feat: use PIC code model for shared libraries, fix shared library bugs

programs/libs/libhello/Makefile

@@ -11,6 +11,8 @@ NM := $(TOOLCHAIN_PREFIX)nm
 STRIP := $(TOOLCHAIN_PREFIX)strip
 
 # Compiler flags: freestanding, no stdlib
+# Build as PIE so library-internal data references remain valid after the
+# kernel maps the image into a per-process library slot.
 override CXXFLAGS := \
     -std=gnu++20 \
     -g -O2 -pipe \
@@ -20,7 +22,7 @@ override CXXFLAGS := \
     -ffreestanding \
     -fno-stack-protector \
     -fno-stack-check \
-    -fno-PIC \
+    -fPIE \
     -fno-rtti \
     -fno-exceptions \
     -ffunction-sections \

programs/libs/libhello/src/libhello.cpp

@@ -8,18 +8,47 @@
 #include <montauk/syscall.h>
 #include <gui/truetype.hpp>
 
-// Exported demo function - creates a window and renders until closed
+// Heap allocation test - allocates, writes, reads, frees
+// Returns 0 on success, -1 on failure
+extern "C" int hello_malloc_test() {
+    // Test 1: Allocate 256 bytes
+    void* buf = montauk::malloc(256);
+    if (!buf) {
+        montauk::print("  [libhello] malloc(256) failed\n");
+        return -1;
+    }
+
+    // Test 2: Write a pattern and verify it
+    uint8_t* bytes = (uint8_t*)buf;
+    for (int i = 0; i < 256; i++) {
+        bytes[i] = (uint8_t)(i & 0xFF);
+    }
+    for (int i = 0; i < 256; i++) {
+        if (bytes[i] != (uint8_t)(i & 0xFF)) {
+            montauk::print("  [libhello] read verification failed\n");
+            montauk::mfree(buf);
+            return -1;
+        }
+    }
+
+    montauk::mfree(buf);
+    return 0;
+}
+
 extern "C" int hello_run() {
     // Create window
+    static constexpr int kInitialWidth = 320;
+    static constexpr int kInitialHeight = 200;
+    static constexpr uint32_t kBackgroundColor = 0xFFFFFFFF;
     Montauk::WinCreateResult wres;
-    if (montauk::win_create("libhello Demo", 320, 200, &wres) < 0 || wres.id < 0) {
+    if (montauk::win_create("libhello Demo", kInitialWidth, kInitialHeight, &wres) < 0 || wres.id < 0) {
         return -1;
     }
 
     int winId = wres.id;
     uint32_t* pixels = (uint32_t*)(uintptr_t)wres.pixelVa;
-    int width = 200;
-    int height = 320;
+    int width = kInitialWidth;
+    int height = kInitialHeight;
 
     gui::TrueTypeFont* font = (gui::TrueTypeFont*)montauk::malloc(sizeof(gui::TrueTypeFont));
     if (!font) {
@@ -36,16 +65,15 @@ extern "C" int hello_run() {
     // Simple render - fill with a color pattern
     for (int y = 0; y < height; y++) {
         for (int x = 0; x < width; x++) {
-            // Dark blue background
-            pixels[y * width + x] = 0xFF1a1a2e;
+            pixels[y * width + x] = kBackgroundColor;
         }
     }
 
     // Render text using TrueType
     gui::Color text_color;
-    text_color.r = 0xF5;
-    text_color.g = 0xF5;
-    text_color.b = 0xF5;
+    text_color.r = 0x11;
+    text_color.g = 0x11;
+    text_color.b = 0x11;
     text_color.a = 255;
     font->draw_to_buffer(pixels, width, height, 20, 20, "Hello from libhello!", text_color, 16);
 
@@ -76,7 +104,7 @@ extern "C" int hello_run() {
             // Re-render on resize
             for (int y = 0; y < height; y++) {
                 for (int x = 0; x < width; x++) {
-                    pixels[y * width + x] = 0xFF1a1a2e;
+                    pixels[y * width + x] = kBackgroundColor;
                 }
             }
             font->draw_to_buffer(pixels, width, height, 20, 20, "Hello from libhello!", text_color, 16);