Rich Felker
114178dc8d
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.
musl libc
musl, pronounced like the word "mussel", is an MIT-licensed
implementation of the standard C library targetting the Linux syscall
API, suitable for use in a wide range of deployment environments. musl
offers efficient static and dynamic linking support, lightweight code
and low runtime overhead, strong fail-safe guarantees under correct
usage, and correctness in the sense of standards conformance and
safety. musl is built on the principle that these goals are best
achieved through simple code that is easy to understand and maintain.
The 1.1 release series for musl features coverage for all interfaces
defined in ISO C99 and POSIX 2008 base, along with a number of
non-standardized interfaces for compatibility with Linux, BSD, and
glibc functionality.
For basic installation instructions, see the included INSTALL file.
Information on full musl-targeted compiler toolchains, system
bootstrapping, and Linux distributions built on musl can be found on
the project website:
http://www.musl-libc.org/