#293 hfst-reweight crashes on TSV reweight file

[sjurum]

To reproduce, store the following content in a file tags.reweight:

+Cmp    +2
+Der    +2

Then run the following command (the input fst can be any fst):

hfst-reweight -T tags.reweight -i generator-fstspeller-gt-norm.hfst > /dev/null 

Actual result:

hfst-reweight(1434,0x7fff753f2300) malloc: *** error for object 0x7fff5d47d390: pointer being realloc'd was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6

Expected result: No crash, and a reweighted fst.

[sjurum]

I looked further into this bug, and located the bug in the function 'hfst_getline()' on line 673 in the file ''tools/src/hfst-commandline.cc''. I added a couple of debug statements, so that the function code looks like the following:

ssize_t
hfst_getline(char** lineptr, size_t* n, FILE* stream)
{
  errno = 0;
  ssize_t rv = -1;
  verbose_printf("Debugging tsv - 1\n"); 
  rv = getline(lineptr, n, stream);
  verbose_printf("Debugging tsv - 2\n"); 
  if ((rv < 0) && errno)
    {
      error(EXIT_FAILURE, errno, "getline failed");
    }
  return rv;
}

When running hfst-reweight using this modified version of hfst-commandline.cc, I get the following:

$ make analyser-fstspeller-gt-norm.hfst 
  CP       generator-fstspeller-gt-norm.tmp.hfst
  GEN      generator-fstspeller-gt-norm.tmp1.hfst
Reading from <stdin>, writing to <stdout>
Modifying weights 0.000000 < w < 340282346638528859811704183484516925440.000000 as 1.000000 * id(w) + 0.000000
Reweighting minimize(determinize(push-weights-f(remove-epsilons(reweight(?stdin?)))))...
Reading reweights from ../../../../../tools/spellcheckers/fstbased/weighting/tags.reweight
Debugging tsv - 1
hfst-reweight(91813,0x7fff774d7300) malloc: *** error for object 0x7fff57a54390: pointer being realloc'd was not allocated
*** set a breakpoint in malloc_error_break to debug
/bin/sh: line 1: 91813 Abort trap: 6           /usr/local/bin/hfst-reweight -v -T ../../../../../tools/spellcheckers/fstbased/weighting/tags.reweight < generator-fstspeller-gt-norm.tmp.hfst > generator-fstspeller-gt-norm.tmp1.hfst
make: *** [generator-fstspeller-gt-norm.tmp1.hfst] Error 134

Based on the above, it looks like the bug is on the line:

  rv = getline(lineptr, n, stream);

[sjurum]

In the end, the error was in hfst-reweight.cc. A pointer was not initialised. The bug should be fixed in revision 4329.

Please review, and close the bug report if the commit is ok.