Exception in libinchi.dll when converting some specific polymer structure.

[dredkin]

1. download libinchi.dll 64 bits (1.0.7.4) from official web site.
2. Call GetStructFromINCHIEx with the string "InChI=1B/C3H3N/c1-2-4-3-1/h4H,2H2/z101-1-4(1,2,1,3,2,4,3,4)"
3. Exception in libinchi.dll occurs.

[djb-rwth]

Hi @dredkin,
Thanks for creating this issue.

2. Call GetStructFromINCHIEx with the string "InChI=1B/C3H3N/c1-2-4-3-1/h4H,2H2/z101-1-4(1,2,1,3,2,4,3,4)"
3. Exception in libinchi.dll occurs.

Please be so kind as to be a bit more specific which exception occurs.
Any screenshot or reproducible information would be much appreciated.

[djb-rwth]

Hi @dredkin,
Here is the output I am getting with the file ghi_189.txt consisting of line InChI=1B/C3H3N/c1-2-4-3-1/h4H,2H2/z101-1-4(1,2,1,3,2,4,3,4) only:

InChI version 1, Software 1.07.5 (inchi-1 executable) 
Windows 64-bit Build (MS VS 2017 or later) of Dec 18 2025 18:22:52

Opened log file 'ghi_189.txt.log'
Opened input file 'ghi_189.txt'
Opened output file 'ghi_189.txt.txt'
Opened problem file 'ghi_189.txt.prb'
The command line used:
"inchi-1 ghi_189.txt /InChI2Struct /OutputSDF /Polymers"
Converting InChI(s) to structure(s) in MOL format
Output SDfile only without stereochemical information and atom coordinates
Input format: InChI (plain identifier)
Output format: SDfile only (without stereochemical info and atom coordinates)
Timeout per structure: 60000 msec
Up to 1024 atoms per structure
Experimental mode: Treating polymers

Finished processing 1 structure: 0 errors, processing time 0:00:00.00

Elapsed walltime: 0 msec.

So, no issues at my end.
Please be so kind as to send more info from my previous reply.

[dredkin]

I've made some research and it looks like the problem is with Function SetInChIExtInputByExtOrigAtData.
Before it polymer.n == 1 and after it outStruct->polymer points to some random memory, which causes the crash on the following call of FreeStructFromInchi

[dredkin]

@djb-rwth, I can't understand the line 3342 of inchi_dll.c

Could you please tell me why iip_tmp structure is freed here?

[dredkin]

I use the last release (1.07.04) source code.

[djb-rwth]

Hi @dredkin,
It looks as if this issue is related to #165.
Two fixes have been applied since then, so you should pull the latest version of InChI from the dev branch (which will very soon become v.1.07.5).
Please let me know if the same issue occurs with the dev version.

[dredkin]

Yes, dev branch fixes the issue.
Could you please make a release publicly available soon? This bug is quite annoying, in some cases the exception cannot be handled and the app just closes silently.
And easily reproduced.

[djb-rwth]

Hi @dredkin,
Thank you for testing the fix on such a short notice.
The new release (v.1.07.5) should be out late next week.
I will let you know as soon as it is out by posting a comment here.