Merge pull request #331 from taartspi/linuxfs_buff_overrun

LinuxFile reused scratch buffers ensuring size was usable. But the …
Pi4J · Mar 3, 2024 · 48f8fb0 · 48f8fb0
2 parents ca45f76 + 2d30fb0
commit 48f8fb0
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Showing 2 changed files with 17 additions and 4 deletions.
diff --git a/libraries/pi4j-library-linuxfs/src/main/java/com/pi4j/library/linuxfs/LinuxFile.java b/libraries/pi4j-library-linuxfs/src/main/java/com/pi4j/library/linuxfs/LinuxFile.java
@@ -214,7 +214,8 @@ protected synchronized IntBuffer getOffsetsBuffer(int size) {
 
         if (byteSize > localBufferSize)
             throw new ScratchBufferOverrun();
-
+        // if no buffer currently exists, new one always created.
+        // if buffer exists and limit is not equal to this getOffsetsBuffer, allocate new
         if (buf == null) {
             ByteBuffer bb = ByteBuffer.allocateDirect(localBufferSize);
 
@@ -223,8 +224,16 @@ protected synchronized IntBuffer getOffsetsBuffer(int size) {
 
             buf = bb.asIntBuffer();
             localOffsetsBuffer.set(buf);
-        }
+        } else if(buf.limit() != size) {
+            localOffsetsBuffer.remove();
+            ByteBuffer bb = ByteBuffer.allocateDirect(localBufferSize);
+
+            //keep native order, set before cast to IntBuffer
+            bb.order(ByteOrder.nativeOrder());
 
+            buf = bb.asIntBuffer();
+            localOffsetsBuffer.set(buf);
+        }
         return buf;
     }
 
@@ -238,6 +247,10 @@ protected  synchronized ByteBuffer getDataBuffer(int size) {
         if (buf == null) {
             buf = ByteBuffer.allocateDirect(size);
             localDataBuffer.set(buf);
+        }else if(buf.limit() != size){
+            localDataBuffer.remove();
+            buf = ByteBuffer.allocateDirect(size);
+            localDataBuffer.set(buf);
         }
 
         return buf;

diff --git a/...ns/pi4j-plugin-linuxfs/src/main/java/com/pi4j/plugin/linuxfs/provider/i2c/LinuxFsI2C.java b/...ns/pi4j-plugin-linuxfs/src/main/java/com/pi4j/plugin/linuxfs/provider/i2c/LinuxFsI2C.java
@@ -243,8 +243,8 @@ public int readRegister(byte[] register, byte[] buffer, int offset, int length)
         short writeLength = (short) register.length;
         // two pointers will be used so 2 pairs of offset entries
         IntBuffer offsets = IntBuffer.allocate(4);
-         // create ByteBuffer, load with write details
-        ByteBuffer ioctlData = ByteBuffer.allocate(500);
+         // create ByteBuffer, load with the write details Matches i2c provider
+        ByteBuffer ioctlData = ByteBuffer.allocate(2048);
         // Ensures Pi BCM little_endian
         ioctlData.order(ByteOrder.nativeOrder());
         ioctlData.putShort(deviceAddr);