan Rajagopal — Tue, 19 Aug 2008 10:40:08 GMT

Dennis
I and Sushant work in the same team,
The same piece of code is running fine on HP-UX 11.0, Can you please let us know if in the old versions you were ignoring the close call on STDIN and STDERR

Re: class "std::basic_ofstream attach function

Kishan Rajagopal — Tue, 19 Aug 2008 10:55:16 GMT

Sorry forgot to mention the compiler we were using,
Our application was running on HP-UX11.0 with aCC: HP ANSI C++ B3910B A.03.31 compiler.
Does the exe generated in this environment ignore the close call on STDIN and STDERR? As we are not getting any core file when we are bringing down the aplication in this environment.

Re: class "std::basic_ofstream attach function

Dennis Handly — Tue, 19 Aug 2008 18:22:26 GMT

>The same piece of code is running fine on HP-UX 11.00, Can you please let us know if in the old versions you were ignoring the close call on STDIN and STDERR

If you were using -AP and attach and detach, it wasn't the same code.

>As we are not getting any core file

If you were using -AP, iostream errors don't throw.