The PostgreSQL 7.1.2 sources can by obtained from ftp://ftp.postgresql.org/pub/postgresql-7.1.2.tar.gz. Use a mirror if possible. Then unpack it:
gunzip postgresql-7.1.2.tar.gz tar xf postgresql-7.1.2.tarThis will create a directory postgresql-7.1.2 with the PostgreSQL sources in the current directory. Change into that directory for the rest of the installation procedure.