[PATCH 14/15] Hurd signals: SA_SIGINFO support

[Jeremie Koenig]

Based on a preliminary patch by Samuel Thibault.

* sysdeps/mach/hurd/bits/sigaction.h: Define SA_SIGINFO.
* sysdeps/mach/hurd/i386/trampoline.c (fill_siginfo): New function,
fill in a siginfo_t structure. (fill_ucontext): New function, fill in a
ucontext_t structure. (_hurd_setup_sighandler): Add support for SA_SIGINFO
handlers.
---
 sysdeps/mach/hurd/bits/sigaction.h  |    1 +
 sysdeps/mach/hurd/i386/trampoline.c |  104 ++++++++++++++++++++++++++++++++---
 2 files changed, 96 insertions(+), 9 deletions(-)

diff --git a/sysdeps/mach/hurd/bits/sigaction.h 
b/sysdeps/mach/hurd/bits/sigaction.h
index adcc276..4528b38 100644
--- a/sysdeps/mach/hurd/bits/sigaction.h
+++ b/sysdeps/mach/hurd/bits/sigaction.h
@@ -59,6 +59,7 @@ struct sigaction
 # define SA_NODEFER    0x0010  /* Don't automatically block the signal when
                                    its handler is being executed.  */
 # define SA_RESETHAND  0x0004  /* Reset to SIG_DFL on entry to handler.  */
+# define SA_SIGINFO    0x0040  /* Signal handler with SA_SIGINFO args */
 #endif
 #define        SA_NOCLDSTOP    0x0008  /* Don't send SIGCHLD when children 
stop.  */
 
diff --git a/sysdeps/mach/hurd/i386/trampoline.c 
b/sysdeps/mach/hurd/i386/trampoline.c
index ec52847..0d2660d 100644
--- a/sysdeps/mach/hurd/i386/trampoline.c
+++ b/sysdeps/mach/hurd/i386/trampoline.c
@@ -21,13 +21,66 @@
 #include <hurd/signal.h>
 #include <hurd/userlink.h>
 #include <thread_state.h>
+#include <mach/exception.h>
 #include <mach/machine/eflags.h>
 #include <assert.h>
 #include <errno.h>
 #include "hurdfault.h"
 #include <intr-msg.h>
+#include <sys/ucontext.h>
 
