A NOTE has been added to this issue. ====================================================================== https://www.austingroupbugs.net/view.php?id=1834 ====================================================================== Reported By: Don Cragun Assigned To: ====================================================================== Project: 1003.1(2024)/Issue8 Issue ID: 1834 Category: System Interfaces Type: Error Severity: Editorial Priority: normal Status: New Name: Don Cragun Organization: User Reference: Section: strlen() & wcslen() Page Number: 2147, 2380 Line Number: 70218-70220, 77131-77134 Interp Status: --- Final Accepted Text: ====================================================================== Date Submitted: 2024-06-20 00:26 UTC Last Modified: 2024-07-10 01:31 UTC ====================================================================== Summary: strnlen() & wcsnlen() descriptions use of "terminating" NUL character ======================================================================
---------------------------------------------------------------------- (0006831) eblake (manager) - 2024-07-10 01:31 https://www.austingroupbugs.net/view.php?id=1834#c6831 ---------------------------------------------------------------------- At https://lists.gnu.org/archive/html/bug-gnulib/2024-07/msg00094.html, Paul Eggert argues: <blockquote> > at which point, strnlen("", SIZE_MAX)_is_ allowed to_access_ beyond > the NUL byte, No it wouldn't, because strnlen must stop counting at the first null byte. If this point isn't made clear in the current proposal, it should be made clear. Lots of user code relies on strnlen doing the right thing even if the string is shorter than n. In practice implementations that screw up in this area, and are incompatible with glibc etc., are deemed broken and are fixed. The standard should not allow further breakage. </blockquote> The proposed wording allows an implementation to access beyond the NUL when a string is passed in, and Paul is arguing that the standard should be stricter and stop accessing at the first NUL or at n bytes, whichever is first (implying a specific linear access pattern, and preventing optimizations such as dividing the array in two, calculating constrained lengths on both halves in parallel, and then doing the appropriate math to return the correct answer even if more bytes than the returned value were accessed). That is, Paul wants code like this (present in the wild) to "work": len = strnlen (string, precision <= 0 ? SIZE_MAX : precision); Issue History Date Modified Username Field Change ====================================================================== 2024-06-20 00:26 Don Cragun New Issue 2024-06-20 00:26 Don Cragun Name => Don Cragun 2024-06-20 00:26 Don Cragun Section => strlen() & wcslen() 2024-06-20 00:26 Don Cragun Page Number => 2147, 2380 2024-06-20 00:26 Don Cragun Line Number => 70218-70220, 77131-77134 2024-06-20 00:26 Don Cragun Interp Status => --- 2024-06-20 00:38 Don Cragun Description Updated 2024-06-20 00:38 Don Cragun Desired Action Updated 2024-06-20 11:15 geoffclare Note Added: 0006820 2024-06-20 14:30 Don Cragun Note Added: 0006821 2024-06-20 14:32 Don Cragun Note Edited: 0006821 2024-06-20 14:57 geoffclare Note Added: 0006822 2024-06-20 15:33 Don Cragun Note Added: 0006823 2024-06-20 18:22 eblake Note Added: 0006824 2024-06-21 15:24 nick File Added: n3252b.pdf 2024-06-21 15:28 nick Note Added: 0006830 2024-07-10 01:31 eblake Note Added: 0006831 ======================================================================
