[PATCH 5/5] linux-user: Implement pivot_root

[YAMAMOTO Takashi]

Used by runc.

Signed-off-by: YAMAMOTO Takashi <yamamoto@midokura.com>
---
 linux-user/syscall.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2947e79dc0..e739921e86 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -35,6 +35,7 @@
 #include <sys/prctl.h>
 #include <sys/resource.h>
 #include <sys/swap.h>
+#include <sys/syscall.h>
 #include <linux/capability.h>
 #include <sched.h>
 #include <sys/timex.h>
@@ -8254,6 +8255,11 @@ static int host_to_target_cpu_mask(const unsigned long 
*host_mask,
     return 0;
 }
 
+static int pivot_root(const char *new_root, const char *put_old)
+{
+    return syscall(SYS_pivot_root, new_root, put_old);
+}
+
 /* This is an internal helper for do_syscall so that it is easier
  * to have a single return point, so that actions, such as logging
  * of syscall results, can be performed.
@@ -13222,6 +13228,23 @@ static abi_long do_syscall1(void *cpu_env, int num, 
abi_long arg1,
         return ret;
 #endif
 
+#if defined(TARGET_NR_pivot_root)
+    case TARGET_NR_pivot_root:
+        {
+            void *p2;
+            p = lock_user_string(arg1); /* new_root */
+            p2 = lock_user_string(arg2); /* put_old */
+            if (!p || !p2) {
+                ret = -TARGET_EFAULT;
+            } else {
+                ret = get_errno(pivot_root(p, p2));
+            }
+            unlock_user(p2, arg2, 0);
+            unlock_user(p, arg1, 0);
+        }
+        return ret;
+#endif
+
     default:
         qemu_log_mask(LOG_UNIMP, "Unsupported syscall: %d\n", num);
         return -TARGET_ENOSYS;
-- 
2.21.1 (Apple Git-122.3)