Bug 472716

SUMMARY
Selecting a large number of files and then copying them tends to not copy at least some without any apparent error or warning message from dolphin. This may make user erroneously believe that operation (in the sense of copying all files to destination) succeeded while it actually did not - which is what happened to me in regards to a large dataset I've been copying.


STEPS TO REPRODUCE
1. Run the following commands in bash to generate a directory with 3000 empty files:
1.1 mkdir /tmp/dolphin_copy_test_src /tmp/dolphin_copy_test_dst
1.2 cd /tmp/dolphin_copy_test_src
1.3 for ((i=1;i<=3000;i++)); do touch $(uuidgen); done
2. Open Dolphin file manager, preferably from terminal
3. Navigate to /tmp/dolphin_copy_test_src
4. Press Ctrl+A to select all 3000 files in directory
5. Press Ctrl+C to copy files; at this point console will be spammed with

QDBusConnection: error: could not send message to service "org.freedesktop.portal.Documents" path "/org/freedesktop/portal/documents" interface "org.freedesktop.portal.FileTransfer" member "AddFiles": Marshalling failed: Invalid file descriptor passed in arguments

6. Navigate to /tmp/dolphin_copy_test_dst
7. Press Ctrl+V to paste files you've copied

OBSERVED RESULT
Only some files will be copied - target directory will contain less than 3000 files. The exact number I've seen in my tests varies from around 1500 to around 2700. Pasting again will results in the exact same files being copied until one selects some files to copy again.

EXPECTED RESULT
All 3000 files are copied.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma:
KDE Plasma Version: 5.27.6
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10

ADDITIONAL INFORMATION
None.