455 lines
12 KiB
Groff
455 lines
12 KiB
Groff
.\"
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.\" Copyright (c) 2013, 2015 Spectra Logic Corporation
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions, and the following disclaimer,
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.\" without modification.
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.\" 2. Redistributions in binary form must reproduce at minimum a disclaimer
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.\" substantially similar to the "NO WARRANTY" disclaimer below
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.\" ("Disclaimer") and any redistribution must be conditioned upon
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.\" including a substantially similar Disclaimer requirement for further
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.\" binary redistribution.
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.\"
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.\" NO WARRANTY
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.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
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.\" A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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.\" HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGES.
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.\"
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.\" Authors: Ken Merry (Spectra Logic Corporation)
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.\"
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.\" $FreeBSD$
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.\"
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.Dd February 13, 2015
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.Dt MT 3
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.Os
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.Sh NAME
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.Nm mt_start_element ,
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.Nm mt_end_element ,
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.Nm mt_char_handler ,
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.Nm mt_status_tree_sbuf ,
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.Nm mt_status_tree_print ,
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.Nm mt_status_entry_free ,
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.Nm mt_status_free ,
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.Nm mt_entry_sbuf ,
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.Nm mt_param_parent_print ,
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.Nm mt_param_entry_print ,
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.Nm mt_protect_print ,
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.Nm mt_param_list ,
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.Nm mt_density_name ,
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.Nm mt_density_bp ,
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.Nm mt_density_num ,
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.Nm mt_get_xml_str ,
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.Nm mt_get_status
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.Nd Magnetic Tape library
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.Sh LIBRARY
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.Lb libmt
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.Sh SYNOPSIS
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.In sys/sbuf.h
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.In bsdxml.h
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.In mtlib.h
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.Ft void
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.Fo mt_start_element
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.Fa "void *user_data"
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.Fa "const char *name"
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.Fa "const char **attr"
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.Fc
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.Ft void
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.Fo mt_end_element
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.Fa "void *user_data"
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.Fa "const char *name"
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.Fc
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.Ft void
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.Fo mt_char_handler
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.Fa "void *user_data"
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.Fa "const XML_Char *str"
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.Fa "int len"
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.Fc
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.Ft void
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.Fo mt_status_tree_sbuf
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.Fa "struct sbuf *sb"
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.Fa "struct mt_status_entry *entry"
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.Fa "int indent"
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.Fa "void (*sbuf_func)(struct sbuf *sb, struct mt_status_entry *entry, void *arg)"
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.Fa "void *arg"
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.Fc
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.Ft void
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.Fo mt_status_tree_print
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.Fa "struct mt_status_entry *entry"
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.Fa "int indent"
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.Fa "void (*print_func)(struct mt_status_entry *entry, void *arg)"
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.Fa "void *arg"
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.Fc
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.Ft "struct mt_status_entry *"
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.Fo mt_entry_find
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.Fa "struct mt_status_entry *entry"
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.Fa "char *name"
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.Fc
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.Ft "struct mt_status_entry *"
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.Fo mt_status_entry_find
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.Fa "struct mt_status_data *status_data"
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.Fa "char *name"
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.Fc
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.Ft void
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.Fo mt_status_entry_free
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.Fa "struct mt_status_entry *entry)"
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.Fc
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.Ft void
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.Fo mt_status_free
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.Fa "struct mt_status_data *status_data"
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.Fc
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.Ft void
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.Fo mt_entry_sbuf
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.Fa "struct sbuf *sb"
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.Fa "struct mt_status_entry *entry"
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.Fa "char *fmt"
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.Fc
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.Ft void
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.Fo mt_param_parent_sbuf
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.Fa "struct sbuf *sb"
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.Fa "struct mt_status_entry *entry"
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.Fa "struct mt_print_params *print_params"
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.Fc
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.Ft void
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.Fo mt_param_parent_print
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.Fa "struct mt_status_entry *entry"
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.Fa "struct mt_print_params *print_params"
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.Fc
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.Ft void
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.Fo mt_param_entry_sbuf
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.Fa "struct sbuf *sb"
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.Fa "struct mt_status_entry *entry"
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.Fa "void *arg"
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.Fc
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.Ft void
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.Fo mt_param_entry_print
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.Fa "struct mt_status_entry *entry"
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.Fa "void *arg"
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.Fc
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.Ft int
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.Fo mt_protect_print
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.Fa "struct mt_status_data *status_data"
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.Fa "int verbose"
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.Fc
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.Ft int
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.Fo mt_param_list
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.Fa "struct mt_status_data *status_data"
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.Fa "char *param_name"
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.Fa "int quiet"
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.Fc
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.Ft "const char *"
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.Fo mt_density_name
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.Fa "int density_num"
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.Fc
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.Ft int
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.Fo mt_density_bp
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.Fa "int density_num"
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.Fa "int bpi"
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.Fc
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.Ft int
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.Fo mt_density_num
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.Fa "const char *density_name"
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.Fc
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.Ft int
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.Fo mt_get_status
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.Fa "char *xml_str"
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.Fa "struct mt_status_data *status_data"
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.Fc
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.Sh DESCRIPTION
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The MT library consists of a number of functions designed to aid in
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interacting with the
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.Xr sa 4
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driver.
