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.
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.
this interface contract is entirely internal to dynlink.c.
the definitions of SO_TIMESTAMP* changed on 32-bit archs in commit 38143339646a4ccce8afe298c34467767c899f51 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.
based on patch by Dan Gohman, who caught this via compiler warnings. analysis by Szabolcs Nagy determined that it's a bug, whereby errno can be set incorrectly for values where the coercion from long double to double causes rounding. it seems likely that floating point status flags may be set incorrectly as a result too. at the same time, clean up use of preprocessor concatenation involving LDBL_MANT_DIG, which spuriously depends on it being a single unadorned decimal integer literal, and instead use the equivalent formulation 2/LDBL_EPSILON. an equivalent change on the printf side was made in commit bff6095d915f3e41206e47ea2a570ecb937ef926.
Some declarations of __tls_get_new were left in the code, even though the definition got removed in commit 9d44b6460ab603487dab4d916342d9ba4467e6b9 install dynamic tls synchronously at dlopen, streamline access this can make the build fail with ld: lib/libc.so: hidden symbol `__tls_get_new' isn't defined when libc.so is linked without --gc-sections, because a .hidden declaration in asm code creates a reference even if the symbol is not actually used.
R_PPC_UADDR32 (R_PPC64_UADDR64) has the same meaning as R_PPC_ADDR32 (R_PPC64_ADDR64), except that its address need not be aligned. For powerpc64, BFD ld(1) will automatically convert between ADDR<->UADDR relocations when the address is/isn't at its native alignment. This will happen if, for example, there is a pointer in a packed struct. gold and lld do not currently generate R_PPC64_UADDR64, but pass through misaligned R_PPC64_ADDR64 relocations from object files, possibly relaxing them to misaligned R_PPC64_RELATIVE. In both cases (relaxed or not) this violates the PSABI, which defines the relevant field type as "a 64-bit field occupying 8 bytes, the alignment of which is 8 bytes unless otherwise specified." All three linkers violate the PSABI on 32-bit powerpc, where the only difference is that the field is 32 bits wide, aligned to 4 bytes. Currently musl fails to load executables linked by BFD ld containing R_PPC64_UADDR64, with the error "unsupported relocation type 43". This change provides compatibility with BFD ld on powerpc64, and any static linker on either architecture that starts following the PSABI more closely.
without this, the SIOCGSTAMP and SIOCGSTAMPNS ioctl commands, for obtaining timestamps, would stop working on pre-5.1 kernels after time_t is switched to 64-bit and their values are changed to the new time64 versions. new code is written such that it's statically unreachable on 64-bit archs, and on existing 32-bit archs until the macro values are changed to activate 64-bit time_t.
without this, the SO_RCVTIMEO and SO_SNDTIMEO socket options would stop working on pre-5.1 kernels after time_t is switched to 64-bit and their values are changed to the new time64 versions. new code is written such that it's statically unreachable on 64-bit archs, and on existing 32-bit archs until the macro values are changed to activate 64-bit time_t.