bsd-user: Implement pdfork(2) system call.

Signed-off-by: Stacey Son <sson@FreeBSD.org>
Signed-off-by: Karim Taha <kariem.taha2.7@gmail.com>
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Warner Losh <imp@bsdimp.com>
Message-Id: <20230925182425.3163-29-kariem.taha2.7@gmail.com>

bsd-user/freebsd/os-proc.h

@@ -258,4 +258,36 @@ static inline abi_long do_freebsd_rfork(void *cpu_env, abi_long flags)
 
 }
 
+/* pdfork(2) */
+static inline abi_long do_freebsd_pdfork(void *cpu_env, abi_ulong target_fdp,
+        abi_long flags)
+{
+    abi_long ret;
+    abi_ulong child_flag;
+    int fd;
+
+    fork_start();
+    ret = pdfork(&fd, flags);
+    if (ret == 0) {
+        /* child */
+        child_flag = 1;
+        target_cpu_clone_regs(cpu_env, 0);
+    } else {
+        /* parent */
+        child_flag = 0;
+        if (put_user_s32(fd, target_fdp)) {
+            return -TARGET_EFAULT;
+        }
+    }
+
+    /*
+     * 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;
+}
+
 #endif /* BSD_USER_FREEBSD_OS_PROC_H */

bsd-user/freebsd/os-syscall.c

@@ -238,6 +238,10 @@ static abi_long freebsd_syscall(void *cpu_env, int num, abi_long arg1,
         ret = do_freebsd_rfork(cpu_env, arg1);
         break;
 
+    case TARGET_FREEBSD_NR_pdfork: /* pdfork(2) */
+        ret = do_freebsd_pdfork(cpu_env, arg1, arg2);
+        break;
+
     case TARGET_FREEBSD_NR_execve: /* execve(2) */
         ret = do_freebsd_execve(arg1, arg2, arg3);
         break;