util_SignalHandler could signpost use of RESOLVE_IDS_TO_NAMES=false

[aldennisa15]

I got Software interrupt forced exit: Segmentation Fault.
I got a corefile, dug out all the symbol files, fired up gdb and got a back trace...

#0  0x0000000000000421 in ?? ()
#1  0x0000000000455f03 in cFCONameTbl::Clear (this=this@entry=0x6f72c0 <cFCOName_i::msNameTbl>) at fconametbl.cpp:216
#2  0x0000000000455f9c in cFCONameTbl::~cFCONameTbl (this=0x6f72c0 <cFCOName_i::msNameTbl>, __in_chrg=<optimized out>) at fconametbl.cpp:160
#3  0x000000000058bf3d in __run_exit_handlers ()
#4  0x000000000058c10a in exit ()
#5  0x000000000044ddef in util_SignalHandler (sig=11) at tw_signal.cpp:71
#6  <signal handler called>
#7  0x00007f81105ec350 in _nss_systemd_is_blocked () from /lib/x86_64-linux-gnu/libnss_systemd.so.2
#8  0x00007f81105ed507 in _nss_systemd_getpwuid_r () from /lib/x86_64-linux-gnu/libnss_systemd.so.2
#9  0x00000000005f44b3 in getpwuid_r ()
#10 0x00000000005f4253 in getpwuid ()
#11 0x000000000049d02b in cUnixFSServices::GetUserName (this=<optimized out>, user_id=502, tstrUser=...) at unixfsservices.cpp:542
#12 0x0000000000462a29 in cFSPropDisplayer::InitForProp (this=0x3008c50, pFCO=<optimized out>, propIdx=<optimized out>) at fspropdisplayer.cpp:270
#13 0x00000000004635c5 in cFSPropDisplayer::InitForFCO (this=this@entry=0x3008c50, ifco=0x2c521d0) at fspropdisplayer.cpp:248
#14 0x000000000046d21b in cFCOReportUtil::InitPropDisplayer (gi=...) at fcoreportutil.cpp:118
#15 0x000000000046d3b5 in cFCOReportUtil::FinalizeReport (rr=...) at fcoreportutil.cpp:86
#16 0x0000000000436a51 in cTWModeIC::Execute (this=0xcb7730, pQueue=0x7ffd735bbd50) at twcmdline.cpp:1464
#17 0x000000000041a7dc in main (argc=<optimized out>, argv=<optimized out>, envp=<optimized out>) at tripwiremain.cpp:229

... Looked at the source, Googled around and found the bit in https://github.com/Tripwire/tripwire-open-source#readme about RESOLVE_IDS_TO_NAMES=false. Setting that cured the segfault.

As there's already a signal handler, it wouldn't be too difficult to surround calls to getpwuid() etc with flag setting/clearing (e.g. boolRunningGetPWuid=true; getpwuid(); boolRunningGetPWuid=false;), then in the signal handler, if the flag is set, emit a message along the lines of Segfault in name resolution, try setting RESOLVE_IDS_TO_NAMES=false. Would be a bit more user-friendly than just Software interrupt forced exit: Segmentation Fault ;-)