Re: sigprocmask.c appears to be incompatible w/ system headers

[Bruno Haible]

Godfrey, Keith wrote:
> Output of the commands are attached

In make.txt you have this command:

/bin/sh ../libtool --tag=CC   --mode=link gcc  -g -O2 -pthread  -no-undefined  
-lm     -lm -lm -lm -lm -L/global/home/keith/lib -o libgnu.la  c-ctype.lo 
c-strcasecmp.lo c-strncasecmp.lo close-hook.lo exitfail.lo localcharset.lo 
malloca.lo openat-die.lo progname.lo sockets.lo strnlen1.lo asnprintf.lo 
basename-lgpl.lo chdir-long.lo cloexec.lo dirname-lgpl.lo dup-safer.lo fcntl.lo 
fd-safer.lo filemode.lo getcwd.lo getopt.lo getopt1.lo glob.lo md5.lo 
nanosleep.lo openat-proc.lo pipe-safer.lo printf-args.lo printf-parse.lo 
save-cwd.lo strftime.lo stripslash.lo tempname.lo vasnprintf.lo  -lm  

There is no sigprocmask.lo in this list. This is normal; gnulib's sigprocmask.c
is not compiled on glibc systems. You can see from the gnulib documentation
<http://www.gnu.org/software/gnulib/manual/html_node/sigprocmask.html>
that this source file is only compiled on mingw platforms.

Also, the generated signal.h is built with HAVE_SIGSET_T being replaced with 1,
therefore it does not redefine the 'sigset_t' type.

In <https://savannah.gnu.org/bugs/?30685> you write:
> A change (similar to Leonardo's) that seems to work while theoretically 
> maintaining sigaction
> functionality is to explicitly call the sigemptyset macro (bits/sigset.h):  
>  
> octave-3.4.0/src/sighandlers.cc line 225 
>  //gnulib::sigemptyset (&act.sa_mask); 
>  //gnulib::sigemptyset (&oact.sa_mask); 
>  //gnulib::sigaction (sig, &act, &oact); 
>  __sigemptyset (&act.sa_mask); 
>  __sigemptyset (&oact.sa_mask); 
>  sigaction (sig, &act, &oact); 
>  
> (only removing the namespace didn't work for me either) 

This indicates that the crucial difference is between the __sigemptyset
macro and the sigemptyset functions, both from glibc.

Or if 'sigemptyset' would work fine, then the crucial difference would
be in the function pointer indirection by which gnulib implements the
'gnulib::sigemptyset' function in term of the 'sigemptyset' function
pointer.

In order to debug this, I would recommend to look at

  - the source code of the __sigemptyset macro and of the sigemptyset
    function,

  - the assembly level instructions where it crashes:

     #0  0xb785896c in sigemptyset () from 
/home/muttoni/a/octave-3.3.53/src/.libs/liboctinterp-3.3.53.so

    because it's not clear why liboctinterp-3.3.53.so would contain
    a sigemptyset function at all (since gnulib's one is not being
    compiled).

  - the preprocessed source file (g++ -E -dD) of the compilation unit
    that contains the gnulib::sigemptyset invocation.

Bruno