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ostest's "vfork" test was never testing vfork(). It has the child write a
global and the parent observe the write -- the defining property of *sharing*,
not of vfork(), whose defining property is that the parent is suspended and
whose contract forbids the child to write anything at all. It passed because
NuttX implemented fork() and vfork() as the same sharing primitive, which
apache/nuttx#19562 separates.
vfork.c is rewritten to test what vfork() promises. The child does only what
POSIX permits -- it calls _exit(42) and nothing else, not even exit(), which
would run atexit handlers and flush stdio in the parent's address space. Since
the child may not write memory and the parent cannot run while the child lives,
the observable is the child's exit status: had the parent not been suspended,
it would have reached waitpid() while the child was still alive. Where child
status is not retained -- ostest_main() sets SA_NOCLDWAIT for the whole run,
deliberately -- ECHILD is accepted as equally good evidence, since it says the
child was already gone when the parent asked.
fork.c is new and tests POSIX fork(): the child's writes to .data, .bss and
the heap are invisible to the parent and vice versa, a pointer to a stack local
taken before the fork names the same object in both, and the child does
everything a vfork() child may not -- calls malloc() and printf(), and returns
from the function that called fork().
Both run at the top of user_main(). They exercise the lowest-level machinery
in the suite -- address environments, stack setup, the architecture's register
context -- so a fault in one takes the process down instead of reporting a
failure. Learning that in seconds rather than after everything else has passed
matters when a port is being brought up.
Each test gates on the one primitive it tests, ARCH_HAVE_VFORK and
ARCH_HAVE_FORK respectively. There is no compatibility layer and no mapping
between symbols. vfork.c no longer requires SCHED_WAITPID: the suspension is
in the kernel primitive now, so the test's core assertion holds without it and
only the status check is conditional.
The simulator is the one exception. It selects ARCH_HAVE_VFORK, but ostest
takes the sim down as soon as the test runs there, so the call keeps the
!ARCH_SIM guard that apps
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| bas | ||
| berry | ||
| duktape | ||
| ficl | ||
| jimtcl | ||
| lua | ||
| luajit | ||
| luamodules | ||
| minibasic | ||
| mquickjs | ||
| python | ||
| quickjs | ||
| toywasm | ||
| wamr | ||
| wasm3 | ||
| .gitignore | ||
| CMakeLists.txt | ||
| Make.defs | ||
| Makefile | ||