Switch to C for userspace, with a very bare-bones libc!!

.gitignore

@@ -4,3 +4,4 @@ build/
 initrd/boot/moon
 env-local.sh
 initrd/bin/**
+base/

CMakeLists.txt

@@ -5,9 +5,10 @@ set(CMAKE_CXX_COMPILER_WORKS 1)
 
 set(CMAKE_CROSSCOMPILING true)
 
-project(Luna LANGUAGES C CXX ASM_NASM VERSION 0.1.0)
+project(Luna LANGUAGES C CXX ASM ASM_NASM VERSION 0.1.0)
 
 set(LUNA_ROOT ${CMAKE_CURRENT_LIST_DIR})
+set(LUNA_BASE ${CMAKE_CURRENT_LIST_DIR}/base)
 
 set(ARCH $ENV{ARCH})
 
@@ -17,6 +18,7 @@ endif()
 
 set(CMAKE_C_COMPILER ${ARCH}-luna-gcc)
 set(CMAKE_CXX_COMPILER ${ARCH}-luna-g++)
+set(CMAKE_ASM_COMPILER ${ARCH}-luna-gcc)
 
 set(CMAKE_ASM_NASM_OBJECT_FORMAT elf64)
 
@@ -27,5 +29,6 @@ set(CMAKE_FIND_ROOT_PATH ${LUNA_ROOT}/toolchain/x86-64-luna)
 message(STATUS "Configuring Luna for ${ARCH}")
 
 add_subdirectory(luna)
+add_subdirectory(libc)
 add_subdirectory(kernel)
 add_subdirectory(apps)

apps/CMakeLists.txt

@@ -1,6 +1,7 @@
 function(luna_app SOURCE_FILE APP_NAME)
     add_executable(${APP_NAME} ${SOURCE_FILE})
-    install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${APP_NAME}" DESTINATION ${LUNA_ROOT}/initrd/bin)
+    add_dependencies(${APP_NAME} libc)
+    install(TARGETS ${APP_NAME} DESTINATION ${LUNA_ROOT}/initrd/bin)
 endfunction()
 
-luna_app(app.asm app)
+luna_app(app.c app)

apps/app.asm

@@ -1,17 +0,0 @@
-section .text
-global _start
-_start:
-    mov rax, 1
-    mov rdi, message
-    int 42h
-    mov rax, 1
-    mov rdi, message2
-    int 42h
-    mov rax, 0
-    int 42h
-
-section .rodata
-message:
-    db "Hello!", 0xa, 0
-message2:
-    db "I am an app", 0xa, 0

apps/app.c

@@ -0,0 +1,9 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int main()
+{
+    for (int i = 0; i < strtol("010", NULL, 0); i++) { console_print("."); }
+
+    console_print("\n");
+}

libc/CMakeLists.txt

@@ -0,0 +1,61 @@
+file(GLOB HEADERS include/*.h)
+
+set(SOURCES
+    ${HEADERS}
+    src/stdio.cpp
+    src/stdlib.cpp
+    src/unistd.cpp
+)
+
+if(${ARCH} STREQUAL "x86_64")
+    set(SOURCES
+        ${SOURCES}
+        src/arch/x86_64/syscall.S
+    )
+endif()
+
+add_library(crt0 STATIC src/arch/${ARCH}/crt0.S)
+add_custom_command(
+    TARGET crt0
+    COMMAND "${CMAKE_COMMAND}" -E copy $<TARGET_OBJECTS:crt0> ${LUNA_BASE}/usr/lib/crt0.o
+)
+
+add_library(crti STATIC src/arch/${ARCH}/crti.S)
+add_custom_command(
+    TARGET crti
+    COMMAND "${CMAKE_COMMAND}" -E copy $<TARGET_OBJECTS:crti> ${LUNA_BASE}/usr/lib/crti.o
+)
+
+add_library(crtn STATIC src/arch/${ARCH}/crtn.S)
+add_custom_command(
+    TARGET crt0
+    COMMAND "${CMAKE_COMMAND}" -E copy $<TARGET_OBJECTS:crtn> ${LUNA_BASE}/usr/lib/crtn.o
+)
+
+add_library(bare_libc STATIC ${SOURCES})
+
+target_link_libraries(bare_libc PUBLIC luna)
+
+target_include_directories(bare_libc PUBLIC include/)
+
+target_compile_options(bare_libc PRIVATE -Wall -Wextra -Werror -pedantic -nostdlib)
+
+target_link_options(bare_libc PRIVATE -nostdlib)
+
+set_target_properties(bare_libc PROPERTIES CXX_STANDARD 20)
+
+add_custom_target(libc
+    COMMAND ${CMAKE_AR} -x $<TARGET_FILE:bare_libc>
+    COMMAND ${CMAKE_AR} -x $<TARGET_FILE:luna>
+    COMMAND ${CMAKE_AR} -rcs ${CMAKE_CURRENT_BINARY_DIR}/libc.a *.o
+    COMMAND rm *.o
+    WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+    DEPENDS bare_libc luna
+)
+
+add_custom_command(
+    TARGET libc
+    COMMAND "${CMAKE_COMMAND}" -E copy ${CMAKE_CURRENT_BINARY_DIR}/libc.a ${LUNA_BASE}/usr/lib/libc.a
+)
+
+file(WRITE "${LUNA_BASE}/usr/lib/libm.a" "INPUT(libc.a)")

