this was apparently omitted long ago out of a lack of understanding of
its importance and the fact that POSIX doesn't specify it. despite not
being officially standardized, however, it turns out that at least
AIX, glibc, NetBSD, OpenBSD, QNX, and Solaris document and support it.
in certain usage cases, such as implementing a DNS gateway on top of
the stub resolver interfaces, it's necessary to distinguish the case
where a name does not exit (NxDomain) from one where it exists but has
no addresses (or other records) of the requested type (NODATA). in
fact, even the legacy gethostbyname API had this distinction, which we
were previously unable to support correctly because the backend lacked
it.
apart from fixing an important functionality gap, adding this
distinction helps clarify to users how search domain fallback works
(falling back in cases corresponding to EAI_NONAME, not in ones
corresponding to EAI_NODATA), a topic that has been a source of
ongoing confusion and frustration.
as a result of this change, EAI_NONAME is no longer a valid universal
error code for getaddrinfo in the case where AI_ADDRCONFIG has
suppressed use of all address families. in order to return an accurate
result in this case, getaddrinfo is modified to still perform at least
one lookup. this will almost surely fail (with a network error, since
there is no v4 or v6 network to query DNS over) unless a result comes
from the hosts file or from ip literal parsing, but in case it does
succeed, the result is replaced by EAI_NODATA.
glibc has a related error code, EAI_ADDRFAMILY, that could be used for
the AI_ADDRCONFIG case and certain NODATA cases, but distinguishing
them properly in full generality seems to require additional DNS
queries that are otherwise not useful. on glibc, it is only used for
ip literals with mismatching family, not for DNS or hosts file results
where the name has addresses only in the opposite family. since this
seems misleading and inconsistent, and since EAI_NODATA already covers
the semantic case where the "name" exists but doesn't have any
addresses in the requested family, we do not adopt EAI_ADDRFAMILY at
this time. this could be changed at some point if desired, but the
logic for getting all the corner cases with AI_ADDRCONFIG right is
slightly nontrivial.
as a result of ISA extensions exploding register file sizes on some
archs, using a constant for minimum signal stack size no longer seems
viably future-proof. add sysconf keys allowing the kernel to provide a
machine-dependent minimum applications can query to ensure they
allocate sufficient space for stacks. the key names and indices align
with the same functionality in glibc.
see commit d5a5045382 for previous
action on this subject.
ultimately, the macros MINSIGSTKSZ and SIGSTKSZ probably need to be
deprecated, but that is standards-amendment work outside the scope of
a single implementation.
_CS_POSIX_V7_THREADS_CFLAGS and _CS_POSIX_V7_THREADS_LDFLAGS have been
missing for a long time, which is a conformance defect. we were
waiting on glibc to add them or at least agree on the numeric values
they will have so as to keep the numbering aligned. it looks like they
will be added to glibc with these numbers, and in any case, this list
does not have any significant churn that would result in the numbers
getting taken.
see
linux commit 90f093fa8ea48e5d991332cee160b761423d55c1
rseq, ptrace: Add PTRACE_GET_RSEQ_CONFIGURATION request
the struct type got __ prefix to follow existing practice.
see
linux commit 321827477360934dc040e9d3c626bf1de6c3ab3c
icmp: don't send out ICMP messages with a source address of 0.0.0.0
"RFC7600 reserves a dummy address to be used as a source for ICMP
messages (192.0.0.8/32), so let's teach the kernel to substitute that
address as a last resort if the regular source address selection procedure
fails."
see
linux commit 7eeba1706eba6def15f6cb2fc7b3c3b9a2651edc
tcp: Add receive timestamp support for receive zerocopy.
linux commit 3c5a2fd042d0bfac71a2dfb99515723d318df47b
tcp: Sanitize CMSG flags and reserved args in tcp_zerocopy_receive.
