8271003: hs_err improvement: handle CLASSPATH env setting longer than O_BUFLEN

Reviewed-by: dholmes, stuefe, iklam, minqi

src/hotspot/share/runtime/os.cpp

@@ -989,7 +989,9 @@ void os::print_environment_variables(outputStream* st, const char** env_list) {
       if (envvar != NULL) {
         st->print("%s", env_list[i]);
         st->print("=");
-        st->print_cr("%s", envvar);
+        st->print("%s", envvar);
+        // Use separate cr() printing to avoid unnecessary buffer operations that might cause truncation.
+        st->cr();
       }
     }
   }

test/hotspot/jtreg/runtime/ErrorHandling/ClassPathEnvVar.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8271003
+ * @summary CLASSPATH env variable setting should not be truncated in a hs err log.
+ * @library /test/lib
+ * @run driver ClassPathEnvVar
+ */
+import java.io.File;
+import java.util.Map;
+
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+
+public class ClassPathEnvVar {
+    private static final String pathSep = File.pathSeparator;
+    private static final String sep = File.separator;
+    private static final String classPathEnv = "CLASSPATH";
+    private static final String endPath = "end-path";
+
+    public static void main(String[] args) throws Exception {
+        OutputAnalyzer output = runCrasher().shouldContain("CreateCoredumpOnCrash turned off, no core file dumped")
+                                             .shouldNotHaveExitValue(0);
+
+        checkErrorLog(output);
+
+    }
+    private static OutputAnalyzer runCrasher() throws Exception {
+        ProcessBuilder pb =
+            ProcessTools.createJavaProcessBuilder("-XX:-CreateCoredumpOnCrash",
+                                                  "-XX:ErrorHandlerTest=14",
+                                                  "-XX:+ErrorFileToStdout");
+
+        // Obtain the CLASSPATH setting and expand it to more than 2000 chars.
+        Map<String, String> envMap = pb.environment();
+        String cp = envMap.get(classPathEnv);
+        if (cp == null) {
+            cp = "this" + sep + "is" + sep + "dummy" + sep + "path";
+        }
+        while (cp.length() < 2000) {
+            cp += pathSep + cp;
+        }
+        cp += pathSep + endPath;
+        envMap.put(classPathEnv, cp);
+
+        return new OutputAnalyzer(pb.start());
+    }
+
+    private static void checkErrorLog(OutputAnalyzer output) throws Exception {
+        String classPathLine = output.firstMatch("CLASSPATH=.*");
+
+        if (classPathLine == null) {
+            throw new RuntimeException("CLASSPATH setting not found in hs err log.");
+        }
+
+        // Check if the CLASSPATH line has been truncated.
+        if (!classPathLine.endsWith(endPath)) {
+            throw new RuntimeException("CLASSPATH was truncated in the hs err log.");
+        }
+    }
+}