rc

commit 31f0826614c17ef69f3cc654f9ede3ca9452522e
parent b12d41f95452f06360d4879bc466469686d167a8
Author: tgoodwin <tgoodwin>
Date:   Thu,  5 Feb 1998 14:51:54 +0000

Initial revision

Diffstat:
A
except.c
 | 
140
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 140 insertions(+), 0 deletions(-)
diff --git a/except.c b/except.c
@@ -0,0 +1,140 @@
+#include <setjmp.h>
+#include <signal.h>
+#include "rc.h"
+#include "jbwrap.h"
+
+/*
+   A return goes back stack frames to the last return. A break does
+   not. A signal goes to the last interactive level. (see below)
+*/
+
+bool nl_on_intr = TRUE;
+
+static Estack *estack;
+
+/* add an exception to the input stack. */
+
+extern void except(ecodes e, Edata data, Estack *ex) {
+	ex->prev = estack;
+	estack = ex;
+	estack->e = e;
+	estack->data = data;
+	if (e == eError || e == eBreak || e == eReturn)
+		estack->interactive = interactive;
+}
+
+/* remove an exception, restore last interactive value */
+
+extern void unexcept() {
+	switch (estack->e) {
+	default:
+		break;
+	case eError:
+		interactive = estack->interactive;
+		break;
+	case eArena:
+		restoreblock(estack->data.b);
+		break;
+	case eFifo:
+		unlink(estack->data.name);
+		break;
+	case eFd:
+		close(estack->data.fd);
+		break;
+	}
+	estack = estack->prev;
+}
+
+/*
+   Raise an exception. The rules are pretty complicated: you can return
+   from a loop inside a function, but you can't break from a function
+   inside of a loop. On errors, rc_raise() goes back to the LAST
+   INTERACTIVE stack frame. If no such frame exists, then rc_raise()
+   exits the shell.  This is what happens, say, when there is a syntax
+   error in a noninteractive shell script. While traversing the
+   exception stack backwards, rc_raise() also removes input sources
+   (closing file-descriptors, etc.) and pops instances of variables
+   that have been pushed onto the variable stack (e.g., for a function
+   call (for $*) or a local assignment).
+*/
+
+extern void rc_raise(ecodes e) {
+	if (e == eError && rc_pid != getpid())
+		exit(1); /* child processes exit on an error/signal */
+	for (; estack != NULL; estack = estack->prev)
+		if (estack->e != e) {
+			if (e == eBreak && estack->e != eArena)
+				rc_error("break outside of loop");
+			else if (e == eReturn && estack->e == eError) /* can return from loops inside functions */
+				rc_error("return outside of function");
+			switch (estack->e) {
+			default:
+				break;
+			case eVarstack:
+				varrm(estack->data.name, TRUE);
+				break;
+			case eArena:
+				restoreblock(estack->data.b);
+				break;
+			case eFifo:
+				unlink(estack->data.name);
+				break;
+			case eFd:
+				close(estack->data.fd);
+				break;
+			}
+		} else {
+			if (e == eError && !estack->interactive) {
+				popinput();
+			} else {
+				Jbwrap *j = estack->data.jb;
+
+				interactive = estack->interactive;
+				estack = estack->prev;
+				longjmp(j->j, 1);
+			}
+		}
+	rc_exit(1); /* top of exception stack */
+}
+
+extern bool outstanding_cmdarg() {
+	return estack->e == eFifo || estack->e == eFd;
+}
+
+extern void pop_cmdarg(bool remove) {
+	for (; estack != NULL; estack = estack->prev)
+		switch (estack->e) {
+		case eFifo:
+			if (remove)
+				unlink(estack->data.name);
+			break;
+		case eFd:
+			if (remove)
+				close(estack->data.fd);
+			break;
+		default:
+			return;
+		}
+}
+
+/* exception handlers */
+
+extern void rc_error(char *s) {
+	pr_error(s);
+	set(FALSE);
+	redirq = NULL;
+	cond = FALSE; /* no longer inside conditional */
+	rc_raise(eError);
+}
+
+extern void sigint(int s) {
+	if (s != SIGINT)
+		panic("s != SIGINT in sigint catcher");
+	/* this is the newline you see when you hit ^C while typing a command */
+	if (interactive && nl_on_intr)
+		fprint(2, "\n");
+	nl_on_intr = TRUE;
+	redirq = NULL;
+	cond = FALSE;
+	rc_raise(eError);
+}