TZ containg a timezone name with >TZNAME_MAX characters currently
breaks musl's timezone parsing. getname() stops after TZNAME_MAX
characters. getoff() will consume no characters (because the next
character is not a digit) and incorrectly return 0. Then, because
there are remaining alphabetic characters, __daylight == 1, and
dst_off == -3600.

getname() must consume the entire timezone name, even if it will not
fit in d/__tzname, so when it returns, s points to the offset digits.

Parsing the timezone name must stop when reaching the null terminator.
In that case, there is no '>' to skip.

Commit d9bdfd16 ("fix memccpy to not access buffer past given size")
correctly added a check for 'n' nonzero, but made the pre-existing test
'*s==c' redundant: n!=0 implies *s==c. Remove the unnecessary check.

Reported by Alexey Izbyshev.

change the current O(n) lookup to O(1) based on the machinery
described in "How To Write Shared Libraries" (Appendix B).

kernel commit 4693916846269d633a3664586650dbfac2c5562f (first included
in release v4.14) silently fixed a bug whereby the reserved space
(which was later used for high bits of time) in IPC_STAT structures
was left untouched rather than zeroed. this means that a caller that
wants to read the high bits needs to pre-zero the memory.

since it's not clear that these operations are permitted to modify the
destination buffer on failure, use a temp buffer and copy back to the
caller's buffer on success.

commit 59324c8b added __socketcall
analogous to __syscall, returning the negated error rather than
setting errno. use it to simplify the fallback path of socket(),
avoiding extern calls and access to errno.

Author: Rich Felker <dalias@aerifal.cx>
Date:   Tue Jul 30 17:51:16 2019 -0400

    make __socketcall analogous to __syscall, error-returning

this reverts commit 4ee039f3, which
added the helper as a hack to make vdprintf usable before relocation,
contingent on strong assumptions about the arch and tooling, back when
the dynamic linker did not have a real staged model for
self-relocation. since commit f3ddd173
this has been unnecessary and the function was just wasting size and
execution time.

The final rounding operation should be done with the correct sign
otherwise huge results may incorrectly get rounded to or away from
infinity in upward or downward rounding modes.

This affected sinh and sinhf which set the sign on the result after
a potentially overflowing mul. There may be other non-nearest rounding
issues, but this was a known long standing issue with large ulp error
(depending on how ulp is defined near infinity).

The fix should have no effect on sinh and sinhf performance but may
have a tiny effect on cosh and coshf.

Handle when after reduction |y| > pi/4+tiny. This happens in directed
rounding modes because the fast round to int code does not give the
nearest integer. In such cases the reduction may not be symmetric
between x and -x so e.g. cos(x)==cos(-x) may not hold (but polynomial
evaluation is not symmetric either with directed rounding so fixing
that would require more changes with bigger performance impact).

The fix only adds two predictable branches in nearest rounding mode,
simple ubenchmark does not show relevant performance regression in
nearest rounding mode.

The code could be improved: e.g reducing the medium size threshold
such that two step reduction is enough instead of three, and the
single precision case can avoid the issue by doing the round to int
differently, but this fix was kept minimal.

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 94938920 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 1c9afd69 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 5a105f19, 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 5a105f19, removing
clock_settime, clock_getres, clock_nanosleep, and settimeofday.

catan was fixed in 10e4bd37 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.

For Thumb2 compatibility, replace two instances of a single
instruction "orr with a variable shift" with the two instruction
equivalent. Neither of the replacements are in a performance critical
loop.

commit 1b0ce9af introduced this bug
back in 2012 and it was never noticed, presumably since the affected
planes are essentially unused in Unicode.

this interface contract is entirely internal to dynlink.c.

adding this condition makes the entire convert_ioctl_struct function
and compat_map table statically unreachable, and thereby optimized out
by dead code elimination, on archs where they are not needed.

VIDIOC_OMAP3ISP_STAT_REQ is a device-specific command for the omap3isp
video device. the command number is in a device-private range and
therefore could theoretically be used by other devices too in the
future, but problematic clashes should not be able to arise without
intentional misuse.

there's only one matching entry for any given command so this had no
functional distinction, but additional loops are pointless and
wasteful.

commit ae388bec accidentally
introduced #define SYSCALL_NO_TLS 1 in mmap.c, which was probably a
stale change left around from unrelated syscall timing measurements.
reverse it.

this commit covers all remaining ioctls I'm aware of that use
time_t-derived types in their interfaces. it may still be incomplete,
and has undergone only minimal testing for a few commands used in
audio playback.

