bin/48616: ld.elf_so errno causes confusing gdb output

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         48616
>Category:       bin
>Synopsis:       ld.elf_so errno causes confusing gdb output
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Feb 25 08:30:00 +0000 2014
>Originator:     Andreas Gustafsson
>Release:        6.1.3
>Organization:
>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

libc and ld.elf_so both contain a variable called "errno".  If you
debug an ordinary single-threaded dynamically linked program using gdb
and enter "print errno", gdb prints the ld.elf_so errno, which is
confusing for the user who was probably more interested in the libc
one.

>How-To-Repeat:

cat >testcase.c <<EOF
#include <errno.h>
#include <stdlib.h>
int main(int argc, char **argv) {
    errno = 42;
    abort();
    return 0;
}
EOF
cat >test.gdb <<EOF
run
print errno
info variables ^errno$
EOF
cc -g testcase.c -o testcase
gdb --batch -x test.gdb ./testcase

This will output "$1 = 2" rather than the expected "$1 = 42", and the
"info variables" command shows two errno variables at different
addresses:

  0x00007f7ff7e13830  errno
  0x00007f7ff7b3a704  errno

>Fix:

Perhaps rename the ld.elf_so errno?