Improve documentation.

1 files changed, 25 insertions, 2 deletions

diff --git a/lib/c-stack.h b/lib/c-stack.h
index 5f80457398..8c06541fd6 100644
--- a/lib/c-stack.h
+++ b/lib/c-stack.h
@@ -1,6 +1,6 @@
 /* Stack overflow handling.
 
-   Copyright (C) 2002, 2004 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2004, 2008 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -15,4 +15,27 @@
    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-int c_stack_action (void (*) (int));
+
+/* Set up ACTION so that it is invoked on C stack overflow and on other,
+   stack-unrelated, segmentation violation.
+   Return -1 (setting errno) if this cannot be done.
+
+   When a stack overflow or segmentation violation occurs:
+   1) ACTION is called.  It is passed an argument equal to
+        - 0, for a stack overflow,
+        - SIGSEGV, for a segmentation violation that does not appear related
+          to stack overflow.
+      On many platforms the two cases are hard to distinguish; when in doubt,
+      zero is passed.
+   2) If ACTION returns, a message is written to standard error, and the
+      program is terminated: in the case of stack overflow, with exit code
+      exit_failure (see "exitfail.h"), otherwise through a signal SIGSEGV.
+
+   A null ACTION acts like an action that does nothing.
+
+   ACTION must be async-signal-safe.  ACTION together with its callees
+   must not require more than SIGSTKSZ bytes of stack space.  Also,
+   ACTION should not call longjmp, because this implementation does
+   not guarantee that it is safe to return to the original stack.  */
+
+extern int c_stack_action (void (* /*action*/) (int));