TCP_NLA_EDT was new in v5.9, see
linux commit 48040793fa6003d211f021c6ad273477bcd90d91
tcp: add earliest departure time to SCM_TIMESTAMPING_OPT_STATS
TCP_NLA_TTL is new in v5.12, see
linux commit e7ed11ee945438b737e2ae2370e35591e16ec371
tcp: add TTL to SCM_TIMESTAMPING_OPT_STATS
see
linux commit a54f0dfda754c5cecc89a14dab68a3edc1e497b5
signal: define the SA_UNSUPPORTED bit in sa_flags
linux commit 6ac05e832a9e96f9b1c42a8917cdd317d7b6c8fa
signal: define the SA_EXPOSE_TAGBITS bit in sa_flags
Note: SA_ is in the posix reserved namespace so these linux specific flags
can be exposed when compiling for posix.
unlike other si_code defines, SYS_ is not in the posix reserved namespace
which is likely the reason why SYS_SECCOMP was previously missing (was new
in linux v3.5).
see
linux commit 18fb76ed53865c1b5d5f0157b1b825704590beb5
net-zerocopy: Copy straggler unaligned data for TCP Rx. zerocopy.
linux commit 94ab9eb9b234ddf23af04a4bc7e8db68e67b8778
net-zerocopy: Defer vm zap unless actually needed.
see
linux commit 1446e1df9eb183fdf81c3f0715402f1d7595d4cb
kernel: Implement selective syscall userspace redirection
linux commit 36a6c843fd0d8e02506681577e96dabd203dd8e8
entry: Use different define for selector variable in SUD
redirect syscalls to a userspace handler via SIGSYS, except for a specific
range of code. can be toggled via a memory write to a selector variable.
mainly for wine.
these are linux specific constants. glibc exposes them behind
_GNU_SOURCE, but, since SEEK_* is reserved for the implementation, we
can simply define them. furthermore, since they can't be used with
fseek() and other functions that deal with FILE, we don't add them to
stdio.h.
we make qsort a wrapper by providing a wrapper_cmp function that uses
the extra argument as a function pointer. should be optimized to a tail
call on most architectures, as long as it's built with
-fomit-frame-pointer, so the performance impact should be minimal.
to keep the git history clean, for now qsort_r is implemented in qsort.c
and qsort is implemented in qsort_nr.c. qsort.c also received a few
trivial cleanups, including replacing (*cmp)() calls with cmp().
qsort_nr.c contains only wrapper_cmp and qsort as a qsort_r wrapper
itself.
since 4.1, gcc has had the __returns_twice__ attribute and has
required functions which return twice to carry it; however it's always
applied it automatically to known setjmp-like function names. clang
however does not do this reliably, at least not with -ffreestanding
and possibly under other conditions, resulting in silent emission of
wrong code.
since the symbol name setjmp is in no way special (setjmp is specified
as a macro that could expand to use any implementation-specific symbol
name or names), a compiler is justified not to do anything special
without further hints, and it's reasonable to do what we can to
provide such hints.
gcc 4.0.x and earlier do not recognize the attribute, so make use
conditional on __GNUC__ macros. clang and other gcc-like compilers
report (and have always reported) a later "GNUC" version so the
preprocessor conditional should function as desired for them as too.
undefine the internal macro after use so that nothing abuses it as a
public feature.
add synchronouse and asynchronous tag check failure codes, see
linux commit 74f1082487feb90bbf880af14beb8e29c3030c9f
arm64: mte: Add specific SIGSEGV codes
these are for the aarch64 MTE (memory tagging extension), see
linux commit 1c101da8b971a36695319dce7a24711dc567a0dd
arm64: mte: Allow user control of the tag check mode via prctl()
linux commit af5ce95282dc99d08a27a407a02c763dde1c5558
arm64: mte: Allow user control of the generated random tags via prctl()
path resolution does not follow symlinks on nosymfollow mounts (but
readlink still does), see
linux commit dab741e0e02bd3c4f5e2e97be74b39df2523fc6e
Add a "nosymfollow" mount option.
can cause rseq restart on another cpu to synchronize with global
memory access from rseq critical sections, see
linux commit 2a36ab717e8fe678d98f81c14a0b124712719840
rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
reallocarray is an extension introduced by OpenBSD, which introduces
calloc overflow checking to realloc.
glibc 2.28 introduced support for this function behind _GNU_SOURCE,
while glibc 2.29 allows its usage in _DEFAULT_SOURCE.
