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574 lines
17 KiB
574 lines
17 KiB
/* Return the next data element from the section after possibly converting it.
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Copyright (C) 1998-2005, 2006, 2007, 2015, 2016 Red Hat, Inc.
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This file is part of elfutils.
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Written by Ulrich Drepper <drepper@redhat.com>, 1998.
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This file is free software; you can redistribute it and/or modify
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it under the terms of either
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at
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your option) any later version
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or
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* the GNU General Public License as published by the Free
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Software Foundation; either version 2 of the License, or (at
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your option) any later version
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or both in parallel, as here.
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elfutils is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received copies of the GNU General Public License and
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the GNU Lesser General Public License along with this program. If
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not, see <http://www.gnu.org/licenses/>. */
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#ifdef HAVE_CONFIG_H
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# include <config.h>
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#endif
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#include <errno.h>
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#include <stddef.h>
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#include <string.h>
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#include <unistd.h>
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#include "libelfP.h"
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#include <system.h>
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#include "common.h"
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#include "elf-knowledge.h"
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#define TYPEIDX(Sh_Type) \
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(Sh_Type >= SHT_NULL && Sh_Type < SHT_NUM \
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? Sh_Type \
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: (Sh_Type >= SHT_GNU_HASH && Sh_Type <= SHT_HISUNW \
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? SHT_NUM + Sh_Type - SHT_GNU_HASH \
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: 0))
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/* Associate section types with libelf types. */
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static const Elf_Type shtype_map[TYPEIDX (SHT_HISUNW) + 1] =
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{
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[SHT_SYMTAB] = ELF_T_SYM,
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[SHT_RELA] = ELF_T_RELA,
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[SHT_HASH] = ELF_T_WORD,
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[SHT_DYNAMIC] = ELF_T_DYN,
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[SHT_REL] = ELF_T_REL,
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[SHT_DYNSYM] = ELF_T_SYM,
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[SHT_INIT_ARRAY] = ELF_T_ADDR,
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[SHT_FINI_ARRAY] = ELF_T_ADDR,
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[SHT_PREINIT_ARRAY] = ELF_T_ADDR,
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[SHT_GROUP] = ELF_T_WORD,
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[SHT_SYMTAB_SHNDX] = ELF_T_WORD,
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[SHT_NOTE] = ELF_T_NHDR, /* Need alignment to guess ELF_T_NHDR8. */
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[TYPEIDX (SHT_GNU_verdef)] = ELF_T_VDEF,
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[TYPEIDX (SHT_GNU_verneed)] = ELF_T_VNEED,
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[TYPEIDX (SHT_GNU_versym)] = ELF_T_HALF,
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[TYPEIDX (SHT_SUNW_syminfo)] = ELF_T_SYMINFO,
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[TYPEIDX (SHT_SUNW_move)] = ELF_T_MOVE,
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[TYPEIDX (SHT_GNU_LIBLIST)] = ELF_T_LIB,
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[TYPEIDX (SHT_GNU_HASH)] = ELF_T_GNUHASH,
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};
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/* Associate libelf types with their internal alignment requirements. */
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const uint_fast8_t __libelf_type_aligns[ELFCLASSNUM - 1][ELF_T_NUM] =
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{
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# define TYPE_ALIGNS(Bits) \
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{ \
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[ELF_T_ADDR] = __alignof__ (ElfW2(Bits,Addr)), \
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[ELF_T_EHDR] = __alignof__ (ElfW2(Bits,Ehdr)), \
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[ELF_T_HALF] = __alignof__ (ElfW2(Bits,Half)), \
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[ELF_T_OFF] = __alignof__ (ElfW2(Bits,Off)), \
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[ELF_T_PHDR] = __alignof__ (ElfW2(Bits,Phdr)), \
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[ELF_T_SHDR] = __alignof__ (ElfW2(Bits,Shdr)), \
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[ELF_T_SWORD] = __alignof__ (ElfW2(Bits,Sword)), \
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[ELF_T_WORD] = __alignof__ (ElfW2(Bits,Word)), \
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[ELF_T_XWORD] = __alignof__ (ElfW2(Bits,Xword)), \
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[ELF_T_SXWORD] = __alignof__ (ElfW2(Bits,Sxword)), \
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[ELF_T_SYM] = __alignof__ (ElfW2(Bits,Sym)), \
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[ELF_T_SYMINFO] = __alignof__ (ElfW2(Bits,Syminfo)), \
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[ELF_T_REL] = __alignof__ (ElfW2(Bits,Rel)), \
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[ELF_T_RELA] = __alignof__ (ElfW2(Bits,Rela)), \
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[ELF_T_DYN] = __alignof__ (ElfW2(Bits,Dyn)), \
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[ELF_T_VDEF] = __alignof__ (ElfW2(Bits,Verdef)), \
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[ELF_T_VDAUX] = __alignof__ (ElfW2(Bits,Verdaux)), \
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[ELF_T_VNEED] = __alignof__ (ElfW2(Bits,Verneed)), \
