From 9933273c5b7b6e0471d9195e8c2facb795b795ae Mon Sep 17 00:00:00 2001 From: Rob Landley Date: Fri, 3 Jul 2015 15:17:25 -0500 Subject: Probe for fork() instead of relying on a distro-specific #define. --- lib/portability.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'lib/portability.c') diff --git a/lib/portability.c b/lib/portability.c index 4da49dd6..78e500b1 100644 --- a/lib/portability.c +++ b/lib/portability.c @@ -6,7 +6,20 @@ #include "toys.h" -#if !defined(__uClinux__) +// We can't fork() on nommu systems, and vfork() requires an exec() or exit() +// before resuming the parent (because they share a heap until then). And no, +// we can't implement our own clone() call that does the equivalent of fork() +// because nommu heaps use physical addresses so if we copy the heap all our +// pointers are wrong. (You need an mmu in order to map two heaps to the same +// address range without interfering with each other.) In the absence of +// a portable way to tell malloc() to start a new heap without freeing the old +// one, you pretty much need the exec().) + +// So we exec ourselves (via /proc/self/exe, if anybody knows a way to +// re-exec self without depending on the filesystem, I'm all ears), +// and use the arguments to signal reentry. + +#if CFG_TOYBOX_FORK pid_t xfork(void) { pid_t pid = fork(); -- cgit v1.2.3