hurd: handle EINTR during critical sections

During critical sections, signal handling is deferred and thus RPCs return
EINTR, even if SA_RESTART is set. We thus have to restart the whole critical
section in that case.

This also adds HURD_CRITICAL_UNLOCK in the cases where one wants to
break the section in the middle.

1 files changed, 4 insertions, 0 deletions

diff --git a/sysdeps/mach/hurd/geteuid.c b/sysdeps/mach/hurd/geteuid.c
index a7af5a9d0d..5312d6bf64 100644
--- a/sysdeps/mach/hurd/geteuid.c
+++ b/sysdeps/mach/hurd/geteuid.c
@@ -27,6 +27,7 @@ __geteuid (void)
   error_t err;
   uid_t euid;
 
+retry:
   HURD_CRITICAL_BEGIN;
   __mutex_lock (&_hurd_id.lock);
 
@@ -49,6 +50,9 @@ __geteuid (void)
 
   __mutex_unlock (&_hurd_id.lock);
   HURD_CRITICAL_END;
+  if (euid == -1 && errno == EINTR)
+    /* Got a signal while inside an RPC of the critical section, retry again */
+    goto retry;
 
   return euid;
 }