for all address types, a scope_id specified as a decimal value is accepted. for addresses with link-local scope, a string containing the interface name is also accepted. some changes are made to error handling to avoid unwanted fallbacks in the case where the scope_id is invalid: if an earlier name lookup backend fails with an error rather than simply "0 results", this failure now suppresses any later attempts with other backends. in getnameinfo, a light "itoa" type function is added for generating decimal scope_id results, and decimal port strings for services are also generated using this function now so as not to pull in the dependency on snprintf. in netdb.h, a definition for the NI_NUMERICSCOPE flag is added. this is required by POSIX (it was previously missing) and needed to allow callers to suppress interface-name lookups.
int8_t, u_int8_t, etc types are moved under _BSD_SOURCE
from linux/in.h and linux/in6.h uapi headers the following missing socket options were added: IP_NODEFRAG - used with customized ipv4 headers IPV6_RECVPATHMTU - for ipv6 path mtu IPV6_PATHMTU - for ipv6 path mtu IPV6_DONTFRAG - for ipv6 path mtu IPV6_ADDR_PREFERENCES - RFC5014 Source Address Selection IPV6_MINHOPCOUNT - RFC5082 Generalized TTL Security Mechanism IPV6_ORIGDSTADDR - used by tproxy IPV6_RECVORIGDSTADDR - used by tproxy IPV6_TRANSPARENT - used by tproxy IPV6_UNICAST_IF - ipv6 version of IP_UNICAST_IF and socket option values: IP_PMTUDISC_OMIT - value for IP_MTU_DISCOVER option, new in linux 3.14 IPV6_PMTUDISC_OMIT - same for IPV6_MTU_DISCOVER IPV6_PMTUDISC_INTERFACE - ipv6 version of IP_PMTUDISC_INTERFACE IPV6_PREFER_* - flags for IPV6_ADDR_PREFERENCES not added: ipv6 flow info and flow label related definitions. (it's unclear if libc should define these and namespace polluting type name is involved so they are not provided for now)
this was introduced to query BPF extension support with getsockopt in linux 3.14, commit ea02f9411d9faa3553ed09ce0ec9f00ceae9885e
linux 3.14 introduced sched_getattr and sched_setattr syscalls in commit d50dde5a10f305253cbc3855307f608f8a3c5f73 and the related SCHED_DEADLINE scheduling policy in commit aab03e05e8f7e26f51dee792beddcb5cca9215a5 but struct sched_attr "extended scheduling parameters data structure" is not yet exported to userspace (necessary for using the syscalls) so related uapi definitions are not added yet.
the main motivation for this change is that, with the previous definition, it was arguably illegal, in standard C, to initialize both si_value and si_pid/si_uid with designated initializers, due to the rule that only one member of a union can have an initializer. whether or not this affected real-world application code, it affected some internal code, and clang was producing warnings (and possibly generating incorrect code). the new definition uses a more complex hierarchy of structs and unions to avoid the need to initialize more than one member of a single union in usage cases that make sense. further work would be needed to eliminate even the ones with no practical applications. at the same time, some fixes are made to the exposed names for nonstandard fields, to match what software using them expects.
some of these may have been from ancient (pre-SUSv2) POSIX versions; more likely, they were from POSIX drafts or glibc interpretations of what ancient versions of POSIX should have added (instead they made they described functionality mandatory and/or dropped it completely). others are purely glibc-isms, many of them ill-thought-out, like providing ways to lookup the min/max values of types at runtime (despite the impossibility of them changing at runtime and the impossibility of representing ULONG_MAX in a return value of type long). since our sysconf implementation does not support or return meaningful values for any of these, it's harmful to have the macros around; applications' build scripts may detect and attempt to use them, only to get -1/EINVAL as a result. if removing them does break some applications, and it's determined that the usage was reasonable, some of these could be added back on an as-needed basis, but they should return actual meaningful values, not junk like they were returning before.
The mips arch is special in that it uses different RLIMIT_ numbers than other archs, so allow bits/resource.h to override the default RLIMIT_ numbers (empty on all archs except mips). Reported by orc.
in a sense this implementation is incomplete since it doesn't provide the HWCAP_* macros for use with AT_HWCAP, which is perhaps the most important intended usage case for getauxval. they will be added at a later time.