Correctly append or remove FD_CLOEXEC

Rather than just setting the flags to 0 or FD_CLOEXEC, read
the current value and append or remove as needed.

1 files changed, 4 insertions, 2 deletions

diff --git a/apt-pkg/install-progress.cc b/apt-pkg/install-progress.cc
index fe3324426..6ff8c3140 100644
--- a/apt-pkg/install-progress.cc
+++ b/apt-pkg/install-progress.cc
@@ -98,7 +98,8 @@ void PackageManagerProgressFd::StartDpkg()
 
    // FIXME: use SetCloseExec here once it taught about throwing
    //        exceptions instead of doing _exit(100) on failure
-   fcntl(OutStatusFd,F_SETFD,FD_CLOEXEC); 
+   if (auto flags = fcntl(OutStatusFd, F_GETFD); flags >= 0)
+      fcntl(OutStatusFd, F_SETFD, flags | FD_CLOEXEC);
 
    // send status information that we are about to fork dpkg
    WriteToStatusFd(GetProgressFdString("pmstatus", "dpkg-exec", StepsDone, StepsTotal, _("Running dpkg")));
@@ -180,7 +181,8 @@ void PackageManagerProgressDeb822Fd::StartDpkg()
 {
    // FIXME: use SetCloseExec here once it taught about throwing
    //        exceptions instead of doing _exit(100) on failure
-   fcntl(OutStatusFd,F_SETFD,FD_CLOEXEC); 
+   if (auto flags = fcntl(OutStatusFd, F_GETFD); flags >= 0)
+      fcntl(OutStatusFd, F_SETFD, flags | FD_CLOEXEC);
 
    WriteToStatusFd(GetProgressDeb822String("progress", nullptr, StepsDone, StepsTotal, _("Running dpkg")));
 }