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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2010 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
/* Copyright (c) 1987, 1988 Microsoft Corporation */
/* All Rights Reserved */
#include <errno.h>
#include <libelf.h>
#include "decl.h"
#include "msg.h"
/*
* Routines for generating a checksum for an elf image. Typically used to create
* a DT_CHECKSUM entry. This checksum is intended to remain constant after
* operations such as strip(1)/mcs(1), thus only allocatable sections are
* processed, and of those, any that might be modified by these external
* commands are skipped.
*/
#define MSW(l) (((l) >> 16) & 0x0000ffffL)
#define LSW(l) ((l) & 0x0000ffffL)
/*
* update and epilogue sum functions (stolen from libcmd)
*/
static long
sumupd(long sum, char *cp, unsigned long cnt)
{
if ((cp == 0) || (cnt == 0))
return (sum);
while (cnt--)
sum += *cp++ & 0x00ff;
return (sum);
}
static long
sumepi(long sum)
{
long _sum;
_sum = LSW(sum) + MSW(sum);
return ((ushort_t)(LSW(_sum) + MSW(_sum)));
}
/*
* This module is compiled twice, the second time having
* -D_ELF64 defined. The following set of macros represent
* the differences between the two compilations. Be
* careful *not* to add any class dependent code (anything
* that has elf32 or elf64 in the name) to this code
* without hiding it behind a switchable macro like these.
*/
#if defined(_ELF64)
#define elf_checksum elf64_checksum
#define Elf_Ehdr Elf64_Ehdr
#define Elf_Shdr Elf64_Shdr
#define getehdr elf64_getehdr
#define getshdr elf64_getshdr
#else /* else ELF32 */
#define elf_checksum elf32_checksum
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Shdr Elf32_Shdr
#define getehdr elf32_getehdr
#define getshdr elf32_getshdr
#endif /* ELF64 */
long
elf_checksum(Elf * elf)
{
long sum = 0;
Elf_Ehdr * ehdr;
Elf_Shdr * shdr;
Elf_Scn * scn;
Elf_Data * data, * (* getdata)(Elf_Scn *, Elf_Data *);
size_t shnum;
if ((ehdr = getehdr(elf)) == 0)
return (0);
/*
* Determine the data information to retrieve. When called from ld()
* we're processing an ELF_C_IMAGE (memory) image and thus need to use
* elf_getdata(), as there is not yet a file image (or raw data) backing
* this. When called from utilities like elfdump(1) we're processing a
* file image and thus using the elf_rawdata() allows the same byte
* stream to be processed from different architectures - presently this
* is irrelevant, as the checksum simply sums the data bytes, their
* order doesn't matter. But being uncooked is slightly less overhead.
*
* If the file is writable, the raw data will not reflect any
* changes made in the process, so the uncooked version is only
* for readonly files.
*/
if ((elf->ed_myflags & (EDF_MEMORY | EDF_WRITE)) != 0)
getdata = elf_getdata;
else
getdata = elf_rawdata;
for (shnum = 1; shnum < ehdr->e_shnum; shnum++) {
if ((scn = elf_getscn(elf, shnum)) == 0)
return (0);
if ((shdr = getshdr(scn)) == 0)
return (0);
/* Exclude strippable sections */
if (!(shdr->sh_flags & SHF_ALLOC))
continue;
/*
* Exclude allocable sections that can change:
* - The .dynsym section can contain section symbols
* that strip might remove.
* - The .dynamic section is modified by the setting of
* this checksum value.
* - The .SUNW_dof section uses ftok(3C), which returns
* different values, to define a key for the
* objects in that section.
*/
if ((shdr->sh_type == SHT_DYNSYM) ||
(shdr->sh_type == SHT_DYNAMIC) ||
(shdr->sh_type == SHT_SUNW_dof))
continue;
data = 0;
while ((data = (*getdata)(scn, data)) != 0)
sum = sumupd(sum, data->d_buf, data->d_size);
}
return (sumepi(sum));
}
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