OS/400 avoids using NOFOLLOW_LINKS (#3905)

* OS/400 avoids using NOFOLLOW_LINKS * Add changelog entry for os-400-no-follow-links
elastic · Dec 12, 2024 · 807b20b · 807b20b
1 parent d3fa9fb
commit 807b20b
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diff --git a/CHANGELOG.asciidoc b/CHANGELOG.asciidoc
@@ -35,6 +35,7 @@ Use subheadings with the "=====" level for adding notes for unreleased changes:
 ===== Bug fixes
 * Prevent NPE in OpenTelemetry metrics bridge in case of asynchronous agent start - {pull}3880[#3880]
 * Fix random Weblogic ClassNotFoundException related to thread context classloader - {pull}3870[#3870]
+* Skips using NOFOLLOW_LINKS file open option when running on OS/400 as it's unsupported there - {pull}3905[#3905]
 
 [[release-notes-1.x]]
 === Java Agent version 1.x

diff --git a/apm-agent-common/src/main/java/co/elastic/apm/agent/common/JvmRuntimeInfo.java b/apm-agent-common/src/main/java/co/elastic/apm/agent/common/JvmRuntimeInfo.java
@@ -39,6 +39,7 @@ public class JvmRuntimeInfo {
     private final boolean isHpUx;
     private final boolean isCoretto;
     private final boolean isZos;
+    private final boolean isOs400;
 
     public static JvmRuntimeInfo ofCurrentVM() {
         return CURRENT_VM;
@@ -68,6 +69,7 @@ private JvmRuntimeInfo(String version, String vmName, String vendorName, @Nullab
         isHpUx = version.endsWith("-hp-ux");
         isCoretto = vendorName != null && vendorName.contains("Amazon");
         isZos = (osName != null) && osName.toLowerCase().contains("z/os");
+        isOs400 = (osName != null) && osName.toLowerCase().contains("os/400");
 
         if (isHpUx) {
             // remove extra hp-ux suffix for parsing
@@ -153,7 +155,7 @@ public boolean isJ9VM() {
         return isJ9;
     }
 
-    public boolean isHpUx(){
+    public boolean isHpUx() {
         return isHpUx;
     }
 
@@ -173,6 +175,10 @@ public boolean isZos() {
         return isZos;
     }
 
+    public boolean isOs400() {
+        return isOs400;
+    }
+
     @Override
     public String toString() {
         return String.format("%s %s %s", javaVersion, javaVmName, javaVmVersion);

diff --git a/apm-agent-common/src/main/java/co/elastic/apm/agent/common/util/ResourceExtractionUtil.java b/apm-agent-common/src/main/java/co/elastic/apm/agent/common/util/ResourceExtractionUtil.java
@@ -101,9 +101,10 @@ public static synchronized Path extractResourceToDirectory(String resource, Stri
                     }
                 }
             } catch (FileAlreadyExistsException e) {
-                try (FileChannel channel = JvmRuntimeInfo.ofCurrentVM().isZos() ?
-                        FileChannel.open(tempFile, READ) :
-                        FileChannel.open(tempFile, READ, NOFOLLOW_LINKS)) {
+                JvmRuntimeInfo jvmRuntimeInfo = JvmRuntimeInfo.ofCurrentVM();
+                try (FileChannel channel = (jvmRuntimeInfo.isZos() || jvmRuntimeInfo.isOs400()) ?
+                    FileChannel.open(tempFile, READ) :
+                    FileChannel.open(tempFile, READ, NOFOLLOW_LINKS)) {
                     // wait until other JVM instances have fully written the file
                     // multiple JVMs can read the file at the same time
                     try (FileLock readLock = channel.lock(0, Long.MAX_VALUE, true)) {