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[ELF_T_VNAUX] = __alignof__ (ElfW2(Bits,Vernaux)), \
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[ELF_T_MOVE] = __alignof__ (ElfW2(Bits,Move)), \
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[ELF_T_LIB] = __alignof__ (ElfW2(Bits,Lib)), \
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[ELF_T_NHDR] = __alignof__ (ElfW2(Bits,Nhdr)), \
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[ELF_T_GNUHASH] = __alignof__ (Elf32_Word), \
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[ELF_T_AUXV] = __alignof__ (ElfW2(Bits,auxv_t)), \
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[ELF_T_CHDR] = __alignof__ (ElfW2(Bits,Chdr)), \
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[ELF_T_NHDR8] = 8 /* Special case for GNU Property note. */ \
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}
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[ELFCLASS32 - 1] = TYPE_ALIGNS (32),
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[ELFCLASS64 - 1] = TYPE_ALIGNS (64),
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# undef TYPE_ALIGNS
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};
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Elf_Type
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internal_function
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__libelf_data_type (GElf_Ehdr *ehdr, int sh_type, GElf_Xword align)
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{
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/* Some broken ELF ABI for 64-bit machines use the wrong hash table
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entry size. See elf-knowledge.h for more information. */
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if (sh_type == SHT_HASH && ehdr->e_ident[EI_CLASS] == ELFCLASS64)
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{
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return (SH_ENTSIZE_HASH (ehdr) == 4 ? ELF_T_WORD : ELF_T_XWORD);
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}
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else
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{
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Elf_Type t = shtype_map[TYPEIDX (sh_type)];
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/* Special case for GNU Property notes. */
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if (t == ELF_T_NHDR && align == 8)
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t = ELF_T_NHDR8;
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return t;
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}
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}
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/* Convert the data in the current section. */
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static void
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convert_data (Elf_Scn *scn, int eclass,
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int data, size_t size, Elf_Type type)
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{
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const size_t align = __libelf_type_align (eclass, type);
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/* Do we need to convert the data and/or adjust for alignment? */
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if (data == MY_ELFDATA || type == ELF_T_BYTE)
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{
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if (((((size_t) (char *) scn->rawdata_base)) & (align - 1)) == 0)
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/* No need to copy, we can use the raw data. */
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scn->data_base = scn->rawdata_base;
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else
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{
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scn->data_base = (char *) malloc (size);
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if (scn->data_base == NULL)
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{
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__libelf_seterrno (ELF_E_NOMEM);
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return;
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}
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/* The copy will be appropriately aligned for direct access. */
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memcpy (scn->data_base, scn->rawdata_base, size);
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}
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}
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else
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{
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xfct_t fp;
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scn->data_base = (char *) malloc (size);
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if (scn->data_base == NULL)
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{
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__libelf_seterrno (ELF_E_NOMEM);
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return;
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}
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/* Make sure the source is correctly aligned for the conversion
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function to directly access the data elements. */
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char *rawdata_source;
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if (((((size_t) (char *) scn->rawdata_base)) & (align - 1)) == 0)
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rawdata_source = scn->rawdata_base;
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else
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{
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rawdata_source = (char *) malloc (size);
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if (rawdata_source == NULL)
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{
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__libelf_seterrno (ELF_E_NOMEM);
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return;
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}
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/* The copy will be appropriately aligned for direct access. */
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memcpy (rawdata_source, scn->rawdata_base, size);
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}
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/* Get the conversion function. */
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fp = __elf_xfctstom[eclass - 1][type];
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fp (scn->data_base, rawdata_source, size, 0);
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if (rawdata_source != scn->rawdata_base)
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free (rawdata_source);
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}
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scn->data_list.data.d.d_buf = scn->data_base;
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scn->data_list.data.d.d_size = size;
