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573456a931
GNU and Oracle libelf implementations added support for section compression, intended to reduce the size of DWARF debug info (which might be an order of magnitude larger than the code). There are two compressed ELF section formats: 1. Old GNU - sections are renmaed to start with 'z'. Section contains a magic number, uncompressed size, and compressed data. 2. Oracle and New GNU - compressed sections use the SHF_COMPRESSED flag. The compression header contains the compression type, uncompressed size, and uncompressed alignment. The second style is preferred and this change implements only that one. Submitted by: Tiger Gao <tig@FreeBSDFoundation.org> Reviewed by: markj MFC after: 2 weeks Relnotes: Yes Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D24566
118 lines
3.2 KiB
Groff
118 lines
3.2 KiB
Groff
.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2020 The FreeBSD Foundation
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.\"
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.\" This document was written by Tiger Gao under sponsorship from
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.\" the FreeBSD Foundation.
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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 are
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.\" 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
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.\" the 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: gelf_getchdr.3 3639 2020-10-20 16:07:02Z tig $
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.\"
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.Dd October 23, 2020
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.Dt GELF_GETCHDR 3
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.Os
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.Sh NAME
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.Nm elf32_getchdr ,
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.Nm elf64_getchdr ,
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.Nm gelf_getchdr
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.Nd retrieve the compression header of a section
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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 "Elf32_Chdr *"
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.Fn elf32_getchdr "Elf_Scn *s"
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.Ft "Elf64_Chdr *"
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.Fn elf64_getchdr "Elf_Scn *s"
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.In gelf.h
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.Ft "GElf_Chdr *"
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.Fn gelf_getchdr "Elf_Scn *scn" "GElf_Chdr *chdr"
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.Sh DESCRIPTION
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These functions return a pointer to the ELF Compression Header data
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structure associated with section descriptor
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.Ar scn .
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.Pp
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Function
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.Fn elf32_getchdr
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retrieves a pointer to an
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.Vt Elf32_Chdr
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structure.
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Section descriptor
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.Ar scn
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must be associated with an ELF descriptor of class
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.Dv ELFCLASS32 .
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.Pp
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Function
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.Fn elf64_getchdr
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retrieves a pointer to an
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.Vt Elf64_Chdr
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structure.
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Section descriptor
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.Ar scn
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must be associated with an ELF descriptor of class
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.Dv ELFCLASS64 .
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.Pp
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Function
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.Fn gelf_getchdr
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copies the values in the compression header associated with argument
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.Ar scn
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to the structure pointed to be argument
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.Ar dst .
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The
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.Vt GElf_Chdr
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data structure is described in
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.Xr gelf 3 .
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.Sh RETURN VALUES
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Functions
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.Fn elf32_getchdr
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and
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.Fn elf64_getchdr
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return a valid pointer to the appropriate compression header on success
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or NULL if an error was encountered.
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.Pp
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Function
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.Fn gelf_getchdr
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returns argument
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.Ar dst
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if successful, or NULL if an error was encountered.
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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_INVALID_SECTION_FLAGS
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Arguments
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.Ar scn
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has invalid flags.
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.It Bq Er ELF_E_INVALID_SECTION_TYPE
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Argument
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.Ar scn
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has invalid type.
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.It Bq Er ELF_E_NOT_COMPRESSED
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Argument
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.Ar scn
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is not compressed.
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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_getscn 3 ,
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.Xr gelf 3 ,
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