linux-user: Fix fcntl() and fcntl64() to return O_LARGEFILE for 32-bit targets

When running a 32-bit guest on a 64-bit host, fcntl[64](F_GETFL) should
return with the TARGET_O_LARGEFILE flag set, because all 64-bit hosts
support large files unconditionally.

But on 64-bit hosts, O_LARGEFILE has the value 0, so the flag
translation can't be done with the fcntl_flags_tbl[]. Instead add the
TARGET_O_LARGEFILE flag afterwards.

Note that for 64-bit guests the compiler will optimize away this code,
since TARGET_O_LARGEFILE is zero.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 08162cc966..10f05b1e55 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -7132,6 +7132,10 @@ static abi_long do_fcntl(int fd, int cmd, abi_ulong arg)
         ret = get_errno(safe_fcntl(fd, host_cmd, arg));
         if (ret >= 0) {
             ret = host_to_target_bitmask(ret, fcntl_flags_tbl);
+            /* tell 32-bit guests it uses largefile on 64-bit hosts: */
+            if (O_LARGEFILE == 0 && HOST_LONG_BITS == 64) {
+                ret |= TARGET_O_LARGEFILE;
+            }
         }
         break;