.\" $File: libmagic.man,v 1.41 2017/05/23 21:54:07 christos Exp $ .\" .\" Copyright (c) Christos Zoulas 2003. .\" All Rights Reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice immediately at the beginning of the file, without modification, .\" this list of conditions, and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR .\" ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd May 23, 2017 .Dt LIBMAGIC 3 .Os .Sh NAME .Nm magic_open , .Nm magic_close , .Nm magic_error , .Nm magic_errno , .Nm magic_descriptor , .Nm magic_buffer , .Nm magic_getflags , .Nm magic_setflags , .Nm magic_check , .Nm magic_compile , .Nm magic_list , .Nm magic_load , .Nm magic_load_buffers , .Nm magic_setparam , .Nm magic_getparam , .Nm magic_version .Nd Magic number recognition library .Sh LIBRARY .Lb libmagic .Sh SYNOPSIS .In magic.h .Ft magic_t .Fn magic_open "int flags" .Ft void .Fn magic_close "magic_t cookie" .Ft const char * .Fn magic_error "magic_t cookie" .Ft int .Fn magic_errno "magic_t cookie" .Ft const char * .Fn magic_descriptor "magic_t cookie" "int fd" .Ft const char * .Fn magic_file "magic_t cookie" "const char *filename" .Ft const char * .Fn magic_buffer "magic_t cookie" "const void *buffer" "size_t length" .Ft int .Fn magic_getflags "magic_t cookie" .Ft int .Fn magic_setflags "magic_t cookie" "int flags" .Ft int .Fn magic_check "magic_t cookie" "const char *filename" .Ft int .Fn magic_compile "magic_t cookie" "const char *filename" .Ft int .Fn magic_list "magic_t cookie" "const char *filename" .Ft int .Fn magic_load "magic_t cookie" "const char *filename" .Ft int .Fn magic_load_buffers "magic_t cookie" "void **buffers" "size_t *sizes" "size_t nbuffers" .Ft int .Fn magic_getparam "magic_t cookie" "int param" "void *value" .Ft int .Fn magic_setparam "magic_t cookie" "int param" "const void *value" .Ft int .Fn magic_version "void" .Sh DESCRIPTION These functions operate on the magic database file which is described in .Xr magic __FSECTION__ . .Pp The function .Fn magic_open creates a magic cookie pointer and returns it. It returns .Dv NULL if there was an error allocating the magic cookie. The .Ar flags argument specifies how the other magic functions should behave: .Bl -tag -width MAGIC_COMPRESS .It Dv MAGIC_NONE No special handling. .It Dv MAGIC_DEBUG Print debugging messages to stderr. .It Dv MAGIC_SYMLINK If the file queried is a symlink, follow it. .It Dv MAGIC_COMPRESS If the file is compressed, unpack it and look at the contents. .It Dv MAGIC_DEVICES If the file is a block or character special device, then open the device and try to look in its contents. .It Dv MAGIC_MIME_TYPE Return a MIME type string, instead of a textual description. .It Dv MAGIC_MIME_ENCODING Return a MIME encoding, instead of a textual description. .It Dv MAGIC_MIME A shorthand for MAGIC_MIME_TYPE | MAGIC_MIME_ENCODING. .It Dv MAGIC_CONTINUE Return all matches, not just the first. .It Dv MAGIC_CHECK Check the magic database for consistency and print warnings to stderr. .It Dv MAGIC_PRESERVE_ATIME On systems that support .Xr utime 3 or .Xr utimes 2 , attempt to preserve the access time of files analysed. .It Dv MAGIC_RAW Don't translate unprintable characters to a \eooo octal representation. .It Dv MAGIC_ERROR Treat operating system errors while trying to open files and follow symlinks as real errors, instead of printing them in the magic buffer. .It Dv MAGIC_APPLE Return the Apple creator and type. .It Dv MAGIC_EXTENSION Return a slash-separated list of extensions for this file type. .It Dv MAGIC_COMPRESS_TRANSP Don't report on compression, only report about the uncompressed data. .It Dv MAGIC_NO_CHECK_APPTYPE Don't check for .Dv EMX application type (only on EMX). .It Dv MAGIC_NO_CHECK_CDF Don't get extra information on MS Composite Document Files. .It Dv MAGIC_NO_CHECK_COMPRESS Don't look inside compressed files. .It Dv MAGIC_NO_CHECK_ELF Don't print ELF details. .It Dv MAGIC_NO_CHECK_ENCODING Don't check text encodings. .It Dv MAGIC_NO_CHECK_SOFT Don't consult magic files. .It Dv MAGIC_NO_CHECK_TAR Don't examine tar files. .It Dv MAGIC_NO_CHECK_TEXT Don't check for various types of text files. .It Dv MAGIC_NO_CHECK_TOKENS Don't look for known tokens inside ascii files. .El .Pp The .Fn magic_close function closes the .Xr magic __FSECTION__ database and deallocates any resources used. .Pp The .Fn magic_error function returns a textual explanation of the last error, or .Dv NULL if there was no error. .Pp The .Fn magic_errno function returns the last operating system error number .Pq Xr errno 2 that was encountered by a system call. .Pp The .Fn magic_file function returns a textual description of the contents of the .Ar filename argument, or .Dv NULL if an error occurred. If the .Ar filename is .Dv NULL , then stdin is used. .Pp The .Fn magic_descriptor function returns a textual description of the contents