On 06/04/2018 22:01, Martin Buchholz wrote:
STDERR_FILENO is 2 so I'm curious which error reporting pipe is bring
discussed here. The jimage file is opened very early when initializing
the VM so it will get a low file descriptor number, seems to be 3. The
only surprise is that it doesn't close as it shouldn't need the file
descriptor after it mmapped.
The design on Unix was that all file descriptors greater than 3 are
closed on fork and before exec.
But regardless of that, we should try to set the CLOEXEC bit on all
our file descriptor (who knows, there might be native code that does
File descriptor 3 is indeed deep magic, used for error reporting.
It's a serious bug if FAIL_FILENO ends up being used for something
other than the error reporting pipe.
I don't think I'm the last (or the first!) person who touched this.