LibC: Add simple definition for realloc

The syscall just crashes the kernel currently. I will implement
this when needed

libc/include/sys/syscall.h

@@ -20,6 +20,7 @@ __BEGIN_DECLS
 #define SYS_FORK 13
 #define SYS_SLEEP 14
 #define SYS_EXEC 15
+#define SYS_REALLOC 16
 
 __END_DECLS
 

libc/stdlib.cpp

@@ -76,6 +76,16 @@ void* calloc(size_t nmemb, size_t size)
 	return ptr;
 }
 
+void* realloc(void* ptr, size_t size)
+{
+	if (ptr == nullptr)
+		return malloc(size);
+	long ret = syscall(SYS_REALLOC, ptr, size);
+	if (ret == -1)
+		return nullptr;
+	return (void*)ret;
+}
+
 void free(void* ptr)
 {
 	if (ptr == nullptr)

libc/unistd.cpp

@@ -130,6 +130,13 @@ long syscall(long syscall, ...)
 			ret = Kernel::syscall(SYS_EXEC, (uintptr_t)pathname, (uintptr_t)argv, (uintptr_t)envp);
 			break;
 		}
+		case SYS_REALLOC:
+		{
+			void* ptr = va_arg(args, void*);
+			size_t size = va_arg(args, size_t);
+			ret = Kernel::syscall(SYS_REALLOC, (uintptr_t)ptr, size);
+			break;
+		}
 		default:
 			puts("LibC: Unhandeled syscall");
 			ret = -ENOSYS;