elf_strptr.c revision 4484
14484Sbinkertn@umich.edu/*- 24484Sbinkertn@umich.edu * Copyright (c) 2006 Joseph Koshy 34484Sbinkertn@umich.edu * All rights reserved. 44484Sbinkertn@umich.edu * 54484Sbinkertn@umich.edu * Redistribution and use in source and binary forms, with or without 64484Sbinkertn@umich.edu * modification, are permitted provided that the following conditions 74484Sbinkertn@umich.edu * are met: 84484Sbinkertn@umich.edu * 1. Redistributions of source code must retain the above copyright 94484Sbinkertn@umich.edu * notice, this list of conditions and the following disclaimer. 104484Sbinkertn@umich.edu * 2. Redistributions in binary form must reproduce the above copyright 114484Sbinkertn@umich.edu * notice, this list of conditions and the following disclaimer in the 124484Sbinkertn@umich.edu * documentation and/or other materials provided with the distribution. 134484Sbinkertn@umich.edu * 144484Sbinkertn@umich.edu * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 154484Sbinkertn@umich.edu * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 164484Sbinkertn@umich.edu * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 174484Sbinkertn@umich.edu * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 184484Sbinkertn@umich.edu * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 194484Sbinkertn@umich.edu * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 204484Sbinkertn@umich.edu * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 214484Sbinkertn@umich.edu * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 224484Sbinkertn@umich.edu * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 234484Sbinkertn@umich.edu * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 244484Sbinkertn@umich.edu * SUCH DAMAGE. 254484Sbinkertn@umich.edu */ 264484Sbinkertn@umich.edu 274484Sbinkertn@umich.edu 284484Sbinkertn@umich.edu#include <sys/param.h> 294484Sbinkertn@umich.edu 304484Sbinkertn@umich.edu#include <assert.h> 314484Sbinkertn@umich.edu#include "gelf.h" 324484Sbinkertn@umich.edu 334484Sbinkertn@umich.edu#include "_libelf.h" 344484Sbinkertn@umich.edu 354484Sbinkertn@umich.edu/* 364484Sbinkertn@umich.edu * Convert an ELF section#,offset pair to a string pointer. 374484Sbinkertn@umich.edu */ 384484Sbinkertn@umich.edu 394484Sbinkertn@umich.educhar * 404484Sbinkertn@umich.eduelf_strptr(Elf *e, size_t scndx, size_t offset) 414484Sbinkertn@umich.edu{ 424484Sbinkertn@umich.edu Elf_Scn *s; 434484Sbinkertn@umich.edu Elf_Data *d; 444484Sbinkertn@umich.edu size_t alignment, count; 454484Sbinkertn@umich.edu GElf_Shdr shdr; 464484Sbinkertn@umich.edu 474484Sbinkertn@umich.edu if (e == NULL || e->e_kind != ELF_K_ELF) { 484484Sbinkertn@umich.edu LIBELF_SET_ERROR(ARGUMENT, 0); 494484Sbinkertn@umich.edu return (NULL); 504484Sbinkertn@umich.edu } 514484Sbinkertn@umich.edu 524484Sbinkertn@umich.edu if ((s = elf_getscn(e, scndx)) == NULL || 534484Sbinkertn@umich.edu gelf_getshdr(s, &shdr) == NULL) 544484Sbinkertn@umich.edu return (NULL); 554484Sbinkertn@umich.edu 564484Sbinkertn@umich.edu if (shdr.sh_type != SHT_STRTAB || 574484Sbinkertn@umich.edu offset >= shdr.sh_size) { 584484Sbinkertn@umich.edu LIBELF_SET_ERROR(ARGUMENT, 0); 594484Sbinkertn@umich.edu return (NULL); 604484Sbinkertn@umich.edu } 614484Sbinkertn@umich.edu 624484Sbinkertn@umich.edu d = NULL; 634484Sbinkertn@umich.edu if (e->e_flags & ELF_F_LAYOUT) { 644484Sbinkertn@umich.edu 654484Sbinkertn@umich.edu /* 664484Sbinkertn@umich.edu * The application is taking responsibility for the 674484Sbinkertn@umich.edu * ELF object's layout, so we can directly translate 684484Sbinkertn@umich.edu * an offset to a `char *' address using the `d_off' 694484Sbinkertn@umich.edu * members of Elf_Data descriptors. 