The si_status field of the siginfo_t, provided by the waitid(2) and

SIGCHLD signal, should keep full 32 bits of the status passed to the
_exit(2).

Split the combined p_xstat of the struct proc into the separate exit
status p_xexit for normal process exit, and signalled termination
information p_xsig.  Kernel-visible macro KW_EXITCODE() reconstructs
old p_xstat from p_xexit and p_xsig.  p_xexit contains complete status
and copied out into si_status.

Requested by:	Joerg Schilling
Reviewed by:	jilles (previous version), pho
Tested by:	pho
Sponsored by:	The FreeBSD Foundation

2 files changed, 12 insertions, 8 deletions

diff --git a/lib/libc/sys/wait.2 b/lib/libc/sys/wait.2
index 84b2b1a..a45e78a 100644
--- a/lib/libc/sys/wait.2
+++ b/lib/libc/sys/wait.2
@@ -362,6 +362,15 @@ field set to
 and the
 .Fa si_pid
 field set to the process ID of the process reporting status.
+For the exited process, the
+.Fa si_status
+field of the
+.Dv siginfo_t
+structure contains the full 32 bit exit status passed to
+.Xr _exit 2 ;
+the
+.Fa status
+argument of other calls only returns 8 lowest bits of the exit status.
 .Pp
 When the
 .Dv WNOHANG
@@ -656,13 +665,6 @@ is an extension;
 .Tn POSIX
 only permits this flag with
 .Fn waitid .
-.Pp
-.Tn POSIX
-requires
-.Fn waitid
-to return the full 32 bits passed to
-.Xr _exit 2 ;
-this implementation only returns 8 bits like the other calls.
 .Sh HISTORY
 The
 .Fn wait
diff --git a/lib/libkvm/kvm_proc.c b/lib/libkvm/kvm_proc.c
index aed61a8..bafe105 100644
--- a/lib/libkvm/kvm_proc.c
+++ b/lib/libkvm/kvm_proc.c
@@ -66,6 +66,8 @@ __FBSDID("$FreeBSD$");
 #include <sys/tty.h>
 #include <sys/file.h>
 #include <sys/conf.h>
+#define	_WANT_KW_EXITCODE
+#include <sys/wait.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -389,7 +391,7 @@ nopgrp:
 		kp->ki_siglist = proc.p_siglist;
 		SIGSETOR(kp->ki_siglist, mtd.td_siglist);
 		kp->ki_sigmask = mtd.td_sigmask;
-		kp->ki_xstat = proc.p_xstat;
+		kp->ki_xstat = KW_EXITCODE(proc.p_xexit, proc.p_xsig);
 		kp->ki_acflag = proc.p_acflag;
 		kp->ki_lock = proc.p_lock;
 		if (proc.p_state != PRS_ZOMBIE) {