elf_strptr.c revision 4484:7c56a6c9c265
16019Shines@cs.fsu.edu/*- 27093Sgblack@eecs.umich.edu * Copyright (c) 2006 Joseph Koshy 37093Sgblack@eecs.umich.edu * All rights reserved. 47093Sgblack@eecs.umich.edu * 57093Sgblack@eecs.umich.edu * Redistribution and use in source and binary forms, with or without 67093Sgblack@eecs.umich.edu * modification, are permitted provided that the following conditions 77093Sgblack@eecs.umich.edu * are met: 87093Sgblack@eecs.umich.edu * 1. Redistributions of source code must retain the above copyright 97093Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer. 107093Sgblack@eecs.umich.edu * 2. Redistributions in binary form must reproduce the above copyright 117093Sgblack@eecs.umich.edu * notice, this list of conditions and the following disclaimer in the 127093Sgblack@eecs.umich.edu * documentation and/or other materials provided with the distribution. 137093Sgblack@eecs.umich.edu * 146019Shines@cs.fsu.edu * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 156019Shines@cs.fsu.edu * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 166019Shines@cs.fsu.edu * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 176019Shines@cs.fsu.edu * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 186019Shines@cs.fsu.edu * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 196019Shines@cs.fsu.edu * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 206019Shines@cs.fsu.edu * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 216019Shines@cs.fsu.edu * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 226019Shines@cs.fsu.edu * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 236019Shines@cs.fsu.edu * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 246019Shines@cs.fsu.edu * SUCH DAMAGE. 256019Shines@cs.fsu.edu */ 266019Shines@cs.fsu.edu 276019Shines@cs.fsu.edu 286019Shines@cs.fsu.edu#include <sys/param.h> 296019Shines@cs.fsu.edu 306019Shines@cs.fsu.edu#include <assert.h> 316019Shines@cs.fsu.edu#include "gelf.h" 326019Shines@cs.fsu.edu 336019Shines@cs.fsu.edu#include "_libelf.h" 346019Shines@cs.fsu.edu 356019Shines@cs.fsu.edu/* 366019Shines@cs.fsu.edu * Convert an ELF section#,offset pair to a string pointer. 376019Shines@cs.fsu.edu */ 386019Shines@cs.fsu.edu 396019Shines@cs.fsu.educhar * 406019Shines@cs.fsu.eduelf_strptr(Elf *e, size_t scndx, size_t offset) 416019Shines@cs.fsu.edu{ 426019Shines@cs.fsu.edu Elf_Scn *s; 436019Shines@cs.fsu.edu Elf_Data *d; 446020Sgblack@eecs.umich.edu size_t alignment, count; 456019Shines@cs.fsu.edu GElf_Shdr shdr; 466019Shines@cs.fsu.edu 476019Shines@cs.fsu.edu if (e == NULL || e->e_kind != ELF_K_ELF) { 486019Shines@cs.fsu.edu LIBELF_SET_ERROR(ARGUMENT, 0); 496019Shines@cs.fsu.edu return (NULL); 506019Shines@cs.fsu.edu } 516116Snate@binkert.org 526019Shines@cs.fsu.edu if ((s = elf_getscn(e, scndx)) == NULL || 536019Shines@cs.fsu.edu gelf_getshdr(s, &shdr) == NULL) 546019Shines@cs.fsu.edu return (NULL); 556019Shines@cs.fsu.edu 566019Shines@cs.fsu.edu if (shdr.sh_type != SHT_STRTAB || 576019Shines@cs.fsu.edu offset >= shdr.sh_size) { 586019Shines@cs.fsu.edu LIBELF_SET_ERROR(ARGUMENT, 0); 596116Snate@binkert.org return (NULL); 606116Snate@binkert.org } 616019Shines@cs.fsu.edu 626019Shines@cs.fsu.edu d = NULL; 636019Shines@cs.fsu.edu if (e->e_flags & ELF_F_LAYOUT) { 646019Shines@cs.fsu.edu 656019Shines@cs.fsu.edu /* 666019Shines@cs.fsu.edu * The application is taking responsibility for the 676019Shines@cs.fsu.edu * ELF object's layout, so we can directly translate 686019Shines@cs.fsu.edu * an offset to a `char *' address using the `d_off' 696019Shines@cs.fsu.edu * members of Elf_Data descriptors. 