|PROC_INITSTDIO(3PROC)||Process Control Library Functions||PROC_INITSTDIO(3PROC)|
proc_finistdio — stdio
Process Control Library (libproc, -lproc)
proc_finistdio() functions are utilities provided to
aid with the possibility of deadlock while doing I/O operations. If a
process is trying to do I/O, but holding the process handle that would
consume that I/O, then eventually the program holding the process handle
will block as none of its I/O has been drained. However, because it is
holding a process handle to that process, it will never be drained.
Consider, for example, the following invocation:
pfiles `pgrep xterm` where the command was launched
from a shell on an xterm. Because the xterm is stopped, it will not be able
to write out any of the standard out that gets passed to it, leading to a
pfiles program cannot release the
xterm process because it still has pending I/O, but
the I/O cannot be drained due to the same hold.
To address this, these functions duplicate the standard output and standard error of the process to temporary files and then flushes it out to the original file descriptors and streams later. When finished, the original file descriptors are restored as standard out and standard error.
function initializes a new standard out and standard error file descriptors
and retains the originals.
functions flushes all of the cached data from the temporary standard out and
standard error back to the underlying ones. This function should only be
called after all process handles have been released. For example, if
iterating on multiple processes, calling this after handling each one is
flushes any outstanding I/O and restores the original standard output and
Once called, the
function must not be called again until a successful call to
|May 11, 2016||OmniOS|