[PATCH v4 26/28] bsd-user: Implement fork(2) and vfork(2) system calls.

[Karim Taha]

From: Stacey Son <sson@FreeBSD.org>

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Karim Taha <kariem.taha2.7@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
---
 bsd-user/freebsd/os-proc.h    | 34 ++++++++++++++++++++++++++++++++++
 bsd-user/freebsd/os-syscall.c |  8 ++++++++
 2 files changed, 42 insertions(+)

diff --git a/bsd-user/freebsd/os-proc.h b/bsd-user/freebsd/os-proc.h
index 42bdd61904..7b2e6a9f79 100644
--- a/bsd-user/freebsd/os-proc.h
+++ b/bsd-user/freebsd/os-proc.h
@@ -185,4 +185,38 @@ static inline abi_long do_freebsd___setugid(abi_long arg1)
     return -TARGET_ENOSYS;
 }
 
+/* fork(2) */
+static inline abi_long do_freebsd_fork(void *cpu_env)
+{
+    abi_long ret;
+    abi_ulong child_flag;
+
+    fork_start();
+    ret = fork();
+    if (ret == 0) {
+        /* child */
+        child_flag = 1;
+        target_cpu_clone_regs(cpu_env, 0);
+    } else {
+        /* parent */
+        child_flag = 0;
+    }
+
+    /*
+     * The fork system call sets a child flag in the second return
+     * value: 0 for parent process, 1 for child process.
+     */
+    set_second_rval(cpu_env, child_flag);
+
+    fork_end(child_flag);
+
+    return ret;
+}
+
+/* vfork(2) */
+static inline abi_long do_freebsd_vfork(void *cpu_env)
+{
+    return do_freebsd_fork(cpu_env);
+}
+
 #endif /* BSD_USER_FREEBSD_OS_PROC_H */
diff --git a/bsd-user/freebsd/os-syscall.c b/bsd-user/freebsd/os-syscall.c
index 99af0f6b15..cb9425c9ba 100644
--- a/bsd-user/freebsd/os-syscall.c
+++ b/bsd-user/freebsd/os-syscall.c
@@ -226,6 +226,14 @@ static abi_long freebsd_syscall(void *cpu_env, int num, 
abi_long arg1,
         /*
          * process system calls
          */
+    case TARGET_FREEBSD_NR_fork: /* fork(2) */
+        ret = do_freebsd_fork(cpu_env);
+        break;
+
+    case TARGET_FREEBSD_NR_vfork: /* vfork(2) */
+        ret = do_freebsd_vfork(cpu_env);
+        break;
+
     case TARGET_FREEBSD_NR_execve: /* execve(2) */
         ret = do_freebsd_execve(arg1, arg2, arg3);
         break;
-- 
2.42.0