libstdc++/4442: bad fstream behavior <synopsis of the problem (one line)>

[Andrew Haydn Grant]

>Number:         4442
>Category:       libstdc++
>Synopsis:       bad fstream behavior
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Oct 02 11:56:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Andrew Haydn Grant
>Release:        3.0.1
>Organization:
>Environment:
System: Linux Goof 2.2.14-5.0 #1 Tue Mar 7 21:07:39 EST 2000 i686 unknown
Architecture: i686

	
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: /usr/local/src/gcc-3.0.1/configure 
>Description:
fstreams handle certain odd situations differently than they used to,
causing old code to break.

This code contains C++ less-than operators, so I don't know if the bug
program will turn them into comment characters.

void fail()
{
  fstream f;
  f.close();
  f.open("hello.txt", ios::in);
  char buffer[2048];
  f.getline(buffer, 2048);
  cout << "FILE CONTENTS" << buffer << "FILE CONTENTS\n";
}

The fail() function does not read "hello.txt".  If you remove the initial
f.close() call, it reads "hello.txt" without difficulty.

void failWrite()
{
  fstream f;
  f.open("/tmp/empire/simout.txt", ios::in);
  f.close();
  f.open("/tmp/empire/simout.txt", ios::out);
  f << "It went out!!!\n";
}

If the simout.txt file does NOT exist, the second open succeeds, 
but the << operator fails.  If the simout file ALREADY exists, then all 
operations succeed.

	
>How-To-Repeat:
	
>Fix:
To work around the problem, only use a given fstream object for one file operation.  Avoid spurious close() calls.

	
>Release-Note:
>Audit-Trail:
>Unformatted: