UserHeap: some nice improvements

kernel/include/memory/UserHeap.h

@@ -23,4 +23,5 @@ struct UserHeap
     void bitmap_set(uint64_t index, bool value);
 
     bool try_expand();
+    bool try_expand_size(uint64_t size);
 };

kernel/src/memory/UserHeap.cpp

@@ -5,6 +5,11 @@
 #include "std/stdlib.h"
 #include "std/string.h"
 
+#ifndef USER_HEAP_DEBUG
+#undef kdbgln
+#define kdbgln(...)
+#endif
+
 #ifndef PAGE_SIZE
 #define PAGE_SIZE 4096
 #endif
@@ -56,6 +61,21 @@ bool UserHeap::try_expand()
     return true;
 }
 
+bool UserHeap::try_expand_size(uint64_t size)
+{
+    void* new_bitmap = krealloc(bitmap, bitmap_size + size);
+    if (!new_bitmap)
+    {
+        kdbgln("expansion failed");
+        return false;
+    }
+    bitmap = (uint8_t*)new_bitmap;
+    memset(bitmap + bitmap_size, 0, size);
+    bitmap_size += size;
+    kdbgln("expanded user heap, bitmap at %p, size %ld", (void*)bitmap, bitmap_size);
+    return true;
+}
+
 bool UserHeap::bitmap_read(uint64_t index)
 {
     return (bitmap[index / 8] & (0b10000000 >> (index % 8))) > 0;
@@ -81,7 +101,7 @@ allocate:
         return ALLOC_BASE + (index * PAGE_SIZE);
     }
 
-    if (attempts < 5 && try_expand())
+    if (attempts == 0 && try_expand()) // We are allocating ONE PAGE, only one attempt should be necessary.
     {
         attempts++;
         goto allocate;