Windows: Add support for returning file IDs from stat and readdir

* Add `FileInfo.getKey()` that returns a file identifier than can be used to compare efficiently files for equality. If the key is not available, the method returns `null`. * This is a similar concept as exposed in the Java 7 nio API https://docs.oracle.com/javase/7/docs/api/java/nio/file/attribute/BasicFileAttributes.html#fileKey() * A WindowsFileKey is a pair of (volume serial number, file id on the volume) * Update the `stat` and `fastReaddirXxx` jni entry points to provide this information * Update the test app to display `file key` if it is available
gradle · Aug 7, 2019 · 3720c9a · 3720c9a
1 parent 3230537
commit 3720c9a
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Showing 13 changed files with 222 additions and 9 deletions.
diff --git a/src/main/cpp/posix.cpp b/src/main/cpp/posix.cpp
@@ -105,6 +105,8 @@ void unpackStat(struct stat* source, file_stat_t* result) {
 #else
     result->lastModified = toMillis(source->st_mtimespec);
 #endif
+    result->volumeId = 0;
+    result->fileId = 0;
 }
 
 JNIEXPORT void JNICALL
@@ -207,6 +209,8 @@ Java_net_rubygrapefruit_platform_internal_jni_PosixFileFunctions_readdir(JNIEnv
             fileResult.fileType = FILE_TYPE_MISSING;
             fileResult.size = 0;
             fileResult.lastModified = 0;
+            fileResult.volumeId = 0;
+            fileResult.fileId = 0;
         } else {
             unpackStat(&fileInfo, &fileResult);
         }

diff --git a/src/main/cpp/win.cpp b/src/main/cpp/win.cpp
@@ -189,11 +189,15 @@ DWORD get_file_stat(wchar_t* pathStr, jboolean followLink, file_stat_t* pFileSta
             pFileStat->lastModified = 0;
             pFileStat->size = 0;
             pFileStat->fileType = FILE_TYPE_MISSING;
+            pFileStat->volumeId = 0;
+            pFileStat->fileId = 0;
             return ERROR_SUCCESS;
         }
         return error;
     }
     pFileStat->lastModified = lastModifiedNanos(&attr.ftLastWriteTime);
+    pFileStat->volumeId = 0;
+    pFileStat->fileId = 0;
     if (attr.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
         pFileStat->size = 0;
         pFileStat->fileType = FILE_TYPE_DIRECTORY;
@@ -223,6 +227,8 @@ DWORD get_file_stat(wchar_t* pathStr, jboolean followLink, file_stat_t* pFileSta
             pFileStat->lastModified = 0;
             pFileStat->size = 0;
             pFileStat->fileType = FILE_TYPE_MISSING;
+            pFileStat->volumeId = 0;
+            pFileStat->fileId = 0;
             return ERROR_SUCCESS;
         }
         return error;
@@ -250,6 +256,8 @@ DWORD get_file_stat(wchar_t* pathStr, jboolean followLink, file_stat_t* pFileSta
 
     pFileStat->lastModified = lastModifiedNanos(&fileInfo.ftLastWriteTime);
     pFileStat->size = 0;
+    pFileStat->volumeId = fileInfo.dwVolumeSerialNumber;
+    pFileStat->fileId = ((LONGLONG)fileInfo.nFileIndexHigh << 32) | fileInfo.nFileIndexLow;
     if (is_file_symlink(fileTagInfo.FileAttributes, fileTagInfo.ReparseTag)) {
         pFileStat->fileType = FILE_TYPE_SYMLINK;
     } else if (fileTagInfo.FileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
@@ -524,12 +532,21 @@ Java_net_rubygrapefruit_platform_internal_jni_FileEventFunctions_closeWatch(JNIE
 
 JNIEXPORT void JNICALL
 Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_stat(JNIEnv *env, jclass target, jstring path, jboolean followLink, jobject dest, jobject result) {
+#ifdef WINDOWS_MIN
     jclass destClass = env->GetObjectClass(dest);
     jmethodID mid = env->GetMethodID(destClass, "details", "(IJJ)V");
     if (mid == NULL) {
         mark_failed_with_message(env, "could not find method", result);
         return;
     }
+#else
+    jclass destClass = env->GetObjectClass(dest);
+    jmethodID mid = env->GetMethodID(destClass, "details", "(IJJIJ)V");
+    if (mid == NULL) {
+        mark_failed_with_message(env, "could not find method", result);
+        return;
+    }
+#endif
 
     wchar_t* pathStr = java_to_wchar_path(env, path, result);
     file_stat_t fileStat;
@@ -539,7 +556,12 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_stat(JNIEnv *
         mark_failed_with_code(env, "could not file attributes", errorCode, NULL, result);
         return;
     }
+
+#ifdef WINDOWS_MIN
     env->CallVoidMethod(dest, mid, fileStat.fileType, fileStat.size, fileStat.lastModified);
+#else
+    env->CallVoidMethod(dest, mid, fileStat.fileType, fileStat.size, fileStat.lastModified, fileStat.volumeId, fileStat.fileId);
+#endif
 }
 
