1LIBMAGIC(3) BSD Library Functions Manual LIBMAGIC(3)
2
4 magic_open, magic_close, magic_error, magic_errno, magic_descriptor,
5 magic_buffer, magic_getflags, magic_setflags, magic_check, magic_compile,
6 magic_list, magic_load, magic_load_buffers, magic_setparam,
7 magic_getparam, magic_version — Magic number recognition library
8
10 Magic Number Recognition Library (libmagic, -lmagic)
11
13 #include <magic.h>
14 magic_t
16 magic_open(int flags);
17 void
19 magic_close(magic_t cookie);
20 const char *
22 magic_error(magic_t cookie);
23 int
25 magic_errno(magic_t cookie);
26 const char *
28 magic_descriptor(magic_t cookie, int fd);
29 const char *
31 magic_file(magic_t cookie, const char *filename);
32 const char *
34 magic_buffer(magic_t cookie, const void *buffer, size_t length);
35 int
37 magic_getflags(magic_t cookie);
38 int
40 magic_setflags(magic_t cookie, int flags);
41 int
43 magic_check(magic_t cookie, const char *filename);
44 int
46 magic_compile(magic_t cookie, const char *filename);
47 int
49 magic_list(magic_t cookie, const char *filename);
50 int
52 magic_load(magic_t cookie, const char *filename);
53 int
55 magic_load_buffers(magic_t cookie, void **buffers, size_t *sizes,
56 size_t nbuffers);
57 int
59 magic_getparam(magic_t cookie, int param, void *value);
60 int
62 magic_setparam(magic_t cookie, int param, const void *value);
63 int
65 magic_version(void);
66
68 These functions operate on the magic database file which is described in
69 magic(5).
70 The function magic_open() creates a magic cookie pointer and returns it.
72 It returns NULL if there was an error allocating the magic cookie. The
73 flags argument specifies how the other magic functions should behave:
74 MAGIC_NONE No special handling.
76 MAGIC_DEBUG Print debugging messages to stderr.
78 MAGIC_SYMLINK If the file queried is a symlink, follow it.
80 MAGIC_COMPRESS If the file is compressed, unpack it and look at the con‐
82 tents.
83 MAGIC_DEVICES If the file is a block or character special device, then
85 open the device and try to look in its contents.
86 MAGIC_MIME_TYPE
88 Return a MIME type string, instead of a textual descrip‐
89 tion.
90 MAGIC_MIME_ENCODING
92 Return a MIME encoding, instead of a textual description.
93 MAGIC_MIME A shorthand for MAGIC_MIME_TYPE | MAGIC_MIME_ENCODING.
95 MAGIC_CONTINUE Return all matches, not just the first.
97 MAGIC_CHECK Check the magic database for consistency and print warn‐
99 ings to stderr.
100 MAGIC_PRESERVE_ATIME
102 On systems that support utime(3) or utimes(2), attempt to
103 preserve the access time of files analysed.
104 MAGIC_RAW Don't translate unprintable characters to a \ooo octal
106 representation.
107 MAGIC_ERROR Treat operating system errors while trying to open files
109 and follow symlinks as real errors, instead of printing
110 them in the magic buffer.
111 MAGIC_APPLE Return the Apple creator and type.
113 MAGIC_EXTENSION
115 Return a slash-separated list of extensions for this file
116 type.
117 MAGIC_COMPRESS_TRANSP
119 Don't report on compression, only report about the uncom‐
120 pressed data.
121 MAGIC_NO_CHECK_APPTYPE
123 Don't check for EMX application type (only on EMX).
124 MAGIC_NO_CHECK_CDF
126 Don't get extra information on MS Composite Document
127 Files.
128 MAGIC_NO_CHECK_COMPRESS
130 Don't look inside compressed files.
131 MAGIC_NO_CHECK_ELF
133 Don't print ELF details.
134 MAGIC_NO_CHECK_ENCODING
136 Don't check text encodings.
137 MAGIC_NO_CHECK_SOFT
139 Don't consult magic files.
140 MAGIC_NO_CHECK_TAR
142 Don't examine tar files.
143 MAGIC_NO_CHECK_TEXT
145 Don't check for various types of text files.
146 MAGIC_NO_CHECK_TOKENS
148 Don't look for known tokens inside ascii files.
149 MAGIC_NO_CHECK_JSON
151 Don't example JSON files.
152 The magic_close() function closes the magic(5) database and deallocates
154 any resources used.
155 The magic_error() function returns a textual explanation of the last
157 error, or NULL if there was no error.
158 The magic_errno() function returns the last operating system error number
160 (errno(2)) that was encountered by a system call.
