GwFileValidatorsPattern

Creating a hash

For each file a hash value can be created. GwFileValidatorsPattern cares about the correct handling of files, even if the file size is too big to get handled in one step.

To create a hash, all you have to do is to use the function hash():

from groundwork_validation.patterns import GwFileValidatorsPattern

class My_Plugin(GwFileValidatorsPattern):
    def __init__(self, app, **kwargs):
        self.name = "My_Plugin"
        super(My_Plugin, self).__init__(app, **kwargs)

    def activate(self):
        my_file = "/path/to/file.txt"

        # Generate and retrieve a string based hash value
        my_hash = self.validators.file.hash(my_file)

        # Store hash value directly into a file
        my_hash = self.validators.file.hash(my_file, hash_file = "/path/to/file.txt.hash")

    def deactivate(self):
        pass

Please see hash() for a complete list of available parameters.

Validate a file

Using a hash string

For validation the function validate() is available:

from groundwork_validation.patterns import GwFileValidatorsPattern

class My_Plugin(GwFileValidatorsPattern):
    def __init__(self, app, **kwargs):
        self.name = "My_Plugin"
        super(My_Plugin, self).__init__(app, **kwargs)

    def activate(self):
        my_file = "/path/to/file.txt"

        my_hash = self.validators.file.hash(my_file)  # Generate a hash

        if self.validators.file.validate(my_file, my_hash):
            print("Hash is valid")
        else:
            print("Hash is NOT valid")

    def deactivate(self):
        pass

Using a hash file

It is also possible to validate a file against a hash file, which has stored the hash at the first line:

from groundwork_validation.patterns import GwFileValidatorsPattern

class My_Plugin(GwFileValidatorsPattern):
    def __init__(self, app, **kwargs):
        self.name = "My_Plugin"
        super(My_Plugin, self).__init__(app, **kwargs)

    def activate(self):
        my_file = "/path/to/file.txt"
        my_hash_file = "/path/to/file.hash"

        if self.validators.file.validate(my_file, hash_file=my_hash_file):
            print("Hash is valid")
        else:
            print("Hash is NOT valid")

    def deactivate(self):
        pass

Please see validate() for a complete list of available parameters.

Requirements & Specifications

The following sections describes the implemented requirements and their related specifications.

Available requirements

ID	Title	Type	Status	Links	Tags
R_8E18E	File validation	Requirement			gwfilevalidators

Available specifications

ID	Title	Type	Status	Links	Tags
S_31C31	Validating a file	Specification		R_8E18E	gwfilevalidators
S_CFBC1	Hashing a file	Specification		R_8E18E	gwfilevalidators

Requirements

Requirement: File validation (R_8E18E)

As developer I want to be able to easily hash and validate files to detect every kind of file corruption.

tags: gwfilevalidators

Specifications

Specification: Hashing a file (S_CFBC1)

A function hash is implemented for self.validators.file, which is able to create a hash value for a given file path. The function must have the following parameters:

• file - file path
• validator - An instance of Validator. Can be None
• hash_file - File to store the hash value. optional
• blocksize - Max. size of a block, which gets read in gets hashed and maybe update the prior hash value.
• return_hash_object - Returns the hashlib hash object instead of a string representation

tags: gwfilevalidators

links: R_8E18E

Specification: Validating a file (S_31C31)

A function validate is implemented for self.validators.file, which allows the validation of a file against a given hash.

The function has the following attributes:

• file - file path
• hash_value
• hash_file - if given, hash_value is read from this file path
• validator - An instance of Validator. Can be None
• blocksize - Max. size of a block, which gets read in gets hashed and maybe update the prior hash value.

Returns True, if calculated hash values is euqal to the given hash value.

tags: gwfilevalidators

links: R_8E18E