initial version

build.gradle

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+apply plugin: 'java'
+apply plugin: 'groovy'
+apply plugin: 'cpp-lib'
+apply plugin: 'idea'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    groovy 'org.codehaus.groovy:groovy:1.8.7'
+    testCompile 'org.spockframework:spock-core:0.6-groovy-1.8'
+}
+
+def nativeHeadersDir = file("$buildDir/nativeHeaders")
+
+libraries {
+    main {
+        spec {
+            includes([nativeHeadersDir])
+            includes(['/System/Library/Frameworks/JavaVM.framework/Versions/Current/Headers/'])
+        }
+    }
+}
+
+task nativeHeaders {
+    def outputFile = file("$nativeHeadersDir/native.h")
+    inputs.files sourceSets.main.output
+    outputs.file outputFile
+    doLast {
+        outputFile.parentFile.mkdirs()
+        exec {
+            executable org.gradle.internal.jvm.Jvm.current().getExecutable('javah')
+            args '-o', outputFile
+            args '-classpath', sourceSets.main.output.classesDir
+            args 'net.rubygrapefruit.platform.internal.PosixFileFunctions'
+        }
+    }
+}
+
+compileMain.dependsOn nativeHeaders
+test.dependsOn compileMain
+

src/main/cpp/posixFileFunctions.c

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+#include "native.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+void markFailed(JNIEnv *env, jobject result) {
+    jclass destClass = env->GetObjectClass(result);
+    jfieldID errnoField = env->GetFieldID(destClass, "errno", "I");
+    env->SetIntField(result, errnoField, errno);
+}
+
+JNIEXPORT void JNICALL
+Java_net_rubygrapefruit_platform_internal_PosixFileFunctions_chmod(JNIEnv *env, jclass target, jstring path, jint mode, jobject result) {
+    const char* pathUtf8 = env->GetStringUTFChars(path, NULL);
+    int retval = chmod(pathUtf8, mode);
+    if (retval != 0) {
+        markFailed(env, result);
+    }
+}
+
+JNIEXPORT void JNICALL
+Java_net_rubygrapefruit_platform_internal_PosixFileFunctions_stat(JNIEnv *env, jclass target, jstring path, jobject dest, jobject result) {
+    struct stat fileInfo;
+    const char* pathUtf8 = env->GetStringUTFChars(path, NULL);
+    int retval = stat(pathUtf8, &fileInfo);
+    if (retval != 0) {
+        markFailed(env, result);
+        return;
+    }
+    jclass destClass = env->GetObjectClass(dest);
+    jfieldID modeField = env->GetFieldID(destClass, "mode", "I");
+    env->SetIntField(dest, modeField, 0777 & fileInfo.st_mode);
+}

src/main/java/net/rubygrapefruit/platform/NativeException.java

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+package net.rubygrapefruit.platform;
+
+public class NativeException extends RuntimeException {
+    public NativeException(String message) {
+        super(message);
+    }
+}

src/main/java/net/rubygrapefruit/platform/NativeIntegration.java

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+package net.rubygrapefruit.platform;
+
+public interface NativeIntegration {
+}

src/main/java/net/rubygrapefruit/platform/Platform.java

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+package net.rubygrapefruit.platform;
+
+import net.rubygrapefruit.platform.internal.FileStat;
+import net.rubygrapefruit.platform.internal.FunctionResult;
+import net.rubygrapefruit.platform.internal.PosixFileFunctions;
+
+import java.io.File;
+import java.io.IOException;
+
+public class Platform {
+    private static final Object lock = new Object();
+    private static boolean loaded;
+
+    static <T extends NativeIntegration> T get(Class<T> type) {
+        synchronized (lock) {
+            if (!loaded) {
+                System.setProperty("java.library.path", new File("build/binaries").getAbsolutePath());
+                try {
+                    System.load(new File("build/binaries/libnative-platform.dylib").getCanonicalPath());
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+                loaded = true;
+            }
+        }
+        return type.cast(new UnixFileMode() {
+            @Override
+            public void setMode(File file, int perms) {
+                FunctionResult result = new FunctionResult();
+                PosixFileFunctions.chmod(file.getPath(), perms, result);
+                if (result.isFailed()) {
+                    throw new NativeException(String.format("Could not set UNIX mode on %s. Errno is %d.", file, result.getErrno()));
+                }
+            }
+
+            @Override
+            public int getMode(File file) {
+                FunctionResult result = new FunctionResult();
+                FileStat stat = new FileStat();
+                PosixFileFunctions.stat(file.getPath(), stat, result);
+                if (result.isFailed()) {
+                    throw new NativeException(String.format("Could not get UNIX mode on %s. Errno is %d.", file, result.getErrno()));
+                }
+                return stat.mode;
+            }
+        });
+    }
+}

src/main/java/net/rubygrapefruit/platform/UnixFileMode.java

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+package net.rubygrapefruit.platform;
+
+import java.io.File;
+
+public interface UnixFileMode extends NativeIntegration {
+    void setMode(File path, int perms) throws NativeException;
+
+    int getMode(File path) throws NativeException;
+}

src/main/java/net/rubygrapefruit/platform/internal/FileStat.java

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+package net.rubygrapefruit.platform.internal;
+
+public class FileStat {
+    public int mode;
+}

src/main/java/net/rubygrapefruit/platform/internal/FunctionResult.java

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+package net.rubygrapefruit.platform.internal;
+
+public class FunctionResult {
+    int errno;
+
+    public boolean isFailed() {
+        return errno != 0;
+    }
+
+    public int getErrno() {
+        return errno;
+    }
+}

src/main/java/net/rubygrapefruit/platform/internal/PosixFileFunctions.java

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+package net.rubygrapefruit.platform.internal;
+
+public class PosixFileFunctions {
+    public static native void chmod(String file, int perms, FunctionResult result);
+
+    public static native void stat(String file, FileStat stat, FunctionResult result);
+}

src/test/groovy/net/rubygrapefruit/platform/UnixFileModeTest.groovy

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+package net.rubygrapefruit.platform
+
+import spock.lang.Specification
+import org.junit.Rule
+import org.junit.rules.TemporaryFolder
+
+class UnixFileModeTest extends Specification {
+    @Rule TemporaryFolder tmpDir
+    final UnixFileMode file = Platform.get(UnixFileMode.class)
+
+    def "can set mode on a file"() {
+        def testFile = tmpDir.newFile("test.txt")
+
+        when:
+        file.setMode(testFile, 0740)
+
+        then:
+        file.getMode(testFile) == 0740
+    }
+
+    def "can set mode on a file with unicode in its name"() {
+        def testFile = tmpDir.newFile("test\u03b1.txt")
+
+        when:
+        file.setMode(testFile, 0740)
+
+        then:
+        file.getMode(testFile) == 0740
+    }
+
+    def "throws exception on failure to set mode"() {
+        def file = new File(tmpDir.root, "unknown")
+
+        when:
+        this.file.setMode(file, 0660)
+
+        then:
+        NativeException e = thrown()
+        e.message == "Could not set UNIX mode on $file. Errno is 2."
+    }
+
+    def "throws exception on failure to get mode"() {
+        def file = new File(tmpDir.root, "unknown")
+
+        when:
+        this.file.getMode(file)
+
+        then:
+        NativeException e = thrown()
+        e.message == "Could not get UNIX mode on $file. Errno is 2."
+    }
+}