704484Sbinkertn@umich.edu */ 714484Sbinkertn@umich.edu while ((d = elf_getdata(s, d)) != NULL) { 724484Sbinkertn@umich.edu 734484Sbinkertn@umich.edu if (d->d_buf == 0 || d->d_size == 0) 744484Sbinkertn@umich.edu continue; 754484Sbinkertn@umich.edu 764484Sbinkertn@umich.edu if (d->d_type != ELF_T_BYTE) { 774484Sbinkertn@umich.edu LIBELF_SET_ERROR(DATA, 0); 784484Sbinkertn@umich.edu return (NULL); 794484Sbinkertn@umich.edu } 804484Sbinkertn@umich.edu 814484Sbinkertn@umich.edu if (offset >= d->d_off && 824484Sbinkertn@umich.edu offset < d->d_off + d->d_size) 834484Sbinkertn@umich.edu return ((char *) d->d_buf + offset - d->d_off); 844484Sbinkertn@umich.edu } 854484Sbinkertn@umich.edu } else { 864484Sbinkertn@umich.edu /* 874484Sbinkertn@umich.edu * Otherwise, the `d_off' members are not useable and 884484Sbinkertn@umich.edu * we need to compute offsets ourselves, taking into 894484Sbinkertn@umich.edu * account 'holes' in coverage of the section introduced 904484Sbinkertn@umich.edu * by alignment requirements. 914484Sbinkertn@umich.edu */ 924484Sbinkertn@umich.edu count = (size_t) 0; /* cumulative count of bytes seen */ 934484Sbinkertn@umich.edu while ((d = elf_getdata(s, d)) != NULL && count <= offset) { 944484Sbinkertn@umich.edu 954484Sbinkertn@umich.edu if (d->d_buf == NULL || d->d_size == 0) 964484Sbinkertn@umich.edu continue; 974484Sbinkertn@umich.edu 984484Sbinkertn@umich.edu if (d->d_type != ELF_T_BYTE) { 994484Sbinkertn@umich.edu LIBELF_SET_ERROR(DATA, 0); 1004484Sbinkertn@umich.edu return (NULL); 1014484Sbinkertn@umich.edu } 1024484Sbinkertn@umich.edu 1034484Sbinkertn@umich.edu if ((alignment = d->d_align) > 1) { 1044484Sbinkertn@umich.edu if ((alignment & (alignment - 1)) != 0) { 1054484Sbinkertn@umich.edu LIBELF_SET_ERROR(DATA, 0); 1064484Sbinkertn@umich.edu return (NULL); 1074484Sbinkertn@umich.edu } 1084484Sbinkertn@umich.edu count = roundup(count, alignment); 1094484Sbinkertn@umich.edu } 1104484Sbinkertn@umich.edu 1114484Sbinkertn@umich.edu if (offset < count) { 1124484Sbinkertn@umich.edu /* offset starts in the 'hole' */ 1134484Sbinkertn@umich.edu LIBELF_SET_ERROR(ARGUMENT, 0); 1144484Sbinkertn@umich.edu return (NULL); 1154484Sbinkertn@umich.edu } 1164484Sbinkertn@umich.edu 1174484Sbinkertn@umich.edu if (offset < count + d->d_size) { 1184484Sbinkertn@umich.edu if (d->d_buf != NULL) 1194484Sbinkertn@umich.edu return ((char *) d->d_buf + 1204484Sbinkertn@umich.edu offset - count); 1214484Sbinkertn@umich.edu LIBELF_SET_ERROR(DATA, 0); 1224484Sbinkertn@umich.edu return (NULL); 1234484Sbinkertn@umich.edu } 1244484Sbinkertn@umich.edu 1254484Sbinkertn@umich.edu count += d->d_size; 1264484Sbinkertn@umich.edu } 1274484Sbinkertn@umich.edu } 1284484Sbinkertn@umich.edu 1294484Sbinkertn@umich.edu LIBELF_SET_ERROR(ARGUMENT, 0); 1304484Sbinkertn@umich.edu return (NULL); 1314484Sbinkertn@umich.edu} 132