the SNDRV_PCM_IOCTL_SYNC_PTR command is special-cased because, rather
than the whole structure expanding, it has two substructures each
padded to 64 bytes that expand within their own 64-byte reserved zone.
as long as it's the only one of its type, it doesn't really make sense
to make a general framework for it, but the existing table framework
is still used for the substructures in the special-case. one of the
substructures, snd_pcm_mmap_status, has a snd_pcm_uframes_t member
which is not a timestamp but is expanded just like one, to match the
64-bit-arch version of the structure. this is handled just like a
timestamp at offset 8, and is the motivation for the conversions table
holding offsets of individual values to be expanded rather than
timespec/timeval type pairs.

for some of the types, the size to which they expand is dependent on
whether the arch's ABI aligns 8-byte types on 8-byte boundaries.
new_req entries in the table need to reflect this size to get the
right ioctl request number that will match what callers pass, but we
don't have access to the actual structure type definitions here and
duplicating them would be cumbersome. instead, the new_misaligned
macro introduced here constructs an artificial object whose size is
the result of expanding a misaligned timespec/timeval to 64-bit and
imposing the arch's alignment on the result, which can be passed to
the _IO{R,W,WR} macros.

record offsets of individual slots that expand from 32- to 64-bit,
rather than timespec/timeval pairs. this flexibility will be needed
for some ioctls. reduce size of types in table. adjust representation
of offsets to include a count rather than needing -1 padding so that
the table is less ugly and doesn't need large diffs if we increase max
number of slots.

with the current set of supported ioctls, this conversion is hardly an
improvement, but it sets the stage for being able to do alsa, v4l2,
ppp, and other ioctls with timespec/timeval-derived types. without
this capability, a lot of functionality users depend on would stop
working with the time64 switchover.

always try the time64 syscall first since we can use its success to
conclude that no conversion is needed (any setsockopt for the
timestamp options would have succeeded without need for fallbacks).
otherwise, we have to remember the original controllen for each
msghdr, requiring O(vlen) space, so vlen must be bounded. linux clamps
it to IOV_MAX for sendmmsg only (not recvmmsg), but doing the same for
recvmmsg is not unreasonable, especially since the limitation will
only apply to old kernels.

we could optimize to avoid trying SYS_recvmmsg_time64 first if all
msghdrs have controllen zero, or support unlimited vlen by looping and
emulating the timeout logic, but I'm not inclined to do complex and
error-prone optimizations on a function that has so many underlying
problems it should really never be used.

the definitions of SO_TIMESTAMP* changed on 32-bit archs in commit
38143339 to the new versions that
provide 64-bit versions of timeval/timespec structure in control
message payload. socket options, being state attached to the socket
rather than function calls, are not trivial to implement as fallbacks
on ENOSYS, and support for them was initially omitted on the
assumption that the ioctl-based polling alternatives (SIOCGSTAMP*)
could be used instead by applications if setsockopt fails.

unfortunately, it turns out that SO_TIMESTAMP is sufficiently old and
widely supported that a number of applications assume it's available
and treat errors as fatal.

this patch introduces emulation of SO_TIMESTAMP[NS] on pre-time64
kernels by falling back to setting the "_OLD" (time32) versions of the
options if the time64 ones are not recognized, and performing
translation of the SCM_TIMESTAMP[NS] control messages in recvmsg.
since recvmsg does not know whether its caller is legacy time32 code
or time64, it performs translation for any SCM_TIMESTAMP[NS]_OLD
control messages it sees, leaving the original time32 timestamp as-is
(it can't be rewritten in-place anyway, and memmove would be mildly
expensive) and appending the converted time64 control message at the
end of the buffer. legacy time32 callers will see the converted one as
a spurious control message of unknown type; time64 callers running on
pre-time64 kernels will see the original one as a spurious control
message of unknown type. a time64 caller running on a kernel with
native time64 support will only see the time64 version of the control
message.

emulation of SO_TIMESTAMPING is not included at this time since (1)
applications which use it seem to be prepared for the possibility that
it's not present or working, and (2) it can also be used in sendmsg
control messages, in a manner that looks complex to emulate
completely, and costly even when running on a time64-supporting
kernel.

corresponding changes in recvmmsg are not made at this time; they will
be done separately.

The R_ARM_THM_JUMP19 relocation type generated for the original code
when targeting Thumb 2 is not supported by the gold linker.

When FE_DFL_ENV is passed to fesetenv(), the very first instruction
lw t1, 0(a0) will fail since a0 is -1.