MFC r304928:

Do not obliterate errno value in the main thread during ptrace(2) call on x86.

MFC r304931:
Follow ABI when calling __error from the ptrace(2) wrapper.

MFC r305012:
Rewrite ptrace(2) wrappers in C.

MFC r305022:
Restore the requirement of setting errno to zero before calling ptrace(2).

3 files changed, 58 insertions, 2 deletions

diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 25bd4a3..0da0f82 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -59,6 +59,7 @@ INTERPOSED = \
 	poll \
 	ppoll \
 	pselect \
+	ptrace \
 	read \
 	readv \
 	recvfrom \
diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2
index eae19cd..6dffefc 100644
--- a/lib/libc/sys/ptrace.2
+++ b/lib/libc/sys/ptrace.2
@@ -2,7 +2,7 @@
 .\"	$NetBSD: ptrace.2,v 1.2 1995/02/27 12:35:37 cgd Exp $
 .\"
 .\" This file is in the public domain.
-.Dd July 28, 2016
+.Dd August 28, 2016
 .Dt PTRACE 2
 .Os
 .Sh NAME
@@ -906,7 +906,13 @@ to return
 \-1
 as a non-error value; to disambiguate,
 .Va errno
-can be set to 0 before the call and checked afterwards.
+is set to 0 in the libc wrapper for the
+.Fn ptrace
+system call and
+.Fn ptrace
+callers can reliably check
+.Va errno
+for non-zero value afterwards.
 .Sh ERRORS
 The
 .Fn ptrace
diff --git a/lib/libc/sys/ptrace.c b/lib/libc/sys/ptrace.c
new file mode 100644
index 0000000..2bb615f
--- /dev/null
+++ b/lib/libc/sys/ptrace.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2016 The FreeBSD Foundation.
+ * All rights reserved.
+ *
+ * Portions of this software were developed by Konstantin Belousov
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice(s), this list of conditions and the following disclaimer as
+ *    the first lines of this file unmodified other than the possible
+ *    addition of one or more copyright notices.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice(s), this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
+ * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+ * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/types.h>
+#include <sys/ptrace.h>
+#include <errno.h>
+#include "libc_private.h"
+
+__weak_reference(_ptrace, ptrace);
+
+int
+_ptrace(int request, pid_t pid, caddr_t addr, int data)
+{
+
+	errno = 0;
+	return (__sys_ptrace(request, pid, addr, data));
+}