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The
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.Xr sa 4
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driver returns some status data as XML-formatted strings, and
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the primary purpose of this library is to make it easier for the
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software developer to parse those strings and extract the status values.
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.Pp
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The
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.Fn mt_start_element ,
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.Fn mt_end_element ,
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and
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.Fn mt_char_handler
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functions are designed to work with the
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.Xr libbsdxml 3
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library, which is an XML parsing library.
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The user data for the XML parser should be set with
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.Fn XML_SetUserData
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to a zeroed struct
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mt_status_data with the entries list initialized.
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The element handlers for the XML parser should be set to
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.Fn mt_start_element
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and
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.Fn mt_end_element
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with
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.Fn XML_SetElementHandler .
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The character data handler should be set to
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.Fn mt_char_handler
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with the
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.Fn XML_SetCharacterDataHandler
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function.
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The error member of the status_data structure will be set to 0 if parsing
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is successful, and non-zero if parsing failed.
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In the event of a failure, the error_str member will contain an error
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message describing the failure.
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These functions will build a tree of tape driver status data that can be
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searched and printed using the other functions in this library.
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.Pp
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.Fn mt_status_tree_sbuf
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takes the root node of a tree of
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.Xr sa 4
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driver status information, and displays it in an
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.Xr sbuf 9 .
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The
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.Ar sb
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argument is the destination sbuf.
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The
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.Ar entry
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argument is the root of the tree.
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The
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.Ar indent
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argument is the number of characters to indent the output.
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Each recursive call to
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.Fn mt_status_tree_sbuf
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will have the indent level incremented by 2.
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The
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.Ar sbuf_func
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argument is for a user-supplied alternate printing function.
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If it is non-NULL, it will be called instead of the default output printing
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code.
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The
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.Ar arg
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argument is an argument for the
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.Ar sbuf_func
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function.
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.Pp
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The
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.Fn mt_status_tree_print
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function is the same as the
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.Fn mt_status_tree_sbuf
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function, except that the tree is printed to standard out instead of to a
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sbuf.
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.Pp
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The
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.Fn mt_entry_find
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function returns the first entry in the tree starting at
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.Ar entry
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that matches
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.Ar name .
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The supplied node name can be a single level name like "foo", or it can
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specify mulitple node names that must be matched, for instance "foo.bar.baz".
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In the case of a single level name, it will match any node beneath
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.Ar entry
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that matches
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.Ar name .
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In the case of a multi-level name like "foo.bar.baz", it will return the
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first entry named "baz" whose immediate parent is "bar" and where the
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parent of "bar" is named "foo".
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.Pp
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The
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.Fn mt_status_entry_find
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is the same as
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.Fn mt_entry_find ,
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except that it operates on the top level mt_status_data and all
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mt_status_entry nodes below it instead of just an mt_status_entry
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structure.
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.Pp
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The
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.Fn mt_status_entry_free
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function frees the tree of status data underneath
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.Ar entry .
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.Pp
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The
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.Fn mt_status_free
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function frees the tree of status data underneath
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.Ar status_data .
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.Pp
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The
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.Fn mt_entry_sbuf
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function prints
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.Ar entry
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to the supplied sbuf
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.Ar sb ,
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optionally using the
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.Xr printf 3
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format
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.Ar fmt .
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If
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.Ar fmt
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is NULL, then
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.Fn mt_entry_sbuf
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will render integer types in base 10 without special formatting and all
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other types as they were rendered in the XML.
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.Pp
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.Fn mt_param_parent_sbuf
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prints the parents of the given
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.Ar entry
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to the supplied sbuf
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.Ar sb
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subject to the print parameters
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.Ar print_params .
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The result will be formatted with a period between each level, like
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"foo.bar.baz".
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.Pp
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.Fn mt_param_parent_print
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is like
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.Fn mt_param_parent_sbuf
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except that it prints the results to standard output instead of an sbuf.
