fix for awslabs#293: as per https://docs.oracle.com/javase/8/docs/api…

…/java/nio/file/Path.html#subpath-int-int- subpath shall return a relative path
stefanofornari · Mar 3, 2024 · 6f05941 · 6f05941
1 parent a197a93
commit 6f05941
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Showing 2 changed files with 45 additions and 4 deletions.
diff --git a/src/main/java/software/amazon/nio/spi/s3/S3Path.java b/src/main/java/software/amazon/nio/spi/s3/S3Path.java
@@ -257,10 +257,6 @@ public S3Path subpath(int beginIndex, int endIndex) {
         }
 
         var path = String.join(PATH_SEPARATOR, pathRepresentation.elements().subList(beginIndex, endIndex));
-        if (this.isAbsolute() && beginIndex == 0) {
-            path = PATH_SEPARATOR + path;
-        }
-
         if (endIndex == size && !pathRepresentation.hasTrailingSeparator()) {
             return from(path);
         } else {
@@ -527,6 +523,7 @@ public S3Path resolveSibling(String other) {
      *                                  against this path
      */
     @Override
+    /*
     public S3Path relativize(Path other) {
         var otherPath = checkPath(other);
 
@@ -569,6 +566,48 @@ public S3Path relativize(Path other) {
 
         return new S3Path(getFileSystem(), new PosixLikePathRepresentation(relativePath));
     }
+    */
+    public S3Path relativize(Path other) {
+        var otherPath = checkPath(other);
+
+        if (this.equals(otherPath)) {
+            return from("");
+        }
+
+        if (this.isAbsolute() != otherPath.isAbsolute()) {
+            throw new IllegalArgumentException("to obtain a relative path both must be absolute or both must be relative");
+        }
+        if (!Objects.equals(this.bucketName(), otherPath.bucketName())) {
+            throw new IllegalArgumentException("cannot relativize S3Paths from different buckets");
+        }
+
+        if (this.isEmpty()) {
+            return otherPath;
+        }
+
+        int nameCount = this.getNameCount();
+        int otherNameCount = otherPath.getNameCount();
+
+        int limit = Math.min(nameCount, otherNameCount);
+        int differenceCount = getDifferenceCount(otherPath, limit);
+
+        int parentDirCount = nameCount - differenceCount;
+        if (differenceCount < otherNameCount) {
+            return getRelativePathFromDifference(otherPath, otherNameCount, differenceCount, parentDirCount);
+        }
+
+        char[] relativePath = new char[parentDirCount*3 - 1];
+        int index = 0;
+        while (parentDirCount > 0) {
+            relativePath[index++] = '.';
+            relativePath[index++] = '.';
+            if (parentDirCount > 1)
+                relativePath[index++] = '/';
+            parentDirCount--;
+        }
+
+        return new S3Path(getFileSystem(), new PosixLikePathRepresentation(relativePath));
+    }
 
     private S3Path getRelativePathFromDifference(S3Path otherPath, int otherNameCount, int differenceCount, int parentDirCount) {
         Objects.requireNonNull(otherPath);

diff --git a/src/test/java/software/amazon/nio/spi/s3/S3PathTest.java b/src/test/java/software/amazon/nio/spi/s3/S3PathTest.java
@@ -336,6 +336,8 @@ public void relativize() {
         var bcd = fileSystem.getPath("b/c/d/");
         var bcdObject = fileSystem.getPath("b/c/d/object");
 
+        assertFalse(root.relativize(ab).isAbsolute());
+
         assertEquals(fileSystem.getPath(""), absoluteObject.relativize(absoluteObject));
         assertEquals(fileSystem.getPath("../.."), abcd.relativize(ab));
         assertEquals(fileSystem.getPath("e/"), abcd.relativize(abcde));