Sys.signal renvoie l'ancien handler

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@2039 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

4 files changed, 45 insertions, 17 deletions

diff --git a/asmrun/signals.c b/asmrun/signals.c
index 1cfa8d7d3..3e8418e8e 100644
--- a/asmrun/signals.c
+++ b/asmrun/signals.c
@@ -25,6 +25,7 @@
 #include "fail.h"
 #include "signals.h"
 #include "stack.h"
+#include "sys.h"
 
 volatile int async_signal_mode = 0;
 volatile int pending_signal = 0;
@@ -226,10 +227,11 @@ value install_signal_handler(value signal_number, value action) /* ML */
                                  
 {
   int sig;
-  void (*act)();
+  void (*act)(int signo), (*oldact)(int signo);
 #ifdef POSIX_SIGNALS
-  struct sigaction sigact;
+  struct sigaction sigact, oldsigact;
 #endif
+  value res;
 
   sig = Int_val(signal_number);
   if (sig < 0) sig = posix_signals[-sig-1];
@@ -255,15 +257,25 @@ value install_signal_handler(value signal_number, value action) /* ML */
     act = handle_signal;
     break;
   }
-#ifndef POSIX_SIGNALS
-  signal(sig, act);
-#else
+#ifdef POSIX_SIGNALS
   sigact.sa_handler = act;
-  sigact.sa_flags = 0;
   sigemptyset(&sigact.sa_mask);
-  sigaction(sig, &sigact, NULL);
+  sigact.sa_flags = 0;
+  if (sigaction(sig, &sigact, &oldsigact) == -1) sys_error(NO_ARG);
+  oldact = oldsigact.sa_handler;
+#else
+  oldact = signal(sig, act);
+  if (oldact == SIG_ERR) sys_error(NO_ARG);
 #endif
-  return Val_unit;
+  if (oldact == handle_signal) {
+    res = alloc(1, 0);          /* Signal_handle */
+    Field(res, 0) = Field(signal_handlers, sig);
+  }
+  else if (oldact == SIG_IGN)
+    res = Val_int(1);           /* Signal_ignore */
+  else
+    res = Val_int(0);           /* Signal_default */
+  return res;
 }
 
 /* Machine- and OS-dependent handling of bound check trap */
diff --git a/byterun/signals.c b/byterun/signals.c
index df01d68cb..67bb7d4bd 100644
--- a/byterun/signals.c
+++ b/byterun/signals.c
@@ -21,6 +21,7 @@
 #include "mlvalues.h"
 #include "roots.h"
 #include "signals.h"
+#include "sys.h"
 
 volatile int async_signal_mode = 0;
 volatile int pending_signal = 0;
@@ -160,10 +161,11 @@ int posix_signals[] = {
 value install_signal_handler(value signal_number, value action) /* ML */
 {
   int sig;
-  void (*act)(int signo);
+  void (*act)(int signo), (*oldact)(int signo);
 #ifdef POSIX_SIGNALS
-  struct sigaction sigact;
+  struct sigaction sigact, oldsigact;
 #endif
+  value res;
 
   sig = Int_val(signal_number);
   if (sig < 0) sig = posix_signals[-sig-1];
@@ -193,9 +195,19 @@ value install_signal_handler(value signal_number, value action) /* ML */
   sigact.sa_handler = act;
   sigemptyset(&sigact.sa_mask);
   sigact.sa_flags = 0;
-  sigaction(sig, &sigact, NULL);
+  if (sigaction(sig, &sigact, &oldsigact) == -1) sys_error(NO_ARG);
+  oldact = oldsigact.sa_handler;
 #else
-  signal(sig, act);
+  oldact = signal(sig, act);
+  if (oldact == SIG_ERR) sys_error(NO_ARG);
 #endif
-  return Val_unit;
+  if (oldact == handle_signal) {
+    res = alloc(1, 0);          /* Signal_handle */
+    Field(res, 0) = Field(signal_handlers, sig);
+  }
+  else if (oldact == SIG_IGN)
+    res = Val_int(1);           /* Signal_ignore */
+  else
+    res = Val_int(0);           /* Signal_default */
+  return res;
 }
diff --git a/stdlib/sys.ml b/stdlib/sys.ml
index ae1494555..c2be9c9de 100644
--- a/stdlib/sys.ml
+++ b/stdlib/sys.ml
@@ -37,7 +37,8 @@ type signal_behavior =
   | Signal_ignore
   | Signal_handle of (int -> unit)
 
-external signal: int -> signal_behavior -> unit = "install_signal_handler"
+external signal: int -> signal_behavior -> signal_behavior
+        = "install_signal_handler"
 
 let sigabrt = -1
 let sigalrm = -2
@@ -67,4 +68,5 @@ let catch_break on =
   if on then
     signal sigint (Signal_handle(fun _ -> raise Break))
   else
-    signal sigint Signal_default
+    signal sigint Signal_default;
+  ()
diff --git a/stdlib/sys.mli b/stdlib/sys.mli
index 2178df5da..1bdbb191b 100644
--- a/stdlib/sys.mli
+++ b/stdlib/sys.mli
@@ -65,9 +65,11 @@ type signal_behavior =
 -          [Signal_handle f]: call function [f], giving it the signal
              number as argument. *)
 
-external signal: int -> signal_behavior -> unit = "install_signal_handler"
+external signal: int -> signal_behavior -> signal_behavior
+      = "install_signal_handler"
         (* Set the behavior of the system on receipt of a given signal.
-           The first argument is the signal number. *)
+           The first argument is the signal number.  Return the behavior
+           previously associated with the signal. *)
 
 val sigabrt: int   (* Abnormal termination *)
 val sigalrm: int   (* Timeout *)