815 lines
24 KiB
Groff
815 lines
24 KiB
Groff
.\" $File: magic.man,v 1.99 2021/05/09 22:37:23 christos Exp $
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.Dd May 9, 2021
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.Dt MAGIC __FSECTION__
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.Os
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.\" install as magic.4 on USG, magic.5 on V7, Berkeley and Linux systems.
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.Sh NAME
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.Nm magic
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.Nd file command's magic pattern file
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.Sh DESCRIPTION
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This manual page documents the format of magic files as
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used by the
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.Xr file __CSECTION__
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command, version __VERSION__.
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The
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.Xr file __CSECTION__
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command identifies the type of a file using,
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among other tests,
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a test for whether the file contains certain
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.Dq "magic patterns" .
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The database of these
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.Dq "magic patterns"
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is usually located in a binary file in
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.Pa __MAGIC__.mgc
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or a directory of source text magic pattern fragment files in
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.Pa __MAGIC__ .
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The database specifies what patterns are to be tested for, what message or
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MIME type to print if a particular pattern is found,
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and additional information to extract from the file.
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.Pp
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The format of the source fragment files that are used to build this database
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is as follows:
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Each line of a fragment file specifies a test to be performed.
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A test compares the data starting at a particular offset
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in the file with a byte value, a string or a numeric value.
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If the test succeeds, a message is printed.
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The line consists of the following fields:
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.Bl -tag -width ".Dv message"
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.It Dv offset
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A number specifying the offset (in bytes) into the file of the data
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which is to be tested.
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This offset can be a negative number if it is:
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.Bl -bullet -compact
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.It
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The first direct offset of the magic entry (at continuation level 0),
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in which case it is interpreted an offset from end end of the file
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going backwards.
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This works only when a file descriptor to the file is available and it
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is a regular file.
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.It
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A continuation offset relative to the end of the last up-level field
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.Dv ( \*[Am] ) .
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.El
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.It Dv type
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The type of the data to be tested.
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The possible values are:
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.Bl -tag -width ".Dv lestring16"
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.It Dv byte
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A one-byte value.
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.It Dv short
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A two-byte value in this machine's native byte order.
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.It Dv long
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A four-byte value in this machine's native byte order.
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.It Dv quad
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An eight-byte value in this machine's native byte order.
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.It Dv float
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A 32-bit single precision IEEE floating point number in this machine's native byte order.
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.It Dv double
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A 64-bit double precision IEEE floating point number in this machine's native byte order.
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.It Dv string
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A string of bytes.
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The string type specification can be optionally followed
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by /[WwcCtbTf]*.
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The
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.Dq W
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flag compacts whitespace in the target, which must
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contain at least one whitespace character.
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If the magic has
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.Dv n
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consecutive blanks, the target needs at least
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.Dv n
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consecutive blanks to match.
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The
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.Dq w
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flag treats every blank in the magic as an optional blank.
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The
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.Dq f
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flags requires that the matched string is a full word, not a partial word match.
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The
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.Dq c
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flag specifies case insensitive matching: lower case
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characters in the magic match both lower and upper case characters in the
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target, whereas upper case characters in the magic only match upper case
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characters in the target.
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The
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.Dq C
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flag specifies case insensitive matching: upper case
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characters in the magic match both lower and upper case characters in the
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target, whereas lower case characters in the magic only match upper case
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characters in the target.
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To do a complete case insensitive match, specify both
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.Dq c
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and
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.Dq C .
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The
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.Dq t
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flag forces the test to be done for text files, while the
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.Dq b
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flag forces the test to be done for binary files.
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The
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.Dq T
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flag causes the string to be trimmed, i.e. leading and trailing whitespace
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is deleted before the string is printed.
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.It Dv pstring
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A Pascal-style string where the first byte/short/int is interpreted as the
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unsigned length.
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The length defaults to byte and can be specified as a modifier.
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The following modifiers are supported:
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.Bl -tag -compact -width B
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.It B
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A byte length (default).
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.It H
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A 2 byte big endian length.
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.It h
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A 2 byte little endian length.
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.It L
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A 4 byte big endian length.
