ae500c1ff8
Highlights: - Make sure that only TLS sections are sorted into TLS segment. - Fixed multiple errors in "Section to Segment mapping". - Man page updates - ar improvements - elfcopy: avoid filter_reloc uninitialized variable for rela - elfcopy: avoid stripping relocations from static binaries - readelf: avoid printing directory in front of absolute path - readelf: add NT_FREEBSD_FEATURE_CTL FreeBSD note type - test improvements NOTES: Some of these changes originated in FreeBSD and simply reduce diffs between contrib and vendor. ELF Tool Chain ar is not (currently) used in FreeBSD, and there are improvements in both FreeBSD and ELF Tool Chain ar that are not in the other. Sponsored by: The FreeBSD Foundation
278 lines
7.4 KiB
Groff
278 lines
7.4 KiB
Groff
.\" Copyright (c) 2006,2008,2018 Joseph Koshy. 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 Joseph Koshy ``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 Joseph Koshy 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: gelf_xlatetof.3 3639 2018-10-14 14:07:02Z jkoshy $
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.\"
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.Dd October 11, 2018
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.Dt GELF_XLATETOF 3
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.Os
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.Sh NAME
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.Nm elf32_xlate ,
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.Nm elf64_xlate ,
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.Nm gelf_xlate
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.Nd translate data between files and memory
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.Sh LIBRARY
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.Lb libelf
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.Sh SYNOPSIS
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.In libelf.h
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.Ft "Elf_Data *"
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.Fn elf32_xlatetof "Elf_Data *dst" "Elf_Data *src" "unsigned int file_encoding"
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.Ft "Elf_Data *"
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.Fn elf32_xlatetom "Elf_Data *dst" "Elf_Data *src" "unsigned int file_encoding"
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.Ft "Elf_Data *"
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.Fn elf64_xlatetof "Elf_Data *dst" "Elf_Data *src" "unsigned int file_encoding"
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.Ft "Elf_Data *"
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.Fn elf64_xlatetom "Elf_Data *dst" "Elf_Data *src" "unsigned int file_encoding"
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.In gelf.h
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.Ft "Elf_Data *"
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.Fo gelf_xlatetof
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.Fa "Elf *elf"
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.Fa "Elf_Data *dst"
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.Fa "Elf_Data *src"
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.Fa "unsigned int file_encoding"
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.Fc
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.Ft "Elf_Data *"
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.Fo gelf_xlatetom
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.Fa "Elf *elf"
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.Fa "Elf_Data *dst"
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.Fa "Elf_Data *src"
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.Fa "unsigned int file_encoding"
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.Fc
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.Sh DESCRIPTION
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These functions translate between the file and memory representations
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of ELF data structures.
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The in-memory representation of an ELF data structure would conform to
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the byte ordering and data alignment restrictions dictated by the host
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processor.
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As described in
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.Xr elf 3 ,
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the file representation of this data structure could use a different byte
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ordering from that of the host, or could use a different layout within
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the file.
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.Pp
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Functions
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.Fn elf32_xlatetom ,
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.Fn elf64_xlatetom ,
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and
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.Fn gelf_xlatetom
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translate data from file representations to native, in-memory representations.
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Functions
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.Fn elf32_xlatetof ,
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.Fn elf64_xlatetof ,
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and
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.Fn gelf_xlatetof
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translate data from in-memory representations to file representations.
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.Pp
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Argument
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.Ar src
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denotes an
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.Vt Elf_Data
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descriptor describing the source to be translated.
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The following elements of the descriptor need to be set before
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invoking these functions:
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.Bl -hang -offset indent
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.It Va d_buf
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Set to a valid pointer value denoting the beginning of the data area
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to be translated.
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.It Va d_size
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Set to the total size in bytes of the source data area to be
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translated.
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.It Va d_type
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Set to the type of the source data being translated.
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This value is one of the values defined in the
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.Vt Elf_Type
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enumeration.
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The
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.Vt Elf_Type
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enumeration is described in
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.Xr elf 3 .
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.It Va d_version
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Set to the version number of the ELF data structures being
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translated.
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Currently only version
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.Dv EV_CURRENT
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is supported.
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.El
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.Pp
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Argument
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.Ar dst
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describes the destination buffer.
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The following elements of the
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.Vt Elf_Data
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descriptor need to be set before invoking these functions:
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.Bl -hang -offset indent
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.It Va d_buf
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Set to a valid pointer value that denotes the start of the destination
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buffer that will hold translated data.
