1 files changed, 120 insertions, 0 deletions
diff --git a/pg/src/main/java/org/spongycastle/bcpg/UserAttributeSubpacketInputStream.java b/pg/src/main/java/org/spongycastle/bcpg/UserAttributeSubpacketInputStream.java
new file mode 100644
index 00000000..d32e0390
--- /dev/null
+++ b/pg/src/main/java/org/spongycastle/bcpg/UserAttributeSubpacketInputStream.java
@@ -0,0 +1,120 @@
+package org.spongycastle.bcpg;
+
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.spongycastle.bcpg.attr.ImageAttribute;
+
+/**
+ * reader for user attribute sub-packets
+ */
+public class UserAttributeSubpacketInputStream
+    extends InputStream implements UserAttributeSubpacketTags
+{
+    InputStream    in;
+    
+    public UserAttributeSubpacketInputStream(
+        InputStream    in)
+    {
+        this.in = in;
+    }
+    
+    public int available()
+        throws IOException
+    {
+        return in.available();
+    }
+    
+    public int read()
+        throws IOException
+    {
+        return in.read();
+    }
+    
+    private void readFully(
+        byte[]    buf,
+        int       off,
+        int       len)
+        throws IOException
+    {
+        if (len > 0)
+        {
+            int    b = this.read();
+            
+            if (b < 0)
+            {
+                throw new EOFException();
+            }
+            
+            buf[off] = (byte)b;
+            off++;
+            len--;
+        }
+        
+        while (len > 0)
+        {
+            int    l = in.read(buf, off, len);
+            
+            if (l < 0)
+            {
+                throw new EOFException();
+            }
+            
+            off += l;
+            len -= l;
+        }
+    }
+    
+    public UserAttributeSubpacket readPacket()
+        throws IOException
+    {
+        int            l = this.read();
+        int            bodyLen = 0;
+        boolean        longLength = false;
+
+        if (l < 0)
+        {
+            return null;
+        }
+
+        if (l < 192)
+        {
+            bodyLen = l;
+        }
+        else if (l <= 223)
+        {
+            bodyLen = ((l - 192) << 8) + (in.read()) + 192;
+        }
+        else if (l == 255)
+        {
+            bodyLen = (in.read() << 24) | (in.read() << 16) |  (in.read() << 8)  | in.read();
+            longLength = true;
+        }
+        else
+        {
+            throw new IOException("unrecognised length reading user attribute sub packet");
+        }
+
+       int        tag = in.read();
+
+       if (tag < 0)
+       {
+           throw new EOFException("unexpected EOF reading user attribute sub packet");
+       }
+       
+       byte[]    data = new byte[bodyLen - 1];
+
+       this.readFully(data, 0, data.length);
+       
+       int       type = tag;
+
+       switch (type)
+       {
+       case IMAGE_ATTRIBUTE:
+           return new ImageAttribute(longLength, data);
+       }
+
+       return new UserAttributeSubpacket(type, longLength, data);
+    }
+}