(doc) Consistently use term "null character"

Author: Marcono1234

src/main/java/org/apache/commons/io/FilenameUtils.java

@@ -195,7 +195,7 @@ public class FilenameUtils {
      * @param basePath  the base path to attach to, always treated as a path
      * @param fullFileNameToAdd  the fileName (or path) to attach to the base
      * @return the concatenated path, or null if invalid
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     public static String concat(final String basePath, final String fullFileNameToAdd) {
         final int prefix = getPrefixLength(fullFileNameToAdd);
@@ -261,7 +261,7 @@ public static boolean directoryContains(final String canonicalParent, final Stri
      * @param fileName  the fileName
      * @param includeSeparator  true to include the end separator
      * @return the path
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     private static String doGetFullPath(final String fileName, final boolean includeSeparator) {
         // TODO: Does not (indirectly) call requireNonNullChars in all cases for result
@@ -295,7 +295,7 @@ private static String doGetFullPath(final String fileName, final boolean include
      * @param fileName  the fileName
      * @param separatorAdd  0 to omit the end separator, 1 to return it
      * @return the path
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     private static String doGetPath(final String fileName, final int separatorAdd) {
         if (fileName == null) {
@@ -320,7 +320,7 @@ private static String doGetPath(final String fileName, final int separatorAdd) {
      * @param separator The separator character to use
      * @param keepSeparator  true to keep the final separator
      * @return the normalized fileName
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     private static String doNormalize(final String fileName, final char separator, final boolean keepSeparator) {
         if (fileName == null) {
@@ -452,7 +452,7 @@ public static boolean equals(String fileName1, String fileName2, final boolean n
         if (fileName1 == null || fileName2 == null) {
             return fileName1 == null && fileName2 == null;
         }
-        // TODO: Should IllegalArgumentException thrown by `normalize` for null bytes be
+        // TODO: Should IllegalArgumentException thrown by `normalize` for null characters be
         // handled? (and for example `false` be returned instead); If not, have to mention it
         // in javadoc of this method and callers
         if (normalized) {
@@ -574,7 +574,7 @@ private static int getAdsCriticalOffset(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the name of the file without the path, or an empty string if none exists
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static String getBaseName(final String fileName) {
         return removeExtension(getName(fileName));
@@ -618,7 +618,7 @@ public static String getExtension(final String fileName) throws IllegalArgumentE
         if (index == NOT_FOUND) {
             return EMPTY_STRING;
         }
-        // TODO: Should check for null bytes?
+        // TODO: Should check for null characters?
         return fileName.substring(index + 1);
     }
 
@@ -648,7 +648,7 @@ public static String getExtension(final String fileName) throws IllegalArgumentE
      *
      * @param fileName  the fileName to query, null returns null
      * @return the path of the file, an empty string if none exists, null if invalid
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     public static String getFullPath(final String fileName) {
         return doGetFullPath(fileName, true);
@@ -681,7 +681,7 @@ public static String getFullPath(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the path of the file, an empty string if none exists, null if invalid
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     public static String getFullPathNoEndSeparator(final String fileName) {
         return doGetFullPath(fileName, false);
@@ -705,7 +705,7 @@ public static String getFullPathNoEndSeparator(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the name of the file without the path, or an empty string if none exists
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static String getName(final String fileName) {
         if (fileName == null) {
@@ -738,7 +738,7 @@ public static String getName(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the path of the file, an empty string if none exists, null if invalid
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     public static String getPath(final String fileName) {
         return doGetPath(fileName, 1);
@@ -769,7 +769,7 @@ public static String getPath(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the path of the file, an empty string if none exists, null if invalid
-     * @throws IllegalArgumentException if the result path contains null bytes
+     * @throws IllegalArgumentException if the result path contains the null character ({@code U+0000})
      */
     public static String getPathNoEndSeparator(final String fileName) {
         return doGetPath(fileName, 0);
@@ -805,7 +805,7 @@ public static String getPathNoEndSeparator(final String fileName) {
      *
      * @param fileName  the fileName to query, null returns null
      * @return the prefix of the file, null if invalid
-     * @throws IllegalArgumentException if the result contains null bytes
+     * @throws IllegalArgumentException if the result contains the null character ({@code U+0000})
      */
     public static String getPrefix(final String fileName) {
         if (fileName == null) {
@@ -850,7 +850,7 @@ public static String getPrefix(final String fileName) {
      * ~user               --> 6           --> named user (slash added)
      * //server/a/b/c.txt  --> 9
      * ///a/b/c.txt        --> -1          --> error
-     * C:                  --> 0           --> valid filename as only null byte and / are reserved characters
+     * C:                  --> 0           --> valid filename as only null character and / are reserved characters
      * </pre>
      * <p>
      * The output will be the same irrespective of the machine that the code is running on.
@@ -999,7 +999,7 @@ private static boolean isEmpty(final String string) {
      * @param fileName  the fileName to query, null returns false
      * @param extensions  the extensions to check for, null checks for no extension
      * @return true if the fileName is one of the extensions
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static boolean isExtension(final String fileName, final Collection<String> extensions) {
         if (fileName == null) {
@@ -1029,7 +1029,7 @@ public static boolean isExtension(final String fileName, final Collection<String
      * @param fileName  the fileName to query, null returns false
      * @param extension  the extension to check for, null or empty checks for no extension
      * @return true if the fileName has the specified extension
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static boolean isExtension(final String fileName, final String extension) {
         if (fileName == null) {
@@ -1053,7 +1053,7 @@ public static boolean isExtension(final String fileName, final String extension)
      * @param fileName  the fileName to query, null returns false
      * @param extensions  the extensions to check for, null checks for no extension
      * @return true if the fileName is one of the extensions
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static boolean isExtension(final String fileName, final String... extensions) {
         if (fileName == null) {
@@ -1266,7 +1266,7 @@ private static boolean isValidHostName(final String name) {
      *
      * @param fileName  the fileName to normalize, null returns null
      * @return the normalized fileName, or null if invalid
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static String normalize(final String fileName) {
         return doNormalize(fileName, SYSTEM_NAME_SEPARATOR, true);
@@ -1314,7 +1314,7 @@ public static String normalize(final String fileName) {
      * @param unixSeparator {@code true} if a unix separator should
      * be used or {@code false} if a windows separator should be used.
      * @return the normalized fileName, or null if invalid
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      * @since 2.0
      */
     public static String normalize(final String fileName, final boolean unixSeparator) {
@@ -1361,7 +1361,7 @@ public static String normalize(final String fileName, final boolean unixSeparato
      *
      * @param fileName  the fileName to normalize, null returns null
      * @return the normalized fileName, or null if invalid
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static String normalizeNoEndSeparator(final String fileName) {
         return doNormalize(fileName, SYSTEM_NAME_SEPARATOR, false);
@@ -1408,7 +1408,7 @@ public static String normalizeNoEndSeparator(final String fileName) {
      * @param unixSeparator {@code true} if a unix separator should
      * be used or {@code false} if a windows separator should be used.
      * @return the normalized fileName, or null if invalid
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      * @since 2.0
      */
     public static String normalizeNoEndSeparator(final String fileName, final boolean unixSeparator) {
@@ -1431,7 +1431,7 @@ public static String normalizeNoEndSeparator(final String fileName, final boolea
      *
      * @param fileName  the fileName to query, null returns null
      * @return the fileName minus the extension
-     * @throws IllegalArgumentException if the fileName contains null bytes
+     * @throws IllegalArgumentException if the fileName contains the null character ({@code U+0000})
      */
     public static String removeExtension(final String fileName) {
         if (fileName == null) {
@@ -1447,18 +1447,18 @@ public static String removeExtension(final String fileName) {
     }
 
