Re: Help debugging Re: bug report

[David Kaelbling]

Is this from the first or second invocation of gtroff?  As I was trying
to explain in my previous message man will invoke the format command
twice: once with all the file descriptors closed just to see if it
exists, and a second time with them open to do the work.

        David

Mathew Yeates wrote:
> 
> Okay, this is all I've been able to figure out. I'm getting an error in
> real_output_file::~real_output_file() of node.cc of gtroff. Line 1519.
> I inserted a perror and got "No such file or directory".
> 
> Here is a bit of the system strace. Notice that file descriptors 0,1,2
> appear to be have been detached from stdin,stdout and stderr. My guess
> (and its only a guess), is that because 0,1,2 have been closed by sgi's man,
> when gtroff tries to printf or puts, it fails.
> 
> Mathew
> 
>  144mS[  7]          gtroff(5017124): read(1, ".\" final startup file for 
> tro",
>  4096) = 694
>   145mS[  7]          gtroff(5017124): read(1, 0x10104788, 4096) = 0
>   145mS[  7]          gtroff(5017124): close(1) OK
>   145mS[  7]          gtroff(5017124): ioctl(0, __OLD_TCGETA, 0x7fff2a10) 
> errno
> = 25 (Inappropriate I/O control operation)
>   145mS[  7]          gtroff(5017124): read(0, "\n# eof\n", 4096) = 7
>   145mS[  7]          gtroff(5017124): read(0, 0xfb5d110, 4096) = 0
>   146mS[  7]          gtroff(5017124): write(2, "gtroff: fatal error: ", 21)
> err
> no = 9 (Bad file number)
>   146mS[  7]          gtroff(5017124): write(2, "error writing output fil"
> , 32) errno = 9 (Bad file number)
>   146mS[  7]          gtroff(5017124): prctl(PR_LASTSHEXIT) = 1
>   146mS[  7]          gtroff(5017124): write(1, "x T ascii\nx res 240 24 40\nx
> i
> n", 104) errno = 9 (Bad file number)
>   146mS[  7]                (5018038): was sent signal SIGCLD
>   146mS[  7]          gtroff(5017124): exit(1)
> 
> > I looked through the source for man.  It closes fd's 0,1,2 before doing
> > an exec in the specific case where it is testing to see if a filter
> > exists.  (It's in "forkandexeclp", if you have some similar source to
> > browse.)  This invocation is expected to die.
> >
> > Later on man will fork() again and use system() to actually run the
> > filter.  You can use "man -p" to see what commands it would run.
> >
> >       David
> >
> > Mathew Yeates wrote:
> > >
> > > I'm tryin to debug groff running on SGI Irix 6.5.
> > >
> > > When I do a system trace on man I see that file descriptors 0,1,2 are
> > > closed by make immediately prior to gnroff being forked. Is this correct
> > > behavior? I tried adding the line "echo HELLO" near the beginning of
> > > gnroff and, as expected, this fails with a "bad file descriptor" message
> > > in my trace.
> > >
> > > Does that happen with other OS's?
> >
> > --
> > David KAELBLING <address@hidden>     Silicon Graphics Computer Systems
> > 1 Cabot Rd, suite 250; Hudson, MA 01749           781.839.2157, fax ...2357

-- 
David KAELBLING <address@hidden>            Silicon Graphics Computer Systems
1 Cabot Rd, suite 250; Hudson, MA 01749     781.839.2157, fax ...2357