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2014-06-06optimize SOCK_CLOEXEC fallback for socket functionRich Felker-2/+2
the fcntl function is heavy, so make the syscall directly instead. also, avoid the code size and runtime overhead of querying the old flags, since it's reasonable to assume nothing will be set on a newly-created socket. this code is only used on old kernels which lack proper atomic close-on-exec support, so future changes that might invalidate such an assumption do not need to be considered.
2012-11-05improve SOCK_NONBLOCK/SOCK_CLOEXEC fallback codeRich Felker-1/+2
checking for EINVAL should be sufficient, but qemu user emulation returns EPROTONOSUPPORT in some of the failure cases, and it seems conceivable that other kernels doing linux-emulation could make the same mistake. since DNS lookups and other important code might break if the fallback does not get invoked, be extra careful and check for either error. note that it's important NOT to perform the fallback code on other errors such as resource-exhaustion cases, since the fallback is not atomic and will lead to file-descriptor leaks in multi-threaded programs that use exec. the fallback code is only "safe" to run when the initial failure is caused by the application's choice of arguments, not the system state.
2012-09-29emulate SOCK_CLOEXEC and SOCK_NONBLOCK for old (pre-2.6.27) kernelsRich Felker-1/+14
also update syslog to use SOCK_CLOEXEC rather than separate fcntl step, to make it safe in multithreaded programs that run external programs. emulation is not atomic; it could be made atomic by holding a lock on forking during the operation, but this seems like overkill. my goal is not to achieve perfect behavior on old kernels (which have plenty of other imperfect behavior already) but to avoid catastrophic breakage in (1) syslog, which would give no output on old kernels with the change to use SOCK_CLOEXEC, and (2) programs built on a new kernel where configure scripts detected a working SOCK_CLOEXEC, which later get run on older kernels (they may otherwise fail to work completely).
2011-02-15cleanup socketcall syscall interface to ease porting to sane(r) archsRich Felker-3/+1
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+9