Kernel: Add 'ptrace' syscall

This commit adds a basic implementation of
the ptrace syscall, which allows one process
(the tracer) to control another process (the tracee).

While a process is being traced, it is stopped whenever a signal is
received (other than SIGCONT).

The tracer can start tracing another thread with PT_ATTACH,
which causes the tracee to stop.

From there, the tracer can use PT_CONTINUE
to continue the execution of the tracee,
or use other request codes (which haven't been implemented yet)
to modify the state of the tracee.

Additional request codes are PT_SYSCALL, which causes the tracee to
continue exection but stop at the next entry or exit from a syscall,
and PT_GETREGS which fethces the last saved register set of the tracee
(can be used to inspect syscall arguments and return value).

A special request code is PT_TRACE_ME, which is issued by the tracee
and causes it to stop when it calls execve and wait for the
tracer to attach.

1 files changed, 7 insertions, 3 deletions

diff --git a/AK/Types.h b/AK/Types.h
index aab08774e5..381b3f8a68 100644
--- a/AK/Types.h
+++ b/AK/Types.h
@@ -70,6 +70,8 @@ typedef i16 int16_t;
 typedef i32 int32_t;
 typedef i64 int64_t;
 
+typedef int pid_t;
+
 #else
 #    include <stdint.h>
 #    include <sys/types.h>
@@ -84,9 +86,9 @@ typedef int16_t i16;
 typedef int32_t i32;
 typedef int64_t i64;
 
-#ifdef __ptrdiff_t
+#    ifdef __ptrdiff_t
 typedef __PTRDIFF_TYPE__ __ptrdiff_t;
-#endif
+#    endif
 
 #endif
 
@@ -115,4 +117,6 @@ inline constexpr size_t align_up_to(const size_t value, const size_t alignment)
     return (value + (alignment - 1)) & ~(alignment - 1);
 }
 
-enum class TriState : u8 { False, True, Unknown };
+enum class TriState : u8 { False,
+    True,
+    Unknown };