Riddle me this my Monkish friends.

I am currently trying to write a perl script to parse a binary file. No problem using unpack(still trying to gernerate all the templates, but not the issue at hand.)

The file is made of of records, each record is made up of a header and data portion. Within the header the length of the data portion is identified. No problem see below

The program reads the header, calculates the the size of the remaining data then reads that information

The problem that I run into is that the system seems to read twice the size I am requesting. i.e. My first read is bytes 0-20, assuming the data portion is 100 bytes it should read 21-120. But instead it reads 0-20, skips 21-40, reads 41-140, skips 141-240, read the next header.

Any Ideas on this. I have tried both read and sysread and I get slightly different results but neither work properly.

System:
Win NT
ActiveState Perl

Thanks

In reply to Reading Binary file confusion by Anonymous Monk

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