Permission problem causes the message of "Another instance of BOINC is running"

[photonxp]

OS: ubuntu
boinc version: 7.6.31+dfsg-6ubuntu1

Problem reduplication:

When user [otheruser] uses the working directory [boinctest] of the user [boinc], boinc program showes "Another instance of BOINC is running":

otheruser@linux $ sudo chown boinc:boinc -R /home/otheruser/boinctest
otheruser@linux $ /usr/bin/boinc --dir /home/otheruser/boinctest

28-Nov-2017 22:21:07 Another instance of BOINC is running.

With enough permission, no message of "Another instance of BOINC is running":

otheruser@linux $ sudo chown boinc:boinc -R /home/otheruser/boinctest
otheruser@linux $ sudo -u boinc /usr/bin/boinc --dir /home/otheruser/boinctest
)) Some files under [boinctest] may need root permission, so the commands here are just for test.

28-Nov-2017 22:53:04 [---] Starting BOINC client version 7.6.31 for x86_64-pc-linux-gnu
28-Nov-2017 22:53:04 [---] log flags: file_xfer, sched_ops, task
28-Nov-2017 22:53:04 [---] Libraries: libcurl/7.47.0 OpenSSL/1.0.2g zlib/1.2.8 libidn/1.32 librtmp/2.3
28-Nov-2017 22:53:04 [---] Data directory: /home/otheruser/boinctest
28-Nov-2017 22:53:04 [---] No usable GPUs found
28-Nov-2017 22:53:04 [---] Host name: linux
... ...
28-Nov-2017 22:53:04 [---] This computer is not attached to any projects
28-Nov-2017 22:53:04 [---] Visit http://boinc.berkeley.edu for instructions
28-Nov-2017 22:53:04 Initialization completed

More info:

I think the problem may lie somewhere around the functions of [wait_client_mutex] and [get_client_mutex] in the lib/util.cpp.

//Codes around here below look suspicious. Perhaps we need to check "retval" for more types of error messages or error handlers. Even better if the file path is attached in the error messages.

    int retval = file_lock.lock(path);
    if (retval == ERR_FCNTL) {
        return ERR_ALREADY_RUNNING;
    } else if (retval) {
        return retval;

[AenBleidd]

Closed as a duplicate of #2156