PNM: New attempt at making the new header parser work on Windows.

(cherry picked from commit 4b951c06cc)

imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/PNMHeaderParser.java

@@ -30,8 +30,10 @@
 
 package com.twelvemonkeys.imageio.plugins.pnm;
 
-import javax.imageio.IIOException;
+import com.twelvemonkeys.io.FastByteArrayOutputStream;
+
 import javax.imageio.stream.ImageInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -70,45 +72,74 @@ final class PNMHeaderParser extends HeaderParser {
 
         List<String> comments = new ArrayList<>();
 
+        StringBuilder tokenBuffer = new StringBuilder();
+
         while (width == 0 || height == 0 || maxSample == 0) {
-            String line = input.readLine();
+            tokenBuffer.delete(0, tokenBuffer.length());
 
-            if (line == null) {
-                throw new IIOException("Unexpected end of stream");
-            }
+            while (tokenBuffer.length() < 16) { // Limit reads if we should read across into the binary part...
+                byte read = input.readByte();
 
-            int commentStart = line.indexOf('#');
-            if (commentStart >= 0) {
-                String comment = line.substring(commentStart + 1).trim();
-                if (!comment.isEmpty()) {
-                    comments.add(comment);
+                if (read == '#') {
+                    // Read rest of the line as comment
+                    String comment = readLineUTF8(input).trim();
+
+                    if (!comment.isEmpty()) {
+                        comments.add(comment);
+                    }
+
+                    break;
+                }
+                else if (Character.isWhitespace((char) read)) {
+                    if (tokenBuffer.length() > 0) {
+                        break;
+                    }
+                }
+                else {
+                    tokenBuffer.append((char) read);
                 }
-
-                line = line.substring(0, commentStart);
             }
 
-            line = line.trim();
+            String token = tokenBuffer.toString().trim();
 
-            if (!line.isEmpty()) {
+            if (!token.isEmpty()) {
                 // We have tokens...
-                String[] tokens = line.split("\\s");
-                for (String token : tokens) {
-                    if (width == 0) {
-                        width = Integer.parseInt(token);
-                    }
-                    else if (height == 0) {
-                        height = Integer.parseInt(token);
-                    }
-                    else if (maxSample == 0) {
-                        maxSample = Integer.parseInt(token);
-                    }
-                    else {
-                        throw new IIOException("Unknown PNM token: " + token);
-                    }
+                if (width == 0) {
+                    width = Integer.parseInt(token);
+                }
+                else if (height == 0) {
+                    height = Integer.parseInt(token);
+                }
+                else {
+                    maxSample = Integer.parseInt(token);
                 }
             }
         }
 
         return new PNMHeader(fileType, tupleType, width, height, tupleType.getSamplesPerPixel(), maxSample, comments);
     }
+
+    // Similar to DataInput.readLine, except it uses UTF8 encoding
+    private static String readLineUTF8(final ImageInputStream input) throws IOException {
+        ByteArrayOutputStream buffer = new FastByteArrayOutputStream(128);
+
+        int value;
+        do {
+            switch (value = input.read()) {
+                case '\r':
+                    // Check for CR + LF pattern and skip, otherwise fall through
+                    if (input.read() != '\n') {
+                        input.seek(input.getStreamPosition() - 1);
+                    }
+                case '\n':
+                case -1:
+                    value = -1;
+                    break;
+                default:
+                    buffer.write(value);
+            }
+        } while (value != -1);
+
+        return buffer.toString("UTF8");
+    }
 }

imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/Plain16BitDecoder.java

@@ -58,17 +58,13 @@ final class Plain16BitDecoder extends InputStream {
         }
 
         // Each number is one byte. Skip whitespace.
-        if (currentLine == null || !currentLine.hasNext()) {
+        while (currentLine == null || !currentLine.hasNext()) {
             String line = reader.readLine();
             if (line == null) {
                 return -1;
             }
 
             currentLine = new StringTokenIterator(line);
-
-            if (!currentLine.hasNext()) {
-                return -1;
-            }
         }
 
         int next = Integer.parseInt(currentLine.next()) & 0xffff;

imageio/imageio-pnm/src/main/java/com/twelvemonkeys/imageio/plugins/pnm/Plain8BitDecoder.java

@@ -50,17 +50,13 @@ final class Plain8BitDecoder extends InputStream {
     @Override
     public int read() throws IOException {
         // Each number is one byte. Skip whitespace.
-        if (currentLine == null || !currentLine.hasNext()) {
+        while (currentLine == null || !currentLine.hasNext()) {
             String line = reader.readLine();
             if (line == null) {
                 return -1;
             }
 
             currentLine = new StringTokenIterator(line);
-
-            if (!currentLine.hasNext()) {
-                return -1;
-            }
         }
 
         return Integer.parseInt(currentLine.next()) & 0xff;