[GR-74747] Fix timezone formatting mismatch when JVM timezone and tzset differ.

PullRequest: graalpython/4373

Author: timfel

graalpython/com.oracle.graal.python.test/src/com/oracle/graal/python/test/builtin/modules/TimeModuleTests.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * The Universal Permissive License (UPL), Version 1.0
+ *
+ * Subject to the condition set forth below, permission is hereby granted to any
+ * person obtaining a copy of this software, associated documentation and/or
+ * data (collectively the "Software"), free of charge and under any and all
+ * copyright rights in the Software, and any and all patent rights owned or
+ * freely licensable by each licensor hereunder covering either (i) the
+ * unmodified Software as contributed to or provided by such licensor, or (ii)
+ * the Larger Works (as defined below), to deal in both
+ *
+ * (a) the Software, and
+ *
+ * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
+ * one is included with the Software each a "Larger Work" to which the Software
+ * is contributed by such licensors),
+ *
+ * without restriction, including without limitation the rights to copy, create
+ * derivative works of, display, perform, and distribute the Software and make,
+ * use, sell, offer for sale, import, export, have made, and have sold the
+ * Software and the Larger Work(s), and to sublicense the foregoing rights on
+ * either these or other terms.
+ *
+ * This license is subject to the following condition:
+ *
+ * The above copyright notice and either this complete permission notice or at a
+ * minimum a reference to the UPL must be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+package com.oracle.graal.python.test.builtin.modules;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.TimeZone;
+
+import org.graalvm.polyglot.Context;
+import org.graalvm.polyglot.Source;
+import org.junit.Test;
+
+public class TimeModuleTests {
+
+    @Test
+    public void strftimeTimezoneMatchesTzsetState() {
+        TimeZone previousDefault = TimeZone.getDefault();
+        try {
+            TimeZone.setDefault(TimeZone.getTimeZone("Europe/Berlin"));
+            String result;
+            try (Context context = Context.newBuilder("python").allowAllAccess(true).build()) {
+                result = context.eval(Source.create("python", """
+                                import os
+                                import time
+
+                                os.environ["TZ"] = "UTC"
+                                time.tzset()
+                                tt = time.localtime()
+
+                                "\\n".join((
+                                    f"tm_zone={tt.tm_zone}",
+                                    f"tzname={time.tzname[tt.tm_isdst > 0]}",
+                                    f"strftime_tuple={time.strftime('%Z', tt)}",
+                                    f"strftime_now={time.strftime('%Z')}",
+                                ))
+                                """)).asString();
+            }
+
+            Map<String, String> values = parseKeyValueLines(result);
+            String details = values.toString();
+            assertEquals(details, values.get("tm_zone"), values.get("tzname"));
+            assertEquals(details, values.get("tm_zone"), values.get("strftime_tuple"));
+            assertEquals(details, values.get("tm_zone"), values.get("strftime_now"));
+        } finally {
+            TimeZone.setDefault(previousDefault);
+        }
+    }
+
+    private static Map<String, String> parseKeyValueLines(String output) {
+        Map<String, String> values = new LinkedHashMap<>();
+        for (String line : output.split("\\R")) {
+            int separator = line.indexOf('=');
+            values.put(line.substring(0, separator), line.substring(separator + 1));
+        }
+        return values;
+    }
+}

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/TimeModuleBuiltins.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2025, Oracle and/or its affiliates.
+ * Copyright (c) 2017, 2026, Oracle and/or its affiliates.
  * Copyright (c) 2013, Regents of the University of California
  *
  * All rights reserved.
@@ -739,15 +739,17 @@ private static String truncYear(int year) {
             return yearstr.substring(yearstr.length() - 2);
         }
 
-        private static GregorianCalendar getCalendar(int[] time) {
+        private static GregorianCalendar getCalendar(int[] time, TimeZone timeZone) {
             Month month = Month.of(time[1]); // GregorianCalendar expect months that starts from 0
-            return new GregorianCalendar(time[0], month.ordinal(), time[2], time[3], time[4], time[5]);
+            GregorianCalendar calendar = new GregorianCalendar(timeZone);
+            calendar.set(time[0], month.ordinal(), time[2], time[3], time[4], time[5]);
+            return calendar;
         }
 