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.It l
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A 4 byte little endian length.
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.It J
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The length includes itself in its count.
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.El
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The string is not NUL terminated.
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.Dq J
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is used rather than the more
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valuable
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.Dq I
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because this type of length is a feature of the JPEG
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format.
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.It Dv date
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A four-byte value interpreted as a UNIX date.
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.It Dv qdate
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An eight-byte value interpreted as a UNIX date.
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.It Dv ldate
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A four-byte value interpreted as a UNIX-style date, but interpreted as
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local time rather than UTC.
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.It Dv qldate
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An eight-byte value interpreted as a UNIX-style date, but interpreted as
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local time rather than UTC.
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.It Dv qwdate
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An eight-byte value interpreted as a Windows-style date.
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.It Dv beid3
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A 32-bit ID3 length in big-endian byte order.
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.It Dv beshort
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A two-byte value in big-endian byte order.
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.It Dv belong
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A four-byte value in big-endian byte order.
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.It Dv bequad
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An eight-byte value in big-endian byte order.
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.It Dv befloat
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A 32-bit single precision IEEE floating point number in big-endian byte order.
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.It Dv bedouble
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A 64-bit double precision IEEE floating point number in big-endian byte order.
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.It Dv bedate
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A four-byte value in big-endian byte order,
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interpreted as a Unix date.
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.It Dv beqdate
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An eight-byte value in big-endian byte order,
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interpreted as a Unix date.
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.It Dv beldate
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A four-byte value in big-endian byte order,
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interpreted as a UNIX-style date, but interpreted as local time rather
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than UTC.
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.It Dv beqldate
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An eight-byte value in big-endian byte order,
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interpreted as a UNIX-style date, but interpreted as local time rather
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than UTC.
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.It Dv beqwdate
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An eight-byte value in big-endian byte order,
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interpreted as a Windows-style date.
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.It Dv bestring16
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A two-byte unicode (UCS16) string in big-endian byte order.
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.It Dv leid3
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A 32-bit ID3 length in little-endian byte order.
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.It Dv leshort
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A two-byte value in little-endian byte order.
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.It Dv lelong
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A four-byte value in little-endian byte order.
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.It Dv lequad
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An eight-byte value in little-endian byte order.
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.It Dv lefloat
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A 32-bit single precision IEEE floating point number in little-endian byte order.
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.It Dv ledouble
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A 64-bit double precision IEEE floating point number in little-endian byte order.
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.It Dv ledate
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A four-byte value in little-endian byte order,
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interpreted as a UNIX date.
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.It Dv leqdate
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An eight-byte value in little-endian byte order,
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interpreted as a UNIX date.
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.It Dv leldate
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A four-byte value in little-endian byte order,
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interpreted as a UNIX-style date, but interpreted as local time rather
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than UTC.
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.It Dv leqldate
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An eight-byte value in little-endian byte order,
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interpreted as a UNIX-style date, but interpreted as local time rather
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than UTC.
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.It Dv leqwdate
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An eight-byte value in little-endian byte order,
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interpreted as a Windows-style date.
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.It Dv lestring16
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A two-byte unicode (UCS16) string in little-endian byte order.
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.It Dv melong
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A four-byte value in middle-endian (PDP-11) byte order.
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.It Dv medate
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A four-byte value in middle-endian (PDP-11) byte order,
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interpreted as a UNIX date.
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.It Dv meldate
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A four-byte value in middle-endian (PDP-11) byte order,
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interpreted as a UNIX-style date, but interpreted as local time rather
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than UTC.
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.It Dv indirect
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Starting at the given offset, consult the magic database again.
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The offset of the
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.Dv indirect
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magic is by default absolute in the file, but one can specify
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.Dv /r
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to indicate that the offset is relative from the beginning of the entry.
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.It Dv name
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Define a
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.Dq named
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magic instance that can be called from another
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.Dv use
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magic entry, like a subroutine call.
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Named instance direct magic offsets are relative to the offset of the
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previous matched entry, but indirect offsets are relative to the beginning
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of the file as usual.
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Named magic entries always match.
