Virgin import of Christos Zoulas's FILE 4.17.

1 files changed, 197 insertions, 40 deletions

diff --git a/contrib/file/magic.man b/contrib/file/magic.man
index 6917bc0..73b6a3d 100644
--- a/contrib/file/magic.man
+++ b/contrib/file/magic.man
@@ -54,6 +54,9 @@ Finally the ``c'' flag, specifies case insensitive matching: lowercase
 characters in the magic match both lower and upper case characters in the
 targer, whereas upper case characters in the magic, only much uppercase
 characters in the target.
+.IP pstring
+A pascal style string where the first byte is interpreted as the an
+unsigned length. The string is not NUL terminated.
 .IP date
 A four-byte value interpreted as a UNIX date.
 .IP ldate
@@ -66,6 +69,12 @@ A four-byte value (on most systems) in big-endian byte order.
 .IP bedate
 A four-byte value (on most systems) in big-endian byte order,
 interpreted as a Unix date.
+.IP beldate
+A four-byte value (on most systems) in big-endian byte order,
+interpreted as a UNIX-style date, but interpreted as local time rather
+than UTC.
+.IP bestring16
+A two-byte unicode (UCS16) string in big-endian byte order.
 .IP leshort
 A two-byte value (on most systems) in little-endian byte order.
 .IP lelong
@@ -77,6 +86,43 @@ interpreted as a UNIX date.
 A four-byte value (on most systems) in little-endian byte order,
 interpreted as a UNIX-style date, but interpreted as local time rather
 than UTC.
+.IP lestring16
+A two-byte unicode (UCS16) string in little-endian byte order.
+.IP melong
+A four-byte value (on most systems) in middle-endian (PDP-11) byte order.
+.IP medate
+A four-byte value (on most systems) in middle-endian (PDP-11) byte order,
+interpreted as a UNIX date.
+.IP meldate
+A four-byte value (on most systems) in middle-endian (PDP-11) byte order,
+interpreted as a UNIX-style date, but interpreted as local time rather
+than UTC.
+.IP regex
+A regular expression match in extended POSIX regular expression syntax
+(much like egrep).
+The type specification can be optionally followed by
+.B /c
+for case-insensitive matches.
+The regular expression is always
+tested against the first
+.B N
+lines, where
+.B N
+is the given offset, thus it
+is only useful for (single-byte encoded) text.
+.B ^
+and
+.B $
+will match the beginning and end of individual lines, respectively,
+not beginning and end of file.
+.IP search
+A literal string search starting at the given offset. It must be followed by
+.B /<number>
+which specifies how many matches shall be attempted (the range).
+This is suitable for searching larger binary expressions with variable
+offsets, using
+.B \e
+escapes for special characters.
 .RE
 .PP
 The numeric types may optionally be followed by
@@ -106,15 +152,26 @@ value,
 to specify that the value from the file must be greater than the specified
 value,
 .BR & ,
-to specify that the value from the file must have set all of the bits 
+to specify that the value from the file must have set all of the bits
 that are set in the specified value,
 .BR ^ ,
-to specify that the value from the file must have clear any of the bits 
+to specify that the value from the file must have clear any of the bits
 that are set in the specified value, or
+.BR ~ ,
+the value specified after is negated before tested.
 .BR x ,
 to specify that any value will match.
 If the character is omitted, it is assumed to be
 .BR = .
+For all tests except
+.B string
+and
+.B regex,
+operation
+.BR !
+specifies that the line matches if the test does
+.B not
+succeed.
 .IP
 Numeric values are specified in C form; e.g.
 .B 13
@@ -125,7 +182,7 @@ is octal, and
 is hexadecimal.
 .IP
 For string values, the byte string from the
-file must match the specified byte string. 
+file must match the specified byte string.
 The operators
 .BR = ,
 .B <
@@ -148,28 +205,36 @@ format specification, the value from the file (with any specified masking
 performed) is printed using the message as the format string.
 .PP
 Some file formats contain additional information which is to be printed
-along with the file type.
-A line which begins with the character
+along with the file type or need additional tests to determine the true
+file type.
+These additional tests are introduced by one or more
 .B >
-indicates additional tests and messages to be printed.
+characters preceding the offset.
 The number of
 .B >
 on the line indicates the level of the test; a line with no
 .B >
 at the beginning is considered to be at level 0.
-Each line at level
-.IB n \(pl1
-is under the control of the line at level
+Tests are arranged in a tree-like hierarchy:
+If a the test on a line at level
 .IB n
-most closely preceding it in the magic file.
-If the test on a line at level
-.I n
-succeeds, the tests specified in all the subsequent lines at level
-.IB n \(pl1
-are performed, and the messages printed if the tests succeed.
-The next line at level
-.I n
-terminates this.
+succeeds, all following tests at level
+.IB n+1
+are performed, and the messages printed if the tests succeed, untile a line
+with level
+.IB n
+(or less) appears.
+For more complex files, one can use empty messages to get just the
+"if/then" effect, in the following way:
+.sp
+.nf
+    0      string   MZ
+    >0x18  leshort  <0x40   MS-DOS executable
+    >0x18  leshort  >0x3f   extended PC executable (e.g., MS Windows)
+.fi
+.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
 .B >
 is a
@@ -181,49 +246,141 @@ The value at that offset is read, and is used again as an offset
 in the file.
