A NOTE has been added to this issue. ====================================================================== https://austingroupbugs.net/view.php?id=1493 ====================================================================== Reported By: geoffclare Assigned To: ====================================================================== Project: 1003.1(2016/18)/Issue7+TC2 Issue ID: 1493 Category: Shell and Utilities Type: Enhancement Request Severity: Comment Priority: normal Status: New Name: Geoff Clare Organization: The Open Group User Reference: Section: 2.7 Page Number: 2360 Line Number: 75306 Interp Status: --- Final Accepted Text: ====================================================================== Date Submitted: 2021-07-29 14:33 UTC Last Modified: 2021-07-29 16:49 UTC ====================================================================== Summary: move XCU 2.7 definition of "file descriptor" into XBD 3 ======================================================================
---------------------------------------------------------------------- (0005422) kre (reporter) - 2021-07-29 16:49 https://austingroupbugs.net/view.php?id=1493#c5422 ---------------------------------------------------------------------- I have no problem with this change in general, though there are a couple of wording changes (just cleanups) I'll suggest in some later note if no-one else gets there first, but this part: The file descriptor underlying stdin is initially 0; this cannot change through the use of interfaces defined in this standard, (and the similar limitations expresseed for stdout and stderr) looks to be simply wrong to me. I'm also not sure there's any need to actually make this point, even if it were true. But consider close(fileno(stdin)); fd = open("/dev/null", 0); freopen("/my/file", "r", stdin); (use fdopen() instead of open() if you prefer, but not fclose() as any use of any stream after it has been fclose'd is undefined, as its data struct may have been discarded). I'm not sure what file descriptor you expect freopen() to assign in that case (assuming the open of /my/file succeeds, etc, of course), but it isn't usually going to be 0, and this is using only interfaces defined by the standard, I believe. Note that freopen() specifically says: If pathname is not a null pointer, freopen() shall close any file descriptor associated with stream. Failure to close the file descriptor successfully shall be ignored. That is, freopen() is defined to work properly if the file descriptor has already been closed (some systems may have other reasons for the close failing, allowing for a different fd to be returned from the open, but that would be using something beyond the standard interfaces I think). Issue History Date Modified Username Field Change ====================================================================== 2021-07-29 14:33 geoffclare New Issue 2021-07-29 14:33 geoffclare Name => Geoff Clare 2021-07-29 14:33 geoffclare Organization => The Open Group 2021-07-29 14:33 geoffclare Section => 2.7 2021-07-29 14:33 geoffclare Page Number => 2360 2021-07-29 14:33 geoffclare Line Number => 75306 2021-07-29 14:33 geoffclare Interp Status => --- 2021-07-29 16:49 kre Note Added: 0005422 ======================================================================
