Fixed cancelling the PlayerPickup event, getAmount(), item duping issue.

src/main/java/net/minecraft/server/EntityItem.java

@@ -127,16 +127,20 @@ public class EntityItem extends Entity {
             int i = this.itemStack.count;
 
             // CraftBukkit start
-            if (this.pickupDelay <= 0 && entityhuman.inventory.canHold(this.itemStack)) { // <-- == to <=
-                Player player = (Player) entityhuman.getBukkitEntity();
-                PlayerPickupItemEvent event = new PlayerPickupItemEvent(player, (org.bukkit.entity.Item) this.getBukkitEntity());
-                world.getServer().getPluginManager().callEvent(event);
+            if (this.pickupDelay <= 0 && entityhuman.inventory.canPickup(this.itemStack) > 0) {
+                PlayerPickupItemEvent event = new PlayerPickupItemEvent((org.bukkit.entity.Player) entityhuman.getBukkitEntity(), (org.bukkit.entity.Item) this.getBukkitEntity());
+                this.world.getServer().getPluginManager().callEvent(event);
 
                 if (event.isCancelled()) {
                     return;
                 }
-                // CraftBukkit end
 
+                // Possibly < 0; fix here so we do not have to modify code below
+                this.pickupDelay = 0;
+            }
+            // CraftBukkit end
+
+            if (this.pickupDelay == 0 && entityhuman.inventory.canHold(this.itemStack)) {
                 if (this.itemStack.id == Block.LOG.id) {
                     entityhuman.a((Statistic) AchievementList.g);
                 }

src/main/java/net/minecraft/server/InventoryPlayer.java

@@ -51,6 +51,22 @@ public class InventoryPlayer implements IInventory {
         return -1;
     }
 
+    // CraftBukkit start - watch method above! :D
+    public int canPickup(ItemStack itemstack) {
+        int remains = itemstack.count;
+        for (int i = 0; i < this.items.length; ++i) {
+            if (this.items[i] == null) return itemstack.count;
+
+            // Taken from d(ItemStack)I
+            if (this.items[i] != null && this.items[i].id == itemstack.id && this.items[i].c() && this.items[i].count < this.items[i].b() && this.items[i].count < this.getMaxStackSize() && (!this.items[i].e() || this.items[i].getData() == itemstack.getData())) {
+                remains -= (this.items[i].b() < this.getMaxStackSize() ? this.items[i].b() : this.getMaxStackSize()) - this.items[i].count;
+            }
+            if (remains <= 0) return itemstack.count;
+        }
+        return itemstack.count - remains;
+    }
+    // CraftBukkit end
+
     private int k() {
         for (int i = 0; i < this.items.length; ++i) {
             if (this.items[i] == null) {