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.Pp
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.Fn mt_param_entry_sbuf
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prints the
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.Ar entry
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to the given sbuf
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.Ar sb .
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The argument
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.Ar arg
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is a pointer to struct mt_print_params, which allows the caller to control
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the printing output.
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This function is intended to be supplied as an argument to
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.Fn mt_status_tree_sbuf .
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.Pp
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.Fn mt_param_entry_print
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is like
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.Fn mt_param_entry_sbuf
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except that it prints to standard output instead of an sbuf.
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It is intended to be used as an argument to
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.Fn mt_status_tree_print .
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.Pp
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.Fn mt_protect_print
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prints tape drive protection information from the supplied
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.Ar status_data
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beginning at the node name defined as the root node for protection data.
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If the
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.Ar verbose
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argument is non-zero, protection entry descriptions will be printed.
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If it is zero, protection entry descriptions will not be printed.
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.Pp
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.Fn mt_param_list
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prints tape driver parameters information from the supplied
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.Ar status_data .
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If the
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.Ar param_name
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is non-NULL, only the named parameter will be printed.
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If
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.Ar quiet
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is non-zero, parameter descriptions will be omitted in the output.
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.Pp
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.Fn mt_density_name
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Returns a text identifier for the supplied numeric
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.Ar density_num .
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The
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.Ar density_num
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should currently be a value between 0 and 255 inclusive, since that is the
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valid range for
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.Tn SCSI
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density code values.
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See below for notes on the return values.
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.Pp
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.Fn mt_density_bp
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Returns the bits per inch or bits per mm values for a given density entry
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specified by the
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.Ar density_num .
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If the
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.Ar bpi
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argument is non-zero, the bits per inch value is returned.
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Otherwise, the bits per mm value is returned.
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.Pp
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.Fn mt_density_num
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returns a numeric value for a text density description.
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It does a case-insensitive comparison of density names in the density table
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to the supplied density name.
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.Pp
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.Fn mt_get_xml_str
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gets the current XML status / parameter string from the sa(4) driver
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instance referenced by the open file descriptor
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.Ar mtfd .
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The
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.Xr mtio 4
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.Xr ioctl 2
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to be used is supplied as the
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.Ar cmd
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argument.
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Currently the
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.Fn mt_get_xml_str
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function will work with the
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.Dv MTIOCEXTGET
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and
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.Dv MTIOCPARAMGET
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ioctls.
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The supplied
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.Ar xml_str
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will be filled in with a pointer to the complete XML status string.
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Multiple calls to the given
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.Xr ioctl 2
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are made and more space is malloced until all of the XML string is fetched.
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The string returned in the
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.Ar xml_str
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argument should be freed when it is no longer in use.
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.Sh RETURN VALUES
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.Fn mt_entry_find
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returns the first matching entry, or NULL if it fails to find a match.
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.Pp
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.Fn mt_status_entry_find
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returns the first matching entry, or NULL if it fails to find a match.
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.Pp
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.Fn mt_protect_print
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Returns 0 for success, and non-zero for failure.
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.Fn mt_protect_print
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can only fail if it cannot find protection information in the supplied
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status data.
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.Pp
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.Fn mt_param_list
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Returns 0 for success and non-zero for failure.
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.Fn mt_param_list
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can only fail if it cannot find parameter information in the supplied
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status data.
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.Pp
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.Fn mt_density_name
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returns a text description of a numeric density.
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The special density value 0 is decoded as "default".
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The special density value 0x7f is decoded as "same".
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If the density is not known,
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.Fn mt_density_name
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will return "UNKNOWN".
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.Pp
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.Fn mt_density_bp
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returns the bits per inch value for the given density (if the
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.Ar bpi
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field is non-zero), the bits per mm value otherwise, or 0 if the supplied
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.Ar density_num
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is not in the density table or the table entry does not include bpi / bpmm
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values.
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.Pp
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.Fn mt_density_num
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returns a numeric density value between 0 and 255 for the supplied density
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name.
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It returns 0 if the density name is not recognized.
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.Pp
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.Fn mt_get_xml_str
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returns 0 for success, and -1 for failure.
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.Sh SEE ALSO
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.Xr mt 1 ,
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.Xr mtio 4 ,
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.Xr sa 4
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.Sh HISTORY
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The MT library first appeared in
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.Fx 10.1 .
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.Sh AUTHORS
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.An Ken Merry Aq ken@FreeBSD.org
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.Sh BUGS
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The library interface is not complete, and may change in the future.
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Application authors should not rely on the library interface to be
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consistent in the immediate future.
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