     /**
-     * Checks the input for null bytes, a sign of unsanitized data being passed to to file level functions.
+     * Checks the input for null characters ({@code U+0000}), a sign of unsanitized data being passed to to file level functions.
      *
      * This may be used for poison byte attacks.
      *
      * @param path the path to check
      * @return The input
-     * @throws IllegalArgumentException if path contains null bytes
+     * @throws IllegalArgumentException if path contains the null character ({@code U+0000})
      */
     private static String requireNonNullChars(final String path) {
         if (path.indexOf(0) >= 0) {
             throw new IllegalArgumentException(
-                "Null byte present in file/path name. There are no known legitimate use cases for such data, but several injection attacks may use it");
+                "Null character present in file/path name. There are no known legitimate use cases for such data, but several injection attacks may use it");
         }
         return path;
     }

src/test/java/org/apache/commons/io/FilenameUtilsTest.java

@@ -229,7 +229,7 @@ public void testGetBaseName() {
     }
 
     @Test
-    public void testGetBaseName_with_nullByte() {
+    public void testGetBaseName_with_null_character() {
         try {
             assertEquals("file.txt", FilenameUtils.getBaseName("fil\u0000e.txt.bak"));
         } catch (final IllegalArgumentException ignore) {
@@ -419,7 +419,7 @@ public void testGetPath() {
 
 
     @Test
-    public void testGetPath_with_nullbyte() {
+    public void testGetPath_with_null_character() {
         assertThrows(IllegalArgumentException.class, () -> FilenameUtils.getPath("~user/a/\u0000b/c.txt"));
     }
 
@@ -461,7 +461,7 @@ public void testGetPathNoEndSeparator() {
     }
 
     @Test
-    public void testGetPathNoEndSeparator_with_null_byte() {
+    public void testGetPathNoEndSeparator_with_null_character() {
         try {
             assertEquals("a/b", FilenameUtils.getPathNoEndSeparator("~user/a\u0000/b/c.txt"));
         } catch (final IllegalArgumentException ignore) {
@@ -515,7 +515,7 @@ public void testGetPrefix() {
     }
 
     @Test
-    public void testGetPrefix_with_nullbyte() {
+    public void testGetPrefix_with_null_character() {
         try {
             assertEquals("~user\\", FilenameUtils.getPrefix("~u\u0000ser\\a\\b\\c.txt"));
         } catch (final IllegalArgumentException ignore) {
@@ -957,7 +957,7 @@ public void testNormalize() {
     /**
      */
     @Test
-    public void testNormalize_with_nullbytes() {
+    public void testNormalize_with_null_character() {
         try {
             assertEquals("a" + SEP + "b" + SEP + "c.txt", FilenameUtils.normalize("a\\b/c\u0000.txt"));
         } catch (final IllegalArgumentException ignore) {