 Indirect offsets are of the form:
 .BI (( x [.[bslBSL]][+\-][ y ]).
-The value of 
+The value of
 .I x
 is used as an offset in the file. A byte, short or long is read at that offset
-depending on the 
-.B [bslBSL] 
+depending on the
+.B [bslBSLm]
 type specifier.
 The capitalized types interpret the number as a big endian
 value, whereas the small letter versions interpret the number as a little
-endian value.
+endian value;
+the
+.B m
+type interprets the number as a middle endian (PDP-11) value.
 To that number the value of
 .I y
 is added and the result is used as an offset in the file.
 The default type if one is not specified is long.
 .PP
-Sometimes you do not know the exact offset as this depends on the length of
-preceding fields.
-You can specify an offset relative to the end of the
-last uplevel field (of course this may only be done for sublevel tests, i.e.
-test beginning with 
-.B >
-).
-Such a relative offset is specified using
-.B &
-as a prefix to the offset.
+That way variable length structures can be examined:
+.sp
+.nf
+    # MS Windows executables are also valid MS-DOS executables
+    0           string  MZ
+    >0x18       leshort <0x40   MZ executable (MS-DOS)
+    # skip the whole block below if it is not an extended executable
+    >0x18       leshort >0x3f
+    >>(0x3c.l)  string  PE\e0\e0  PE executable (MS-Windows)
+    >>(0x3c.l)  string  LX\e0\e0  LX executable (OS/2)
+.fi
+.PP
+This strategy of examining has one drawback: You must make sure that
+you eventually print something, or users may get empty output (like, when
+there is neither PE\e0\e0 nor LE\e0\e0 in the above example)
+.PP
+If this indirect offset cannot be used as-is, there are simple calculations
+possible: appending
+.BI [+-*/%&|^]<number>
+inside parentheses allows one to modify
+the value read from the file before it is used as an offset:
+.sp
+.nf
+    # 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
+    >0x18       leshort <0x40
+    >>(4.s*512) leshort 0x014c  COFF executable (MS-DOS, DJGPP)
+    >>(4.s*512) leshort !0x014c MZ executable (MS-DOS)
+.fi
+.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 uplevel field using
+.BI &
+as a prefix to the offset:
+.sp
+.nf
+    0           string  MZ
+    >0x18       leshort >0x3f
+    >>(0x3c.l)  string  PE\e0\e0    PE executable (MS-Windows)
+    # immediately following the PE signature is the CPU type
+    >>>&0       leshort 0x14c     for Intel 80386
+    >>>&0       leshort 0x184     for DEC Alpha
+.fi
+.PP
+Indirect and relative offsets can be combined:
+.sp
+.nf
+    0             string  MZ
+    >0x18         leshort <0x40
+    >>(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
+    >>>&(2.s-514) string  LE      LE executable (MS Windows VxD driver)
+.fi
+.PP
+Or the other way around:
+.sp
+.nf
+    0                 string  MZ
+    >0x18             leshort >0x3f
+    >>(0x3c.l)        string  LE\e0\e0  LE executable (MS-Windows)
+    # at offset 0x80 (-4, since relative offsets start at the end
+    # of the uplevel match) inside the LE header, we find the absolute
+    # offset to the code area, where we look for a specific signature
+    >>>(&0x7c.l+0x26) string  UPX     \eb, UPX compressed
+.fi
+.PP
+Or even both!
+.sp
+.nf
+    0                string  MZ
+    >0x18            leshort >0x3f
+    >>(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
+    >>>&(&0x54.l-3)  string  UNACE  \eb, ACE self-extracting archive
+.fi
+.PP
+Finally, if you have to deal with offset/length pairs in your file, even the
+second value in a parenthesed 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.
+.sp
+.nf
+    0                 string       MZ
+    >0x18             leshort      >0x3f
+    >>(0x3c.l)        string       PE\e0\e0 PE executable (MS-Windows)
+    # search for the PE section called ".idata"...
+    >>>&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
+    >>>>(&0xe.l+(-4)) string       PK\e3\e4 \eb, ZIP self-extracting archive
+.fi
 .SH BUGS
-The formats 
+The formats
 .IR long ,
 .IR belong ,
 .IR lelong ,
+.IR melong ,
 .IR short ,
 .IR beshort ,
 .IR leshort ,
 .IR date ,
 .IR bedate ,
+.IR medate ,
+.IR ledate ,
+.IR beldate ,
+.IR leldate ,
 and
-.I ledate
+.I meldate
 are system-dependent; perhaps they should be specified as a number
-of bytes (2B, 4B, etc), 
+of bytes (2B, 4B, etc),
 since the files being recognized typically come from
 a system on which the lengths are invariant.
-.PP
-There is (currently) no support for specified-endian data to be used in
-indirect offsets.
 .SH SEE ALSO
 .BR file (__CSECTION__)
 \- the command that reads this file.
@@ -235,9 +392,9 @@ indirect offsets.
 .\" 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.
-.\" @(#)$Id: magic.man,v 1.27 2003/09/12 19:43:30 christos Exp $
+.\" @(#)$Id: magic.man,v 1.30 2006/02/19 18:16:03 christos Exp $