remove another invalid skip of locking in ungetwc

[oweals/musl.git] / src / unistd / dup2.c

diff --git a/src/unistd/dup2.c b/src/unistd/dup2.c
index 87a0d44538eb49162bf4d26824b0d35de19af0fb..8f43c6ddfe8983e9565d6a14a10f423c9fd55f05 100644 (file)
--- a/src/unistd/dup2.c
+++ b/src/unistd/dup2.c
@@ -1,10 +1,20 @@
 #include <unistd.h>
 #include <errno.h>
+#include <fcntl.h>
 #include "syscall.h"
 
 int dup2(int old, int new)
 {
        int r;
+#ifdef SYS_dup2
        while ((r=__syscall(SYS_dup2, old, new))==-EBUSY);
+#else
+       if (old==new) {
+               r = __syscall(SYS_fcntl, old, F_GETFD);
+               if (r >= 0) return old;
+       } else {
+               while ((r=__syscall(SYS_dup3, old, new, 0))==-EBUSY);
+       }
+#endif
        return __syscall_ret(r);
 }