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

[David Holmes]

On 3/02/2020 10:35 pm, Baesken, Matthias wrote:
> 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."

I expect it to be applicable but does it actually do anything such that 
it is necessary to go and make these changes for /proc filesystem 
usages? This is probably harmless but it also seems somewhat unnecessary 
to do.

David

> 
> 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
>>>