magic.man 21 KB

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  1. .\" $File: magic.man,v 1.83 2014/06/03 17:36:13 christos Exp $
  2. .Dd June 3, 2014
  3. .Dt MAGIC __FSECTION__
  4. .Os
  5. .\" install as magic.4 on USG, magic.5 on V7, Berkeley and Linux systems.
  6. .Sh NAME
  7. .Nm magic
  8. .Nd file command's magic pattern file
  9. .Sh DESCRIPTION
  10. This manual page documents the format of the magic file as
  11. used by the
  12. .Xr file __CSECTION__
  13. command, version __VERSION__.
  14. The
  15. .Xr file __CSECTION__
  16. command identifies the type of a file using,
  17. among other tests,
  18. a test for whether the file contains certain
  19. .Dq "magic patterns" .
  20. The file
  21. .Pa __MAGIC__
  22. specifies what patterns are to be tested for, what message or
  23. MIME type to print if a particular pattern is found,
  24. and additional information to extract from the file.
  25. .Pp
  26. Each line of the file specifies a test to be performed.
  27. A test compares the data starting at a particular offset
  28. in the file with a byte value, a string or a numeric value.
  29. If the test succeeds, a message is printed.
  30. The line consists of the following fields:
  31. .Bl -tag -width ".Dv message"
  32. .It Dv offset
  33. A number specifying the offset, in bytes, into the file of the data
  34. which is to be tested.
  35. .It Dv type
  36. The type of the data to be tested.
  37. The possible values are:
  38. .Bl -tag -width ".Dv lestring16"
  39. .It Dv byte
  40. A one-byte value.
  41. .It Dv short
  42. A two-byte value in this machine's native byte order.
  43. .It Dv long
  44. A four-byte value in this machine's native byte order.
  45. .It Dv quad
  46. An eight-byte value in this machine's native byte order.
  47. .It Dv float
  48. A 32-bit single precision IEEE floating point number in this machine's native byte order.
  49. .It Dv double
  50. A 64-bit double precision IEEE floating point number in this machine's native byte order.
  51. .It Dv string
  52. A string of bytes.
  53. The string type specification can be optionally followed
  54. by /[WwcCtbT]*.
  55. The
  56. .Dq W
  57. flag compacts whitespace in the target, which must
  58. contain at least one whitespace character.
  59. If the magic has
  60. .Dv n
  61. consecutive blanks, the target needs at least
  62. .Dv n
  63. consecutive blanks to match.
  64. The
  65. .Dq w
  66. flag treats every blank in the magic as an optional blank.
  67. The
  68. .Dq c
  69. flag specifies case insensitive matching: lower case
  70. characters in the magic match both lower and upper case characters in the
  71. target, whereas upper case characters in the magic only match upper case
  72. characters in the target.
  73. The
  74. .Dq C
  75. flag specifies case insensitive matching: upper case
  76. characters in the magic match both lower and upper case characters in the
  77. target, whereas lower case characters in the magic only match upper case
  78. characters in the target.
  79. To do a complete case insensitive match, specify both
  80. .Dq c
  81. and
  82. .Dq C .
  83. The
  84. .Dq t
  85. flag forces the test to be done for text files, while the
  86. .Dq b
  87. flag forces the test to be done for binary files.
  88. The
  89. .Dq T
  90. flag causes the string to be trimmed, i.e. leading and trailing whitespace
  91. is deleted before the string is printed.
  92. .It Dv pstring
  93. A Pascal-style string where the first byte/short/int is interpreted as the
  94. unsigned length.
  95. The length defaults to byte and can be specified as a modifier.
  96. The following modifiers are supported:
  97. .Bl -tag -compact -width B
  98. .It B
  99. A byte length (default).
  100. .It H
  101. A 2 byte big endian length.
  102. .It h
  103. A 2 byte big little length.
  104. .It L
  105. A 4 byte big endian length.
  106. .It l
  107. A 4 byte big little length.
  108. .It J
  109. The length includes itself in its count.
  110. .El
  111. The string is not NUL terminated.
  112. .Dq J
  113. is used rather than the more
  114. valuable
  115. .Dq I
  116. because this type of length is a feature of the JPEG
  117. format.