Update fanotify.h, see
linux commit 929943b38daf817f2e6d303ea04401651fc3bc05
fanotify: add support for FAN_REPORT_NAME
linux commit 83b7a59896dd24015a34b7f00027f0ff3747972f
fanotify: add basic support for FAN_REPORT_DIR_FID
linux commit 08b95c338e0c5a96e47f4ca314ea1e7580ecb5d7
fanotify: remove event FAN_DIR_MODIFY
FAN_DIR_MODIFY that was new in v5.7 is now removed from linux uapi,
but kept in musl, so we don't break api, linux cannot reuse the
value anyway.
the _Fork interface is defined for future issue of POSIX as the
outcome of Austin Group issue 62, which drops the AS-safety
requirement for fork, and provides an AS-safe replacement that does
not run the registered atfork handlers.
Ethernet protocol number for media redundancy protocol, see
linux commit 4714d13791f831d253852c8b5d657270becb8b2a
bridge: uapi: mrp: Add mrp attributes.
add TCP_NLA_BYTES_NOTSENT and new tcp_zerocopy_receive fields, see
linux commit c8856c051454909e5059df4e81c77b9c366c5515
tcp-zerocopy: Return inq along with tcp receive zerocopy.
linux commit 33946518d493cdf10aedb4a483f1aa41948a3dab
tcp-zerocopy: Return sk_err (if set) along with tcp receive zerocopy.
linux commit e08ab0b377a1489760533424437c5f4be7f484a4
tcp: add bytes not sent to SCM_TIMESTAMPING_OPT_STATS
it remaps anon mappings without unmapping the original. chromeos plans
to use it with userfaultfd, see:
linux commit e346b3813067d4b17383f975f197a9aa28a3b077
mm/mremap: add MREMAP_DONTUNMAP to mremap()
see
linux commit 9e2ba2c34f1922ca1e0c7d31b30ace5842c2e7d1
fanotify: send FAN_DIR_MODIFY event flavor with dir inode and name
linux commit 44d705b0370b1d581f46ff23e5d33e8b5ff8ec58
fanotify: report name info for FAN_DIR_MODIFY event
reuses a bit from CSIGNAL so it can only be used with unshare
and clone3, added in
linux commit 769071ac9f20b6a447410c7eaa55d1a5233ef40c
ns: Introduce Time Namespace
needed for storage drivers with userspace component that may
run in the IO path, see
linux commit 8d19f1c8e1937baf74e1962aae9f90fa3aeab463
prctl: PR_{G,S}ET_IO_FLUSHER to support controlling memory reclaim
The use of TCP_ in udp.h is not known, fortunately udp.h is not
specified by posix so there are no strict namespace rules, added in
linux commit e27cca96cd68fa2c6814c90f9a1cfd36bb68c593
xfrm: add espintcp (RFC 8229)
TCP_NLA_TIMEOUT_REHASH queries timeout-triggered rehash attempts,
tcpm_ifindex limits the scope of TCP_MD5SIG* sockopt to a device.
see
linux commit 32efcc06d2a15fa87585614d12d6c2308cc2d3f3
tcp: export count for rehash attempts
linux commit 6b102db50cdde3ba2f78631ed21222edf3a5fb51
net: Add device index to tcp_md5sig
add IPPROTO_ETHERNET and IPPROTO_MPTCP, see
linux commit 2677625387056136e256c743e3285b4fe3da87bb
seg6: fix SRv6 L2 tunnels to use IANA-assigned protocol number
linux commit faf391c3826cd29feae02078ca2022d2f912f7cc
tcp: Define IPPROTO_MPTCP
