Forensic recovery deleted pgdump custom format file

Hello. I need some help.

I have the following situation. My client deleted a number of old backups from a drive disc made by PGDUMP with custom flag activated. I could not find any program to recover backup files made by PGDUMP of customized / binary form. So I decided to try to understand the file format generated by pgdump. Analyzing the source code of pgdump/recovery, i concluded a few things:

The header of the file always starts with "PGDMP" followed by pgdump version number used, followed by int size, offset, etc. followed by TOCs.

My question is how to know the end of the file? Are there any signature that I can use? Or would have to analyze the whole file?