  118. .It Dv date
  119. A four-byte value interpreted as a UNIX date.
  120. .It Dv qdate
  121. A eight-byte value interpreted as a UNIX date.
  122. .It Dv ldate
  123. A four-byte value interpreted as a UNIX-style date, but interpreted as
  124. local time rather than UTC.
  125. .It Dv qldate
  126. An eight-byte value interpreted as a UNIX-style date, but interpreted as
  127. local time rather than UTC.
  128. .It Dv qwdate
  129. An eight-byte value interpreted as a Windows-style date.
  130. .It Dv beid3
  131. A 32-bit ID3 length in big-endian byte order.
  132. .It Dv beshort
  133. A two-byte value in big-endian byte order.
  134. .It Dv belong
  135. A four-byte value in big-endian byte order.
  136. .It Dv bequad
  137. An eight-byte value in big-endian byte order.
  138. .It Dv befloat
  139. A 32-bit single precision IEEE floating point number in big-endian byte order.
  140. .It Dv bedouble
  141. A 64-bit double precision IEEE floating point number in big-endian byte order.
  142. .It Dv bedate
  143. A four-byte value in big-endian byte order,
  144. interpreted as a Unix date.
  145. .It Dv beqdate
  146. An eight-byte value in big-endian byte order,
  147. interpreted as a Unix date.
  148. .It Dv beldate
  149. A four-byte value in big-endian byte order,
  150. interpreted as a UNIX-style date, but interpreted as local time rather
  151. than UTC.
  152. .It Dv beqldate
  153. An eight-byte value in big-endian byte order,
  154. interpreted as a UNIX-style date, but interpreted as local time rather
  155. than UTC.
  156. .It Dv beqwdate
  157. An eight-byte value in big-endian byte order,
  158. interpreted as a Windows-style date.
  159. .It Dv bestring16
  160. A two-byte unicode (UCS16) string in big-endian byte order.
  161. .It Dv leid3
  162. A 32-bit ID3 length in little-endian byte order.
  163. .It Dv leshort
  164. A two-byte value in little-endian byte order.
  165. .It Dv lelong
  166. A four-byte value in little-endian byte order.
  167. .It Dv lequad
  168. An eight-byte value in little-endian byte order.
  169. .It Dv lefloat
  170. A 32-bit single precision IEEE floating point number in little-endian byte order.
  171. .It Dv ledouble
  172. A 64-bit double precision IEEE floating point number in little-endian byte order.
  173. .It Dv ledate
  174. A four-byte value in little-endian byte order,
  175. interpreted as a UNIX date.
  176. .It Dv leqdate
  177. An eight-byte value in little-endian byte order,
  178. interpreted as a UNIX date.
  179. .It Dv leldate
  180. A four-byte value in little-endian byte order,
  181. interpreted as a UNIX-style date, but interpreted as local time rather
  182. than UTC.
  183. .It Dv leqldate
  184. An eight-byte value in little-endian byte order,
  185. interpreted as a UNIX-style date, but interpreted as local time rather
  186. than UTC.
  187. .It Dv leqwdate
  188. An eight-byte value in little-endian byte order,
  189. interpreted as a Windows-style date.
  190. .It Dv lestring16
  191. A two-byte unicode (UCS16) string in little-endian byte order.
  192. .It Dv melong
  193. A four-byte value in middle-endian (PDP-11) byte order.
  194. .It Dv medate
  195. A four-byte value in middle-endian (PDP-11) byte order,
  196. interpreted as a UNIX date.
  197. .It Dv meldate
  198. A four-byte value in middle-endian (PDP-11) byte order,
  199. interpreted as a UNIX-style date, but interpreted as local time rather
  200. than UTC.
