From 055fa4f22f4add7a486acf495345f266934edc52 Mon Sep 17 00:00:00 2001
From: Ingo Weinhold <ingo_weinhold@gmx.de>
Date: Sun, 8 Apr 2007 02:04:21 +0000
Subject: [PATCH] Assigning values to errno would not work; the next invocation
 would overwrite them with the host platform errno again. We do now track
 changes and use a hopefully reasonable strategy for updating the host errno.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@20608 a95241bf-73f2-0310-859d-f6bbb57e9c96
---
 src/build/libroot/errors.cpp | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/build/libroot/errors.cpp b/src/build/libroot/errors.cpp
index 2ebea8c6dd..1b6c548937 100644
--- a/src/build/libroot/errors.cpp
+++ b/src/build/libroot/errors.cpp
@@ -159,8 +159,24 @@ _haiku_build_strerror(int errnum)
 int *
 _haiku_build_errno()
 {
+	static int previousErrno = 0;
 	static int localErrno = 0;
-	localErrno = to_haiku_error(errno);
+	static int previousLocalErrno = 0;
+
+	// If the localErrno has been changed and the real errno has not changed
+	// in the meantime, we update errno itself, so that the local update will
+	// be reflected. If errno has changed we always update localErrno.
+	int currentErrno = errno;
+	if (currentErrno == previousErrno) {
+		if (localErrno != previousLocalErrno) {
+			errno = previousErrno = to_host_error(localErrno);
+			previousLocalErrno = localErrno;
+		}
+	} else {
+		previousErrno = currentErrno;
+		previousLocalErrno = localErrno = to_haiku_error(errno);
+	}
+
 	return &localErrno;
 }