Re-introduction of sigcontext.

struct sigcontext and ucontext_t/mcontext_t are defined in such
a way that both (ie struct sigcontext and ucontext_t) can be
passed on to sigreturn. The signal handler is still given a
ucontext_t for maximum flexibility.

For backward compatibility sigreturn restores the state for the
alternate signal stack from sigcontext.sc_onstack and not from
ucontext_t.uc_stack. A good way to determine which value the
application has set and thus which value to use, is still open
for discussion.

NOTE: This change should only affect those binaries that use
      sigcontext and/or ucontext_t. In the source tree itself
      this is only doscmd. Recompilation is required for those
      applications.

This commit also fixes a lot of style bugs without hopefully
adding new ones.

NOTE: struct sigaltstack.ss_size now has type size_t again. For
      some reason I changed that into unsigned int.

Parts submitted by: bde
sigaltstack bug found by: bde

1 files changed, 9 insertions, 0 deletions

diff --git a/sys/alpha/include/reg.h b/sys/alpha/include/reg.h
index 341a396..879aeed 100644
--- a/sys/alpha/include/reg.h
+++ b/sys/alpha/include/reg.h
@@ -73,6 +73,15 @@
 #define	R_SP	30
 #define	R_ZERO	31
 
+/*
+ * Register extensions used in mcontext_t
+ */
+#define	R_PS		32
+#define	R_PC		33
+#define	R_TRAPARG_A0	34
+#define	R_TRAPARG_A1	35
+#define	R_TRAPARG_A2	36
+
 struct reg {
 	u_int64_t	r_regs[32];
 };