gdb x86_64 ERESTARTNOHAND

gdb x86_64 ERESTARTNOHAND

[Rich Coe]

Run the program below in gdb on x86_64, compiled either -m32 or 64 bit,
    stop the execution with control-C
    call a function, in this case doNothing(), but sleep(1) works as well
    continue
gdb passes errno 514 to the program.  514=ERESTARTNOHAND

I see that strace prints out information about ERESTARTNOHAND, so it knows
about it.  I was wondering if gdb should know about this, is this an 
x86_64 kernel error, or what?

Even though strace knows about ERESTARTNOHAND on i386, and prints it,
gdb does not print or cause the program to receive this errno on a 32bit kernel.

-- 
Rich Coe		richard.coe@med.ge.com
General Electric Healthcare Technologies
Global Software Platforms, Computer Technology Team

#include <stdio.h>
#include <sys/select.h>
#include <errno.h>
#include <signal.h>

int myselect(int fd, void* ptr)
{
    printf("myselect\n");
    fd_set in;

AGAIN:
    FD_ZERO(&in);
    FD_SET(fd, &in);

    if(select(32, &in, 0, 0, 0) == -1)
    {
        printf("select error=%d: %s\n", errno, strerror(errno));
    }

    goto AGAIN;

   return 0;
}

int func_two(int fd, void* ptr)
{
    printf("func_two\n");
    return myselect(fd, ptr);
}

int func_one(int fd, void*ptr)
{
    printf("func_one\n");
    return func_two(fd, ptr);
}

void catch(int sig)
{
    char buf[218];
    sprintf(buf, "caught %d\n", sig);
    write(fileno(stdout), buf, strlen(buf));
}

void docatch()
{
    struct sigaction act = { 0 } ;

    act.sa_handler = catch;
    //act.sa_mask = 0;
    act.sa_flags = 0;
    /* auto restart interrupted system calls */
    act.sa_flags = SA_RESTART;

    if(sigaction(SIGINT, &act, NULL) < 0) {
        perror(__FILE__ ": sigaction");
        exit(1);
    }
    if(sigaction(SIGHUP, &act, NULL) < 0) {
        perror(__FILE__ ": sigaction");
        exit(1);
    }
    if(sigaction(SIGTERM, &act, NULL) < 0) {
        perror(__FILE__ ": sigaction");
        exit(1);
    }
}

int a = 0;

void
doNothing()
{
    a += 5;
}

int main(int argc, char*argv[])
{
    doNothing();
    docatch();
    printf("main\n");
    return func_one(fileno(stdin), myselect);
}

Re: gdb x86_64 ERESTARTNOHAND

[Daniel Jacobowitz]

On Tue, Jun 14, 2005 at 08:54:25AM -0500, Rich Coe wrote:
> Run the program below in gdb on x86_64, compiled either -m32 or 64 bit,
>     stop the execution with control-C
>     call a function, in this case doNothing(), but sleep(1) works as well
>     continue
> gdb passes errno 514 to the program.  514=ERESTARTNOHAND
> 
> I see that strace prints out information about ERESTARTNOHAND, so it knows
> about it.  I was wondering if gdb should know about this, is this an 
> x86_64 kernel error, or what?
> 
> Even though strace knows about ERESTARTNOHAND on i386, and prints it,
> gdb does not print or cause the program to receive this errno on a 32bit kernel.

amd64-linux-tdep.c requires a write_pc method, just like the one in
i386-linux-tdep.c.  Nice catch.

-- 
Daniel Jacobowitz
CodeSourcery, LLC

Re: gdb x86_64 ERESTARTNOHAND

[Rich Coe]

when running 32bit apps on a 64bit system, doesn't gdb use
i386-linux-tdep ?

On Tue, 14 Jun 2005 10:32:52 -0400
Daniel Jacobowitz <drow@false.org> wrote:
> On Tue, Jun 14, 2005 at 08:54:25AM -0500, Rich Coe wrote:
> > Run the program below in gdb on x86_64, compiled either -m32 or 64 bit,
> >     stop the execution with control-C
> >     call a function, in this case doNothing(), but sleep(1) works as well
> >     continue
> > gdb passes errno 514 to the program.  514=ERESTARTNOHAND
> > 
> > I see that strace prints out information about ERESTARTNOHAND, so it knows
> > about it.  I was wondering if gdb should know about this, is this an 
> > x86_64 kernel error, or what?
> > 
> > Even though strace knows about ERESTARTNOHAND on i386, and prints it,
> > gdb does not print or cause the program to receive this errno on a 32bit kernel.
> 
> amd64-linux-tdep.c requires a write_pc method, just like the one in
> i386-linux-tdep.c.  Nice catch.
> 
> -- 
> Daniel Jacobowitz
> CodeSourcery, LLC
> 


-- 
Rich Coe		richard.coe@med.ge.com
General Electric Healthcare Technologies
Global Software Platforms, Computer Technology Team

Re: gdb x86_64 ERESTARTNOHAND

[Daniel Jacobowitz]

On Tue, Jun 14, 2005 at 03:19:27PM -0500, Rich Coe wrote:
> when running 32bit apps on a 64bit system, doesn't gdb use
> i386-linux-tdep ?

It ought to.  I hadn't stopped to think about that; it's odd that you
see the problem for -m32.  I'm afraid I can't guess why without time to
reproduce it myself.

The 64-bit file probably wants a fix for this, anyway.

-- 
Daniel Jacobowitz
CodeSourcery, LLC