HIVE-26685: Improve path name escaping/unescaping (apache#3721)

sjf0115 · Dec 5, 2022 · dbe2a32 · dbe2a32
1 parent 10805bc
commit dbe2a32
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Showing 2 changed files with 42 additions and 4 deletions.
diff --git a/common/src/java/org/apache/hadoop/hive/common/FileUtils.java b/common/src/java/org/apache/hadoop/hive/common/FileUtils.java
@@ -258,6 +258,11 @@ public static String makeListBucketingDirName(List<String> lbCols, List<String>
     }
   }
 
+  /**
+   * Hex encoding characters indexed by integer value
+   */
+  private static final char[] HEX_UPPER_CHARS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
+
   static boolean needsEscaping(char c) {
     return c < charToEscape.size() && charToEscape.get(c);
   }
@@ -287,12 +292,28 @@ public static String escapePathName(String path, String defaultPath) {
       }
     }
 
-    StringBuilder sb = new StringBuilder();
+    //  Fast-path detection, no escaping and therefore no copying necessary
+    int firstEscapeIndex = -1;
     for (int i = 0; i < path.length(); i++) {
+      if (needsEscaping(path.charAt(i))) {
+        firstEscapeIndex = i;
+        break;
+      }
+    }
+    if (firstEscapeIndex == -1) {
+      return path;
+    }
+
+    // slow path, escape beyond the first required escape character into a new string
+    StringBuilder sb = new StringBuilder();
+    if (firstEscapeIndex > 0) {
+      sb.append(path, 0, firstEscapeIndex);
+    }
+
+    for (int i = firstEscapeIndex; i < path.length(); i++) {
       char c = path.charAt(i);
       if (needsEscaping(c)) {
-        sb.append('%');
-        sb.append(String.format("%1$02X", (int) c));
+        sb.append('%').append(HEX_UPPER_CHARS[(0xF0 & c) >>> 4]).append(HEX_UPPER_CHARS[(0x0F & c)]);
       } else {
         sb.append(c);
       }
@@ -301,8 +322,17 @@ public static String escapePathName(String path, String defaultPath) {
   }
 
   public static String unescapePathName(String path) {
+    int firstUnescapeIndex = path.indexOf('%');
+    if (firstUnescapeIndex == -1) {
+      return path;
+    }
+
     StringBuilder sb = new StringBuilder();
-    for (int i = 0; i < path.length(); i++) {
+    if (firstUnescapeIndex > 0) {
+      sb.append(path, 0, firstUnescapeIndex);
+    }
+
+    for (int i = firstUnescapeIndex; i < path.length(); i++) {
       char c = path.charAt(i);
       if (c == '%' && i + 2 < path.length()) {
         int code = -1;

diff --git a/common/src/test/org/apache/hadoop/hive/common/TestFileUtils.java b/common/src/test/org/apache/hadoop/hive/common/TestFileUtils.java
@@ -303,6 +303,14 @@ public void testListStatusIterator() throws Exception {
     assertEquals(1, assertExpectedFilePaths(itr, Collections.singletonList("mock:/tmp/dummy")));
   }
 
+  @Test
+  public void testPathEscapeChars() {
+    StringBuilder sb = new StringBuilder();
+    FileUtils.charToEscape.stream().forEach(integer -> sb.append((char) integer));
+    String path = sb.toString();
+    assertEquals(path, FileUtils.unescapePathName(FileUtils.escapePathName(path)));
+  }
+
   private int assertExpectedFilePaths(RemoteIterator<? extends FileStatus> lfs, List<String> expectedPaths)
       throws Exception {
     int count = 0;