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This value may be the same as that of the source buffer, in which case
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an in-place conversion will be attempted.
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.It Va d_size
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Set to the size of the destination buffer in bytes.
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This value will be modified if the function call succeeds.
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.It Va d_version
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Set to the desired version number of the destination.
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Currently only version
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.Dv EV_CURRENT
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is supported.
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.El
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.Pp
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These translations routines allow the source and destination buffers
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to coincide, in which case an in-place translation will be done
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if the destination is large enough to hold the translated data.
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Other kinds of overlap between the source and destination buffers
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are not permitted.
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.Pp
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On successful completion of the translation request the following
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fields of the
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.Ar dst
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descriptor would be modified:
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.Bl -hang -offset indent
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.It Va d_size
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Set to the size in bytes of the translated data.
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.It Va d_type
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Set to the
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.Va d_type
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value of the source data descriptor.
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.El
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.Pp
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Argument
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.Ar file_encoding
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specifies the encoding in which the file objects are represented.
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It must be one of:
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.Bl -hang -offset indent
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.It Dv ELFDATANONE
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File objects use the library's native byte ordering.
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.It Dv ELFDATA2LSB
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File objects use a little-endian ordering.
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.It Dv ELFDATA2MSB
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File objects use a big-endian ordering.
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.El
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.Pp
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The functions
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.Fn gelf_xlatetof
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and
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.Fn gelf_xlatetom
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select the appropriate translation scheme based on the properties of
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argument
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.Ar elf .
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.Sh RETURN VALUES
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These functions return argument
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.Ar dst
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if successful, or NULL in case of an error.
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.Sh EXAMPLES
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To translate a
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.Vt GElf_Rel
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structure to its LSB file representation use:
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.Bd -literal -offset indent
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Elf_Data dst, src;
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GElf_Rel rel;
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Elf *e;
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e = ...; /* See elf_begin(3). */
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/* Set up the 'src' descriptor. */
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memset(&src, 0, sizeof src);
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src.d_buf = &rel;
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src.d_size = sizeof(rel);
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src.d_type = ELF_T_REL;
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src.d_version = EV_CURRENT;
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/* Set up the 'dst' descriptor. */
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memset(&dst, 0, sizeof dst);
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dst.d_buf = filebuf;
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dst.d_size = gelf_fsize(e, ELF_T_REL, 1, EV_CURRENT);
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dst.d_version = EV_CURRENT;
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if (gelf_xlatetof(e, &dst, &src, ELFDATA2LSB) == NULL) {
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printf("error: %s", elf_errmsg(0));
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}
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.Ed
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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 "[ELF_E_RESOURCE]"
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.It Bq Er ELF_E_ARGUMENT
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One of arguments
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.Ar src ,
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.Ar dst
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or
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.Ar elf
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was NULL.
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.It Bq Er ELF_E_ARGUMENT
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Arguments
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.Ar src
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and
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.Ar dst
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were equal.
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.It Bq Er ELF_E_ARGUMENT
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The desired encoding parameter was not one of
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.Dv ELFDATANONE ,
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.Dv ELFDATA2LSB
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or
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.Dv ELFDATA2MSB .
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.It Bq Er ELF_E_ARGUMENT
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The
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.Ar d_type
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field of argument
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.Ar src
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specified an unsupported type.
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.It Bq Er ELF_E_DATA
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The
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.Ar src
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argument specified a buffer size that was not an integral multiple of
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its underlying type.
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.It Bq Er ELF_E_DATA
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The
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.Ar dst
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argument specified a buffer size that was too small.
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.It Bq Er ELF_E_DATA
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Argument
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.Ar dst
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specified a destination buffer that overlaps with the source
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buffer.
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.It Bq Er ELF_E_DATA
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The destination buffer for a conversion to memory had an alignment
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inappropriate for the underlying ELF type.
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.It Bq Er ELF_E_DATA
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The source buffer for a conversion to file had an alignment
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inappropriate for the underlying ELF type.
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.It Bq Er ELF_E_UNIMPL
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The version numbers for arguments
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.Ar dst
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and
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.Ar src
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were not identical.
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.It Bq Er ELF_E_UNIMPL
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The argument
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.Ar src
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requested conversion for a type which is not currently
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supported.
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.It Bq Er ELF_E_VERSION
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Argument
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.Ar src
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specified an unsupported version number.
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.El
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.Sh SEE ALSO
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.Xr elf 3 ,
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.Xr elf_getdata 3 ,
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.Xr gelf 3
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