Add custom JDK tmpdir folder under .github/tmpdir for CI to work

stupid perms I swear

.github/workflows/build-hotspot.yml

@@ -53,8 +53,9 @@ jobs:
             ${{ runner.os }}-hotspot-maven-${{ inputs.JDK_VENDOR }}-${{ inputs.JDK_VERSION }}-
       - name: "Build and test"
         run: |
+          set -euo pipefail
           export VERSION="git-$(date -d "$CI_COMMIT_TIMESTAMP" +'%Y%m%d-%H%M')-$CI_COMMIT_SHORT_SHA"
-          mvn -B -e -fae --show-version -T$(nproc)C -Drevision="$VERSION" verify package
+          mvn -B -e -fae --show-version -T$(nproc)C -Drevision="$VERSION" -DsurefireTmpDir="$(pwd)/.github/tmpdir" verify package
           awk -F"," '{ instructions += $4 + $5; covered += $5 } END { print covered, "/", instructions, " instructions covered"; print 100*covered/instructions, "% covered" }' target/site/jacoco/jacoco.csv
       - name: "Archive jarfile"
         uses: "actions/upload-artifact@v4"

.gitignore

@@ -1,4 +1,5 @@
 *.iml
 .idea
+.github/tmpdir
 target
 zlib/

pom.xml

@@ -22,6 +22,8 @@
         <revision>local-SNAPSHOT</revision>
         <build.timestamp>${maven.build.timestamp}</build.timestamp>
 
+        <surefireTmpDir>${java.io.tmpdir}</surefireTmpDir>
+
         <maven-compiler-plugin.version>3.13.0</maven-compiler-plugin.version>
         <maven-pmd-plugin.version>3.26.0</maven-pmd-plugin.version>
         <maven-surefire-plugin.version>3.5.2</maven-surefire-plugin.version>
@@ -84,7 +86,7 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>${maven-surefire-plugin.version}</version>
                 <configuration>
-                    <argLine>--enable-preview @{jacoco.surefireArgLine} -javaagent:${org.mockito:mockito-core:jar} -Dspring.profiles.active=test</argLine>
+                    <argLine>--enable-preview -Djava.io.tmpdir=${surefireTmpDir} @{jacoco.surefireArgLine} -javaagent:${org.mockito:mockito-core:jar} -Dspring.profiles.active=test</argLine>
                     <redirectTestOutputToFile>true</redirectTestOutputToFile>
                 </configuration>
             </plugin>