commit 895736d49b made these changes
along with fixing a real bug in LOG_MAKEPRI. based on further
information, they do not seem to be well-motivated or in line with
policy.
the result of LOG_FAC is not a meaningful facility value if we shift
it down like before, but apparently the way it is used by applications
is as an index into an array of facility names. moreover, all
historical systems which define it do so with the shift. as it is a
nonstandard interface, there is no justification for providing a macro
by the same name that is incompatible with historical practice.
the value of LOG_FACMASK likewise is 0x3f8 on all historical systems
checked. while only 5 bits are used for existing facility codes, the
convention seems to be that all 7 bits belong to the facility field
and theoretically could be used to expand to having more facilities.
that seems unlikely to happen, but there is no reason to make a
gratuitously incompatible change here.
add two ioctls to get and set struct epoll_params to allow users to
control epoll based busy polling of network sockets.
added to uapi in commit 18e2bf0edf4dd88d9656ec92395aa47392e85b61 (Linux
kernel 6.9 and newer).
these are nonstandard and unnecessary for using the associated
functionality, but resulted in applications that used them
malfunctioning.
patch based on proposed fix by erny hombre.
This syscall is available since Linux 3.15 and also implemented in
glibc from version 2.28. It is commonly used in filesystem or security
contexts.
Constants RENAME_NOREPLACE, RENAME_EXCHANGE, RENAME_WHITEOUT are
guarded by _GNU_SOURCE as with glibc.
this interface was added as the outcome of Austin Group tracker issue
697. no error is specified for unsupported flags, which is probably an
oversight. for now, EOPNOTSUPP is used so as not to overload EINVAL.
previously, only a few archs defined it here. this change makes the
presence consistent across all archs, and reduces the amount of header
duplication (and potential for future inconsistency) between archs.
added in linux kernel commit 73fa7547c70b32cc69685f79be31135797734eb6.
this is added now as a prerequisite for fixing pwrite/pwritev behavior
for O_APPEND files.
originally, compilers did not provide these macros and we had to
provide them ourselves. this meant we were redefining them, which was
technically invalid unless the token sequence of the original
definition matched exactly.
the original patch proposed by Jules Maselbas to fix this made the
definitions conditional on them not already being defined; however I
suggested using #undef to avoid any possibly-wrong definitions already
in place and ensure that the definitions are 1. the version adopted as
commit 8b70486807 made this change.
unfortunately, gcc is loud about not liking #undef of any __STDC_*
macro name, and while warnings are suppressed in the system include
path, there is apparently no way to suppress this warning if the
system include dir has also been provided via -I.
while normally we don't go out of our way to satisfy warnings over
style in the public headers, in this case, it seems to be a matter of
disagreement over contract of which part of "the implementation" is
entitled to define or undefine macros belonging to the implementation,
and it's quite reasonable to conclude that the compiler may reject
attempts to undefine them.
this commit reverts to the originally-submitted version of the patch
making the definitions conditional.
commit f247462b08 incorrectly hid ppoll
in the presence of _GNU_SOURCE due to an oversight that defining
_BSD_SOURCE does not implicitly define _GNU_SOURCE. at present,
headers still have to explicitly check for each feature profile level;
this may be changed at some point in the future via features.h, but
has not been changed yet.
Undefine any previous __STDC_UTF_{16,32}__ macros before defining
them to prenvent any warnings of redefining macros.
This happens as a result of some compiler versions defining the macros
themselves.
Note: Some relocation types were only used by binutils and
accidentally exposed to previous versions of psABI. One of the values
has been reused by GOT32_PCREL.
the ppoll function has been accepted as a future part of the standard
as the outcome of Austin Group tracker issue 1263. at some point it
should be exposed unconditionally, but for now, expose it in the
default feature profile.
commit 37bb3cce45 suppressed the
declaration for C++, where it is wrongly interpreted as declaring the
function as taking no arguments. with C23 removing non-prototype
declarations, that problem is now also relevant to C.
the non-prototype declaration for basename originates with commit
06aec8d715, where it was designed to
avoid conflicts with programs which declare basename with the GNU
signature taking const char *. that change was probably misguided, as
it represents not only misaligned expectations with the caller, but
also undefined behavior (calling a function that's been declared with
the wrong type).
we could opt to fix the declaration, but since glibc, with the
gratuitously incompatible GNU-basename function, seems to be the only
implementation that declares it in string.h, it seems better to just
remove the declaration. this provides some warning if applications are
being built expecting the GNU behavior but not getting it. if we
declared it here, it would only produce a warning if the caller also
declares it themselves (rare) or if the caller attempts to pass a
const-qualified pointer.
These were overlooked when DT_RELR was added in commit
d32dadd60e, potentially breaking
software that treats presence of the DT_RELR macro as implying they
exist.
This is the only missing part in struct statvfs. The LSB calls
[f]statfs() deprecated, and its weird types are definitely
off-putting. However, its use is required to get f_type.
Instead, allocate one of the six spares to f_type, copied directly
from struct statfs. This then becomes a small extension to the
standard interface on Linux, instead of two different interfaces, one
of which is quite odd due to being an ABI type, and there no longer is
any reason to use statfs().
The underlying kernel type is a mess, but all architectures agree on u32
(or more) for the ABI, and all filesystem magicks are 32-bit integers.
Since commit 6567db65f4 (prior to
1.0.0), the spare slots have been zero-filled, so on all versions that
may be reasonably be encountered in the wild, applications can rely on
a nonzero f_type as indication that the new field has been filled in.
the result of the 0xffff mask with the exit status could have bit 15
set, in which case multiplying by 0x10001 overflows 32-bit signed int.
making the multiply unsigned avoids the overflow. it also changes the
sign extension behavior of the subsequent >> operation, but the
affected bits are all unwanted anyway and all discarded by the cast to
short.
memmem has been adopted for the next issue of POSIX (outcome of
tracker item 1061). since mem* is in the reserved namespace for
string.h it's already fully conforming to expose it by default, so
just do so.
these badly pollute the namespace with macros whenever _GNU_SOURCE is
defined, which is always the case with g++, and especially tends to
interfere with C++ constructs.
as our implementation of these was macro-only, their removal cannot
affect any existing binaries. at the source level, portable software
should be prepared for them not to exist.
for now, they are left in place with explicit _LARGEFILE64_SOURCE.
this provides an easy temporary path for integrators/distributions to
get packages building again right away if they break while working on
a proper, upstreamable fix. the intent is that this be a very
short-term measure and that the macros be removed entirely in the next
release cycle.
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.
