cf781b2e16
This brings a number of fixes to elfcopy/strip and DWARF4 improvements. Sponsored by: The FreeBSD Foundation
279 lines
7.3 KiB
Groff
279 lines
7.3 KiB
Groff
.\" Copyright (c) 2010,2014 Kai Wang
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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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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, 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, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $Id: dwarf_child.3 3127 2014-12-21 19:09:19Z jkoshy $
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.\"
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.Dd December 21, 2014
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.Os
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.Dt DWARF_CHILD 3
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.Sh NAME
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.Nm dwarf_child ,
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.Nm dwarf_offdie ,
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.Nm dwarf_offdie_b ,
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.Nm dwarf_siblingof ,
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.Nm dwarf_siblingof_b
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.Nd retrieve DWARF Debugging Information Entry descriptors
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.Sh LIBRARY
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.Lb libdwarf
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.Sh SYNOPSIS
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.In libdwarf.h
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.Ft int
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.Fn dwarf_child "Dwarf_Die die" "Dwarf_Die *ret_die" "Dwarf_Error *err"
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.Ft int
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.Fo dwarf_offdie
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.Fa "Dwarf_Debug dbg"
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.Fa "Dwarf_Off offset"
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.Fa "Dwarf_Die *ret_die"
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.Fa "Dwarf_Error *err"
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.Fc
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.Ft int
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.Fo dwarf_offdie_b
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.Fa "Dwarf_Debug dbg"
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.Fa "Dwarf_Off offset"
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.Fa "Dwarf_Bool is_info"
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.Fa "Dwarf_Die *ret_die"
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.Fa "Dwarf_Error *err"
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.Fc
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.Ft int
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.Fo dwarf_siblingof
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.Fa "Dwarf_Debug dbg"
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.Fa "Dwarf_Die die"
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.Fa "Dwarf_Die *ret_die"
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.Fa "Dwarf_Error *err"
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.Fc
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.Ft int
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.Fo dwarf_siblingof_b
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.Fa "Dwarf_Debug dbg"
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.Fa "Dwarf_Die die"
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.Fa "Dwarf_Die *ret_die"
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.Fa "Dwarf_Bool is_info"
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.Fa "Dwarf_Error *err"
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.Fc
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.Sh DESCRIPTION
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These functions are used to retrieve and traverse DWARF
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Debugging Information Entry (DIE) descriptors associated with
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a compilation unit.
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These descriptors are arranged in the form of a tree, traversable
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using
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.Dq child
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and
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.Dq sibling
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links; see
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.Xr dwarf 3
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for more information.
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DWARF Debugging Information Entry descriptors are represented
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by the
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.Vt Dwarf_Die
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opaque type.
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.Pp
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Function
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.Fn dwarf_child
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retrieves the child of descriptor denoted by argument
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.Ar die ,
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and stores it in the location pointed to by argument
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.Ar ret_die .
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.Pp
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Function
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.Fn dwarf_siblingof
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retrieves the sibling of the descriptor denoted by argument
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.Ar die ,
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and stores it in the location pointed to by argument
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.Ar ret_die .
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If argument
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.Ar die
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is NULL, the first debugging information entry descriptor for the
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current compilation unit will be returned.
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This function and function
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.Fn dwarf_child
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may be used together to traverse the tree of debugging information
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entry descriptors for a compilation unit.
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.Pp
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Function
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.Fn dwarf_siblingof_b
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is identical to the function
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.Fn dwarf_siblingof
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except that it can retrieve the sibling descriptor from either the
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current compilation unit or type unit.
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If argument
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.Ar is_info
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is non-zero, the function behaves identically to function
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.Fn dwarf_siblingof .
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If argument
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.Ar is_info
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is zero, the descriptor referred by argument
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.Ar die
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should be associated with a debugging information entry in the
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type unit.
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The function will store the sibling of the descriptor in the location
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pointed to by argument
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.Ar ret_die .
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If argument
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.Ar is_info
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is zero and argument
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.Ar die
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is
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.Dv NULL ,
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the first debugging information entry descriptor for the
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current type unit will be returned.
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.Pp
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Function
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.Fn dwarf_offdie
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retrieves the debugging information entry descriptor at global offset
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.Ar offset
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in the
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.Dq .debug_info
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section of the object associated with argument
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.Ar dbg .
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The returned descriptor is written to the location pointed to by argument
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.Ar ret_die .
