Templated free logic and os mem handles

Author: Zia-Rashid

allocators/zialloc/alloc.cpp

@@ -3,6 +3,8 @@
 #include "allocator.h"
 #include "types.h"
 #include "segments.cpp"
+#include "os.cpp"
+#include "free.cpp"
 #include <cstddef>
 #include <cstdint>
 #include <cstring>
@@ -38,17 +40,46 @@ class Allocator {
 };
 
 void* Allocator::malloc(size_t size) {
-    // impl here using mmap, free lists, etc...
+    // TODO: 
+    //   1. Determine size class (small / med / large / XL)
+    //   2. Fast path: check tcache for a free chunk of this size
+    //   3. Slow path: find a page with space via Heap -> Segment -> Page
+    //   4. If no page has space, allocate a new segment via os::alloc_segment()
+    //   5. Update stats (alloc_count, bytes_in_use, etc.)
+    //   6. Return pointer to chunk data
+    (void)size;
+    return nullptr;
 }
-void Allocator::free(void* ptr) {
 
+void Allocator::free(void* ptr) {
+    // TODO: delegate to the free dispatch in free.cpp
+    //   zialloc::zialloc_free_dispatch(ptr);
+    //   Update stats (free_count, bytes_in_use, etc.)
+    (void)ptr;
 }
-void* Allocator::realloc(void* ptr, size_t size) {
 
+void* Allocator::realloc(void* ptr, size_t size) {
+    // TODO:
+    //   1. If ptr == nullptr, equivalent to malloc(size)
+    //   2. If size == 0, equivalent to free(ptr), return nullptr
+    //   3. Find the chunk's current size via Page::get_chunk_size()
+    //   4. If new size fits in current chunk, return ptr as-is
+    //   5. Otherwise: malloc(size), memcpy, free(ptr)
+    //   6. Update stats (realloc_count)
+    (void)ptr; (void)size;
+    return nullptr;
 }
-// nmemb is the # of values of size `size`. So calloc(4, sizeof(int)) may produce a 16 butes chunk
-void* Allocator::calloc(size_t nmemb, size_t size) {   
 
+// nmemb is the # of values of size `size`. So calloc(4, sizeof(int)) may produce a 16 bytes chunk
+void* Allocator::calloc(size_t nmemb, size_t size) {   
+    // TODO:
+    //   1. Check for overflow: nmemb * size
+    //   2. total = nmemb * size
+    //   3. ptr = malloc(total)
+    //   4. memset(ptr, 0, total)  — or skip if os_mmap already zeroed it
+    //   5. return ptr
+    (void)nmemb; (void)size;
+    return nullptr;
 }
 
 
@@ -71,16 +102,26 @@ static bool g_initialized = false;
 // Statistics tracking
 static allocator_stats_t g_stats = {0};
 
-// Round up to alignment
-static inline size_t align_up(size_t size, size_t alignment) {}
-
-
+// Round up to alignment — delegate to os.cpp
+static inline size_t align_up(size_t size, size_t alignment) {
+    // TODO: return zialloc::os::align_up(size, alignment)
+    //   or inline: (size + alignment - 1) & ~(alignment - 1)
+    (void)size; (void)alignment;
+    return 0;
+}
 
-// Get memory from OS
-static void *os_alloc(size_t size) {}
+// Get memory from OS — delegate to os.cpp
+static void *os_alloc(size_t size) {
+    // TODO: return zialloc::os::alloc_segment(size)
+    (void)size;
+    return nullptr;
+}
 
-// Return memory to OS
-static void os_free(void *ptr, size_t size) {}
+// Return memory to OS — delegate to os.cpp
+static void os_free(void *ptr, size_t size) {
+    // TODO: zialloc::os::free_segment(ptr, size)
+    (void)ptr; (void)size;
+}
 
 static void *zialloc_malloc(size_t size) {
   return zialloc::Allocator::instance().malloc(size);
@@ -141,13 +182,46 @@ static void zialloc_print_stats(void) {
   printf("  munmap calls:  %lu\n", (unsigned long)g_stats.munmap_count);
 }
 
-static bool zialloc_validate_heap(void) {}
+static bool zialloc_validate_heap(void) {
+    // TODO: 
+    //   1. Walk all segments via Heap::instance()
+    //   2. For each segment, check_canary()
+    //   3. For each page, verify used count matches bitmap popcount
+    //   4. Return false if any inconsistency found
+    return true;
+}
 
-static bool zialloc_get_stats(allocator_stats_t *stats) {}
+static bool zialloc_get_stats(allocator_stats_t *stats) {
+    // TODO: copy g_stats into *stats
+    if (!stats) return false;
+    *stats = g_stats;
+    return true;
+}
 
-static int zialloc_init(void) {}
+static int zialloc_init(void) {
+    // TODO:
+    //   1. If already initialized, return 0
+    //   2. Allocate initial segments via os::alloc_segment() 
+    //      (e.g. 1 small-page segment + 1 medium-page segment)
+    //   3. Initialize Heap::instance() with the segments
+    //   4. Initialize canaries via generate_canary()
+    //   5. Initialize segment keys via Segment::init_key()
+    //   6. Set g_initialized = true
+    //   7. Return 0 on success, -1 on failure
+    if (g_initialized) return 0;
+    // ... your init logic here ...
+    g_initialized = true;
+    return 0;
+}
 
-static void zialloc_teardown(void) {}
+static void zialloc_teardown(void) {
+    // TODO:
+    //   1. Walk all segments, munmap each via os::free_segment()
+    //   2. Reset Heap metadata
+    //   3. Zero out g_stats
+    //   4. Set g_initialized = false
+    g_initialized = false;
+}
 
 allocator_t zialloc_allocator = {
     // Required functions