 JNIEXPORT void JNICALL
@@ -587,6 +609,8 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_readdir(JNIEn
                     FILE_TYPE_FILE;
             fileInfo.lastModified = lastModifiedNanos(&entry.ftLastWriteTime);
             fileInfo.size = ((jlong)entry.nFileSizeHigh << 32) | entry.nFileSizeLow;
+            fileInfo.volumeId = 0;
+            fileInfo.fileId = 0;
         }
 
         // Add entry
@@ -619,6 +643,7 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_fastReaddirIs
 typedef struct fast_readdir_handle {
     HANDLE handle;
     wchar_t* pathStr;
+    ULONG volumeSerialNumber;
 } readdir_fast_handle_t;
 #endif
 
@@ -666,6 +691,17 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_fastReaddirOp
         free(pathStr);
         return NULL;
     }
+
+    // This call allows retrieving the volume ID of this directory (and all its entries)
+    BY_HANDLE_FILE_INFORMATION fileInfo;
+    BOOL ok = GetFileInformationByHandle(handle, &fileInfo);
+    if (!ok) {
+        mark_failed_with_errno(env, "could not open directory", result);
+        free(pathStr);
+        CloseHandle(handle);
+        return NULL;
+    }
+
     readdir_fast_handle_t* readdirHandle = (readdir_fast_handle_t*)LocalAlloc(LPTR, sizeof(readdir_fast_handle_t));
     if (readdirHandle == NULL) {
         mark_failed_with_code(env, "Out of native memory", ERROR_OUTOFMEMORY, NULL, result);
@@ -675,6 +711,7 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_fastReaddirOp
     }
     readdirHandle->handle = handle;
     readdirHandle->pathStr = pathStr;
+    readdirHandle->volumeSerialNumber = fileInfo.dwVolumeSerialNumber;
     return (jlong)readdirHandle;
 #endif
 }
@@ -694,6 +731,20 @@ Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_fastReaddirCl
 #endif
 }
 
+//
+// Returns the volume id of the directory opened by fastReaddirOpen
+//
+JNIEXPORT jint JNICALL
+Java_net_rubygrapefruit_platform_internal_jni_WindowsFileFunctions_fastReaddirGetVolumeId(JNIEnv *env, jclass target, jlong handle, jobject result) {
+#ifdef WINDOWS_MIN
+    mark_failed_with_code(env, "Operation not supported", ERROR_CALL_NOT_IMPLEMENTED, NULL, result);
+    return 0;
+#else
+    readdir_fast_handle_t* readdirHandle = (readdir_fast_handle_t*)handle;
+    return readdirHandle->volumeSerialNumber;
+#endif
+}
+
 //
 // Reads the next batch of entries from the directory.
 // Returns JNI_TRUE on success and if there are more entries found

diff --git a/src/main/java/net/rubygrapefruit/platform/file/FileInfo.java b/src/main/java/net/rubygrapefruit/platform/file/FileInfo.java
@@ -44,4 +44,12 @@ enum Type {
      * Returns the last modification time of this file, in ms since epoch. Returns 0 when this file does not exist.
      */
     long getLastModifiedTime();
+
+    /**
+     * Returns an object that uniquely identifies the given file, or null if a file key is not available.
+     *
+     * <p>See <a href="https://docs.oracle.com/javase/7/docs/api/java/nio/file/attribute/BasicFileAttributes.html#fileKey()">BasicFileAttributes.fileKey()</a>
+     * for a more in depth explanation.</p>
+     */
+    Object getKey();
 }
diff --git a/src/main/java/net/rubygrapefruit/platform/file/WindowsFileInfo.java b/src/main/java/net/rubygrapefruit/platform/file/WindowsFileInfo.java
@@ -25,4 +25,13 @@
  */
 @ThreadSafe
 public interface WindowsFileInfo extends FileInfo {
+    /**
+     * Returns the volume ID (serial number) of the file.
+     */
+    int getVolumeId();
+
+    /**
+     * Returns the file ID of the file, unique within the volume identified by {@link #getVolumeId()}.
+     */
+    long getFileId();
 }
diff --git a/src/main/java/net/rubygrapefruit/platform/internal/DefaultWindowsFiles.java b/src/main/java/net/rubygrapefruit/platform/internal/DefaultWindowsFiles.java
@@ -86,6 +86,7 @@ private class FastLister implements DirectoryLister {
         private static final int OFFSETOF_FILE_ATTRIBUTES = 56;
         private static final int OFFSETOF_FILENAME_LENGTH = 60;
         private static final int OFFSETOF_EA_SIZE = 64;
+        private static final int OFFSETOF_FILE_ID = 72;
         private static final int OFFSETOF_FILENAME = 80;
 