  201. .It Dv indirect
  202. Starting at the given offset, consult the magic database again.
  203. .It Dv name
  204. Define a
  205. .Dq named
  206. magic instance that can be called from another
  207. .Dv use
  208. magic entry, like a subroutine call.
  209. Named instance direct magic offsets are relative to the offset of the
  210. previous matched entry, but indirect offsets are relative to the beginning
  211. of the file as usual.
  212. Named magic entries always match.
  213. .It Dv use
  214. Recursively call the named magic starting from the current offset.
  215. If the name of the referenced begins with a
  216. .Dv ^
  217. then the endianness of the magic is switched; if the magic mentioned
  218. .Dv leshort
  219. for example,
  220. it is treated as
  221. .Dv beshort
  222. and vice versa.
  223. This is useful to avoid duplicating the rules for different endianness.
  224. .It Dv regex
  225. A regular expression match in extended POSIX regular expression syntax
  226. (like egrep).
  227. Regular expressions can take exponential time to process, and their
  228. performance is hard to predict, so their use is discouraged.
  229. When used in production environments, their performance
  230. should be carefully checked.
  231. The size of the string to search should also be limited by specifying
  232. .Dv /<length> ,
  233. to avoid performance issues scanning long files.
  234. The type specification can also be optionally followed by
  235. .Dv /[c][s][l] .
  236. The
  237. .Dq c
  238. flag makes the match case insensitive, while the
  239. .Dq s
  240. flag update the offset to the start offset of the match, rather than the end.
  241. The
  242. .Dq l
  243. modifier, changes the limit of length to mean number of lines instead of a
  244. byte count.
  245. Lines are delimited by the platforms native line delimiter.
  246. When a line count is specified, an implicit byte count also computed assuming
  247. each line is 80 characters long.
  248. If neither a byte or line count is specified, the search is limited automatically
  249. to 8KiB.
  250. .Dv ^
  251. and
  252. .Dv $
  253. match the beginning and end of individual lines, respectively,
  254. not beginning and end of file.
  255. .It Dv search
  256. A literal string search starting at the given offset.
  257. The same modifier flags can be used as for string patterns.
  258. The search expression must contain the range in the form
  259. .Dv /number,
  260. that is the number of positions at which the match will be
  261. attempted, starting from the start offset.
  262. This is suitable for
  263. searching larger binary expressions with variable offsets, using
  264. .Dv \e
  265. escapes for special characters.
  266. The order of modifier and number is not relevant.
  267. .It Dv default
  268. This is intended to be used with the test
  269. .Em x
  270. (which is always true) and it has no type.
  271. It matches when no other test at that continuation level has matched before.
  272. Clearing that matched tests for a continuation level, can be done using the
  273. .Dv clear
  274. test.
  275. .It Dv clear
  276. This test is always true and clears the match flag for that continuation level.
  277. It is intended to be used with the
  278. .Dv default
  279. test.
  280. .El
  281. .Pp
  282. For compatibility with the Single
  283. .Ux
  284. Standard, the type specifiers
  285. .Dv dC
  286. and
  287. .Dv d1
  288. are equivalent to
  289. .Dv byte ,
  290. the type specifiers
  291. .Dv uC
  292. and
  293. .Dv u1
  294. are equivalent to
  295. .Dv ubyte ,
  296. the type specifiers
  297. .Dv dS
  298. and
  299. .Dv d2
  300. are equivalent to
  301. .Dv short ,
  302. the type specifiers
  303. .Dv uS
  304. and
  305. .Dv u2
  306. are equivalent to
  307. .Dv ushort ,
  308. the type specifiers
  309. .Dv dI ,
  310. .Dv dL ,
  311. and
  312. .Dv d4
  313. are equivalent to
  314. .Dv long ,
  315. the type specifiers
  316. .Dv uI ,
  317. .Dv uL ,
  318. and
  319. .Dv u4
  320. are equivalent to
  321. .Dv ulong ,
  322. the type specifier
  323. .Dv d8
  324. is equivalent to
  325. .Dv quad ,
  326. the type specifier
  327. .Dv u8
  328. is equivalent to
  329. .Dv uquad ,
  330. and the type specifier
  331. .Dv s
  332. is equivalent to
  333. .Dv string .
