229 lines
6.7 KiB
Groff
229 lines
6.7 KiB
Groff
.\" Copyright (c) 2011 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_get_relocation_info.3 2071 2011-10-27 03:20:00Z jkoshy $
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.\"
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.Dd September 3, 2011
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.Os
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.Dt DWARF_GET_RELOCATION_INFO 3
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.Sh NAME
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.Nm dwarf_get_relocation_info
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.Nd retrieve generated relocation arrays
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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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.Fo dwarf_get_relocation_info
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.Fa "Dwarf_P_Debug dbg"
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.Fa "Dwarf_Signed *elf_section_index"
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.Fa "Dwarf_Signed *elf_section_link"
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.Fa "Dwarf_Unsigned *reloc_entry_count"
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.Fa "Dwarf_Relocation_Data *reloc_buf"
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.Fa "Dwarf_Error *err"
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.Fc
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.Sh DESCRIPTION
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The function
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.Fn dwarf_get_relocation_info
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is used to retrieve the relocation arrays generated by a prior call to
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.Xr dwarf_transform_to_disk_form 3 .
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.Pp
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Each call to this function retrieves the next available relocation
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array.
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Application code should call this function repeatly to retrieve all
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the relocation arrays.
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The total number of generated relocation arrays retrievable
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by this function may be obtained by calling function
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.Xr dwarf_get_relocation_info_count 3 .
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.Pp
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Argument
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.Ar dbg
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should reference a DWARF producer instance allocated using
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.Xr dwarf_producer_init 3 in sequence.
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or
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.Xr dwarf_producer_init_b 3 .
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The
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.Dv DW_DLC_SYMBOLIC_RELOCATIONS
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flag should have been set on the DWARF producer instance.
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.Pp
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Argument
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.Ar elf_section_index
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should point to a location which will be set to the ELF section index
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of the relocation section to which the retrieved relocation array
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belongs.
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.Pp
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Argument
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.Ar elf_section_link
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should point to a location which will be set to the section index of
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the ELF section to which the retrieved relocation array applies.
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.Pp
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Argument
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.Ar reloc_entry_count
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should point to a location which will be set to the total number of
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relocation entries contained in the relocation array.
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.Pp
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Argument
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.Ar reloc_buf
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should point to a location which will be set to a pointer to the
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retrieved array of relocation entries.
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.Pp
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If argument
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.Ar err
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is not NULL, it will be used to store error information in case
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of an error.
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.Pp
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The retrieved relocation entries are described using structure
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.Vt Dwarf_Relocation_Data_s ,
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defined in the header file
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.In libdwarf.h :
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.Bd -literal -offset indent
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typedef struct Dwarf_Relocation_Data_s {
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unsigned char drd_type;
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unsigned char drd_length;
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Dwarf_Unsigned drd_offset;
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Dwarf_Unsigned drd_symbol_index;
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} *Dwarf_Relocation_Data;
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.Ed
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.Pp
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Struct
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.Vt Dwarf_Relocation_Data_s
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consists of following fields:
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.Bl -tag -width ".Va drd_symbol_index" -compact -offset indent
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.It Va drd_type
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The type code of the relocation entry.
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The
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.Vt Dwarf_Rel_Type
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enumeration defined in the header file
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.In libdwarf.h
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specifies legal values for this field.
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.It Va drd_length
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The size in bytes of the field to be relocated.
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.It Va drd_offset
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The section-relative offset of the field to be relocated.
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.It Va drd_symbol_index
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The symbol index associated with the relocation entry.
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.El
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.Ss Memory Management
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The memory area used for the relocation arrays is managed by the
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.Lb libdwarf .
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The function
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.Fn dwarf_producer_finish
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may be used to release it, along with other resources associated
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with the producer instance.
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.Sh RETURN VALUES
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On success, function
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.Fn dwarf_get_relocation_info
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returns
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.Dv DW_DLV_OK .
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It returns
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.Dv DW_DLV_NO_ENTRY
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if there were no more relocation arrays to retrieve, or if the flag
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.Dv DW_DLC_SYMBOLIC_RELOCATIONS
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was not set on the producer instance.
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In case of an error, function
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.Fn dwarf_get_relocation_info
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returns
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.Dv DW_DLV_ERROR
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and sets the argument
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.Ar err .
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.Sh ERRORS
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Function
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.Fn dwarf_get_relocation_info
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can fail with:
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.Bl -tag -width ".Bq Er DW_DLE_NO_ENTRY"
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.It Bq Er DW_DLE_ARGUMENT
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One of the arguments
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.Ar dbg ,
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.Ar elf_section_index ,
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.Ar elf_section_link ,
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.Ar reloc_entry_count
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or
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.Ar reloc_buf
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was NULL.
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.It Bq Er DW_DLE_NO_ENTRY
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There were no more ELF relocation arrays to retrieve.
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.It Bq Er DW_DLE_NO_ENTRY
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The flag
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.Dv DW_DLC_SYMBOLIC_RELOCATIONS
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was not set on the producer instance.
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.It Bq Er DW_DLE_NO_ENTRY
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Function
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.Xr dwarf_transform_to_disk_form 3
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was not called prior to calling function
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.Fn dwarf_get_relocation_info .
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.El
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.Sh EXAMPLES
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To generate relocation entries and retrieve them, use:
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.Bd -literal -offset indent
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Dwarf_P_Debug dbg;
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Dwarf_Relocation_Data buf;
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Dwarf_Signed count, index, link;
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Dwarf_Unsigned reloc_cnt, entry_cnt;
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Dwarf_Error de;
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int version, i, j;
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/*
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* Assume that dbg refers to a DWARF producer instance created
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* created with DW_DLC_SYMBOLIC_RELOCATIONS flag set and that
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* application code has added DWARF debugging information
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* to the producer instance.
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*/
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if ((count = dwarf_transform_to_disk_form(dbg, &de)) ==
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DW_DLV_NOCOUNT) {
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warnx("dwarf_transform_to_disk_form failed: %s",
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dwarf_errmsg(-1));
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return;
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}
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/* ... process generated section byte streams ... */
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if (dwarf_get_relocation_info_count(dbg, &reloc_cnt, &version, &de) !=
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DW_DLV_OK) {
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warnx("dwarf_get_relocation_info_count failed: %s",
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dwarf_errmsg(-1));
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return;
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}
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for (i = 0; (Dwarf_Unsigned) i < reloc_cnt; i++) {
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if (dwarf_get_relocation_info(dbg, &index, &link, &entry_cnt,
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&buf, &de) != DW_DLV_OK) {
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warnx("dwarf_get_relocation_info failed: %s",
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dwarf_errmsg(-1));
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continue;
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}
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for (j = 0; (Dwarf_Unsigned) j < entry_cnt; j++) {
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/* ...use each reloc data in buf[j]... */
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}
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}
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dwarf_producer_finish(dbg, &de);
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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_get_relocation_info_count 3 ,
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.Xr dwarf_reset_section_bytes 3 ,
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.Xr dwarf_producer_finish 3 ,
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.Xr dwarf_producer_init 3 ,
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.Xr dwarf_producer_init_b 3 ,
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.Xr dwarf_transform_to_disk_form 3
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