         /**
@@ -109,6 +110,10 @@ public List<? extends DirEntry> listDir(File dir, boolean linkTarget) throws Nat
             if (result.isFailed()) {
                 throw listDirFailure(dir, result);
             }
+            int volumeId = WindowsFileFunctions.fastReaddirGetVolumeId(handle, result);
+            if (result.isFailed()) {
+                throw listDirFailure(dir, result);
+            }
             try {
                 NtQueryDirectoryFileContext context = getNtQueryDirectoryFileContext();
 
@@ -120,7 +125,7 @@ public List<? extends DirEntry> listDir(File dir, boolean linkTarget) throws Nat
                     int entryOffset = 0;
                     while (true) {
                         // Read entry from buffer
-                        entryOffset = addFullDirEntry(context, dir, linkTarget, entryOffset, dirList);
+                        entryOffset = addFullDirEntry(context, dir, linkTarget, volumeId, entryOffset, dirList);
 
                         // If we reached end of buffer, fetch next set of entries
                         if (entryOffset == 0) {
@@ -148,7 +153,7 @@ public List<? extends DirEntry> listDir(File dir, boolean linkTarget) throws Nat
          * <p>Returns the byte offset of the next entry in {@link NtQueryDirectoryFileContext#buffer} if there is one,
          * or {@code 0} if there is no next entry.</p>
          */
-        private int addFullDirEntry(NtQueryDirectoryFileContext context, File dir, boolean followLink, int entryOffset, WindowsDirList dirList) {
+        private int addFullDirEntry(NtQueryDirectoryFileContext context, File dir, boolean followLink, int volumeId, int entryOffset, WindowsDirList dirList) {
             // typedef struct _FILE_ID_FULL_DIR_INFORMATION {
             //  ULONG         NextEntryOffset;  // offset = 0
             //  ULONG         FileIndex;        // offset = 4
@@ -175,6 +180,7 @@ private int addFullDirEntry(NtQueryDirectoryFileContext context, File dir, boole
             //
             int fileAttributes = context.buffer.getInt(entryOffset + OFFSETOF_FILE_ATTRIBUTES);
             int reparseTagData = context.buffer.getInt(entryOffset + OFFSETOF_EA_SIZE);
+            long fileId = context.buffer.getLong(entryOffset + OFFSETOF_FILE_ID);
 
             FileInfo.Type type = getFileType(fileAttributes, reparseTagData);
 
@@ -189,7 +195,7 @@ private int addFullDirEntry(NtQueryDirectoryFileContext context, File dir, boole
                     WindowsFileInfo targetInfo = stat(new File(dir, fileName), true);
                     dirList.addFile(fileName, targetInfo);
                 } else {
-                    dirList.addFile(fileName, type.ordinal(), fileSize, lastModified);
+                    dirList.addFile(fileName, type, fileSize, WindowsFileTime.toJavaTime(lastModified), volumeId, fileId);
                 }
             }
 

diff --git a/src/main/java/net/rubygrapefruit/platform/internal/DirList.java b/src/main/java/net/rubygrapefruit/platform/internal/DirList.java
@@ -28,11 +28,19 @@ public class DirList {
     // Called from native code
     @SuppressWarnings("UnusedDeclaration")
     public void addFile(String name, int type, long size, long lastModified) {
-        DefaultDirEntry fileStat = new DefaultDirEntry(name, FileInfo.Type.values()[type], size, lastModified);
-        files.add(fileStat);
+        addFile(name, FileInfo.Type.values()[type], size, lastModified);
     }
 
