Class: Secret::File

Inherits:
Object
  • Object
show all
Defined in:
lib/secret/file.rb

Overview

Handles file operations. Uses Ruby’s internal file locking mechanisms.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(container, identifier) ⇒ File

Creates a new secret file. The specified identifier doesn’t already need to exist.

Parameters:

  • container (Secret::Container) —

    the container object

  • identifier (Symbol) —

    an unique identifier for this container

Raises:

  • (ArgumentError) 


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# File 'lib/secret/file.rb', line 12

def initialize(container, identifier)
  raise ArgumentError, "Container must be a Secret::Container object" unless container.is_a?(Secret::Container)
  @container = container; @identifier = identifier
  touch!
  ensure_writeable!
end

Instance Attribute Details

#container ⇒ Object (readonly)

include Secret::Encryption



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# File 'lib/secret/file.rb', line 7

def container
  @container
end

#identifier ⇒ Object (readonly)

include Secret::Encryption



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# File 'lib/secret/file.rb', line 7

def identifier
  @identifier
end

Instance Method Details

#contents ⇒ String

Gets the contents of the file in a string format. Will return an empty string if the file doesn’t exist, or the file just so happens to be empty.

Returns:

  • (String) —

    the contents of the file



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# File 'lib/secret/file.rb', line 62

def contents
  str = nil
  stream 'r' do |f|
    str = f.read
  end
  return str
end

#ensure_writeable! ⇒ Object 



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# File 'lib/secret/file.rb', line 129

def ensure_writeable!
  unless ::File.writable?(file_path)
    raise FileUnreadableError, "File is not writeable - perhaps it was created by a different process?"
  end
end

#exist? ⇒ Boolean

Checks whether this file actually exists or not

Returns:

  • (Boolean) —

    true if the file exists (i.e. has content), false if otherwise.



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# File 'lib/secret/file.rb', line 21

def exist?
  ::File.exist?(file_path)
end

#restore_backup! ⇒ Boolean

Attempts to restore a backup (i.e. if the computer crashed while doing a stash command)

Returns:

  • (Boolean) —

    true if the backup was successfully restored, false otherwise



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# File 'lib/secret/file.rb', line 137

def restore_backup!
  return false unless ::File.exist?(backup_file_path)
  
  # We know backup exists, so let's write to the file. We want to truncate file contents.
  # Now copy file contents over from the backup file. We use this method to use locking.
  ::File.open(file_path, 'w', container.chmod_mode) do |f|
    begin
      f.flock ::File::LOCK_EX
      ::File.open(backup_file_path, 'r', container.chmod_mode) do |b|
        f.write b.read
      end
    ensure
      f.flock ::File::LOCK_UN
    end
  end
  return true
  
end

#secure! ⇒ Object

Secures the file by chmoding it to 0700

Raises:

  • (IOError) —

    if the file doesn’t exist on the server.



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# File 'lib/secret/file.rb', line 84

def secure!
  raise IOError, "File doesn't exist" unless exist?
  ::File.chmod(container.chmod_mode, file_path)
end

#stash(content) ⇒ Object

Stashes some content into the file! This will write a temporary backup file before stashing, in order to prevent any partial writes if the server crashes. Once this finishes executing, you can be sure that contents have been written.

Parameters:

  • content (String) —

    the contents to stash. **Must be a string!**

Raises:

  • (ArgumentError) —

    if content is anything other than a String object!



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# File 'lib/secret/file.rb', line 95

def stash(content)
  raise ArgumentError, "Content must be a String (was type of type #{content.class.name})" unless content.is_a?(String)
  touch!
  ensure_writeable!
  
  # Think of this as a beginning of a transaction.
  ::File.open(file_path, 'a', container.chmod_mode) do |f|
    begin
      f.flock(::File::LOCK_EX)
  
      # Open a temporary file for writing, and close it immediately
      ::File.open(tmp_file_path, "w", container.chmod_mode){|f| f.write content }
  
      # Rename tmp file to backup file now we know contents are sane
      ::File.rename(tmp_file_path, backup_file_path)
      
      # Truncate file contents to zero bytes
      f.truncate 0
      
      # Write content
      f.write content
    ensure
      # Now unlock file!
      f.flock(::File::LOCK_UN)
    end
    
    # Delete backup file
    ::File.delete(backup_file_path)
  end

  # Committed! Secure it just in case
  secure!
end

#stream(mode = 'r', &block) ⇒ IO

Note:

Uses an exclusive lock on this file

Gets a file stream of this file. If the file doesn’t exist, then a blank file will be created. By default, this allows you to write to the file. However, please use the #stash command, as it accounts for mid-write crashes. Don’t forget to close the file stream when you’re done!

Examples:

file = container.some_file

# Unsafe way!
io = file.stream
io.write "Hello World!"
io.close

# Safe way, with locking support
file.stream do |f|
  f.write "Hello World!"
end

Parameters:

  • mode (String) (defaults to: 'r') —

    the mode for this file. Currently defaults to ‘r+’, which is read-write, with the file pointer at the beginning of the file.

Returns:

  • (IO) —

    an IO stream to this file, if not using a block



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# File 'lib/secret/file.rb', line 44

def stream(mode = 'r', &block)
  touch!
  ensure_writeable!
  return ::File.open(file_path, mode, container.chmod_mode)  unless block_given?
  ::File.open(file_path, mode, container.chmod_mode) do |f|
    begin
      f.flock(::File::LOCK_EX) # Lock with exclusive mode
      block.call(f)
    ensure
      f.flock(::File::LOCK_UN)
    end
  end
end

#touch! ⇒ Boolean

Creates a new file if it doesn’t exist. Doesn’t actually change the last updated timestamp.

Returns:

  • (Boolean) —

    true if an empty file was created, false if the file already existed.



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# File 'lib/secret/file.rb', line 73

def touch!
  unless exist?
    ::File.open(file_path, 'w', container.chmod_mode) {}
    secure!
    return true
  end
  return false
end