gbak terminates/crashes when a read error occurs during restore

[ilya071294]

FB5 on Linux.
When os_read function fails to read a backup file, gbak (or the server process in a case of restore via services) terminates/crashes with this backtrace:

#0  0x00007fb90d47541f in raise ()
#1  0x00007fb90d45f895 in abort ()
#2  0x00007fb8fc2ed24f in __gnu_cxx::__verbose_terminate_handler()
#3  0x00007fb8fca28316 in __cxxabiv1::__terminate(void (*)()) ()
#4  0x00007fb8fcac1cc9 in __cxa_call_terminate ()
#5  0x00007fb8fca27fc1 in __gxx_personality_v0 ()
#6  0x00007fb90de353c4 in _Unwind_RaiseException_Phase2 ()
#7  0x00007fb90de35a61 in _Unwind_RaiseException ()
#8  0x00007fb8fca284c7 in __cxa_throw ()
#9  0x00007fb8fc2e3b6a in Firebird::system_call_failed::raise (syscall=0x7fb8fcacb118 "pthread_mutex_destroy", error_code=16)
#10 0x00007fb8fc853d12 in Firebird::Mutex::~Mutex (this=0x7fb783a20138, __in_chrg=<optimized out>)
#11 Burp::IOBuffer::~IOBuffer (this=0x7fb783a200f0, __in_chrg=<optimized out>)
#12 Burp::RestoreRelationTask::~RestoreRelationTask (this=this@entry=0x7fb8bb07d4f0, __in_chrg=<optimized out>)
#13 0x00007fb8fc2da7b1 in (anonymous namespace)::restore (tdgbl=<optimized out>, provider=<optimized out>, file_name=<optimized out>, database_name=<optimized out>)
#14 0x00007fb8fc8ae251 in RESTORE_restore (file_name=file_name@entry=0x7fb78d659960 "backup.fbk", database_name=database_name@entry=0x7fb78d659a20 "database.fdb")
#15 0x00007fb8fc877744 in gbak (uSvc=<optimized out>)
#16 0x00007fb8fc879728 in BURP_main (uSvc=0x7fb862c44340)
#17 0x00007fb8fc556818 in Jrd::Service::run (arg=arg@entry=0x7fb862c44340)
#18 0x00007fb8fc912349 in (anonymous namespace)::ThreadArgs::run (this=<synthetic pointer>)
#19 (anonymous namespace)::threadStart (arg=0x7fb85fe4aa50)
#20 0x00007fb90da6358e in start_thread ()
#21 0x00007fb90d53a2d3 in clone ()

RestoreRelationTask::m_buffers contains 2 buffers, and one of them stayed locked (IOBuffer::m_locked is true). AFAIU, this happend because the buffer was pointed by ioBuf in RestoreRelationTask::fileReader and it was not unlocked when the exception occured.

[hvlad]

Should be fixed in v5.0-release, please check

[ilya071294]

Should be fixed in v5.0-release, please check

The issue is fixed.