LibC: add needed stubs to build executables with our compiler

kernel/arch/i386/crt0.S

@@ -9,7 +9,7 @@ _start:
 	movl %esp, %ebp
 
 	# Prepare signals, memory allocation, stdio and such.
-	call initialize_standard_library
+	#call initialize_standard_library
 
 	# Run the global constructors.
 	call _init

kernel/arch/x86_64/crt0.S

@@ -13,7 +13,7 @@ _start:
 	pushq %rdi
 
 	# Prepare signals, memory allocation, stdio and such.
-	call initialize_standard_library
+	#call initialize_standard_library
 
 	# Run the global constructors.
 	call _init

libc/include/stdio.h

@@ -15,6 +15,9 @@
 #define SEEK_END 1
 #define SEEK_SET 2
 
+#define EXIT_FAILURE 1
+#define EXIT_SUCCESS 0
+
 __BEGIN_DECLS
 
 struct FILE;

libc/include/stdlib.h

@@ -6,6 +6,7 @@
 __BEGIN_DECLS
 
 [[noreturn]] void abort(void);
+[[noreturn]] void exit(int);
 
 int abs(int);
 

libc/include/sys/syscall.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#include <kernel/Syscall.h>

libc/include/unistd.h

@@ -6,16 +6,17 @@
 #define STDOUT_FILENO 1
 #define STDERR_FILENO 2
 
-// fork(), execv(), execve(), execvp(), getpid()
-
 __BEGIN_DECLS
 
+[[noreturn]] void _exit(int);
+
 pid_t fork(void);
+pid_t getpid(void);
 
 int execv(const char*, char* const[]);
 int execve(const char*, char* const[], char* const[]);
 int execvp(const char*, char* const[]);
 
-pid_t getpid(void);
+long syscall(long, ...);
 
 __END_DECLS

libc/stdlib.cpp

@@ -1,10 +1,18 @@
+#include <BAN/Assert.h>
+#include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
-#include <ctype.h>
+#include <unistd.h>
 
 void abort(void)
 {
+	ASSERT_NOT_REACHED();
+}
 
+void exit(int status)
+{
+	_exit(status);
+	ASSERT_NOT_REACHED();
 }
 
 int abs(int val)

libc/unistd.cpp

@@ -1,5 +1,40 @@
+#include <BAN/Assert.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <sys/syscall.h>
 #include <unistd.h>
 
+void _exit(int status)
+{
+	syscall(SYS_EXIT, status);
+	ASSERT_NOT_REACHED();
+}
+
+long syscall(long syscall, ...)
+{
+	va_list args;
+	va_start(args, syscall);
+
+	long ret = 0;
+
+	switch (syscall)
+	{
+	case SYS_EXIT:
+		ret = Kernel::syscall(SYS_EXIT, va_arg(args, int));
+		break;
+	case SYS_READ:
+		ret = Kernel::syscall(SYS_READ, va_arg(args, int), va_arg(args, void*), va_arg(args, size_t));
+		break;
+	case SYS_WRITE:
+		ret = Kernel::syscall(SYS_WRITE, va_arg(args, int), va_arg(args, const void*), va_arg(args, size_t));
+		break;
+	}
+
+	va_end(args);
+	
+	return ret;
+}
+
 pid_t fork(void)
 {
 	return -1;