of the .Ar fd argument, or .Dv NULL if an error occurred. .Pp The .Fn magic_buffer function returns a textual description of the contents of the .Ar buffer argument with .Ar length bytes size. .Pp The .Fn magic_getflags functions returns a value representing current .Ar flags set. .Pp The .Fn magic_setflags function sets the .Ar flags described above. Note that using both MIME flags together can also return extra information on the charset. .Pp The .Fn magic_check function can be used to check the validity of entries in the colon separated database files passed in as .Ar filename , or .Dv NULL for the default database. It returns 0 on success and \-1 on failure. .Pp The .Fn magic_compile function can be used to compile the colon separated list of database files passed in as .Ar filename , or .Dv NULL for the default database. It returns 0 on success and \-1 on failure. The compiled files created are named from the .Xr basename 1 of each file argument with .Dq .mgc appended to it. .Pp The .Fn magic_list function dumps all magic entries in a human readable format, dumping first the entries that are matched against binary files and then the ones that match text files. It takes and optional .Fa filename argument which is a colon separated list of database files, or .Dv NULL for the default database. .Pp The .Fn magic_load function must be used to load the colon separated list of database files passed in as .Ar filename , or .Dv NULL for the default database file before any magic queries can performed. .Pp The default database file is named by the MAGIC environment variable. If that variable is not set, the default database file name is __MAGIC__. .Fn magic_load adds .Dq .mgc to the database filename as appropriate. .Pp The .Fn magic_load_buffers function takes an array of size .Fa nbuffers of .Fa buffers with a respective size for each in the array of .Fa sizes loaded with the contents of the magic databases from the filesystem. This function can be used in environment where the magic library does not have direct access to the filesystem, but can access the magic database via shared memory or other IPC means. .Pp The .Fn magic_getparam and .Fn magic_setparam allow getting and setting various limits related to the magic library. .Bl -column "MAGIC_PARAM_ELF_PHNUM_MAX" "size_t" "Default" -offset indent .It Sy "Parameter" Ta Sy "Type" Ta Sy "Default" .It Li MAGIC_PARAM_INDIR_MAX Ta size_t Ta 15 .It Li MAGIC_PARAM_NAME_MAX Ta size_t Ta 30 .It Li MAGIC_PARAM_ELF_NOTES_MAX Ta size_t Ta 256 .It Li MAGIC_PARAM_ELF_PHNUM_MAX Ta size_t Ta 128 .It Li MAGIC_PARAM_ELF_SHNUM_MAX Ta size_t Ta 32768 .It Li MAGIC_PARAM_REGEX_MAX Ta size_t Ta 8192 .It Li MAGIC_PARAM_BYTES_MAX Ta size_t Ta 1048576 .El .Pp The .Dv MAGIC_PARAM_INDIR_RECURSION parameter controls how many levels of recursion will be followed for indirect magic entries. .Pp The .Dv MAGIC_PARAM_NAME_RECURSION parameter controls how many levels of recursion will be followed for for name/use calls. .Pp The .Dv MAGIC_PARAM_NAME_MAX parameter controls the maximum number of calls for name/use. .Pp The .Dv MAGIC_PARAM_NOTES_MAX parameter controls how many ELF notes will be processed. .Pp The .Dv MAGIC_PARAM_PHNUM_MAX parameter controls how many ELF program sections will be processed. .Pp The .Dv MAGIC_PARAM_SHNUM_MAX parameter controls how many ELF sections will be processed. .Pp The .Fn magic_version command returns the version number of this library which is compiled into the shared library using the constant .Dv MAGIC_VERSION from .In magic.h . This can be used by client programs to verify that the version they compile against is the same as the version that they run against. .Sh RETURN VALUES The function .Fn magic_open returns a magic cookie on success and .Dv NULL on failure setting errno to an appropriate value. It will set errno to .Er EINVAL if an unsupported value for flags was given. The .Fn magic_list , .Fn magic_load , .Fn magic_compile , and .Fn magic_check functions return 0 on success and \-1 on failure. The .Fn magic_buffer , .Fn magic_getpath , and .Fn magic_file , functions return a string on success and .Dv NULL on failure. The .Fn magic_error function returns a textual description of the errors of the above functions, or .Dv NULL if there was no error. The .Fn magic_version always returns the version number of the library. Finally, .Fn magic_setflags returns \-1 on systems that don't support .Xr utime 3 , or .Xr utimes 2 when .Dv MAGIC_PRESERVE_ATIME is set. .Sh FILES .Bl -tag -width __MAGIC__.mgc -compact .It Pa __MAGIC__ The non-compiled default magic database. .It Pa __MAGIC__.mgc The compiled default magic database. .El .Sh SEE ALSO .Xr file __CSECTION__ , .Xr magic __FSECTION__ .Sh AUTHORS .An M\(oans Rullg\(oard Initial libmagic implementation, and configuration. .An Christos Zoulas API cleanup, error code and allocation handling.