libc/include/bits/attrs.h

@@ -0,0 +1,10 @@
+#ifndef _BITS_ATTRS_H
+#define _BITS_ATTRS_H
+
+#if !defined(_STDLIB_H)
+#error "Never include bits/attrs.h directly; use one of the standard library headers."
+#endif
+
+#define __noreturn __attribute__((noreturn))
+
+#endif

libc/include/stdio.h

@@ -0,0 +1,15 @@
+#ifndef _STDIO_H
+#define _STDIO_H
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    void console_print(const char*);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/include/stdlib.h

@@ -0,0 +1,73 @@
+#ifndef _STDLIB_H
+#define _STDLIB_H
+
+#include <bits/attrs.h>
+#include <stddef.h>
+
+typedef struct
+{
+    int quot;
+    int rem;
+} div_t;
+
+typedef struct
+{
+    long quot;
+    long rem;
+} ldiv_t;
+
+typedef struct
+{
+    long long quot;
+    long long rem;
+} lldiv_t;
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    int abs(int);
+    long labs(long);
+    long long llabs(long long);
+
+    div_t div(int, int);
+    ldiv_t ldiv(long, long);
+    lldiv_t lldiv(long long, long long);
+
+    void* malloc(size_t);
+    void* calloc(size_t, size_t);
+    void* realloc(void*, size_t);
+    void free(void*);
+
+    __noreturn void abort();
+    int atexit(void (*)(void));
+
+    int atoi(const char*);
+    long atol(const char*);
+    long long atoll(const char*);
+
+    double atof(const char*);
+
+    double strtod(const char*, char**);
+
+    long strtol(const char*, char**, int);
+    unsigned long strtoul(const char*, char**, int);
+
+    int rand();
+    void srand(int);
+
+    __noreturn void exit(int);
+
+    int system(const char*);
+
+    char* getenv(const char*);
+
+    void qsort(void*, size_t, size_t, int (*)(const void*, const void*));
+    void* bsearch(const void*, const void*, size_t, size_t, int (*)(const void*, const void*));
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/include/sys/syscall.h

@@ -0,0 +1,6 @@
+#ifndef _SYS_SYSCALL_H
+#define _SYS_SYSCALL_H
+
+#include <luna/Syscall.h>
+
+#endif

libc/include/sys/types.h

@@ -0,0 +1,9 @@
+#ifndef _SYS_TYPES_H
+#define _SYS_TYPES_H
+
+#define __need_size_t
+#include <stddef.h>
+
+typedef int pid_t;
+
+#endif

libc/include/unistd.h

@@ -0,0 +1,15 @@
+#ifndef _UNISTD_H
+#define _UNISTD_H
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+    long syscall(long, ...);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

libc/src/arch/x86_64/crt0.S

@@ -0,0 +1,20 @@
+.section .text
+
+.global _start
+.extern exit
+_start:
+	# Set up end of the stack frame linked list.
+	movq $0, %rbp
+	pushq %rbp # rip=0
+	pushq %rbp # rbp=0
+	movq %rsp, %rbp
+
+	# Run the global constructors.
+	call _init
+
+	# Run main
+	call main
+
+	# Terminate the process with the exit code.
+	movl %eax, %edi
+	call exit

libc/src/arch/x86_64/crti.S

@@ -0,0 +1,13 @@
+.section .init
+.global _init
+_init:
+   push %rbp
+   movq %rsp, %rbp
+   /* gcc will nicely put the contents of crtbegin.o's .init section here. */
+
+.section .fini
+.global _fini
+_fini:
+   push %rbp
+   movq %rsp, %rbp
+   /* gcc will nicely put the contents of crtbegin.o's .fini section here. */

libc/src/arch/x86_64/crtn.S

@@ -0,0 +1,9 @@
+.section .init
+   /* gcc will nicely put the contents of crtend.o's .init section here. */
+   popq %rbp
+   ret
+
+.section .fini
+   /* gcc will nicely put the contents of crtend.o's .fini section here. */
+   popq %rbp
+   ret

libc/src/arch/x86_64/syscall.S

@@ -0,0 +1,10 @@
+.global arch_invoke_syscall
+arch_invoke_syscall:
+    mov %rdi, %rax
+    mov %rsi, %rdi
+    mov %rdx, %rsi
+    mov %rcx, %rdx
+    mov %r8, %r10
+    mov %r9, %r8
+    int $66
+    ret

libc/src/stdio.cpp

@@ -0,0 +1,11 @@
+#include <stdio.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    void console_print(const char* str)
+    {
+        syscall(SYS_console_print, str);
+    }
+}