161 The magic_file() function returns a textual description of the contents
163 of the filename argument, or NULL if an error occurred. If the filename
164 is NULL, then stdin is used.
165 The magic_descriptor() function returns a textual description of the con‐
167 tents of the fd argument, or NULL if an error occurred.
168 The magic_buffer() function returns a textual description of the contents
170 of the buffer argument with length bytes size.
171 The magic_getflags() functions returns a value representing current flags
173 set.
174 The magic_setflags() function sets the flags described above. Note that
176 using both MIME flags together can also return extra information on the
177 charset.
178 The magic_check() function can be used to check the validity of entries
180 in the colon separated database files passed in as filename, or NULL for
181 the default database. It returns 0 on success and -1 on failure.
182 The magic_compile() function can be used to compile the colon separated
184 list of database files passed in as filename, or NULL for the default
185 database. It returns 0 on success and -1 on failure. The compiled files
186 created are named from the basename(1) of each file argument with “.mgc”
187 appended to it.
188 The magic_list() function dumps all magic entries in a human readable
190 format, dumping first the entries that are matched against binary files
191 and then the ones that match text files. It takes and optional filename
192 argument which is a colon separated list of database files, or NULL for
193 the default database.
194 The magic_load() function must be used to load the colon separated list
196 of database files passed in as filename, or NULL for the default database
197 file before any magic queries can performed.
198 The default database file is named by the MAGIC environment variable. If
200 that variable is not set, the default database file name is
201 /usr/share/misc/magic. magic_load() adds “.mgc” to the database filename
202 as appropriate.
203 The magic_load_buffers() function takes an array of size nbuffers of
205 buffers with a respective size for each in the array of sizes loaded with
206 the contents of the magic databases from the filesystem. This function
207 can be used in environment where the magic library does not have direct
208 access to the filesystem, but can access the magic database via shared
209 memory or other IPC means.
210 The magic_getparam() and magic_setparam() allow getting and setting vari‐
212 ous limits related to the magic library.
213 Parameter Type Default
215 MAGIC_PARAM_INDIR_MAX size_t 15
216 MAGIC_PARAM_NAME_MAX size_t 30
217 MAGIC_PARAM_ELF_NOTES_MAX size_t 256
218 MAGIC_PARAM_ELF_PHNUM_MAX size_t 128
219 MAGIC_PARAM_ELF_SHNUM_MAX size_t 32768
220 MAGIC_PARAM_REGEX_MAX size_t 8192
221 MAGIC_PARAM_BYTES_MAX size_t 1048576
222 The MAGIC_PARAM_INDIR_RECURSION parameter controls how many levels of
224 recursion will be followed for indirect magic entries.
225 The MAGIC_PARAM_NAME_RECURSION parameter controls how many levels of
227 recursion will be followed for for name/use calls.
228 The MAGIC_PARAM_NAME_MAX parameter controls the maximum number of calls
230 for name/use.
231 The MAGIC_PARAM_NOTES_MAX parameter controls how many ELF notes will be
233 processed.
234 The MAGIC_PARAM_PHNUM_MAX parameter controls how many ELF program sec‐
236 tions will be processed.
237 The MAGIC_PARAM_SHNUM_MAX parameter controls how many ELF sections will
239 be processed.
240 The magic_version() command returns the version number of this library
242 which is compiled into the shared library using the constant
243 MAGIC_VERSION from <magic.h>. This can be used by client programs to
244 verify that the version they compile against is the same as the version
245 that they run against.
246
248 The function magic_open() returns a magic cookie on success and NULL on
249 failure setting errno to an appropriate value. It will set errno to
250 EINVAL if an unsupported value for flags was given. The magic_list(),
251 magic_load(), magic_compile(), and magic_check() functions return 0 on
252 success and -1 on failure. The magic_buffer(), magic_getpath(), and
253 magic_file(), functions return a string on success and NULL on failure.
254 The magic_error() function returns a textual description of the errors of
255 the above functions, or NULL if there was no error. The magic_version()
256 always returns the version number of the library. Finally,
257 magic_setflags() returns -1 on systems that don't support utime(3), or
258 utimes(2) when MAGIC_PRESERVE_ATIME is set.
259
261 /usr/share/misc/magic The non-compiled default magic database.
262 /usr/share/misc/magic.mgc The compiled default magic database.
263
265 file(1), magic(5)
266
268 The results from magic_buffer() and magic_file() where the buffer and the
269 file contain the same data can produce different results, because in the
270 magic_file() case, the program can lseek(2) and stat(2) the file descrip‐
271 tor.
272
274 Måns Rullgård Initial libmagic implementation, and configuration.
275 Christos Zoulas API cleanup, error code and allocation handling.
276BSD August 18, 2018 BSD