Runaway stack problem

[sjamaan]

Occasionally we still run out of stack. See for example:

• ​Today's Salmonella run of scsh-process (somewhere halfway down the page is an ERROR)
• ​Stack overflow in scsh-process, experienced by TheLemonMan
• ​Valgrind run of the above

[sjamaan]

OK, the reason for this is extremely simple and I don't understand why this hasn't caused problems before:

• When a signal is received by the process, we call C_raise_interrupt, which resets the stack pointer to the bottom of the stack, so that the stack checks "think" the stack is full (while really it isn't)
• Normally, a C_demand() call will take care of handling this by triggering a GC/signal handler.
• A C_stack_overflow_check (or a direct call to C_stack_check1) performs more or less the same checks as C_demand() does, so if this is the first thing that happens after a signal arrived, it will simply bomb. That's why sometimes it shows a stack overflow error and other times a C_CIRCULAR_DATA_ERROR, if the signal happens just before a call to equal?.

[evhan]

Fixed by 5d2a17a, f2ed421, 10ef6f6.