  334. In addition, the type specifier
  335. .Dv dQ
  336. is equivalent to
  337. .Dv quad
  338. and the type specifier
  339. .Dv uQ
  340. is equivalent to
  341. .Dv uquad .
  342. .Pp
  343. Each top-level magic pattern (see below for an explanation of levels)
  344. is classified as text or binary according to the types used.
  345. Types
  346. .Dq regex
  347. and
  348. .Dq search
  349. are classified as text tests, unless non-printable characters are used
  350. in the pattern.
  351. All other tests are classified as binary.
  352. A top-level
  353. pattern is considered to be a test text when all its patterns are text
  354. patterns; otherwise, it is considered to be a binary pattern.
  355. When
  356. matching a file, binary patterns are tried first; if no match is
  357. found, and the file looks like text, then its encoding is determined
  358. and the text patterns are tried.
  359. .Pp
  360. The numeric types may optionally be followed by
  361. .Dv \*[Am]
  362. and a numeric value,
  363. to specify that the value is to be AND'ed with the
  364. numeric value before any comparisons are done.
  365. Prepending a
  366. .Dv u
  367. to the type indicates that ordered comparisons should be unsigned.
  368. .It Dv test
  369. The value to be compared with the value from the file.
  370. If the type is
  371. numeric, this value
  372. is specified in C form; if it is a string, it is specified as a C string
  373. with the usual escapes permitted (e.g. \en for new-line).
  374. .Pp
  375. Numeric values
  376. may be preceded by a character indicating the operation to be performed.
  377. It may be
  378. .Dv = ,
  379. to specify that the value from the file must equal the specified value,
  380. .Dv \*[Lt] ,
  381. to specify that the value from the file must be less than the specified
  382. value,
  383. .Dv \*[Gt] ,
  384. to specify that the value from the file must be greater than the specified
  385. value,
  386. .Dv \*[Am] ,
  387. to specify that the value from the file must have set all of the bits
  388. that are set in the specified value,
  389. .Dv ^ ,
  390. to specify that the value from the file must have clear any of the bits
  391. that are set in the specified value, or
  392. .Dv ~ ,
  393. the value specified after is negated before tested.
  394. .Dv x ,
  395. to specify that any value will match.
  396. If the character is omitted, it is assumed to be
  397. .Dv = .
  398. Operators
  399. .Dv \*[Am] ,
  400. .Dv ^ ,
  401. and
  402. .Dv ~
  403. don't work with floats and doubles.
  404. The operator
  405. .Dv !\&
  406. specifies that the line matches if the test does
  407. .Em not
  408. succeed.
  409. .Pp
  410. Numeric values are specified in C form; e.g.
  411. .Dv 13
  412. is decimal,
  413. .Dv 013
  414. is octal, and
  415. .Dv 0x13
  416. is hexadecimal.
  417. .Pp
  418. Numeric operations are not performed on date types, instead the numeric
  419. value is interpreted as an offset.
  420. .Pp
  421. For string values, the string from the
  422. file must match the specified string.
  423. The operators
  424. .Dv = ,
  425. .Dv \*[Lt]
  426. and
  427. .Dv \*[Gt]
  428. (but not
  429. .Dv \*[Am] )
  430. can be applied to strings.
  431. The length used for matching is that of the string argument
  432. in the magic file.
  433. This means that a line can match any non-empty string (usually used to
  434. then print the string), with
  435. .Em \*[Gt]\e0
  436. (because all non-empty strings are greater than the empty string).
  437. .Pp
  438. Dates are treated as numerical values in the respective internal
  439. representation.