libc/src/stdlib.cpp

@@ -0,0 +1,30 @@
+#include <luna/NumberParsing.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+extern "C"
+{
+    // FIXME: Check for overflow in both strtol() and strtoul().
+    long strtol(const char* str, char** endptr, int base)
+    {
+        return (long)parse_signed_integer(str, const_cast<const char**>(endptr), base);
+    }
+
+    unsigned long strtoul(const char* str, char** endptr, int base)
+    {
+        return (unsigned long)parse_unsigned_integer(str, const_cast<const char**>(endptr), base);
+    }
+
+    __noreturn void abort()
+    {
+        syscall(SYS_exit);
+        __builtin_unreachable();
+    }
+
+    __noreturn void exit(int)
+    {
+        syscall(SYS_exit);
+        __builtin_unreachable();
+    }
+}

libc/src/unistd.cpp

@@ -0,0 +1,26 @@
+#include <stdarg.h>
+#include <stdint.h>
+#include <unistd.h>
+
+extern "C" long arch_invoke_syscall(long, uintptr_t, uintptr_t, uintptr_t, uintptr_t, uintptr_t);
+
+extern "C"
+{
+    long syscall(long num, ...)
+    {
+        va_list ap;
+        va_start(ap, num);
+
+        uintptr_t arg0 = va_arg(ap, uintptr_t);
+        uintptr_t arg1 = va_arg(ap, uintptr_t);
+        uintptr_t arg2 = va_arg(ap, uintptr_t);
+        uintptr_t arg3 = va_arg(ap, uintptr_t);
+        uintptr_t arg4 = va_arg(ap, uintptr_t);
+
+        long rc = arch_invoke_syscall(num, arg0, arg1, arg2, arg3, arg4);
+
+        va_end(ap);
+
+        return rc;
+    }
+}

luna/CMakeLists.txt

@@ -36,24 +36,23 @@ target_compile_options(luna-freestanding PRIVATE -nostdlib -mcmodel=kernel)
 target_include_directories(luna-freestanding PUBLIC include/)
 set_target_properties(luna-freestanding PROPERTIES CXX_STANDARD 20)
 
-#add_library(luna ${SOURCES})
-#target_compile_options(luna PRIVATE -Wall -Wextra -Werror -Wvla)
-#target_compile_options(luna PRIVATE -Wdisabled-optimization -Wformat=2 -Winit-self)
-#target_compile_options(luna PRIVATE -Wmissing-include-dirs -Wswitch-default -Wcast-qual -Wundef) 
-#target_compile_options(luna PRIVATE -Wcast-align -Wwrite-strings -Wlogical-op -Wredundant-decls -Wshadow -Wconversion)
-#target_compile_options(luna PRIVATE -fno-asynchronous-unwind-tables -fno-omit-frame-pointer)
-#target_include_directories(luna PUBLIC include/)
-#set_target_properties(luna PROPERTIES CXX_STANDARD 20)
+add_library(luna ${SOURCES})
+target_compile_options(luna PRIVATE -Wall -Wextra -Werror -Wvla)
+target_compile_options(luna PRIVATE -Wdisabled-optimization -Wformat=2 -Winit-self)
+target_compile_options(luna PRIVATE -Wmissing-include-dirs -Wswitch-default -Wcast-qual -Wundef) 
+target_compile_options(luna PRIVATE -Wcast-align -Wwrite-strings -Wlogical-op -Wredundant-decls -Wshadow -Wconversion)
+target_compile_options(luna PRIVATE -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -std=c++20)
+target_include_directories(luna PUBLIC include/)
 
 if("${ARCH}" MATCHES "x86_64")
 target_compile_options(luna-freestanding PRIVATE -mno-red-zone)
 target_compile_options(luna-freestanding PRIVATE -mno-80387 -mno-mmx -mno-sse -mno-sse2)
 target_compile_definitions(luna-freestanding PUBLIC ARCH_X86_64)
-#target_compile_definitions(luna PUBLIC ARCH_X86_64)
+target_compile_definitions(luna PUBLIC ARCH_X86_64)
 endif()
 
 if(LUNA_DEBUG_SYMBOLS)
     message(STATUS "Building Luna with debug symbols")
-    #target_compile_options(luna PRIVATE -ggdb)
+    target_compile_options(luna PRIVATE -ggdb)
     target_compile_options(luna-freestanding PRIVATE -ggdb)
 endif()

tools/install-headers.sh

@@ -7,8 +7,7 @@ cd $LUNA_ROOT
 
 mkdir -p $LUNA_BASE
 mkdir -p $LUNA_BASE/usr/include
-mkdir -p $LUNA_BASE/usr/include/moon
 mkdir -p $LUNA_BASE/usr/include/luna
 
-cp -RT kernel/**/*.h $LUNA_BASE/usr/include/moon
-cp -RT luna/include/luna/*.h $LUNA_BASE/usr/include/luna
+cp -RT libc/include/ $LUNA_BASE/usr/include
+cp -RT luna/include/luna/ $LUNA_BASE/usr/include/luna