         // This taken from JPython + some switches were corrected to provide the
         // same result as CPython
         @TruffleBoundary
-        public static TruffleString format(String format, int[] date, TruffleString.FromJavaStringNode fromJavaStringNode) {
+        public static TruffleString format(String format, int[] date, TimeZone timeZone, TruffleString.FromJavaStringNode fromJavaStringNode) {
             String s = "";
             int lastc = 0;
             int j;
@@ -869,7 +871,7 @@ public static TruffleString format(String format, int[] date, TruffleString.From
                         // TODO this is not correct, CPython counts the week of year
                         // from day of year item [8]
                         if (cal == null) {
-                            cal = getCalendar(date);
+                            cal = getCalendar(date, timeZone);
                         }
 
                         cal.setFirstDayOfWeek(Calendar.SUNDAY);
@@ -900,7 +902,7 @@ public static TruffleString format(String format, int[] date, TruffleString.From
                         // from day of year item [8]
 
                         if (cal == null) {
-                            cal = getCalendar(date);
+                            cal = getCalendar(date, timeZone);
                         }
                         cal.setFirstDayOfWeek(Calendar.MONDAY);
                         cal.setMinimalDaysInFirstWeek(7);
@@ -945,7 +947,7 @@ public static TruffleString format(String format, int[] date, TruffleString.From
                     case 'Z':
                         // timezone name
                         if (cal == null) {
-                            cal = getCalendar(date);
+                            cal = getCalendar(date, timeZone);
                         }
                         // If items[8] == 1, we're in daylight savings time.
                         // -1 means the information was not available; treat this as if not in dst.
@@ -964,6 +966,16 @@ public static TruffleString format(String format, int[] date, TruffleString.From
             return fromJavaStringNode.execute(s, TS_ENCODING);
         }
 
+        @TruffleBoundary
+        public static TruffleString format(String format, int[] date, TruffleString.FromJavaStringNode fromJavaStringNode) {
+            return format(format, date, TimeZone.getDefault(), fromJavaStringNode);
+        }
+
+        @TruffleBoundary
+        private static TimeZone getTimeZone(ZoneId currentZoneId) {
+            return TimeZone.getTimeZone(currentZoneId);
+        }
+
         @Specialization
         static TruffleString formatTime(PythonModule module, TruffleString format, @SuppressWarnings("unused") PNone time,
                         @Bind Node inliningTarget,
@@ -972,11 +984,11 @@ static TruffleString formatTime(PythonModule module, TruffleString format, @Supp
                         @Shared("js2ts") @Cached TruffleString.FromJavaStringNode fromJavaStringNode,
                         @Exclusive @Cached PRaiseNode raiseNode) {
             ModuleState moduleState = module.getModuleState(ModuleState.class);
-            return format(toJavaStringNode.execute(format), getIntLocalTimeStruct(moduleState.currentZoneId, (long) timeSeconds()), fromJavaStringNode);
+            return format(toJavaStringNode.execute(format), getIntLocalTimeStruct(moduleState.currentZoneId, (long) timeSeconds()), getTimeZone(moduleState.currentZoneId), fromJavaStringNode);
         }
 
         @Specialization
-        static TruffleString formatTime(VirtualFrame frame, @SuppressWarnings("unused") PythonModule module, TruffleString format, PTuple time,
+        static TruffleString formatTime(VirtualFrame frame, PythonModule module, TruffleString format, PTuple time,
                         @Bind Node inliningTarget,
                         @Cached SequenceStorageNodes.GetInternalObjectArrayNode getArray,
                         @Cached PyNumberAsSizeNode asSizeNode,
@@ -985,7 +997,7 @@ static TruffleString formatTime(VirtualFrame frame, @SuppressWarnings("unused")
                         @Shared("js2ts") @Cached TruffleString.FromJavaStringNode fromJavaStringNode,
                         @Exclusive @Cached PRaiseNode raiseNode) {
             int[] date = checkStructtime(frame, inliningTarget, time, getArray, asSizeNode, raiseNode);
-            return format(toJavaStringNode.execute(format), date, fromJavaStringNode);
+            return format(toJavaStringNode.execute(format), date, getTimeZone(module.getModuleState(ModuleState.class).currentZoneId), fromJavaStringNode);
         }
 
         @Specialization