  440. .Pp
  441. The special test
  442. .Em x
  443. always evaluates to true.
  444. .It Dv message
  445. The message to be printed if the comparison succeeds.
  446. If the string contains a
  447. .Xr printf 3
  448. format specification, the value from the file (with any specified masking
  449. performed) is printed using the message as the format string.
  450. If the string begins with
  451. .Dq \eb ,
  452. the message printed is the remainder of the string with no whitespace
  453. added before it: multiple matches are normally separated by a single
  454. space.
  455. .El
  456. .Pp
  457. An APPLE 4+4 character APPLE creator and type can be specified as:
  458. .Bd -literal -offset indent
  459. !:apple CREATYPE
  460. .Ed
  461. .Pp
  462. A MIME type is given on a separate line, which must be the next
  463. non-blank or comment line after the magic line that identifies the
  464. file type, and has the following format:
  465. .Bd -literal -offset indent
  466. !:mime MIMETYPE
  467. .Ed
  468. .Pp
  469. i.e. the literal string
  470. .Dq !:mime
  471. followed by the MIME type.
  472. .Pp
  473. An optional strength can be supplied on a separate line which refers to
  474. the current magic description using the following format:
  475. .Bd -literal -offset indent
  476. !:strength OP VALUE
  477. .Ed
  478. .Pp
  479. The operand
  480. .Dv OP
  481. can be:
  482. .Dv + ,
  483. .Dv - ,
  484. .Dv * ,
  485. or
  486. .Dv /
  487. and
  488. .Dv VALUE
  489. is a constant between 0 and 255.
  490. This constant is applied using the specified operand
  491. to the currently computed default magic strength.
  492. .Pp
  493. Some file formats contain additional information which is to be printed
  494. along with the file type or need additional tests to determine the true
  495. file type.
  496. These additional tests are introduced by one or more
  497. .Em \*[Gt]
  498. characters preceding the offset.
  499. The number of
  500. .Em \*[Gt]
  501. on the line indicates the level of the test; a line with no
  502. .Em \*[Gt]
  503. at the beginning is considered to be at level 0.
  504. Tests are arranged in a tree-like hierarchy:
  505. if the test on a line at level
  506. .Em n
  507. succeeds, all following tests at level
  508. .Em n+1
  509. are performed, and the messages printed if the tests succeed, until a line
  510. with level
  511. .Em n
  512. (or less) appears.
  513. For more complex files, one can use empty messages to get just the
  514. "if/then" effect, in the following way:
  515. .Bd -literal -offset indent
  516. 0 string MZ
  517. \*[Gt]0x18 leshort \*[Lt]0x40 MS-DOS executable
  518. \*[Gt]0x18 leshort \*[Gt]0x3f extended PC executable (e.g., MS Windows)
  519. .Ed
  520. .Pp
  521. Offsets do not need to be constant, but can also be read from the file
  522. being examined.
  523. If the first character following the last
  524. .Em \*[Gt]
  525. is a
  526. .Em \&(
  527. then the string after the parenthesis is interpreted as an indirect offset.
  528. That means that the number after the parenthesis is used as an offset in
  529. the file.
  530. The value at that offset is read, and is used again as an offset
  531. in the file.
  532. Indirect offsets are of the form:
  533. .Em (( x [.[bislBISL]][+\-][ y ]) .
  534. The value of
  535. .Em x
  536. is used as an offset in the file.
  537. A byte, id3 length, short or long is read at that offset depending on the
  538. .Em [bislBISLm]
  539. type specifier.
  540. The capitalized types interpret the number as a big endian
  541. value, whereas the small letter versions interpret the number as a little
  542. endian value;
  543. the
  544. .Em m
  545. type interprets the number as a middle endian (PDP-11) value.
  546. To that number the value of
  547. .Em y
  548. is added and the result is used as an offset in the file.
