[xen stable-4.18] tools/libxs: Fix fcntl() invocation in set_cloexec()

[patchbot@xxxxxxx]

commit 81f1e807fadb8111d71b78191e01ca688d74eac7
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Jul 25 16:20:53 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Jul 25 16:20:53 2024 +0200

    tools/libxs: Fix fcntl() invocation in set_cloexec()
    
    set_cloexec() had a bit too much copy&pate from setnonblock(), and
    insufficient testing on ancient versions of Linux...
    
    As written (emulating ancient linux by undef'ing O_CLOEXEC), strace shows:
    
      open("/dev/xen/xenbus", O_RDWR)         = 3
      fcntl(3, F_GETFL)                       = 0x8002 (flags 
O_RDWR|O_LARGEFILE)
      fcntl(3, 0x8003 /* F_??? */, 0x7ffe4a771d90) = -1 EINVAL (Invalid 
argument)
      close(3)                                = 0
    
    which is obviously nonsense.
    
    Switch F_GETFL -> F_GETFD, and fix the second invocation to use F_SETFD.  
With
    this, strace is rather happer:
    
      open("/dev/xen/xenbus", O_RDWR)         = 3
      fcntl(3, F_GETFD)                       = 0
      fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
    
    Fixes: bf7c1464706a ("tools/libxs: Fix CLOEXEC handling in get_dev()")
    Reported-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
    Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
    master commit: 37810b52d003f8a04af41d7b1f85eff24af9f804
    master date: 2024-07-09 15:32:18 +0100
---
 tools/libs/store/xs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/libs/store/xs.c b/tools/libs/store/xs.c
index c8845b69e2..38a6ce3cf2 100644
--- a/tools/libs/store/xs.c
+++ b/tools/libs/store/xs.c
@@ -182,12 +182,12 @@ static bool setnonblock(int fd, int nonblock) {
 
 static bool set_cloexec(int fd)
 {
-       int flags = fcntl(fd, F_GETFL);
+       int flags = fcntl(fd, F_GETFD);
 
        if (flags < 0)
                return false;
 
-       return fcntl(fd, flags | FD_CLOEXEC) >= 0;
+       return fcntl(fd, F_SETFD, flags | FD_CLOEXEC) >= 0;
 }
 
 static int pipe_cloexec(int fds[2])
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18