Implement fork()!

This is quite cool! The syscall entry point plumbs the register dump
down to sys$fork(), which uses it to set up the child process's TSS
in order to resume execution right after the int 0x80 fork() call. :^)

This works pretty well, although there is some problem with the kernel
alias mappings used to clone the parent process's regions. If I disable
the MM::release_page_directory() code, there's no problem. Probably there's
a premature freeing of a physical page somehow.

2 files changed, 6 insertions, 0 deletions

diff --git a/LibC/unistd.cpp b/LibC/unistd.cpp
index 3492430198..9a3b2459b8 100644
--- a/LibC/unistd.cpp
+++ b/LibC/unistd.cpp
@@ -5,6 +5,11 @@
 
 extern "C" {
 
+pid_t fork()
+{
+    return Syscall::invoke(Syscall::PosixFork);
+}
+
 uid_t getuid()
 {
     return Syscall::invoke(Syscall::PosixGetuid);
diff --git a/LibC/unistd.h b/LibC/unistd.h
index cf2df7e97d..205002dff8 100644
--- a/LibC/unistd.h
+++ b/LibC/unistd.h
@@ -8,6 +8,7 @@ __BEGIN_DECLS
 extern char** environ;
 
 inline int getpagesize() { return 4096; }
+pid_t fork();
 pid_t getsid(pid_t);
 pid_t setsid();
 int setpgid(pid_t pid, pid_t pgid);