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.It Dv use
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Recursively call the named magic starting from the current offset.
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If the name of the referenced begins with a
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.Dv ^
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then the endianness of the magic is switched; if the magic mentioned
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.Dv leshort
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for example,
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it is treated as
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.Dv beshort
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and vice versa.
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This is useful to avoid duplicating the rules for different endianness.
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.It Dv regex
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A regular expression match in extended POSIX regular expression syntax
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(like egrep).
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Regular expressions can take exponential time to process, and their
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performance is hard to predict, so their use is discouraged.
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When used in production environments, their performance
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should be carefully checked.
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The size of the string to search should also be limited by specifying
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.Dv /<length> ,
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to avoid performance issues scanning long files.
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The type specification can also be optionally followed by
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.Dv /[c][s][l] .
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The
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.Dq c
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flag makes the match case insensitive, while the
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.Dq s
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flag update the offset to the start offset of the match, rather than the end.
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The
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.Dq l
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modifier, changes the limit of length to mean number of lines instead of a
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byte count.
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Lines are delimited by the platforms native line delimiter.
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When a line count is specified, an implicit byte count also computed assuming
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each line is 80 characters long.
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If neither a byte or line count is specified, the search is limited automatically
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to 8KiB.
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.Dv ^
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and
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.Dv $
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match the beginning and end of individual lines, respectively,
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not beginning and end of file.
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.It Dv search
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A literal string search starting at the given offset.
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The same modifier flags can be used as for string patterns.
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The search expression must contain the range in the form
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.Dv /number,
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that is the number of positions at which the match will be
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attempted, starting from the start offset.
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This is suitable for
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searching larger binary expressions with variable offsets, using
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.Dv \e
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escapes for special characters.
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The order of modifier and number is not relevant.
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.It Dv default
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This is intended to be used with the test
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.Em x
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(which is always true) and it has no type.
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It matches when no other test at that continuation level has matched before.
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Clearing that matched tests for a continuation level, can be done using the
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.Dv clear
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test.
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.It Dv clear
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This test is always true and clears the match flag for that continuation level.
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It is intended to be used with the
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.Dv default
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test.
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.It Dv der
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Parse the file as a DER Certificate file.
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The test field is used as a der type that needs to be matched.
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The DER types are:
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.Dv eoc ,
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.Dv bool ,
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.Dv int ,
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.Dv bit_str ,
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.Dv octet_str ,
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.Dv null ,
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.Dv obj_id ,
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.Dv obj_desc ,
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.Dv ext ,
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.Dv real ,
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.Dv enum ,
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.Dv embed ,
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.Dv utf8_str ,
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.Dv rel_oid ,
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.Dv time ,
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.Dv res2 ,
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.Dv seq ,
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.Dv set ,
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.Dv num_str ,
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.Dv prt_str ,
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.Dv t61_str ,
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.Dv vid_str ,
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.Dv ia5_str ,
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.Dv utc_time ,
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.Dv gen_time ,
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.Dv gr_str ,
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.Dv vis_str ,
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.Dv gen_str ,
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.Dv univ_str ,
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.Dv char_str ,
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.Dv bmp_str ,
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.Dv date ,
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.Dv tod ,
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.Dv datetime ,
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.Dv duration ,
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.Dv oid-iri ,
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.Dv rel-oid-iri .
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These types can be followed by an optional numeric size, which indicates
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the field width in bytes.
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.It Dv guid
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A Globally Unique Identifier, parsed and printed as
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XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX.
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It's format is a string.
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.It Dv offset
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This is a quad value indicating the current offset of the file.
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It can be used to determine the size of the file or the magic buffer.
