realpath() in my env doesn't like NULL as second argument?

Question

I'm on a linux box and /proc/self/exe does seem to be supported:

ls -l /proc/self/exe shows that it's linked to /usr/bin/ls at the moment I run the command
realpath /proc/self/exe prints out /usr/bin/realpath as expected
both commands exit with status 0

But:

if (NULL == realpath("/proc/self/exe", NULL))
{
  printf("this prints unexpectedly, %s\n", strerror(errno));
}

At this point, errno is 22 and I see Invalid argument. Why? Or -- how does one figure out why?

Well, you should check you glibc package version (which disto is it?). But 2.2 is lower than 2.3, so my answer is valid. — Eugene Sh., Jan 20 '17 at 23:11

score 4 · Accepted Answer · answered Jan 20 '17 at 20:33

4

This behavior would occur on glibc versions below 2.3 as stated in man realpath:

ERRORS
............
EINVAL - path is NULL. (In glibc versions before 2.3, this error is also returned if resolved_path is NULL.)

answered Jan 20 '17 at 20:33

Eugene Sh.

1 Answers1