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scn->data_list.data.d.d_type = type;
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scn->data_list.data.d.d_off = scn->rawdata.d.d_off;
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scn->data_list.data.d.d_align = scn->rawdata.d.d_align;
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scn->data_list.data.d.d_version = scn->rawdata.d.d_version;
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scn->data_list.data.s = scn;
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}
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/* Store the information for the raw data in the `rawdata' element. */
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int
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internal_function
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__libelf_set_rawdata_wrlock (Elf_Scn *scn)
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{
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Elf64_Off offset;
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Elf64_Xword size;
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Elf64_Xword align;
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Elf64_Xword flags;
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int type;
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Elf *elf = scn->elf;
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if (elf->class == ELFCLASS32)
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{
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Elf32_Shdr *shdr
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= scn->shdr.e32 ?: __elf32_getshdr_wrlock (scn);
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if (shdr == NULL)
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/* Something went terribly wrong. */
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return 1;
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offset = shdr->sh_offset;
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size = shdr->sh_size;
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type = shdr->sh_type;
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align = shdr->sh_addralign;
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flags = shdr->sh_flags;
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}
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else
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{
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Elf64_Shdr *shdr
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= scn->shdr.e64 ?: __elf64_getshdr_wrlock (scn);
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if (shdr == NULL)
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/* Something went terribly wrong. */
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return 1;
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offset = shdr->sh_offset;
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size = shdr->sh_size;
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type = shdr->sh_type;
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align = shdr->sh_addralign;
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flags = shdr->sh_flags;
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}
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/* If the section has no data (for whatever reason), leave the `d_buf'
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pointer NULL. */
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if (size != 0 && type != SHT_NOBITS)
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{
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/* First a test whether the section is valid at all. */
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size_t entsize;
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/* Compressed data has a header, but then compressed data.
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Make sure to set the alignment of the header explicitly,
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don't trust the file alignment for the section, it is
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often wrong. */
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if ((flags & SHF_COMPRESSED) != 0)
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{
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entsize = 1;
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align = __libelf_type_align (elf->class, ELF_T_CHDR);
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}
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else if (type == SHT_HASH)
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{
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GElf_Ehdr ehdr_mem;
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GElf_Ehdr *ehdr = __gelf_getehdr_rdlock (elf, &ehdr_mem);
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if (unlikely (ehdr == NULL))
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return 1;
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entsize = SH_ENTSIZE_HASH (ehdr);
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}
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else
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{
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Elf_Type t = shtype_map[TYPEIDX (type)];
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if (t == ELF_T_NHDR && align == 8)
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t = ELF_T_NHDR8;
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if (t == ELF_T_VDEF || t == ELF_T_NHDR || t == ELF_T_NHDR8
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|| (t == ELF_T_GNUHASH && elf->class == ELFCLASS64))
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entsize = 1;
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else
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entsize = __libelf_type_sizes[elf->class - 1][t];
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}
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/* We assume it is an array of bytes if it is none of the structured
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sections we know of. */
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if (entsize == 0)
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entsize = 1;
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if (unlikely (size % entsize != 0))
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{
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__libelf_seterrno (ELF_E_INVALID_DATA);
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return 1;
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}
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/* We can use the mapped or loaded data if available. */
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if (elf->map_address != NULL)
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{
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/* First see whether the information in the section header is
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valid and it does not ask for too much. Check for unsigned
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overflow. */
