debugging rlimit

[Eric Blake <eblake at redhat dot com>]

How am I supposed to debug code related to rlimit, when it appears that
gdb/strace resets it to default values?

$ cat foo.c
#include <stdio.h>
#include <unistd.h>
#include <sys/resource.h>
int main(void) {
  struct rlimit r;
  if (!getrlimit(RLIMIT_NOFILE, &r))
    printf("%ld %ld\n", r.rlim_cur, r.rlim_max);
  return 0;
}
$ ./foo
256 3200
$ (ulimit -n 1000; ./foo)
1000 3200
$ (ulimit -n 1000; strace -o /dev/null ./foo)
256 3200

Since rlimit is intertwined with getdtablesize(), I'd like to be able to
debug a process that starts with a different limit than normal.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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