trig2disk segmentation fault and out-of-bound array indexes in sacputaway.c

Recently we are detecting that trig2disk dies due to segmentation fault.

Investigating in depth I discovered that this mainly depends on 2 causes:

  1. the triggers message exceeds the number of SCNLs allowed in DB_MAX_PHS_PER_EQ, equal to 1000 at moment [earthworm_defs.h]. (Our production Earthworm configuration currently handles 3200 channels.)
  2. the handling of exceeding the maximum possible index of the FileList array in sacputaway.c is incorrect

Details below.

trig2disk version:

trig2disk: version 1.0.8 2023-09-18

gdb backtrace:

b443d20ae789-hew:/opt/ew_env/params $ gdb /opt/earthworm/bin/trig2disk $EW_PARAMS/core
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Reading symbols from /opt/earthworm/bin/trig2disk...

warning: Can't open file /SYSV00000410 (deleted) during file-backed mapping note processing

warning: Can't open file /SYSV000007cf (deleted) during file-backed mapping note processing
[New LWP 8620]
[New LWP 8618]
[New LWP 8619]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `trig2disk out/trig2disk.d'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000056109407e4a0 in SACPABase_end_scnl () at sacputaway.c:1258
1258	  FileList[FileIndex].sort_param = SAC_starttime;
[Current thread is 1 (Thread 0x7f05a1ed1700 (LWP 8620))]
(gdb) bt
#0  0x000056109407e4a0 in SACPABase_end_scnl () at sacputaway.c:1258
#1  0x000056109407c308 in SACPA_next (getThis=0x7f05a39f7230, GapThresh=1.5, OutBufferLen=262776, debug=0) at sacputaway.c:375
#2  0x0000561094078005 in PA_next (getThis=0x7f05a39f7230, FormatInd=1, GapThresh=1.5, OutBufferLen=262776, debug=0) at putaway.c:438
#3  0x000056109406c371 in SnippetMaker (dummy=0x0) at trig2disk.c:1534
#4  0x00007f05a3e82ea7 in start_thread (arg=<optimized out>) at pthread_create.c:477
#5  0x00007f05a3d72a2f in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#6  0x0000000000000000 in ?? ()
quit)

sacputaway source line where segmentation fault occurs:

https://gitlab.com/seismic-software/earthworm/-/blob/578dba680486496f3c827b48305165318a857aaf/src/libsrc/util/sacputaway.c#L1258

  /* Update SAC file list with file name and arrival time */
  sprintf (FileList[FileIndex].filename, "%s.%s.%s.%s",  SAC_szSta, SAC_szChan, 
           SAC_szNet, SAC_szLoc);
  FileList[FileIndex].sort_param = SAC_starttime;

  if ((FileIndex = FileIndex + 1) > DB_MAX_PHS_PER_EQ)
  {
    logit ("e", "SACPABase_end_scnl: WARNING: Maximum number of phases per "
           "event (%d) exceeded.\n", DB_MAX_PHS_PER_EQ);

    FileIndex = FileIndex - 1;
  }