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For example the magic entries:
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.Bd -literal -offset indent
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-0 offset x this file is %lld bytes
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-0 offset <=100 must be more than 100 \e
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bytes and is only %lld
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.Ed
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.El
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.Pp
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For compatibility with the Single
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.Ux
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Standard, the type specifiers
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.Dv dC
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and
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.Dv d1
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are equivalent to
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.Dv byte ,
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the type specifiers
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.Dv uC
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and
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.Dv u1
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are equivalent to
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.Dv ubyte ,
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the type specifiers
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.Dv dS
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and
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.Dv d2
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are equivalent to
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.Dv short ,
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the type specifiers
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.Dv uS
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and
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.Dv u2
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are equivalent to
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.Dv ushort ,
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the type specifiers
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.Dv dI ,
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.Dv dL ,
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and
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.Dv d4
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are equivalent to
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.Dv long ,
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the type specifiers
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.Dv uI ,
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.Dv uL ,
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and
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.Dv u4
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are equivalent to
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.Dv ulong ,
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the type specifier
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|
.Dv d8
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|
is equivalent to
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.Dv quad ,
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the type specifier
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|
.Dv u8
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is equivalent to
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.Dv uquad ,
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and the type specifier
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|
.Dv s
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|
is equivalent to
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.Dv string .
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|
In addition, the type specifier
|
|
.Dv dQ
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is equivalent to
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|
.Dv quad
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|
and the type specifier
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.Dv uQ
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is equivalent to
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.Dv uquad .
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.Pp
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|
Each top-level magic pattern (see below for an explanation of levels)
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is classified as text or binary according to the types used.
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Types
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.Dq regex
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and
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|
.Dq search
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|
are classified as text tests, unless non-printable characters are used
|
|
in the pattern.
|
|
All other tests are classified as binary.
|
|
A top-level
|
|
pattern is considered to be a test text when all its patterns are text
|
|
patterns; otherwise, it is considered to be a binary pattern.
|
|
When
|
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matching a file, binary patterns are tried first; if no match is
|
|
found, and the file looks like text, then its encoding is determined
|
|
and the text patterns are tried.
|
|
.Pp
|
|
The numeric types may optionally be followed by
|
|
.Dv \*[Am]
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|
and a numeric value,
|
|
to specify that the value is to be AND'ed with the
|
|
numeric value before any comparisons are done.
|
|
Prepending a
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|
.Dv u
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|
to the type indicates that ordered comparisons should be unsigned.
|
|
.It Dv test
|
|
The value to be compared with the value from the file.
|
|
If the type is
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numeric, this value
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is specified in C form; if it is a string, it is specified as a C string
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|
with the usual escapes permitted (e.g. \en for new-line).
|
|
.Pp
|
|
Numeric values
|
|
may be preceded by a character indicating the operation to be performed.
|
|
It may be
|
|
.Dv = ,
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|
to specify that the value from the file must equal the specified value,
|
|
.Dv \*[Lt] ,
|
|
to specify that the value from the file must be less than the specified
|
|
value,
|
|
.Dv \*[Gt] ,
|
|
to specify that the value from the file must be greater than the specified
|
|
value,
|
|
.Dv \*[Am] ,
|
|
to specify that the value from the file must have set all of the bits
|
|
that are set in the specified value,
|
|
.Dv ^ ,
|
|
to specify that the value from the file must have clear any of the bits
|
|
that are set in the specified value, or
|
|
.Dv ~ ,
|
|
the value specified after is negated before tested.
|
|
.Dv x ,
|
|
to specify that any value will match.
|
|
If the character is omitted, it is assumed to be
|
|
.Dv = .
|
|
Operators
|
|
.Dv \*[Am] ,
|
|
.Dv ^ ,
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|
and
|
|
.Dv ~
|
|
don't work with floats and doubles.
|
|
The operator
|
|
.Dv !\&
|
|
specifies that the line matches if the test does
|
|
.Em not
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|
succeed.
|
|
.Pp
|
|
Numeric values are specified in C form; e.g.
