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nuttx implements fork() and vfork() as the same function, and is gaining the three separate primitives its issue #19540 describes: task_fork() (shares memory, private stack copy, both running), vfork() (shares memory, parent suspended) and POSIX fork() (child gets its own copy). This is the apps side of that, and it lands first: it works against nuttx with or without the split, so the tests keep running across the transition rather than silently compiling out. ostest's "vfork" test was never testing vfork(). It has the child write a global and the parent observe the write -- which is 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 is renamed to task_fork.c, unchanged, because that is the primitive it has always described. 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. The observable is therefore the child's exit status rather than a memory write. Where child status is not retained -- ostest_main() sets SA_NOCLDWAIT for the whole run, deliberately -- waitpid() returning ECHILD is accepted as equally good evidence: 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(). All three run at the top of user_main() rather than in the middle. 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, and finding that out in seconds rather than after everything else has passed is the difference between a usable iteration and a coffee break when a port is being brought up. The other in-tree callers are audited for which primitive they actually meant. nand_sim wants a daemon that outlives its caller and shares its memory, which is task_fork(). bas's SHELL and EDIT statements, python's _posixsubprocess and libwebsockets' feature macros want the fork-then-exec path, which vfork() serves; python's os.fork() and libwebsockets' LWS_HAVE_FORK stay on fork() proper. fdsantest's vfork case follows vfork(). Two third-party suites need their source lists narrowed, because they call fork() from code that is compiled unconditionally: * system/libuv -- test-fork.c and test-pipe-close-stdout-read-stdin.c are filtered out of the test-*.c glob. Every test they define is already excluded from the task list on NuttX by 0001-libuv-port-for-nuttx.patch -- the nine fork_* entries and pipe_close_stdout_read_stdin -- so they were dead code being compiled only because fork() happened to be declared. * testing/ltp -- the open_posix_testsuite is filtered through the existing BLACKWORDS mechanism, which already drops tests for absent features and is already conditioned on configuration symbols. Where fork() is not provided this drops 278 of 1943 test files; the pattern is written to spare vfork() and task_fork(), which remain available. Where fork() is provided -- which today is everywhere -- nothing is dropped. Compatibility: the nuttx symbols this keys on do not exist yet. task_fork.c is built where CONFIG_TASK_FORK says task_fork() was built and, on a nuttx that has no CONFIG_ARCH_HAVE_TASK_FORK at all -- which is the pre-split one -- where CONFIG_ARCH_HAVE_FORK does. Today's fork() *is* task_fork(), so the test that has always covered that primitive keeps running, under its own name, and no coverage is lost across the transition. Both spellings are needed because CONFIG_TASK_FORK is optional on the nuttx side: ARCH_HAVE_TASK_FORK says the architecture can clone a task, TASK_FORK says this build asked for it. A follow-up removes the fallback once the split has landed. vfork_test() and fork_test() deliberately have no such fallback. Both check semantics a pre-split nuttx does not describe -- the parent suspension and the private copy -- and ARCH_HAVE_VFORK is the evidence that the split has landed. Mapping them onto ARCH_HAVE_FORK would also add a test to configurations that never had one, which is not free: vfork.c costs about 470 bytes of .text on armv7-m at -Os, and that is what put lm3s6965-ek:qemu-protected over its 128 KiB user flash region. Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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