because struct stat is no longer assumed to correspond to the structure used by the stat-family syscalls, it's not valid to make any of these syscalls directly using a buffer of type struct stat. commit 9493892021eac4edf1776d945bcdd3f7a96f6978 moved all logic around this change for stat-family functions into fstatat.c, making the others wrappers for it. but a few other direct uses of the syscall were overlooked. the ones in tmpnam/tempnam are harmless since the syscalls are just used to test for file existence. however, the uses in fchmodat and __map_file depend on getting accurate file properties, and these functions may actually have been broken one or more mips variants due to removal of conversion hacks from syscall_arch.h. as a low-risk fix, simply use struct kstat in place of struct stat in the affected places.
these did not truncate excess precision in the return value. fixing them looks like considerable work, and the current C code seems to outperform them significantly anyway. long double functions are left in place because they are not subject to excess precision issues and probably better than the C code.
this commit is for the sake of reviewable history.
analogous to commit 1c9afd69051a64cf085c6fb3674a444ff9a43857 for atan[2][f].
for functions implemented in C, this is a requirement of C11 (F.6); strictly speaking that text does not apply to standard library functions, but it seems to be intended to apply to them, and C2x is expected to make it a requirement. failure to drop excess precision is particularly bad for inverse trig functions, where a value with excess precision can be outside the range of the function (entire range, or range for a particular subdomain), breaking reasonable invariants a caller may expect.
this extends commit 5a105f19b5aae79dd302899e634b6b18b3dcd0d6, removing timer[fd]_settime and timer[fd]_gettime. the timerfd ones are likely to have been used in software that started using them before it could rely on libc exposing functions.
this extends commit 5a105f19b5aae79dd302899e634b6b18b3dcd0d6, removing clock_settime, clock_getres, clock_nanosleep, and settimeofday.
catan was fixed in 10e4bd3780050e75b72aac5d85c31816419bb17d but the same bug in catanf and catanl was overlooked. the patch is completely analogous.
some nontrivial number of applications have historically performed direct syscalls for these operations rather than using the public functions. such usage is invalid now that time_t is 64-bit and these syscalls no longer match the types they are used with, and it was already harmful before (by suppressing use of vdso). since syscall() has no type safety, incorrect usage of these syscalls can't be caught at compile-time. so, without manually inspecting or running additional tools to check sources, the risk of such errors slipping through is high. this patch renames the syscalls on 32-bit archs to clock_gettime32 and gettimeofday_time32, so that applications using the original names will fail to build without being fixed. note that there are a number of other syscalls that may also be unsafe to use directly after the time64 switchover, but (1) these are the main two that seem to be in widespread use, and (2) most of the others continue to have valid usage with a null timeval/timespec argument, as the argument is an optional timeout or similar.