newlib: Impl sbrk() emulation for malloc/free

- Added malloc test;
- Test sources are now in one dir.

Signed-off-by: Maxim Logaev <maxlogaev@proton.me>

CMakeLists.txt

@@ -26,4 +26,16 @@ message(STATUS "SDK_SYSROOT_DIR=${KOS_PORTS_DIR}")
 
 add_subdirectory(toolchain)
 add_subdirectory(libraries)
-add_subdirectory(tests)
+
+ExternalProject_Add(
+    tests
+    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/tests
+    CMAKE_ARGS
+        -DCMAKE_C_COMPILER=i586-kolibrios-gcc
+        -DCMAKE_C_COMPILER_WORKS=1
+        -DCMAKE_INSTALL_PREFIX=${KOS_PORTS_DIR}
+    BUILD_ALWAYS TRUE
+    DEPENDS
+        gcc
+        newlib
+)

libraries/newlib/newlib/libc/sys/kolibrios/sbrk.c

@@ -1,20 +1,67 @@
-/* Version of sbrk for no operating system.  */
+/*
+ * SPDX-License-Identifier: GPL-2.0-only
+ * Copyright (C) 2026 KolibriOS team
+ * Author: Maxim Logaev <maxlogaev@proton.me>
+ */
 
 #include <_syslist.h>
+#include <errno.h>
+
+#include <kolibrios/syscall.h>
+
+static struct
+{
+  char *start;
+  unsigned long brk;
+  // TODO: Add mutex
+} heap;
 
 void *
-_sbrk (incr)
-     int incr;
+_sbrk (long incr)
 {
-   extern char   end; /* Set by linker.  */
-   static char * heap_end;
-   char *        prev_heap_end;
+  unsigned long new_brk = 0;
+  void *brk_addr = (void *)-1;
 
-   if (heap_end == 0)
-     heap_end = & end;
+#if 0
+  fprintf(stderr, "sbrk: start=%p, brk=%lu, incr=%ld\n", heap.start, heap.brk, incr);
+#endif
 
-   prev_heap_end = heap_end;
-   heap_end += incr;
+  // TODO: Mutex lock;
 
-   return (void *) prev_heap_end;
+  if (incr == 0)
+    {
+      brk_addr = heap.start + heap.brk;
+      goto ok;
+    }
+
+  if (incr < 0)
+    {
+      if (__builtin_usubl_overflow (heap.brk, (unsigned long)(-incr),
+                                    &new_brk))
+        new_brk = 0;
+    }
+  else
+    {
+      if (__builtin_uaddl_overflow (heap.brk, (unsigned long)incr, &new_brk))
+        goto fail;
+    }
+
+  char *const new_start = (char *)_ksys (SF_SYS_MISC, SSF_MEM_REALLOC, new_brk,
+                                         (unsigned long)heap.start);
+
+  if (new_start == NULL && new_brk)
+    goto fail;
+
+  brk_addr = new_start + heap.brk;
+  heap.brk = new_brk;
+  heap.start = new_start;
+
+ok:
+  // TODO: Mutex unlock
+  return brk_addr;
+
+fail:
+  // TODO: Mutex unlock
+  errno = ENOMEM;
+  return (void *)-1;
 }

tests/CMakeLists.txt

@@ -1,14 +1,9 @@
-# Rules for building tests
+cmake_minimum_required(VERSION 3.31)
 
-ExternalProject_Add(
-    test-hello
-    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/hello
-    CMAKE_ARGS
-        -DCMAKE_C_COMPILER=i586-kolibrios-gcc
-        -DCMAKE_C_COMPILER_WORKS=1
-        -DCMAKE_INSTALL_PREFIX=${KOS_PORTS_DIR}
-    BUILD_ALWAYS TRUE
-    DEPENDS
-        gcc
-        newlib
-)
+project(tests)
+
+add_executable(hello hello.c)
+add_executable(malloc malloc.c)
+
+install(TARGETS hello DESTINATION tests)
+install(TARGETS malloc DESTINATION tests)

tests/hello.c

@@ -0,0 +1,10 @@
+#include <stdio.h>
+#include <errno.h>
+
+int
+main ()
+{
+  errno = ENOSYS;
+  puts ("I: Hello KolibriOS from GCC!");
+  return 0;
+}

tests/hello/CMakeLists.txt

@@ -1,5 +0,0 @@
-cmake_minimum_required(VERSION 3.31)
-
-project(hello)
-add_executable(hello hello.c)
-install(TARGETS hello DESTINATION tests)

tests/hello/hello.c

@@ -1,13 +0,0 @@
-/*
- * SPDX-License-Identifier: GPL-2.0
- * Copyright (C) 2025 KolibriOS team
-*/
-
-int main()
-{
-    char *hello = "I: Hello KolibriOS from GCC!\n";
-    while(*hello) {
-        __asm__ __inline__("int $0x40" ::"a"(63), "b"(1), "c"(*hello));
-        hello++;
-    }
-}

tests/malloc.c

@@ -0,0 +1,45 @@
+#include <assert.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <kolibrios/syscall.h>
+
+#define MAX_ALLOCS 10000
+
+int
+main ()
+{
+  void *allocs[MAX_ALLOCS] = { 0 };
+
+  // Check zero param
+  void *ptr = malloc (0);
+  free (ptr);
+  free (NULL);
+
+  // malloc() and free()
+  for (size_t i = 0; i < 1000; i++)
+    {
+      void *ptr = malloc (9999);
+      memset (ptr, 0xFF, 9999);
+      assert (ptr != NULL);
+      free (ptr);
+    }
+
+  // malloc()
+  for (size_t i = 0; i < MAX_ALLOCS; i++)
+    {
+      allocs[i] = malloc (9999);
+      assert (allocs[i] != NULL);
+      memset (allocs[i], 0xFF, 9999);
+    }
+
+  // free()
+  for (size_t i = 0; i < MAX_ALLOCS; i++)
+    {
+        free(allocs[i]);
+    }
+
+  _ksys_dbg_print("I: Malloc test: OK");
+  return 0;
+}