c34a5f16fa
Described in [1], signal handlers running in a vfork child have opportunities to corrupt the parent's state. Address this by adding a new rfork(2) flag, RFSPAWN, that has vfork(2) semantics but also resets signal handlers in the child during creation. x86 uses rfork_thread(3) instead of a direct rfork(2) because rfork with RFMEM/RFSPAWN cannot work when the return address is stored on the stack -- further information about this problem is described under RFMEM in the rfork(2) man page. Addressing this has been identified as a prerequisite to using posix_spawn in subprocess on FreeBSD [2]. [1] https://ewontfix.com/7/ [2] https://bugs.python.org/issue35823 Reviewed by: jilles, kib Differential Revision: https://reviews.freebsd.org/D19058
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include System include files.
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