[BusyBox] Implement fork using longjmp [PATCH]

[Shaun Jackman]

I'm using busybox on a single process embedded system that does not
have the fork system call. This patch implements fork using longjmp
when CONFIG_FEATURE_IMPLEMENT_FORK_USING_LONGJMP is selected in the
configuration.

config CONFIG_FEATURE_IMPLEMENT_FORK_USING_LONGJMP
	bool "Implement fork using longjmp"
	default n
	help
	  Implement fork, exit, and waitpid using macros. This is most
	  useful for systems missing these functions. Fork is implemented
	  using setjmp and exit using longjump. The exit value can be
	  returned by waitpid. The current implementation does not provide
	  for nested forks.

Cheers,
Shaun

2005-03-03  Shaun Jackman  <sjackman at gmail.com>

	* include/libbb.h (bb_fork, bb_exit, bb_wait): New function.
	(fork, exit, _exit, waitpid): New macro.
	* libbb/Makefile.in (LIBBB_SRC): Add fork.c
	* libbb/fork.c: New file.
	* shell/lash.c (run_command): Do not call close_all after forking
	if CONFIG_FEATURE_IMPLEMENT_FORK_USING_LONGJMP is used.
	* sysdeps/linux/Config.in: Add CONFIG_FEATURE_IMPLEMENT_FORK_USING_LONGJMP.

$ diffstat busybox-1.00-fork.diff
 include/libbb.h         |   14 +++++++++++
 libbb/Makefile.in       |    2 -
 libbb/fork.c            |   58 ++++++++++++++++++++++++++++++++++++++++++++++++
 shell/lash.c            |    2 +
 sysdeps/linux/Config.in |   10 ++++++++
 5 files changed, 85 insertions(+), 1 deletion(-)
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