libmagic.man 7.1 KB

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  1. .\"
  2. .\" Copyright (c) Christos Zoulas 2003.
  3. .\" All Rights Reserved.
  4. .\"
  5. .\" Redistribution and use in source and binary forms, with or without
  6. .\" modification, are permitted provided that the following conditions
  7. .\" are met:
  8. .\" 1. Redistributions of source code must retain the above copyright
  9. .\" notice immediately at the beginning of the file, without modification,
  10. .\" this list of conditions, and the following disclaimer.
  11. .\" 2. Redistributions in binary form must reproduce the above copyright
  12. .\" notice, this list of conditions and the following disclaimer in the
  13. .\" documentation and/or other materials provided with the distribution.
  14. .\"
  15. .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  16. .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  17. .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  18. .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
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  26. .\"
  27. .Dd November 15, 2006
  28. .Dt MAGIC 3
  29. .Os
  30. .Sh NAME
  31. .Nm magic_open ,
  32. .Nm magic_close ,
  33. .Nm magic_error ,
  34. .Nm magic_file ,
  35. .Nm magic_buffer ,
  36. .Nm magic_setflags ,
  37. .Nm magic_check ,
  38. .Nm magic_compile ,
  39. .Nm magic_load
  40. .Nd Magic number recognition library.
  41. .Sh LIBRARY
  42. .Lb libmagic
  43. .Sh SYNOPSIS
  44. .In magic.h
  45. .Ft magic_t
  46. .Fn magic_open "int flags"
  47. .Ft void
  48. .Fn magic_close "magic_t cookie"
  49. .Ft const char *
  50. .Fn magic_error "magic_t cookie"
  51. .Ft int
  52. .Fn magic_errno "magic_t cookie"
  53. .Ft const char *
  54. .Fn magic_file "magic_t cookie, const char *filename"
  55. .Ft const char *
  56. .Fn magic_buffer "magic_t cookie, const void *buffer, size_t length"
  57. .Ft int
  58. .Fn magic_setflags "magic_t cookie, int flags"
  59. .Ft int
  60. .Fn magic_check "magic_t cookie, const char *filename"
  61. .Ft int
  62. .Fn magic_compile "magic_t cookie, const char *filename"
  63. .Ft int
  64. .Fn magic_load "magic_t cookie, const char *filename"
  65. .Sh DESCRIPTION
  66. These functions
  67. operate on the magic database file
  68. which is described
  69. in
  70. .Xr magic __FSECTION__ .
  71. .Pp
  72. The function
  73. .Fn magic_open
  74. creates a magic cookie pointer and returns it. It returns NULL if
  75. there was an error allocating the magic cookie. The
  76. .Ar flags
  77. argument specifies how the other magic functions should behave:
  78. .Bl -tag -width MAGIC_COMPRESS
  79. .It Dv MAGIC_NONE
  80. No special handling.
  81. .It Dv MAGIC_DEBUG
  82. Print debugging messages to stderr.
  83. .It Dv MAGIC_SYMLINK
  84. If the file queried is a symlink, follow it.
  85. .It Dv MAGIC_COMPRESS
  86. If the file is compressed, unpack it and look at the contents.
  87. .It Dv MAGIC_DEVICES
  88. If the file is a block or character special device, then open the device
  89. and try to look in its contents.
  90. .It Dv MAGIC_MIME
  91. Return a mime string, instead of a textual description.
  92. .It Dv MAGIC_CONTINUE
  93. Return all matches, not just the first.
  94. .It Dv MAGIC_CHECK
  95. Check the magic database for consistency and print warnings to stderr.
  96. .It Dv MAGIC_PRESERVE_ATIME
  97. On systems that support
  98. .Xr utime 2
  99. or
  100. .Xr utimes 2 ,
  101. attempt to preserve the access time of files analyzed.
  102. .It Dv MAGIC_RAW
  103. Don't translate unprintable characters to a \eooo octal representation.
  104. .It Dv MAGIC_ERROR
  105. Treat operating system errors while trying to open files and follow symlinks
  106. as real errors, instead of printing them in the magic buffer.
  107. .It Dv MAGIC_NO_CHECK_APPTYPE
  108. Check for
  109. .Dv EMX
  110. application type (only on EMX).