706019Shines@cs.fsu.edu */ 716019Shines@cs.fsu.edu while ((d = elf_getdata(s, d)) != NULL) { 726019Shines@cs.fsu.edu 736019Shines@cs.fsu.edu if (d->d_buf == 0 || d->d_size == 0) 746019Shines@cs.fsu.edu continue; 756019Shines@cs.fsu.edu 766019Shines@cs.fsu.edu if (d->d_type != ELF_T_BYTE) { 776019Shines@cs.fsu.edu LIBELF_SET_ERROR(DATA, 0); 786019Shines@cs.fsu.edu return (NULL); 796019Shines@cs.fsu.edu } 806019Shines@cs.fsu.edu 816019Shines@cs.fsu.edu if (offset >= d->d_off && 826019Shines@cs.fsu.edu offset < d->d_off + d->d_size) 836019Shines@cs.fsu.edu return ((char *) d->d_buf + offset - d->d_off); 846019Shines@cs.fsu.edu } 856019Shines@cs.fsu.edu } else { 866019Shines@cs.fsu.edu /* 876019Shines@cs.fsu.edu * Otherwise, the `d_off' members are not useable and 886019Shines@cs.fsu.edu * we need to compute offsets ourselves, taking into 896019Shines@cs.fsu.edu * account 'holes' in coverage of the section introduced 906019Shines@cs.fsu.edu * by alignment requirements. 916019Shines@cs.fsu.edu */ 926019Shines@cs.fsu.edu count = (size_t) 0; /* cumulative count of bytes seen */ 936019Shines@cs.fsu.edu while ((d = elf_getdata(s, d)) != NULL && count <= offset) { 946019Shines@cs.fsu.edu 956019Shines@cs.fsu.edu if (d->d_buf == NULL || d->d_size == 0) 966019Shines@cs.fsu.edu continue; 976019Shines@cs.fsu.edu 986019Shines@cs.fsu.edu if (d->d_type != ELF_T_BYTE) { 996019Shines@cs.fsu.edu LIBELF_SET_ERROR(DATA, 0); 1006019Shines@cs.fsu.edu return (NULL); 1016019Shines@cs.fsu.edu } 1026019Shines@cs.fsu.edu 1036019Shines@cs.fsu.edu if ((alignment = d->d_align) > 1) { 1046019Shines@cs.fsu.edu if ((alignment & (alignment - 1)) != 0) { 1056019Shines@cs.fsu.edu LIBELF_SET_ERROR(DATA, 0); 1066019Shines@cs.fsu.edu return (NULL); 1076019Shines@cs.fsu.edu } 1086019Shines@cs.fsu.edu count = roundup(count, alignment); 1096019Shines@cs.fsu.edu } 1106019Shines@cs.fsu.edu 1116019Shines@cs.fsu.edu if (offset < count) { 1126019Shines@cs.fsu.edu /* offset starts in the 'hole' */ 1136019Shines@cs.fsu.edu LIBELF_SET_ERROR(ARGUMENT, 0); 1146019Shines@cs.fsu.edu return (NULL); 1156019Shines@cs.fsu.edu } 1166019Shines@cs.fsu.edu 1176019Shines@cs.fsu.edu if (offset < count + d->d_size) { 1186019Shines@cs.fsu.edu if (d->d_buf != NULL) 1196019Shines@cs.fsu.edu return ((char *) d->d_buf + 1206019Shines@cs.fsu.edu offset - count); 1216019Shines@cs.fsu.edu LIBELF_SET_ERROR(DATA, 0); 1226019Shines@cs.fsu.edu return (NULL); 1236019Shines@cs.fsu.edu } 1246019Shines@cs.fsu.edu 1256019Shines@cs.fsu.edu count += d->d_size; 1266019Shines@cs.fsu.edu } 1276019Shines@cs.fsu.edu } 1286019Shines@cs.fsu.edu 1296019Shines@cs.fsu.edu LIBELF_SET_ERROR(ARGUMENT, 0); 1306019Shines@cs.fsu.edu return (NULL); 1316019Shines@cs.fsu.edu} 1326019Shines@cs.fsu.edu