-    private static class DefaultDirEntry implements DirEntry {
+    void addFile(String name, FileInfo.Type type, long size, long lastModified) {
+        DefaultDirEntry fileStat = new DefaultDirEntry(name, type, size, lastModified);
+        addEntry(fileStat);
+    }
+
+    void addEntry(DirEntry entry) {
+        files.add(entry);
+    }
+
+    protected static class DefaultDirEntry implements DirEntry {
         private final String name;
         private final Type type;
         private final long size;
@@ -65,5 +73,9 @@ public long getLastModifiedTime() {
         public long getSize() {
             return size;
         }
+
+        public Object getKey() {
+            return null;
+        }
     }
 }
diff --git a/src/main/java/net/rubygrapefruit/platform/internal/FileStat.java b/src/main/java/net/rubygrapefruit/platform/internal/FileStat.java
@@ -74,4 +74,8 @@ public long getBlockSize() {
     public long getLastModifiedTime() {
         return modificationTime;
     }
+
+    public Object getKey() {
+        return null;
+    }
 }
diff --git a/src/main/java/net/rubygrapefruit/platform/internal/WindowsDirList.java b/src/main/java/net/rubygrapefruit/platform/internal/WindowsDirList.java
@@ -16,17 +16,54 @@
 
 package net.rubygrapefruit.platform.internal;
 
+import net.rubygrapefruit.platform.file.FileInfo;
 import net.rubygrapefruit.platform.file.WindowsFileInfo;
 
 public class WindowsDirList extends DirList {
     // Called from native code
     @SuppressWarnings("UnusedDeclaration")
     @Override
     public void addFile(String name, int type, long size, long lastModified) {
-        super.addFile(name, type, size, WindowsFileTime.toJavaTime(lastModified));
+        addFile(name, FileInfo.Type.values()[type], size, WindowsFileTime.toJavaTime(lastModified), 0, 0);
     }
 
-    public void addFile(String name, WindowsFileInfo fileInfo) {
-        super.addFile(name, fileInfo.getType().ordinal(), fileInfo.getSize(), fileInfo.getLastModifiedTime());
+    void addFile(String name, WindowsFileInfo fileInfo) {
+        addFile(name, fileInfo.getType(), fileInfo.getSize(), fileInfo.getLastModifiedTime(), fileInfo.getVolumeId(), fileInfo.getFileId());
+    }
+
+    void addFile(String name, FileInfo.Type type, long size, long lastModified, int volumeId, long fileId) {
+        if (volumeId == 0 && fileId == 0) {
+            super.addFile(name, type, size, lastModified);
+        } else {
+            WindowsDirListEntry entry = new WindowsDirListEntry(name, type, size, lastModified, volumeId, fileId);
+            addEntry(entry);
+        }
+    }
+
+    protected static class WindowsDirListEntry extends DefaultDirEntry {
+        private final int volumeId;
+        private final long fileId;
+        // Lazily initialized to avoid extra allocation if not needed
+        private volatile WindowsFileKey key;
+
+        WindowsDirListEntry(String name, Type type, long size, long lastModified, int volumeId, long fileId) {
+            super(name, type, size, lastModified);
+            this.volumeId = volumeId;
+            this.fileId = fileId;
+        }
+
+        public Object getKey() {
+            if (volumeId == 0 && fileId == 0) {
+                return null;
+            }
+            if (key == null) {
+                synchronized (this) {
+                    if (key == null) {
+                        key = new WindowsFileKey(volumeId, fileId);
+                    }
+                }
+            }
+            return key;
+        }
     }
 }
diff --git a/src/main/java/net/rubygrapefruit/platform/internal/WindowsFileKey.java b/src/main/java/net/rubygrapefruit/platform/internal/WindowsFileKey.java
@@ -0,0 +1,39 @@
+package net.rubygrapefruit.platform.internal;
+
+final class WindowsFileKey {
+    private final int volumeId;
+    private final long fileId;
+
+    WindowsFileKey(int volumeId, long fileId) {
+        this.volumeId = volumeId;
+        this.fileId = fileId;
+    }
+
+    @Override
+    public int hashCode() {
+        return (int)(volumeId * 31 + fileId);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (obj == this)
+            return true;
+        if (!(obj instanceof WindowsFileKey))
+            return false;
+
+        WindowsFileKey other = (WindowsFileKey) obj;
+        return (this.volumeId == other.volumeId) &&
+                (this.fileId == other.fileId);
+    }
+
+    @Override
+    public String toString() {
+        StringBuilder sb = new StringBuilder();
+        sb.append("(volumeId=")
+                .append(Integer.toHexString(volumeId))
+                .append(",fileId=")
+                .append(Long.toHexString(fileId))
+                .append(')');
+        return sb.toString();
+    }
+}