Add frailbox buddy allocator

build.py

@@ -720,7 +720,7 @@ def main():
         print(f"\n  {color('⚠ Some tools missing  -  will try anyway:', Colors.YELLOW)}")
         for m in missing:
             print(f"    {m}")
-        print(f"  {color('Not all modules will build. That\'s fine.', Colors.GRAY)}")
+        print("  " + color("Not all modules will build. That's fine.", Colors.GRAY))
     else:
         print(f"  {color('✓ All prerequisites found', Colors.GREEN)}")
 

diagnostic/build-2b54872c.json

@@ -0,0 +1,23 @@
+{
+  "generated_at": "2026-06-23T04:05:10.650191+00:00",
+  "commit": "2b54872c",
+  "diagnostic_logd": null,
+  "diagnostic_logd_error": "191814fb92eb3c934cfb",
+  "chunked": false,
+  "chunk_size_bytes": null,
+  "password": null,
+  "decrypt_command": null,
+  "total_modules": 1,
+  "passed": 1,
+  "failed": 0,
+  "modules": [
+    {
+      "name": "frailbox",
+      "status": "PASS",
+      "elapsed_seconds": 0.557,
+      "artifact": "/Volumes/Soengkit\u786c\u76d8/Codex\u65b0\u9879\u76ee\u4e0e\u8f93\u51fa/2026-06-19_Agent Bounty Workbench/02_candidate_bounties/gautam-tentoftrials-buddy-4/repo/frailbox/frailbox",
+      "output": "gcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude -MMD -MP -c src/arena.c -o build/src/arena.o\ngcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude -MMD -MP -c src/buddy.c -o build/src/buddy.o\ngcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude -MMD -MP -c src/logger.c -o build/src/logger.o\ngcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude -MMD -MP -c src/sandbox.c -o build/src/sandbox.o\ngcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude -MMD -MP -c main.c -o build/main.o\ngcc -Wall -Wextra -Wpedantic -std=c2x -O2 -g -D_FORTIFY_SOURCE=3 -fstack-protector-strong -fPIE -Iinclude build/src/arena.o build/src/buddy.o build/src/logger.o build/src/sandbox.o build/main.o -o frailbox"
+    }
+  ],
+  "pr_note": "Encrypted diagnostic logd artifact was not created; include this JSON report showing why. The encrypted .logd is the required diagnostic content for PR review; this JSON file is metadata. Maintainers may ask you to remove these diagnostic artifacts before merging."
+}

frailbox/Makefile

@@ -1,9 +1,13 @@
 CC = gcc
+UNAME_S := $(shell uname -s)
 CFLAGS = -Wall -Wextra -Wpedantic -std=c2x -O2 -g
 CFLAGS += -D_FORTIFY_SOURCE=3
 CFLAGS += -fstack-protector-strong
 CFLAGS += -fPIE
-LDFLAGS = -pie -z relro -z now
+LDFLAGS =
+ifeq ($(UNAME_S),Linux)
+LDFLAGS += -pie -z relro -z now
+endif
 
 SRCDIR = src
 INCDIR = include
@@ -14,8 +18,9 @@ OBJS = $(patsubst %.c, $(BUILDDIR)/%.o, $(SRCS))
 DEPS = $(OBJS:.o=.d)
 
 TARGET = frailbox
+BUDDY_TEST = $(BUILDDIR)/test_buddy
 
-.PHONY: all clean
+.PHONY: all clean test-buddy
 
 all: $(TARGET)
 
@@ -26,6 +31,10 @@ $(BUILDDIR)/%.o: %.c
 	@mkdir -p $(dir $@)
 	$(CC) $(CFLAGS) -I$(INCDIR) -MMD -MP -c $< -o $@
 
+$(BUDDY_TEST): tests/test_buddy.c $(SRCDIR)/buddy.c $(INCDIR)/buddy.h
+	@mkdir -p $(dir $@)
+	$(CC) $(CFLAGS) -I$(INCDIR) tests/test_buddy.c $(SRCDIR)/buddy.c -o $@ $(LDFLAGS)
+
 -include $(DEPS)
 
 clean:
@@ -37,7 +46,10 @@ distclean: clean
 test: $(TARGET)
 	./$(TARGET) --sandbox-type seccomp --memory-limit 64 --verbose
 
+test-buddy: $(BUDDY_TEST)
+	./$(BUDDY_TEST)
+
 valgrind: $(TARGET)
 	valgrind --leak-check=full --show-leak-kinds=all ./$(TARGET)
 
-.PHONY: all clean distclean test valgrind
+.PHONY: all clean distclean test test-buddy valgrind

frailbox/include/buddy.h

@@ -0,0 +1,41 @@
+#ifndef FRAILBOX_BUDDY_H
+#define FRAILBOX_BUDDY_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define BUDDY_MIN_BLOCK_SIZE 64u
+
+typedef struct buddy_allocator buddy_allocator_t;
+
+typedef struct buddy_stats {
+    size_t   capacity_bytes;
+    size_t   allocated_bytes;
+    size_t   reserved_bytes;
+    size_t   free_bytes;
+    size_t   largest_free_block;
+    uint64_t allocation_count;
+    uint64_t deallocation_count;
+    uint64_t split_count;
+    uint64_t coalesce_count;
+    double   fragmentation_ratio;
+} buddy_stats_t;
+
+buddy_allocator_t *buddy_create(size_t capacity_bytes);
+void               buddy_destroy(buddy_allocator_t *allocator);
+
+void *buddy_alloc(buddy_allocator_t *allocator, size_t size);
+void  buddy_free(buddy_allocator_t *allocator, void *ptr);
+
+buddy_stats_t buddy_stats(const buddy_allocator_t *allocator);
+int           buddy_contains(const buddy_allocator_t *allocator, const void *ptr);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

frailbox/src/arena.c

@@ -14,7 +14,11 @@ static arena_region_t *region_alloc(size_t size, uint32_t flags) {
     int mmap_prot = PROT_READ | PROT_WRITE;
 
     if (flags & ARENA_HUGE_PAGES) {
+#ifdef MAP_HUGETLB
         mmap_flags |= MAP_HUGETLB;
+#else
+        return NULL;
+#endif
     }
 
     void *addr = mmap(NULL, size, mmap_prot, mmap_flags, -1, 0);
@@ -175,8 +179,9 @@ size_t arena_total_capacity(const arena_t *arena) {
 int arena_contains(const arena_t *arena, const void *ptr) {
     arena_region_t *region = arena->regions;
     while (region) {
-        if (ptr >= region->start &&
-            ptr < (char *)region->start + region->size) {
+        const char *byte_ptr = ptr;
+        if (byte_ptr >= (const char *)region->start &&
+            byte_ptr < (const char *)region->start + region->size) {
             return 1;
         }
         region = region->next;