IABSD.fr/src/lib/libelf/elf_strptr.c

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• Author : jmc
  Date : 2022-12-27 17:10:05
  Hash : 2c53affb
  Message : spelling fixes; from paul tagliamonte any changes not taken noted on tech, but chiefly here i did not take the cancelation - cancellation changes;

• lib/libelf/elf_strptr.c

• /*-
   * Copyright (c) 2006,2008 Joseph Koshy
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <assert.h>
  #include <gelf.h>
  
  #include "_libelf.h"
  
  ELFTC_VCSID("$Id: elf_strptr.c,v 1.3 2022/12/27 17:10:06 jmc Exp $");
  
  /*
   * Convert an ELF section#,offset pair to a string pointer.
   */
  
  char *
  elf_strptr(Elf *e, size_t scndx, size_t offset)
  {
  	Elf_Scn *s;
  	Elf_Data *d;
  	GElf_Shdr shdr;
  	uint64_t alignment, count;
  
  	if (e == NULL || e->e_kind != ELF_K_ELF) {
  		LIBELF_SET_ERROR(ARGUMENT, 0);
  		return (NULL);
  	}
  
  	if ((s = elf_getscn(e, scndx)) == NULL ||
  	    gelf_getshdr(s, &shdr) == NULL)
  		return (NULL);
  
  	if (shdr.sh_type != SHT_STRTAB ||
  	    offset >= shdr.sh_size) {
  		LIBELF_SET_ERROR(ARGUMENT, 0);
  		return (NULL);
  	}
  
  	d = NULL;
  	if (e->e_flags & ELF_F_LAYOUT) {
  
  		/*
  		 * The application is taking responsibility for the
  		 * ELF object's layout, so we can directly translate
  		 * an offset to a `char *' address using the `d_off'
  		 * members of Elf_Data descriptors.
  		 */
  		while ((d = elf_getdata(s, d)) != NULL) {
  
  			if (d->d_buf == 0 || d->d_size == 0)
  				continue;
  
  			if (d->d_type != ELF_T_BYTE) {
  				LIBELF_SET_ERROR(DATA, 0);
  				return (NULL);
  			}
  
  			if (offset >= d->d_off &&
  			    offset < d->d_off + d->d_size)
  				return ((char *) d->d_buf + offset - d->d_off);
  		}
  	} else {
  		/*
  		 * Otherwise, the `d_off' members are not usable and
  		 * we need to compute offsets ourselves, taking into
  		 * account 'holes' in coverage of the section introduced
  		 * by alignment requirements.
  		 */
  		count = (uint64_t) 0;	/* cumulative count of bytes seen */
  		while ((d = elf_getdata(s, d)) != NULL && count <= offset) {
  
  			if (d->d_buf == NULL || d->d_size == 0)
  				continue;
  
  			if (d->d_type != ELF_T_BYTE) {
  				LIBELF_SET_ERROR(DATA, 0);
  				return (NULL);
  			}
  
  			if ((alignment = d->d_align) > 1) {
  				if ((alignment & (alignment - 1)) != 0) {
  					LIBELF_SET_ERROR(DATA, 0);
  					return (NULL);
  				}
  				count = roundup2(count, alignment);
  			}
  
  			if (offset < count) {
  				/* offset starts in the 'hole' */
  				LIBELF_SET_ERROR(ARGUMENT, 0);
  				return (NULL);
  			}
  
  			if (offset < count + d->d_size) {
  				if (d->d_buf != NULL)
  					return ((char *) d->d_buf +
  					    offset - count);
  				LIBELF_SET_ERROR(DATA, 0);
  				return (NULL);
  			}
  
  			count += d->d_size;
  		}
  	}
  
  	LIBELF_SET_ERROR(ARGUMENT, 0);
  	return (NULL);
  }