From 85600f263999b160cb2eedfa1dc389b540edcd76 Mon Sep 17 00:00:00 2001
From: Jeff Genovy <29107334+jefgen@users.noreply.github.com>
Date: Mon, 21 Jan 2019 16:52:15 -0800
Subject: [PATCH] ICU-20370 Fix error checking in uloc_getLCID function.

---
 icu4c/source/common/uloc.cpp         |  2 +-
 icu4c/source/test/cintltst/cloctst.c | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/icu4c/source/common/uloc.cpp b/icu4c/source/common/uloc.cpp
index 3827457e982..6b65c626222 100644
--- a/icu4c/source/common/uloc.cpp
+++ b/icu4c/source/common/uloc.cpp
@@ -2191,7 +2191,7 @@ uloc_getLCID(const char* localeID)
     }
 
     uloc_getLanguage(localeID, langID, sizeof(langID), &status);
-    if (U_FAILURE(status)) {
+    if (U_FAILURE(status) || status == U_STRING_NOT_TERMINATED_WARNING) {
         return 0;
     }
 
diff --git a/icu4c/source/test/cintltst/cloctst.c b/icu4c/source/test/cintltst/cloctst.c
index 41f6d915e89..2268486a9f1 100644
--- a/icu4c/source/test/cintltst/cloctst.c
+++ b/icu4c/source/test/cintltst/cloctst.c
@@ -52,6 +52,7 @@ static void TestUnicodeDefines(void);
 
 static void TestIsRightToLeft(void);
 static void TestBadLocaleIDs(void);
+static void TestBug20370(void);
 
 void PrintDataTable();
 
@@ -266,6 +267,7 @@ void addLocaleTest(TestNode** root)
     TESTCASE(TestToUnicodeLocaleType);
     TESTCASE(TestToLegacyType);
     TESTCASE(TestBadLocaleIDs);
+    TESTCASE(TestBug20370);
 }
 
 
@@ -6498,3 +6500,13 @@ static void TestBadLocaleIDs() {
         }
     }
 }
+
+// Test case for ICU-20370.
+// The issue shows as an Addresss Sanitizer failure.
+static void TestBug20370() {
+    const char *localeID = "x-privatebutreallylongtagfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobarfoobar";
+    uint32_t lcid = uloc_getLCID(localeID);
+    if (lcid != 0) {
+        log_err("FAIL: Expected LCID value of 0 for invalid localeID input.");
+    }
+}
-- 
2.40.0