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if (unlikely (offset > elf->maximum_size
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|| elf->maximum_size - offset < size))
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{
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/* Something is wrong. */
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__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
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return 1;
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}
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scn->rawdata_base = scn->rawdata.d.d_buf
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= (char *) elf->map_address + elf->start_offset + offset;
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}
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else if (likely (elf->fildes != -1))
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{
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/* First see whether the information in the section header is
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valid and it does not ask for too much. Check for unsigned
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overflow. */
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if (unlikely (offset > elf->maximum_size
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|| elf->maximum_size - offset < size))
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{
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/* Something is wrong. */
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__libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);
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return 1;
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}
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/* We have to read the data from the file. Allocate the needed
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memory. */
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scn->rawdata_base = scn->rawdata.d.d_buf
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= (char *) malloc (size);
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if (scn->rawdata.d.d_buf == NULL)
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{
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__libelf_seterrno (ELF_E_NOMEM);
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return 1;
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}
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ssize_t n = pread_retry (elf->fildes, scn->rawdata.d.d_buf, size,
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elf->start_offset + offset);
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if (unlikely ((size_t) n != size))
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{
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/* Cannot read the data. */
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free (scn->rawdata.d.d_buf);
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scn->rawdata_base = scn->rawdata.d.d_buf = NULL;
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__libelf_seterrno (ELF_E_READ_ERROR);
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return 1;
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}
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}
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else
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{
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/* The file descriptor is already closed, we cannot get the data
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anymore. */
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__libelf_seterrno (ELF_E_FD_DISABLED);
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return 1;
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}
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}
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scn->rawdata.d.d_size = size;
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/* Compressed data always has type ELF_T_CHDR regardless of the
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section type. */
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if ((flags & SHF_COMPRESSED) != 0)
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scn->rawdata.d.d_type = ELF_T_CHDR;
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else
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{
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GElf_Ehdr ehdr_mem;
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GElf_Ehdr *ehdr = __gelf_getehdr_rdlock (elf, &ehdr_mem);
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if (unlikely (ehdr == NULL))
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return 1;
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scn->rawdata.d.d_type = __libelf_data_type (ehdr, type, align);
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}
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scn->rawdata.d.d_off = 0;
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/* Make sure the alignment makes sense. d_align should be aligned both
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in the section (trivially true since d_off is zero) and in the file.
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Unfortunately we cannot be too strict because there are ELF files
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out there that fail this requirement. We will try to fix those up
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in elf_update when writing out the image. But for very large
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alignment values this can bloat the image considerably. So here
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just check and clamp the alignment value to not be bigger than the
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actual offset of the data in the file. Given that there is always
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at least an ehdr this will only trigger for alignment values > 64
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which should be uncommon. */
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align = align ?: 1;
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if (type != SHT_NOBITS && align > offset)
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align = offset;
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scn->rawdata.d.d_align = align;
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if (elf->class == ELFCLASS32
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|| (offsetof (struct Elf, state.elf32.ehdr)
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== offsetof (struct Elf, state.elf64.ehdr)))
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scn->rawdata.d.d_version =
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elf->state.elf32.ehdr->e_ident[EI_VERSION];
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else
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scn->rawdata.d.d_version =
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elf->state.elf64.ehdr->e_ident[EI_VERSION];
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scn->rawdata.s = scn;