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.Pp
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Function
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.Fn dwarf_offdie_b
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is identical to the function
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.Fn dwarf_offdie
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except that it can retrieve the debugging information entry descriptor at
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global offset
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.Ar offset
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from either of the
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.Dq .debug_info
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and
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.Dq .debug_types
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sections of the object associated with argument
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.Ar dbg .
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If argument
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.Ar is_info
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is non-zero, the function will retrieve the debugging information
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entry from the
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.Dq .debug_info
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section, otherwise the function will retrieve the debugging
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information entry from the
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.Dq .debug_types
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section.
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The returned descriptor is written to the location pointed to by argument
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.Ar ret_die .
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.Ss Memory Management
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The memory area used for the
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.Vt Dwarf_Die
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descriptor returned in argument
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.Ar ret_die
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is allocated by the
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.Lb libdwarf .
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Application code should use function
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.Fn dwarf_dealloc
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with the allocation type
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.Dv DW_DLA_DIE
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to free the memory area when the
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.Vt Dwarf_Die
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descriptor is no longer needed.
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.Sh RETURN VALUES
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These functions return the following values:
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.Bl -tag -width ".Bq Er DW_DLV_NO_ENTRY"
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.It Bq Er DW_DLV_OK
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The call succeeded.
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.It Bq Er DW_DLV_ERROR
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The requested operation failed.
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Additional information about the error encountered will be recorded in
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argument
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.Ar err ,
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if it is not NULL.
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.It Bq Er DW_DLV_NO_ENTRY
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For functions
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.Fn dwarf_child ,
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.Fn dwarf_siblingof
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and
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.Fn dwarf_siblingof_b ,
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the descriptor denoted by argument
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.Ar die
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did not have a child or sibling.
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.Pp
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For functions
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.Fn dwarf_offdie
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and
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.Fn dwarf_offdie_b ,
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there was no debugging information entry at the offset specified by
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argument
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.Ar offset .
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.El
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.Sh ERRORS
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These functions may fail with the following errors:
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.Bl -tag -width ".Bq Er DW_DLE_DIE_NO_CU_CONTEXT"
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.It Bq Er DW_DLE_ARGUMENT
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Arguments
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.Ar dbg ,
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.Ar die
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or
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.Ar ret_die
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were NULL.
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.It Bq Er DW_DLE_DIE_NO_CU_CONTEXT
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Argument
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.Ar dbg
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was not associated with a compilation unit.
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.It Bq Er DW_DLE_NO_ENTRY
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The descriptor denoted by argument
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.Ar die
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had no child or sibling, or there was no DWARF debugging information
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entry at the offset specified by argument
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.Va offset .
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.El
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.Sh EXAMPLES
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To retrieve the first DWARF Debugging Information Entry descriptor for
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the first compilation unit associated with a
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.Vt Dwarf_Debug
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instance, and to traverse all its children, use:
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.Bd -literal -offset indent
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Dwarf_Debug dbg;
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Dwarf_Die die, die0;
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Dwarf_Error de;
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\&... allocate dbg using dwarf_init() etc ...
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if (dwarf_next_cu_header(dbg, NULL, NULL, NULL, NULL, NULL, &de) !=
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DW_DLV_OK)
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errx(EXIT_FAILURE, "dwarf_next_cu_header: %s",
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dwarf_errmsg(de));
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/* Get the first DIE for the current compilation unit. */
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die = NULL;
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if (dwarf_siblingof(dbg, die, &die0, &de) != DW_DLV_OK)
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errx(EXIT_FAILURE, "dwarf_siblingof: %s", dwarf_errmsg(de));
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/* Get the first child of this DIE. */
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die = die0;
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if (dwarf_child(die, &die0, &de) != DW_DLV_OK)
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errx(EXIT_FAILURE, "dwarf_child: %s", dwarf_errmsg(de));
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/* Get the rest of children. */
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do {
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die = die0;
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if (dwarf_siblingof(dbg, die, &die0, &de) == DW_DLV_ERROR)
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errx(EXIT_FAILURE, "dwarf_siblingof: %s",
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dwarf_errmsg(de));
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} while (die0 != NULL);
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.Ed
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.Sh SEE ALSO
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.Xr dwarf 3 ,
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.Xr dwarf_errmsg 3 ,
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.Xr dwarf_get_die_infotypes_flag.3 ,
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.Xr dwarf_next_cu_header 3
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