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|
.Dv 13
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is decimal,
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|
.Dv 013
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|
is octal, and
|
|
.Dv 0x13
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|
is hexadecimal.
|
|
.Pp
|
|
Numeric operations are not performed on date types, instead the numeric
|
|
value is interpreted as an offset.
|
|
.Pp
|
|
For string values, the string from the
|
|
file must match the specified string.
|
|
The operators
|
|
.Dv = ,
|
|
.Dv \*[Lt]
|
|
and
|
|
.Dv \*[Gt]
|
|
(but not
|
|
.Dv \*[Am] )
|
|
can be applied to strings.
|
|
The length used for matching is that of the string argument
|
|
in the magic file.
|
|
This means that a line can match any non-empty string (usually used to
|
|
then print the string), with
|
|
.Em \*[Gt]\e0
|
|
(because all non-empty strings are greater than the empty string).
|
|
.Pp
|
|
Dates are treated as numerical values in the respective internal
|
|
representation.
|
|
.Pp
|
|
The special test
|
|
.Em x
|
|
always evaluates to true.
|
|
.It Dv message
|
|
The message to be printed if the comparison succeeds.
|
|
If the string contains a
|
|
.Xr printf 3
|
|
format specification, the value from the file (with any specified masking
|
|
performed) is printed using the message as the format string.
|
|
If the string begins with
|
|
.Dq \eb ,
|
|
the message printed is the remainder of the string with no whitespace
|
|
added before it: multiple matches are normally separated by a single
|
|
space.
|
|
.El
|
|
.Pp
|
|
An APPLE 4+4 character APPLE creator and type can be specified as:
|
|
.Bd -literal -offset indent
|
|
!:apple CREATYPE
|
|
.Ed
|
|
.Pp
|
|
A MIME type is given on a separate line, which must be the next
|
|
non-blank or comment line after the magic line that identifies the
|
|
file type, and has the following format:
|
|
.Bd -literal -offset indent
|
|
!:mime MIMETYPE
|
|
.Ed
|
|
.Pp
|
|
i.e. the literal string
|
|
.Dq !:mime
|
|
followed by the MIME type.
|
|
.Pp
|
|
An optional strength can be supplied on a separate line which refers to
|
|
the current magic description using the following format:
|
|
.Bd -literal -offset indent
|
|
!:strength OP VALUE
|
|
.Ed
|
|
.Pp
|
|
The operand
|
|
.Dv OP
|
|
can be:
|
|
.Dv + ,
|
|
.Dv - ,
|
|
.Dv * ,
|
|
or
|
|
.Dv /
|
|
and
|
|
.Dv VALUE
|
|
is a constant between 0 and 255.
|
|
This constant is applied using the specified operand
|
|
to the currently computed default magic strength.
|
|
.Pp
|
|
Some file formats contain additional information which is to be printed
|
|
along with the file type or need additional tests to determine the true
|
|
file type.
|
|
These additional tests are introduced by one or more
|
|
.Em \*[Gt]
|
|
characters preceding the offset.
|
|
The number of
|
|
.Em \*[Gt]
|
|
on the line indicates the level of the test; a line with no
|
|
.Em \*[Gt]
|
|
at the beginning is considered to be at level 0.
|
|
Tests are arranged in a tree-like hierarchy:
|
|
if the test on a line at level
|
|
.Em n
|
|
succeeds, all following tests at level
|
|
.Em n+1
|
|
are performed, and the messages printed if the tests succeed, until a line
|
|
with level
|
|
.Em n
|
|
(or less) appears.
|
|
For more complex files, one can use empty messages to get just the
|
|
"if/then" effect, in the following way:
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Lt]0x40 MS-DOS executable
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f extended PC executable (e.g., MS Windows)
|
|
.Ed
|
|
.Pp
|
|
Offsets do not need to be constant, but can also be read from the file
|
|
being examined.
|
|
If the first character following the last
|
|
.Em \*[Gt]
|
|
is a
|
|
.Em \&(
|
|
then the string after the parenthesis is interpreted as an indirect offset.
|
|
That means that the number after the parenthesis is used as an offset in
|
|
the file.
|
|
The value at that offset is read, and is used again as an offset
|
|
in the file.
|
|
Indirect offsets are of the form:
|
|
.Em (( x [[.,][bBcCeEfFgGhHiIlmsSqQ]][+\-][ y ]) .
|
|
The value of
|
|
.Em x
|
|
is used as an offset in the file.
|
|
A byte, id3 length, short or long is read at that offset depending on the
|
|
.Em [bBcCeEfFgGhHiIlmsSqQ]
|
|
type specifier.
|
|
The value is treated as signed if
|
|
.Dq ,
|
|
is specified or unsigned if
|
|
.Dq .
