RFR: 8238161: use os::fopen in HS code where possible

[Baesken, Matthias]

Hi David, from what I understand it should behave in the same way it does when a file descriptor to a "normal" file is opened .
At least checking for  the FD_CLOEXEC   flag for such an fd  works as expected 

  /* check that O_CLOEXEC works */
  int fd = open64("/proc/cpuinfo", O_CLOEXEC, 0444);
  int flags;

  flags = ::fcntl(fd, F_GETFD);
  if (flags != -1) {
    if ((flags & FD_CLOEXEC) != 0) {
      printf("setting O_CLOEXEC with open seems to work.\n");
    } else {
      printf("PROBLEM setting O_CLOEXEC with open !\n");
    }
  }


 ... outputs  :  "setting O_CLOEXEC with open seems to work."


Best regards, Matthias




> Hi Matthias,
> 
> Does close-on-exec have any meaning when applied to /proc filesystem ??
> 
> Thanks,
> David
> 
> On 31/01/2020 1:47 am, Baesken, Matthias wrote:
> > Please review this change which adjusts a number of calls (in HS code)
> from using  fopen  to os::fopen .
> >
> > There exists for some time  a function os::fopen in HS code . This function
> sets "close-on-exec" flags (when possible) to the opened filedescriptor.
> > It might have some benefits to use os::fopen more in HS code, currently
> there are still quite a few calls directly to fopen .
> > (however there are also  already a number of calls to os::fopen  e.g.    some
> calls   in  os_linux.cpp /os_solaris.cpp should already look up  os::fopen  , and
> logFileOutput.cpp  uses os::fopen directly   )
> >
> >
> > see also the thread
> > https://mail.openjdk.java.net/pipermail/hotspot-dev/2020-
> January/040641.html
> > on hotspot-dev about the topic.
> >
> >
> >
> > Bug/webrev :
> >
> > https://bugs.openjdk.java.net/browse/JDK-8238161
> >
> > http://cr.openjdk.java.net/~mbaesken/webrevs/8238161.0/
> >
> >
> > Thanks, Matthias
> >