class Magic::TypeChecker

• Magic::TypeChecker
• Reference
• Object

Overview

A TypeChecker checks the Magic database on the system for a given file, filepath, file descriptor, or byte stream (IO) on its .of instance method. It contains methods for changing how its output is given. While the primary use cases for this module can be performed with the module-level functions, instances of TypeChecker provide the full flexibility of libmagic in a syntax that still makes sense in crystal.

Examples:

# get all matching mime types and the encoding from a series of files
mime_types = TypeChecker.new.all_types.get_mime_type.get_mime_encoding

def type_of_each(files : Indexable(File) | Set(File))
  files.each do |file|
    # and yield the list of mimes to a block
    yield mime_types.of(file).split('\n')
  end
end

# alternately, return the list of mimes.
def types_of_each(files)
  files.each do |file|
    mime_types.of(file).split("\n")
  end
end

# do the same thing but now follow symbolic links
def types_of_each(files)
  mime_types.follow_symlinks
  files.each do |file|
    yield mime_types.of(file).split("\n")
  end
  mime_types.follow_symlinks = false
end

Defined in:

Constant Summary

DEFAULT_OPTIONS = LibMagic::RAW | LibMagic::ERROR

Integer = ((((((Int8 | Int16) | Int32) | Int64) | UInt8) | UInt16) | UInt32) | UInt64

Constructors

• .new(options = DEFAULT_OPTIONS, database_files : IterableOfStrings? = nil, limit_settings : Hash(Limit, Int32)? = nil)

Instance Method Summary

• #all_types

  Return all matches, not just the first.

• #all_types=(setting : Bool)
• #all_types?
• #apple

  Return the Apple creator and type.

• #apple=(setting : Bool)
• #apple?
• #check_db

  Check the magic database for consistency and printwarnings to stderr, while checking a file.

• #check_db=(setting : Bool)
• #check_db?
• #check_device

  If the file is a block or character special device, thenopen the device and try to look in its contents.

• #check_device=(setting : Bool)
• #check_device?
• #checker=(chkr : LibMagic::MagicT)

  Manually set the checker to a given LibMagic::MagicT (libmagic's magic_t).

• #db_files : Set(String)?

  database files to read from

• #db_files=(files : IterableOfStrings)

  Load a new set of database files into the magic database.

• #debug_output

  Have libmagic(2) print debugging messages to stderr.

• #debug_output=(setting : Bool)
• #debug_output?
• #default_options?
• #error(msg)
• #escape_unprintable

  escapes non-printable bytes as their 0oOOO octal numeric forms.By default crystal handles this in cases where it's important (inputs for example), so by default strings contain the raw values forunprintable characters.

• #escape_unprintable=(setting : Bool)
• #escape_unprintable?
• #extensions(this)

  like #of() and #for() but returns a Set of valid extensions, rather than a single string.

• #follow_symlinks

  If the file queried is a symlink, follow it.

• #follow_symlinks=(setting : Bool)
• #follow_symlinks?
• #for(this)

  same as #of()

• #get_extensions

  Makes #of() return a slash-separated list of extensions for this file type.

• #get_extensions=(setting : Bool)
• #get_extensions?
• #get_mime

  sets both #get_mime_type and #get_mime_encoding

• #get_mime=(setting : Bool)
• #get_mime?
• #get_mime_encoding

  Return a MIME encoding, instead of a textual description.

• #get_mime_encoding=(setting : Bool)
• #get_mime_encoding?
• #get_mime_type

  Return a MIME type string, instead of a textual description.

• #get_mime_type=(setting : Bool)
• #get_mime_type?
• #libmagic_defaults

  use the MAGIC_NONE option (the default for libmagic) instead of the default for magic.cr

• #libmagic_defaults?
• #look_into_compressed_files

  If the file is compressed, unpack it and look at the contents.

• #look_into_compressed_files=(setting : Bool)
• #look_into_compressed_files?
• #max_bytes(&block)

  Yields the current value of the max_bytes to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_bytes

  Get the current limit of the LibMagic::PARAM_BYTES_MAX libmagic param.

