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From "Martin Sebor (JIRA)" <j...@apache.org>
Subject [jira] Commented: (STDCXX-308) filebuf dtor doesn't close fd after exception
Date Thu, 23 Aug 2007 22:26:31 GMT

    [ https://issues.apache.org/jira/browse/STDCXX-308?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12522292
] 

Martin Sebor commented on STDCXX-308:
-------------------------------------

Filed issue 622:
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-active.html#622

> filebuf dtor doesn't close fd after exception
> ---------------------------------------------
>
>                 Key: STDCXX-308
>                 URL: https://issues.apache.org/jira/browse/STDCXX-308
>             Project: C++ Standard Library
>          Issue Type: Bug
>          Components: 27. Input/Output
>    Affects Versions: 4.1.2, 4.1.3
>         Environment: all
>            Reporter: Martin Sebor
>            Assignee: Martin Sebor
>
> -------- Original Message --------
> Subject: Re:  aCC 3.70 -AA fd's close not being called.
> Date: Thu, 7 Dec 2006 23:17:55 -0800 (PST)
> From: Dennis Handly <dhandly@cup.hp.com>
> To: sebor@roguewave.com
> CC: Boris.Gubenko@hp.com, al.simons@hp.com, dhandly@cup.hp.com
> It appears this problem is still in the apache code:
> http://svn.apache.org/repos/asf/incubator/stdcxx/trunk/include/fstream.cc
> It seems to violate 27.8.1.3(6), which says it always "finally" calls
> "as if" fclose(3).  And returns an error if any calls fail.
> ================================================================
> >From: "Levie, Barry" <barry.levie@hp.com>
> Date: Thu, 7 Dec 2006 15:36:33 -0000
> Subject: aCC 3.70 -AA fd's close not being called.
> I am not sure if this exactly represents the problem the customer is
> having as I am still waiting for more details (versions/test case etc
> etc). However this could be close and I think it shows a problem.
> Why does the ofstream destructor not close the file descriptor when its
> called after its thrown an exception for "out of disk space".  
> This aCC 3.70 -AA example shows an ever increasing number of open file
> descriptors in glance
> # what /usr/lib/libstd_v2.2:
>    HP aC++ B3910B A.03.30 C++ Standard Library (RogueWave Version 2.02.01)
> #include <iostream>
> #include <fstream>
> #include <string.h>
> using namespace std;
> struct dummy {
>    dummy() { cout << "\ndummy created \n" ;}
>    ~dummy() { cout << "\ndummy deleted \n"; }
> };
> void bar() {
>   char buf[1024*1024];
>   memset(buf,'A',1024*1024);
>   buf[1024*1024 -1] = 0;
>   ofstream of;
>   dummy df;
>   of.exceptions(ofstream::eofbit | ofstream::failbit | ofstream::badbit);
>   try {
>     of.open("/home/test.txt"); // this is on a volume that is nearly full.
>     while(1) {
>         of << buf;
>     }
>   }
>   catch(ofstream::failure& e) {
>     cout << "\nException write/file";
>   }
> }
> int main () {
>    while(1) bar();
> }
> # ./a.out
> dummy created
> msgcnt 160 vxfs: mesg 001: vx_nospace - /dev/vg00/lvol5 file system full
> (1 block extent)
> Exception write/file
> dummy deleted
> ....
> Glance output shows
> D  File Name              Type   Mode  Count Offset
> ---------------------------------------------------
>   0 /dev/pts/ta            stream rd/wr   6 333822
>   1 /dev/pts/ta            stream rd/wr   6 333822
>   2 /dev/pts/ta            stream rd/wr   6 333822
>   3 /home/test.txt         reg    write   1 101957632
>   4 /home/test.txt         reg    write   1 101957632
>   5 /home/test.txt         reg    write   1 101957632
> ...
> ================================================================
> >From: Dennis Handly <dhandly@cup.hp.com>
> Date: Thu, 7 Dec 2006 23:03:08 -0800 (PST)
> To: acxx@cup.hp.com, barry.levie@hp.com
> Subject: Re:  aCC 3.70 -AA fd's close not being called.
> >From: "Levie, Barry" <barry.levie@hp.com>
> >I am not sure if this exactly represents the problem the customer is
> >having as I am still waiting for more details (versions/test case etc
> >etc). However this could be close and I think it shows a problem.
> >Why does the ofstream destructor not close the file descriptor when its
> >called after its thrown an exception for "out of disk space".  
> A highly modified version works for me.
> And it isn't closed on the throw but by falling off the bar body.
> >This aCC 3.70 -AA example shows an ever increasing number of open file
> >descriptors in glance
> Hmm.
> ># what /usr/lib/libstd_v2.2:
> >   HP aC++ B3910B A.03.30 C++ Standard Library (RogueWave Version 2.02.01)
> This obsolete version isn't supported.
> Here is what I have and it shows close being called after I throw.
> I've manually modified the write return to -1 and that throws and is caught.
> (The debugger was broken and it didn't really happen.  )-:
> #include <iostream>
> #include <fstream>
> #include <string.h>
> #include <stdio.h>
> using namespace std;
> struct dummy {
>    dummy() { fprintf(stdout, "dummy created\n"); fflush(stdout); }
>    ~dummy() { fprintf(stdout, "dummy deleted\n"); fflush(stdout);  }
> };
> extern "C" int _close(int fd);
> extern "C" int close(int fd) {
>    if (fd > STDERR_FILENO) {
>       fprintf(stdout, "close(%d)\n", fd);
>       fflush(stdout);
>    }
>    return _close(fd);
> }
> char buf[1024];
> void bar() {
>    ofstream of;
>    dummy df;
>    of.exceptions(ofstream::eofbit | ofstream::failbit | ofstream::badbit);
>    try {
>       of.open("test.txt"); // this is on a volume that is nearly full.
>       fprintf(stdout, "FD = %d\n", of.rdbuf()->fd());
>       fflush(stdout);
>       for (int i = 0; i < 2; ++i)
>          of << buf;
>       throw ios_base::failure();
>    }
>    catch(ofstream::failure &e) {
>       fprintf(stdout, "Exception write/file\n");
>       fflush(stdout);
>    }
> }
> int main() {
>    memset(buf,'A',sizeof(buf));
>    buf[sizeof(buf)-1] = '\0';
>    int i;
>    for (i = 0; i < 10; ++i)
>       bar();
> }
> Ah, it's catch 22.  When it destroys ofstream it calls close, which calls
> overflow which calls _C_write which calls write which gets an error and
> then returns before closing.
> It seems it is working as designed be RW.
> But this seems to violate 27.8.1.3(6), which says it always calls
> fclose(3).
> File a CR.

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