 
+/* Fill in a siginfo_t structure for SA_SIGINFO-enabled handlers.  */
+static void fill_siginfo (siginfo_t *si, int signo,
+                         const struct hurd_signal_detail *detail,
+                         const struct machine_thread_all_state *state)
+{
+  si->si_signo = signo;
+  si->si_errno = detail->error;
+  si->si_code = detail->code;
+
+  /* XXX We would need a protocol change for sig_post to include
+   * this information.  */
+  si->si_pid = -1;
+  si->si_uid = -1;
+
+  /* Address of the faulting instruction or memory access.  */
+  if (detail->exc == EXC_BAD_ACCESS)
+    si->si_addr = (void *) detail->exc_subcode;
+  else
+    si->si_addr = (void *) state->basic.eip;
+
+  /* XXX On SIGCHLD, this should be the exit status of the child
+   * process.  We would need a protocol change for the proc server
+   * to send this information along with the signal.  */
+  si->si_status = 0;
+
+  si->si_band = 0;              /* SIGPOLL is not supported yet.  */
+  si->si_value.sival_int = 0;   /* sigqueue() is not supported yet.  */
+}
+
+/* Fill in a ucontext_t structure SA_SIGINFO-enabled handlers.  */
+static void fill_ucontext (ucontext_t *uc, const struct sigcontext *sc)
+{
+  uc->uc_flags = 0;
+  uc->uc_link = NULL;
+  uc->uc_sigmask = sc->sc_mask;
+  uc->uc_stack.ss_sp = (__ptr_t) sc->sc_esp;
+  uc->uc_stack.ss_size = 0;
+  uc->uc_stack.ss_flags = 0;
+
+  /* Registers.  */
+  memcpy (&uc->uc_mcontext.gregs[REG_GS], &sc->sc_gs,
+         (REG_TRAPNO - REG_GS) * sizeof (int));
+  uc->uc_mcontext.gregs[REG_TRAPNO] = 0;
+  uc->uc_mcontext.gregs[REG_ERR] = 0;
+  memcpy (&uc->uc_mcontext.gregs[REG_EIP], &sc->sc_eip,
+         (NGREG - REG_EIP) * sizeof (int));
+
+  /* XXX FPU state.  */
+  memset (&uc->uc_mcontext.fpregs, 0, sizeof (fpregset_t));
+}
+
 struct sigcontext *
 _hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
                        int signo, struct hurd_signal_detail *detail,
@@ -40,18 +93,37 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, 
__sighandler_t handler,
   extern const void _hurd_intr_rpc_msg_in_trap;
   extern const void _hurd_intr_rpc_msg_cx_sp;
   extern const void _hurd_intr_rpc_msg_sp_restored;
+  struct sigaction *action;
   void *volatile sigsp;
   struct sigcontext *scp;
   struct
     {
       int signo;
-      long int sigcode;
-      struct sigcontext *scp;  /* Points to ctx, below.  */
+      union
+       {
+         /* Extra arguments for traditional signal handlers */
+         struct
+           {
+             long int sigcode;
+             struct sigcontext *scp;       /* Points to ctx, below.  */
+           } legacy;
+
+         /* Extra arguments for SA_SIGINFO handlers */
+         struct
+           {
+             siginfo_t *siginfop;          /* Points to siginfo, below.  */
+             ucontext_t *uctxp;            /* Points to uctx, below.  */
+           } posix;
+       };
       void *sigreturn_addr;
       void *sigreturn_returns_here;
       struct sigcontext *return_scp; /* Same; arg to sigreturn.  */
+
+      /* NB: sigreturn assumes link is next to ctx.  */
       struct sigcontext ctx;
       struct hurd_userlink link;
+      ucontext_t ucontext;
+      siginfo_t siginfo;
     } *stackframe;
 
   if (ss->context)
@@ -143,15 +215,9 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, 
__sighandler_t handler,
          = &stackframe->link.thread.next;
       ss->active_resources = &stackframe->link;
 
-      /* Set up the arguments for the signal handler.  */
-      stackframe->signo = signo;
-      stackframe->sigcode = detail->code;
-      stackframe->scp = stackframe->return_scp = scp = &stackframe->ctx;
-      stackframe->sigreturn_addr = &__sigreturn;
-      stackframe->sigreturn_returns_here = firewall; /* Crash on return.  */
-
       /* Set up the sigcontext from the current state of the thread.  */
 
+      scp = &stackframe->ctx;
       scp->sc_onstack = ss->sigaltstack.ss_flags & SS_ONSTACK ? 1 : 0;
 
       /* struct sigcontext is laid out so that starting at sc_gs mimics a
@@ -165,6 +231,26 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, 
__sighandler_t handler,
                              &state->fpu, &scp->sc_i386_float_state,
                              sizeof (state->fpu));
 
+      /* Set up the arguments for the signal handler.  */
+      stackframe->signo = signo;
+      if (action->sa_flags & SA_SIGINFO)
+       {
+         stackframe->posix.siginfop = &stackframe->siginfo;
+         stackframe->posix.uctxp = &stackframe->ucontext;
+         fill_siginfo (&stackframe->siginfo, signo, detail, state);
+         fill_ucontext (&stackframe->ucontext, scp);
+       }
+      else
+       {
+         stackframe->legacy.sigcode = detail->code;
+         stackframe->legacy.scp = &stackframe->ctx;
+       }
+
+      /* Set up the bottom of the stack.  */
+      stackframe->sigreturn_addr = &__sigreturn;
+      stackframe->sigreturn_returns_here = firewall; /* Crash on return.  */
+      stackframe->return_scp = &stackframe->ctx;
+
       _hurdsig_end_catch_fault ();
 
       if (! ok)
-- 
1.7.5.3