• #max_bytes=(value : Int32)

  Limit LibMagic::PARAM_BYTES_MAX to the given value.

• #max_elf_notes

  Get the current limit of the LibMagic::PARAM_ELF_NOTES_MAX libmagic param.

• #max_elf_notes(&block)

  Yields the current value of the max_elf_notes to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_elf_notes=(value : Int32)

  Limit LibMagic::PARAM_ELF_NOTES_MAX to the given value.

• #max_elf_phnum

  Get the current limit of the LibMagic::PARAM_ELF_PHNUM_MAX libmagic param.

• #max_elf_phnum(&block)

  Yields the current value of the max_elf_phnum to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_elf_phnum=(value : Int32)

  Limit LibMagic::PARAM_ELF_PHNUM_MAX to the given value.

• #max_elf_shnum

  Get the current limit of the LibMagic::PARAM_ELF_SHNUM_MAX libmagic param.

• #max_elf_shnum(&block)

  Yields the current value of the max_elf_shnum to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_elf_shnum=(value : Int32)

  Limit LibMagic::PARAM_ELF_SHNUM_MAX to the given value.

• #max_indir(&block)

  Yields the current value of the max_indir to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_indir

  Get the current limit of the LibMagic::PARAM_INDIR_MAX libmagic param.

• #max_indir=(value : Int32)

  Limit LibMagic::PARAM_INDIR_MAX to the given value.

• #max_name

  Get the current limit of the LibMagic::PARAM_NAME_MAX libmagic param.

• #max_name(&block)

  Yields the current value of the max_name to the block, then sets the value to the result of the block, unless the block returns nil, of course.

• #max_name=(value : Int32)

  Limit LibMagic::PARAM_NAME_MAX to the given value.

• #no_compression_info

  Don't report on compression, only report about the uncompressed data.

• #no_compression_info=(setting : Bool)
• #no_compression_info?
• #of(file : File)

  Get the filetype "of" the given file.

• #of(this : Int32)

  get the filetype "of" the open file at the given file descriptor integer.

• #of(this : IO)

  Get the filetype "of" the given bytes.

• #of(filepath)

  Get the filetype "of" the given file.

• #of?(file_descriptor : Int32)

  Get the filetype "of" the given file.

• #of?(filepath, opts)

  Get the filetype "of" the given file, passing opts to libmagic(2).

• #of?(file : File)

  Get the filetype "of" the given file.

• #of?(bytes : IO)

  Get the filetype "of" the given file.

• #of?(filepath)

  Get the filetype "of" the given file.

• #options

  The current value of the magic flags.

• #options=(options)

  Directly set the options parameter.

• #preserve_atime
• #preserve_atime=(setting : Bool)
• #preserve_atime?
• #reset_options

  reset any options set on this instance back to the magic.cr default.

• #return_error_as_text

  Return errors while trying to open files and follow symlinks in thefiletype text rather than raising an error.

• #return_error_as_text=(setting : Bool)
• #return_error_as_text?
• #try_to_preserve_access_time

  On systems that support utime(3) or utimes(2), attempt topreserve the access time of files analysed.

• #try_to_preserve_access_time=(setting : Bool)
• #try_to_preserve_access_time?

Constructor Detail

Instance Method Detail

check_ft = Magic::TypeChecker.new
check_ft.database = [ "/path/to/file", File.join("other", "path")]
...
check_ft.database = :default

# doubles the PARAM_BYTES_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_bytes do |current|
  current * 2
end

# doubles the PARAM_ELF_NOTES_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_elf_notes do |current|
  current * 2
end

# doubles the PARAM_ELF_PHNUM_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_elf_phnum do |current|
  current * 2
end

# doubles the PARAM_ELF_SHNUM_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_elf_shnum do |current|
  current * 2
end

# doubles the PARAM_INDIR_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_indir do |current|
  current * 2
end

# doubles the PARAM_NAME_MAX limit
ft_checker = Magic::TypeChecker.new
ft_checker.max_name do |current|
  current * 2
end