The accept4() syscall takes two flags only: SOCK_NONBLOCK and
SOCK_CLOEXEC.
Even the real Linux kernel returns -EINVAL if any other bits
have been set.

Change the implementation of accept4() to recognize those two values
only, instead of using the fcntl_flags_tbl[] bitmask translation.

Beside this correction in behaviour, it actually fixes the accept4()
emulation for hppa, mips and alpha targets for which SOCK_NONBLOCK is
different than TARGET_SOCK_NONBLOCK.

I noticed this wrong behaviour with the testcase of the debian lwt package
which failed (by timeout while hanging in the read() syscall) in qemu but
succeeded on real hardware.

Signed-off-by: Helge Deller <del...@gmx.de>
---
 linux-user/syscall.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 3f1e8e7ad9..9e9317237d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3440,7 +3440,18 @@ static abi_long do_accept4(int fd, abi_ulong target_addr,
     abi_long ret;
     int host_flags;

-    host_flags = target_to_host_bitmask(flags, fcntl_flags_tbl);
+    host_flags = 0;
+#if defined(SOCK_NONBLOCK)
+    if (flags & ~(TARGET_SOCK_CLOEXEC | TARGET_SOCK_NONBLOCK)) {
+        return -TARGET_EINVAL;
+    }
+    if (flags & TARGET_SOCK_NONBLOCK) {
+        host_flags |= SOCK_NONBLOCK;
+    }
+#endif
+    if (flags & TARGET_SOCK_CLOEXEC) {
+        host_flags |= SOCK_CLOEXEC;
+    }

     if (target_addr == 0) {
         return get_errno(safe_accept4(fd, NULL, NULL, host_flags));
--
2.41.0


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