Re: Possible bug?

["D Burgess" <db@...>]

Refer http://lua-users.org/lists/lua-l/2004-07/msg00430.html

regards
David B

On 2004-08-03 at 00:13:10 David Given <dg@cowlark.com> wrote:

>I think I've just found a bug in Lua.
>
>In liolib.c, there's the following code in aux_close():
>
>    int ok = (pclose(f) != -1) || (fclose(f) == 0);
>
>That is, it first tries to close the file with pclose(), and if that fails, it 
>tries to close the file with fclose(). It does this on all files, regardless 
>of how they were opened.
>
>Unfortunately, it's not legal to call pclose() on a file that wasn't allocated 
>with popen(). This causes it to fall over on my embedded device. My libc's 
>implementation of pclose() calls fclose() and then wait(). wait() is failing 
>because there are no children; which means than pclose() is returning an 
>error code; which is causing Lua to call fclose() again; which is causing a 
>crash.
>
>I refer you to the Posix standard:
>
>http://www.opengroup.org/onlinepubs/009695399/functions/pclose.html
>> If the stream pointed to by stream was not created by popen(), historical
>> implementations of pclose() return -1 without setting errno. To avoid
>> requiring pclose() to set errno in this case, IEEE Std 1003.1-2001 makes the
>> behavior unspecified. An application should not use pclose() to close any
>> stream that was not created by popen().    
>
>Most desktop libc implementations check to make sure the file was allocated by 
>popen() before touching it, which is why this hasn't come up before, but as 
>the above document says, this isn't required.
>
>Fixing this is going to be annoying, because it means that the file userdata 
>is going to have to become two quads instead of just one, because Lua is 
>going to have to keep track of how the file was opened. Alternatively it 
>might be easier to keep a table somewhere of fopen() files vs. popen() files. 
>I don't think there's any standard-compliant way of distinguishing the two 
>types at run-time.
>
>Any comments?
>
>-- 
>+- David Given --McQ-+ "Quantum materiae materietur marmota monax si
>|  dg@cowlark.com    | marmota monax meteriam possit materiari?" --- Henry
>| (dg@tao-group.com) | Beard
>+- www.cowlark.com --+ 
>