  111. .It Dv MAGIC_NO_CHECK_ASCII
  112. Check for various types of ascii files.
  113. .It Dv MAGIC_NO_CHECK_COMPRESS
  114. Don't look for, or inside compressed files.
  115. .It Dv MAGIC_NO_CHECK_ELF
  116. Don't print elf details.
  117. .It Dv MAGIC_NO_CHECK_FORTRAN
  118. Don't look for fortran sequences inside ascii files.
  119. .It Dv MAGIC_NO_CHECK_SOFT
  120. Don't consult magic files.
  121. .It Dv MAGIC_NO_CHECK_TAR
  122. Don't examine tar files.
  123. .It Dv MAGIC_NO_CHECK_TOKENS
  124. Don't look for known tokens inside ascii files.
  125. .It Dv MAGIC_NO_CHECK_TROFF
  126. Don't look for troff sequences inside ascii files.
  127. .El
  128. .Pp
  129. The
  130. .Fn magic_close
  131. function closes the
  132. .Xr magic __FSECTION__
  133. database and deallocates any resources used.
  134. .Pp
  135. The
  136. .Fn magic_error
  137. function returns a textual explanation of the last error, or NULL if there was
  138. no error.
  139. .Pp
  140. The
  141. .Fn magic_errno
  142. function returns the last operating system error number
  143. .Pq Xr errno 2
  144. that was encountered by a system call.
  145. .Pp
  146. The
  147. .Fn magic_file
  148. function returns a textual description of the contents of the
  149. .Ar filename
  150. argument, or NULL if an error occurred.
  151. If the
  152. .Ar filename
  153. is NULL, then stdin is used.
  154. .Pp
  155. The
  156. .Fn magic_buffer
  157. function returns a textual description of the contents of the
  158. .Ar buffer
  159. argument with
  160. .Ar length
  161. bytes size.
  162. .Pp
  163. The
  164. .Fn magic_setflags
  165. function, sets the
  166. .Ar flags
  167. described above.
  168. .Pp
  169. The
  170. .Fn magic_check
  171. function can be used to check the validity of entries in the colon
  172. separated database files passed in as
  173. .Ar filename ,
  174. or NULL for the default database. It returns 0 on success and -1 on
  175. failure.
  176. .Pp
  177. The
  178. .Fn magic_compile
  179. function can be used to compile the the colon
  180. separated list of database files passed in as
  181. .Ar filename ,
  182. or NULL for the default database. It returns 0 on success and -1 on
  183. failure. The compiled files created are named from the
  184. .Xr basename 1
  185. of each file argument with ".mgc" appended to it.
  186. .Pp
  187. The
  188. .Fn magic_load
  189. function must be used to load the the colon
  190. separated list of database files passed in as
  191. .Ar filename ,
  192. or NULL for the default database file
  193. before any magic queries can performed.
  194. .Pp
  195. The default database file is named by the MAGIC environment variable. If
  196. that variable is not set, the default database file name is __MAGIC__.
  197. .Pp
  198. .Fn magic_load
  199. adds ".mime" and/or ".mgc" to the database filename as appropriate.
  200. .Sh RETURN VALUES
  201. The function
  202. .Fn magic_open
  203. returns a magic cookie on success and NULL on failure setting errno to
  204. an appropriate value. It will set errno to EINVAL if an unsupported
  205. value for flags was given.
  206. The
  207. .Fn magic_load ,
  208. .Fn magic_compile ,
  209. and
  210. .Fn magic_check
  211. functions return 0 on success and -1 on failure.
  212. The
  213. .Fn magic_file ,
  214. and
  215. .Fn magic_buffer
  216. functions return a string on success and NULL on failure. The
  217. .Fn magic_error
  218. function returns a textual description of the errors of the above
  219. functions, or NULL if there was no error.
  220. Finally,
  221. .Fn magic_setflags
  222. returns -1 on systems that don't support
  223. .Xr utime 2 ,
  224. or
  225. .Xr utimes 2
  226. when
  227. .Dv MAGIC_PRESERVE_ATIME
  228. is set.
  229. .Sh FILES
  230. .Bl -tag -width __MAGIC__.mime.mgc -compact
  231. .It Pa __MAGIC__.mime
  232. The non-compiled default magic mime database.
  233. .It Pa __MAGIC__.mime.mgc
  234. The compiled default magic mime database.
  235. .It Pa __MAGIC__
  236. The non-compiled default magic database.
  237. .It Pa __MAGIC__.mgc
  238. The compiled default magic database.
  239. .El
  240. .Sh SEE ALSO
  241. .Xr file __CSECTION__ ,
  242. .Xr magic __FSECTION__
  243. .Sh AUTHORS
  244. Måns Rullgård Initial libmagic implementation,
  245. and configuration.
  246. Christos Zoulas API cleanup, error code and allocation handling.