Lots of hacking:

- Turn Keyboard into a CharacterDevice (85,1) at /dev/keyboard.
- Implement MM::unmapRegionsForTask() and MM::unmapRegion()
- Save SS correctly on interrupt.
- Add a simple Spawn syscall for launching another process.
- Move a bunch of IO syscall debug output behind DEBUG_IO.
- Have ASSERT do a "cli" immediately when failing.
  This makes the output look proper every time.
- Implement a bunch of syscalls in LibC.
- Add a simple shell ("sh"). All it can do now is read a line
  of text from /dev/keyboard and then try launching the specified
  executable by calling spawn().

There are definitely bugs in here, but we're moving on forward.

LibC/Makefile

@@ -1,6 +1,8 @@
 OBJS = \
        stdio.o \
        unistd.o \
+       string.o \
+       process.o \
        entry.o
 
 LIBRARY = LibC.a

LibC/process.cpp

@@ -0,0 +1,12 @@
+#include "process.h"
+#include <Kernel/Syscall.h>
+
+extern "C" {
+
+int spawn(const char* path)
+{
+    return Syscall::invoke(Syscall::Spawn, (dword)path);
+}
+
+}
+

LibC/process.h

@@ -0,0 +1,8 @@
+#pragma once
+
+extern "C" {
+
+int spawn(const char* path);
+
+}
+

LibC/stdio.cpp

@@ -141,7 +141,8 @@ extern "C" {
 
 int putchar(int ch)
 {
-    return ch;
+    Syscall::invoke(Syscall::PutCharacter, ch);
+    return (byte)ch;
 }
 
 int printf(const char* fmt, ...)

LibC/string.cpp

@@ -0,0 +1,14 @@
+#include "string.h"
+
+extern "C" {
+
+size_t strlen(const char* str)
+{
+    size_t len = 0;
+    while (*(str++))
+        ++len;
+    return len;
+}
+
+}
+

LibC/string.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include "types.h"
+
+extern "C" {
+
+size_t strlen(const char*);
+
+}
+

LibC/types.h

@@ -6,9 +6,16 @@ typedef unsigned int dword;
 typedef unsigned short word;
 typedef unsigned char byte;
 
+typedef signed int signed_dword;
+typedef signed short signed_word;
+typedef signed char signed_byte;
+
 typedef dword uid_t;
 typedef dword gid_t;
 typedef dword pid_t;
 
+typedef dword size_t;
+typedef signed_dword ssize_t;
+
 }
 

LibC/unistd.cpp

@@ -1,4 +1,5 @@
 #include "unistd.h"
+#include "string.h"
 #include <Kernel/Syscall.h>
 
 extern "C" {
@@ -18,5 +19,21 @@ uid_t getpid()
     return Syscall::invoke(Syscall::PosixGetpid);
 }
 
+int open(const char* path)
+{
+    size_t length = strlen(path);
+    return Syscall::invoke(Syscall::PosixOpen, (dword)path, (dword)length);
+}
+
+ssize_t read(int fd, void* buf, size_t count)
+{
+    return Syscall::invoke(Syscall::PosixRead, (dword)fd, (dword)buf, (dword)count);
+}
+
+int close(int fd)
+{
+    return Syscall::invoke(Syscall::PosixClose, fd);
+}
+
 }
 

LibC/unistd.h

@@ -7,6 +7,9 @@ extern "C" {
 uid_t getuid();
 gid_t getgid();
 pid_t getpid();
+int open(const char* path);
+ssize_t read(int fd, void* buf, size_t count);
+int close(int fd);
 
 }