This should allow most typical cases of arguments with spaces to work correctly, although it will still break down in some cases. We can't do this perfectly, because we're ultimately dependent on the argument parsing code in the target application, and at least the code generated by ORCA/C doesn't give us a way to make an arbitrary string be treated as a single argument.
*Most significantly, we avoid using setpgid(), because it doesn't work and in fact corrupts the kernel's process group table.
*Also, work around tctpgrp() returning garbage instead of 0 on success.
This adds an implementation of tcsetpgrp that works by reading the process tables to find a process in the appropriate group. This isn't used for the main job control operations, though, since it might be relatively slow.
At this point, basic job control seems to work.
* Push/pop environment to make sure it is isolated from our parents and children.
* Make all environment vars (and shell vars) case-insensitive, consistent with GNO's internal handling of environment vars.
* Wrap putenv and unsetenv to make sure they are called with lower-case variable names, which is necessary to maintain consistency between the environ array and the kernel's internal representation of variables.
The version in libc both matches things it shouldn't and doesn't match things it should, in (at least) cases where a pattern includes additional stuff beyond a *.
This should avoid strange behavior due to races when the parent has resumed but the child is still running the exec* code in libc, which mainly manifests itself when running at low speed.
We also change to signaling the child's completion with SIGALRM, and setting an extra alarm in the parent in case the child doesn't actually do it.
GNO's _exit (contrary to its man page) does clean-up for stuff like the memory allocator, which is inappropriate in a forked child process and leads to hangs and crashes.
*Use .null instead of /dev/null
*Account for GNO's dup2(), which non-standardly returns 0 on success
*Always call open with appropriate number of arguments
*Use STDIN_FILENO instead of (implicitly) 0
In particular, it will buffer information about children other than the one being waited for, so it isn't lost. It can also emulate a non-blocking wait by arranging to interrupt the wait with a signal.
This involved breaking things up into more segments in debug mode, since the code is larger. I also had to remove some unused extern definitions, which were causing link errors when debug code was enabled.
To enable debug code, pass "DEBUG=1" to make or build.gs.
At this point, hush can successfully build and run, although it doesn't work correctly.
The main Makefile is now dedicated to the GNO build. There's now a separate makefile for building on modern systems with GCC/Clang.
It would have been possible to add a version of strftime(), but it didn't seem worth it for this little bit of functionality. It should also be possible to get similar functionality by invoking an external program like "date" in PS1.
This involved using signal() rather than sigaction(), which GNO doesn't have. signal() doesn't have the signal-blocking feature of sigaction(), but I've tried to emulate it.
This code could theoretically break if the ORCA/C varargs implementation changed, but it should be OK in practice.
Also removed some unused code in libbb/xfuncs.printf.c that includes potentially problematic varargs use (defining varargs functions but not necessarily calling va_start/va_end in them).
This disables long argument support, since that requires getopt_long(), which isn't included in GNO. There is a separate library available for it, but it's simpler to avoid depending on that.
