verifying a decryption

[openssl]

I am working on writing a program that performs encryption uses triple-DES. I am reading(decrypting) and writing(encrypting) a linked list to a file. The program will read and write the individual structures that make up the linked list using OpenSSL. The problem that I am running into, is that I cannot figure out a way to check to ensure that the data that is being decrypted, is actually being decrypted properly. In other words, if I write out my linked list, encrypting each structure as I write it I end up with a file that is encrypted. If I edit the file using a binary file editor(emacs), and I try and run the decryption program, the output to the screen is human readable, until it hits the point where I made changes in the encrypted file. Is there a way to stop the decryption once the data is deemed to be "bad".

thank you.