|
|
is specified.
|
|
The capitalized types interpret the number as a big endian
|
|
value, whereas the small letter versions interpret the number as a little
|
|
endian value;
|
|
the
|
|
.Em m
|
|
type interprets the number as a middle endian (PDP-11) value.
|
|
To that number the value of
|
|
.Em y
|
|
is added and the result is used as an offset in the file.
|
|
The default type if one is not specified is long.
|
|
The following types are recognized:
|
|
.Bl -column -offset indent "Type" "Half/Short" "Little" "Size"
|
|
.It Sy Type Sy Mnemonic Sy Endian Sy Size
|
|
.It bcBc Byte/Char N/A 1
|
|
.It efg Double Little 8
|
|
.It EFG Double Big 8
|
|
.It hs Half/Short Little 2
|
|
.It HS Half/Short Big 2
|
|
.It i ID3 Little 4
|
|
.It I ID3 Big 4
|
|
.It m Middle Middle 4
|
|
.It q Quad Little 8
|
|
.It Q Quad Big 8
|
|
.El
|
|
.Pp
|
|
That way variable length structures can be examined:
|
|
.Bd -literal -offset indent
|
|
# MS Windows executables are also valid MS-DOS executables
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Lt]0x40 MZ executable (MS-DOS)
|
|
# skip the whole block below if it is not an extended executable
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f
|
|
\*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
|
|
\*[Gt]\*[Gt](0x3c.l) string LX\e0\e0 LX executable (OS/2)
|
|
.Ed
|
|
.Pp
|
|
This strategy of examining has a drawback: you must make sure that you
|
|
eventually print something, or users may get empty output (such as when
|
|
there is neither PE\e0\e0 nor LE\e0\e0 in the above example).
|
|
.Pp
|
|
If this indirect offset cannot be used directly, simple calculations are
|
|
possible: appending
|
|
.Em [+-*/%\*[Am]|^]number
|
|
inside parentheses allows one to modify
|
|
the value read from the file before it is used as an offset:
|
|
.Bd -literal -offset indent
|
|
# MS Windows executables are also valid MS-DOS executables
|
|
0 string MZ
|
|
# sometimes, the value at 0x18 is less that 0x40 but there's still an
|
|
# extended executable, simply appended to the file
|
|
\*[Gt]0x18 leshort \*[Lt]0x40
|
|
\*[Gt]\*[Gt](4.s*512) leshort 0x014c COFF executable (MS-DOS, DJGPP)
|
|
\*[Gt]\*[Gt](4.s*512) leshort !0x014c MZ executable (MS-DOS)
|
|
.Ed
|
|
.Pp
|
|
Sometimes you do not know the exact offset as this depends on the length or
|
|
position (when indirection was used before) of preceding fields.
|
|
You can specify an offset relative to the end of the last up-level
|
|
field using
|
|
.Sq \*[Am]
|
|
as a prefix to the offset:
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f
|
|
\*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
|
|
# immediately following the PE signature is the CPU type
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Am]0 leshort 0x14c for Intel 80386
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Am]0 leshort 0x184 for DEC Alpha
|
|
.Ed
|
|
.Pp
|
|
Indirect and relative offsets can be combined:
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Lt]0x40
|
|
\*[Gt]\*[Gt](4.s*512) leshort !0x014c MZ executable (MS-DOS)
|
|
# if it's not COFF, go back 512 bytes and add the offset taken
|
|
# from byte 2/3, which is yet another way of finding the start
|
|
# of the extended executable
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Am](2.s-514) string LE LE executable (MS Windows VxD driver)
|
|
.Ed
|
|
.Pp
|
|
Or the other way around:
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f
|
|
\*[Gt]\*[Gt](0x3c.l) string LE\e0\e0 LE executable (MS-Windows)
|
|
# at offset 0x80 (-4, since relative offsets start at the end
|
|
# of the up-level match) inside the LE header, we find the absolute
|
|
# offset to the code area, where we look for a specific signature
|
|
\*[Gt]\*[Gt]\*[Gt](\*[Am]0x7c.l+0x26) string UPX \eb, UPX compressed
|
|
.Ed
|
|
.Pp
|
|
Or even both!