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scn->data_read = 1;
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/* We actually read data from the file. At least we tried. */
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scn->flags |= ELF_F_FILEDATA;
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return 0;
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}
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int
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internal_function
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__libelf_set_rawdata (Elf_Scn *scn)
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{
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int result;
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if (scn == NULL)
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return 1;
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rwlock_wrlock (scn->elf->lock);
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result = __libelf_set_rawdata_wrlock (scn);
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rwlock_unlock (scn->elf->lock);
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return result;
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}
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void
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internal_function
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__libelf_set_data_list_rdlock (Elf_Scn *scn, int wrlocked)
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{
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if (scn->rawdata.d.d_buf != NULL && scn->rawdata.d.d_size > 0)
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{
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Elf *elf = scn->elf;
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/* Upgrade the lock to a write lock if necessary and check
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nobody else already did the work. */
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if (!wrlocked)
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{
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rwlock_unlock (elf->lock);
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rwlock_wrlock (elf->lock);
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if (scn->data_list_rear != NULL)
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return;
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}
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/* Convert according to the version and the type. */
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convert_data (scn, elf->class,
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(elf->class == ELFCLASS32
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|| (offsetof (struct Elf, state.elf32.ehdr)
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== offsetof (struct Elf, state.elf64.ehdr))
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? elf->state.elf32.ehdr->e_ident[EI_DATA]
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: elf->state.elf64.ehdr->e_ident[EI_DATA]),
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scn->rawdata.d.d_size, scn->rawdata.d.d_type);
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}
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else
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{
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/* This is an empty or NOBITS section. There is no buffer but
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the size information etc is important. */
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scn->data_list.data.d = scn->rawdata.d;
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scn->data_list.data.s = scn;
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}
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scn->data_list_rear = &scn->data_list;
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}
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Elf_Data *
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internal_function
|
|
__elf_getdata_rdlock (Elf_Scn *scn, Elf_Data *data)
|
|
{
|
|
Elf_Data *result = NULL;
|
|
Elf *elf;
|
|
int locked = 0;
|
|
|
|
if (scn == NULL)
|
|
return NULL;
|
|
|
|
if (unlikely (scn->elf->kind != ELF_K_ELF))
|
|
{
|
|
__libelf_seterrno (ELF_E_INVALID_HANDLE);
|
|
return NULL;
|
|
}
|
|
|
|
/* We will need this multiple times later on. */
|
|
elf = scn->elf;
|
|
|
|
/* If `data' is not NULL this means we are not addressing the initial
|
|
data in the file. But this also means this data is already read
|
|
(since otherwise it is not possible to have a valid `data' pointer)
|
|
and all the data structures are initialized as well. In this case
|
|
we can simply walk the list of data records. */
|
|
if (data != NULL)
|
|
{
|
|
Elf_Data_List *runp;
|
|
|
|
/* It is not possible that if DATA is not NULL the first entry is
|
|
returned. But this also means that there must be a first data
|
|
entry. */
|
|
if (scn->data_list_rear == NULL
|
|
/* The section the reference data is for must match the section
|
|
parameter. */
|
|
|| unlikely (((Elf_Data_Scn *) data)->s != scn))
|
|
{
|
|
__libelf_seterrno (ELF_E_DATA_MISMATCH);
|
|
goto out;
|
|
}
|
|
|
|
/* We start searching with the first entry. */
|
|
runp = &scn->data_list;
|
|
|
|
while (1)
|
|
{
|
|
/* If `data' does not match any known record punt. */
|
|
if (runp == NULL)
|
|
{
|
|
__libelf_seterrno (ELF_E_DATA_MISMATCH);
|
|
goto out;
|
|
}
|
|
|
|
if (&runp->data.d == data)
|
|
/* Found the entry. */
|
|
break;
|
|
|
|
runp = runp->next;
|
|
}
|
|
|
|
/* Return the data for the next data record. */
|
|
result = runp->next ? &runp->next->data.d : NULL;
|
|
goto out;
|
|
}
|
|
|
|
/* If the data for this section was not yet initialized do it now. */
|
|
if (scn->data_read == 0)
|
|
{
|
|
/* We cannot acquire a write lock while we are holding a read
|
|
lock. Therefore give up the read lock and then get the write
|
|
lock. But this means that the data could meanwhile be
|
|
modified, therefore start the tests again. */
|
|
rwlock_unlock (elf->lock);
|
|
rwlock_wrlock (elf->lock);
|
|
locked = 1;
|
|
|
|
/* Read the data from the file. There is always a file (or
|
|
memory region) associated with this descriptor since
|
|
otherwise the `data_read' flag would be set. */
|
|
if (scn->data_read == 0 && __libelf_set_rawdata_wrlock (scn) != 0)
|
|
/* Something went wrong. The error value is already set. */
|
|
goto out;
|
|
}
|
|
|
|
/* At this point we know the raw data is available. But it might be
|
|
empty in case the section has size zero (for whatever reason).
|
|
Now create the converted data in case this is necessary. */
|
|
if (scn->data_list_rear == NULL)
|
|
__libelf_set_data_list_rdlock (scn, locked);
|
|
|
|
/* Return the first data element in the list. */
|
|
result = &scn->data_list.data.d;
|
|
|
|
out:
|
|
return result;
|
|
}
|
|
|
|
Elf_Data *
|
|
elf_getdata (Elf_Scn *scn, Elf_Data *data)
|
|
{
|
|
Elf_Data *result;
|
|
|
|
if (scn == NULL)
|
|
return NULL;
|
|
|
|
rwlock_rdlock (scn->elf->lock);
|
|
result = __elf_getdata_rdlock (scn, data);
|
|
rwlock_unlock (scn->elf->lock);
|
|
|
|
return result;
|
|
}
|
|
INTDEF(elf_getdata)
|