  549. The default type if one is not specified is long.
  550. .Pp
  551. That way variable length structures can be examined:
  552. .Bd -literal -offset indent
  553. # MS Windows executables are also valid MS-DOS executables
  554. 0 string MZ
  555. \*[Gt]0x18 leshort \*[Lt]0x40 MZ executable (MS-DOS)
  556. # skip the whole block below if it is not an extended executable
  557. \*[Gt]0x18 leshort \*[Gt]0x3f
  558. \*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
  559. \*[Gt]\*[Gt](0x3c.l) string LX\e0\e0 LX executable (OS/2)
  560. .Ed
  561. .Pp
  562. This strategy of examining has a drawback: You must make sure that
  563. you eventually print something, or users may get empty output (like, when
  564. there is neither PE\e0\e0 nor LE\e0\e0 in the above example)
  565. .Pp
  566. If this indirect offset cannot be used directly, simple calculations are
  567. possible: appending
  568. .Em [+-*/%\*[Am]|^]number
  569. inside parentheses allows one to modify
  570. the value read from the file before it is used as an offset:
  571. .Bd -literal -offset indent
  572. # MS Windows executables are also valid MS-DOS executables
  573. 0 string MZ
  574. # sometimes, the value at 0x18 is less that 0x40 but there's still an
  575. # extended executable, simply appended to the file
  576. \*[Gt]0x18 leshort \*[Lt]0x40
  577. \*[Gt]\*[Gt](4.s*512) leshort 0x014c COFF executable (MS-DOS, DJGPP)
  578. \*[Gt]\*[Gt](4.s*512) leshort !0x014c MZ executable (MS-DOS)
  579. .Ed
  580. .Pp
  581. Sometimes you do not know the exact offset as this depends on the length or
  582. position (when indirection was used before) of preceding fields.
  583. You can specify an offset relative to the end of the last up-level
  584. field using
  585. .Sq \*[Am]
  586. as a prefix to the offset:
  587. .Bd -literal -offset indent
  588. 0 string MZ
  589. \*[Gt]0x18 leshort \*[Gt]0x3f
  590. \*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
  591. # immediately following the PE signature is the CPU type
  592. \*[Gt]\*[Gt]\*[Gt]\*[Am]0 leshort 0x14c for Intel 80386
  593. \*[Gt]\*[Gt]\*[Gt]\*[Am]0 leshort 0x184 for DEC Alpha
  594. .Ed
  595. .Pp
  596. Indirect and relative offsets can be combined:
  597. .Bd -literal -offset indent
  598. 0 string MZ
  599. \*[Gt]0x18 leshort \*[Lt]0x40
  600. \*[Gt]\*[Gt](4.s*512) leshort !0x014c MZ executable (MS-DOS)
  601. # if it's not COFF, go back 512 bytes and add the offset taken
  602. # from byte 2/3, which is yet another way of finding the start
  603. # of the extended executable
  604. \*[Gt]\*[Gt]\*[Gt]\*[Am](2.s-514) string LE LE executable (MS Windows VxD driver)
  605. .Ed
  606. .Pp
  607. Or the other way around:
  608. .Bd -literal -offset indent
  609. 0 string MZ
  610. \*[Gt]0x18 leshort \*[Gt]0x3f
  611. \*[Gt]\*[Gt](0x3c.l) string LE\e0\e0 LE executable (MS-Windows)
  612. # at offset 0x80 (-4, since relative offsets start at the end
  613. # of the up-level match) inside the LE header, we find the absolute
  614. # offset to the code area, where we look for a specific signature
  615. \*[Gt]\*[Gt]\*[Gt](\*[Am]0x7c.l+0x26) string UPX \eb, UPX compressed
  616. .Ed
  617. .Pp
  618. Or even both!
  619. .Bd -literal -offset indent
  620. 0 string MZ
  621. \*[Gt]0x18 leshort \*[Gt]0x3f
  622. \*[Gt]\*[Gt](0x3c.l) string LE\e0\e0 LE executable (MS-Windows)
  623. # at offset 0x58 inside the LE header, we find the relative offset
  624. # to a data area where we look for a specific signature
  625. \*[Gt]\*[Gt]\*[Gt]\*[Am](\*[Am]0x54.l-3) string UNACE \eb, ACE self-extracting archive
  626. .Ed
  627. .Pp
  628. If you have to deal with offset/length pairs in your file, even the
  629. second value in a parenthesized expression can be taken from the file itself,
  630. using another set of parentheses.