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f
|
|
\*[Gt]\*[Gt](0x3c.l) string LE\e0\e0 LE executable (MS-Windows)
|
|
# at offset 0x58 inside the LE header, we find the relative offset
|
|
# to a data area where we look for a specific signature
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Am](\*[Am]0x54.l-3) string UNACE \eb, ACE self-extracting archive
|
|
.Ed
|
|
.Pp
|
|
If you have to deal with offset/length pairs in your file, even the
|
|
second value in a parenthesized expression can be taken from the file itself,
|
|
using another set of parentheses.
|
|
Note that this additional indirect offset is always relative to the
|
|
start of the main indirect offset.
|
|
.Bd -literal -offset indent
|
|
0 string MZ
|
|
\*[Gt]0x18 leshort \*[Gt]0x3f
|
|
\*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
|
|
# search for the PE section called ".idata"...
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Am]0xf4 search/0x140 .idata
|
|
# ...and go to the end of it, calculated from start+length;
|
|
# these are located 14 and 10 bytes after the section name
|
|
\*[Gt]\*[Gt]\*[Gt]\*[Gt](\*[Am]0xe.l+(-4)) string PK\e3\e4 \eb, ZIP self-extracting archive
|
|
.Ed
|
|
.Pp
|
|
If you have a list of known values at a particular continuation level,
|
|
and you want to provide a switch-like default case:
|
|
.Bd -literal -offset indent
|
|
# clear that continuation level match
|
|
\*[Gt]18 clear
|
|
\*[Gt]18 lelong 1 one
|
|
\*[Gt]18 lelong 2 two
|
|
\*[Gt]18 default x
|
|
# print default match
|
|
\*[Gt]\*[Gt]18 lelong x unmatched 0x%x
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr file __CSECTION__
|
|
\- the command that reads this file.
|
|
.Sh BUGS
|
|
The formats
|
|
.Dv long ,
|
|
.Dv belong ,
|
|
.Dv lelong ,
|
|
.Dv melong ,
|
|
.Dv short ,
|
|
.Dv beshort ,
|
|
and
|
|
.Dv leshort
|
|
do not depend on the length of the C data types
|
|
.Dv short
|
|
and
|
|
.Dv long
|
|
on the platform, even though the Single
|
|
.Ux
|
|
Specification implies that they do. However, as OS X Mountain Lion has
|
|
passed the Single
|
|
.Ux
|
|
Specification validation suite, and supplies a version of
|
|
.Xr file __CSECTION__
|
|
in which they do not depend on the sizes of the C data types and that is
|
|
built for a 64-bit environment in which
|
|
.Dv long
|
|
is 8 bytes rather than 4 bytes, presumably the validation suite does not
|
|
test whether, for example
|
|
.Dv long
|
|
refers to an item with the same size as the C data type
|
|
.Dv long .
|
|
There should probably be
|
|
.Dv type
|
|
names
|
|
.Dv int8 ,
|
|
.Dv uint8 ,
|
|
.Dv int16 ,
|
|
.Dv uint16 ,
|
|
.Dv int32 ,
|
|
.Dv uint32 ,
|
|
.Dv int64 ,
|
|
and
|
|
.Dv uint64 ,
|
|
and specified-byte-order variants of them,
|
|
to make it clearer that those types have specified widths.
|
|
.\"
|
|
.\" From: guy@sun.uucp (Guy Harris)
|
|
.\" Newsgroups: net.bugs.usg
|
|
.\" Subject: /etc/magic's format isn't well documented
|
|
.\" Message-ID: <2752@sun.uucp>
|
|
.\" Date: 3 Sep 85 08:19:07 GMT
|
|
.\" Organization: Sun Microsystems, Inc.
|
|
.\" Lines: 136
|
|
.\"
|
|
.\" Here's a manual page for the format accepted by the "file" made by adding
|
|
.\" the changes I posted to the S5R2 version.
|
|
.\"
|
|
.\" Modified for Ian Darwin's version of the file command.
|