  631. Note that this additional indirect offset is always relative to the
  632. start of the main indirect offset.
  633. .Bd -literal -offset indent
  634. 0 string MZ
  635. \*[Gt]0x18 leshort \*[Gt]0x3f
  636. \*[Gt]\*[Gt](0x3c.l) string PE\e0\e0 PE executable (MS-Windows)
  637. # search for the PE section called ".idata"...
  638. \*[Gt]\*[Gt]\*[Gt]\*[Am]0xf4 search/0x140 .idata
  639. # ...and go to the end of it, calculated from start+length;
  640. # these are located 14 and 10 bytes after the section name
  641. \*[Gt]\*[Gt]\*[Gt]\*[Gt](\*[Am]0xe.l+(-4)) string PK\e3\e4 \eb, ZIP self-extracting archive
  642. .Ed
  643. .Pp
  644. If you have a list of known avalues at a particular continuation level,
  645. and you want to provide a switch-like default case:
  646. .Bd -literal -offset indent
  647. # clear that continuation level match
  648. \*[Gt]18 clear
  649. \*[Gt]18 lelong 1 one
  650. \*[Gt]18 lelong 2 two
  651. \*[Gt]18 default x
  652. # print default match
  653. \*[Gt]\*[Gt]18 lelong x unmatched 0x%x
  654. .Ed
  655. .Sh SEE ALSO
  656. .Xr file __CSECTION__
  657. \- the command that reads this file.
  658. .Sh BUGS
  659. The formats
  660. .Dv long ,
  661. .Dv belong ,
  662. .Dv lelong ,
  663. .Dv melong ,
  664. .Dv short ,
  665. .Dv beshort ,
  666. and
  667. .Dv leshort
  668. do not depend on the length of the C data types
  669. .Dv short
  670. and
  671. .Dv long
  672. on the platform, even though the Single
  673. .Ux
  674. Specification implies that they do. However, as OS X Mountain Lion has
  675. passed the Single
  676. .Ux
  677. Specification validation suite, and supplies a version of
  678. .Xr file __CSECTION__
  679. in which they do not depend on the sizes of the C data types and that is
  680. built for a 64-bit environment in which
  681. .Dv long
  682. is 8 bytes rather than 4 bytes, presumably the validation suite does not
  683. test whether, for example
  684. .Dv long
  685. refers to an item with the same size as the C data type
  686. .Dv long .
  687. There should probably be
  688. .Dv type
  689. names
  690. .Dv int8 ,
  691. .Dv uint8 ,
  692. .Dv int16 ,
  693. .Dv uint16 ,
  694. .Dv int32 ,
  695. .Dv uint32 ,
  696. .Dv int64 ,
  697. and
  698. .Dv uint64 ,
  699. and specified-byte-order variants of them,
  700. to make it clearer that those types have specified widths.
  701. .\"
  702. .\" From: guy@sun.uucp (Guy Harris)
  703. .\" Newsgroups: net.bugs.usg
  704. .\" Subject: /etc/magic's format isn't well documented
  705. .\" Message-ID: <2752@sun.uucp>
  706. .\" Date: 3 Sep 85 08:19:07 GMT
  707. .\" Organization: Sun Microsystems, Inc.
  708. .\" Lines: 136
  709. .\"
  710. .\" Here's a manual page for the format accepted by the "file" made by adding
  711. .\" the changes I posted to the S5R2 version.
  712. .\"
  713. .\" Modified for Ian Darwin's version of the file command.