283 lines
7.3 KiB
C
283 lines
7.3 KiB
C
/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <sys/param.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <nlist.h>
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#include "local-elf.h"
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#define SIZE_T_MAX 0xffffffffU
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/* Note: This function is used by libkvm0, so we need to export it.
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* It is not declared in the include files though. */
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int __fdnlist(int, struct nlist *);
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#define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
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/*
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* __elf_is_okay__ - Determine if ehdr really
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* is ELF and valid for the target platform.
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*
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* WARNING: This is NOT an ELF ABI function and
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* as such its use should be restricted.
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*/
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static int
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__elf_is_okay__(Elf_Ehdr *ehdr)
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{
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int retval = 0;
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/*
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* We need to check magic, class size, endianess,
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* and version before we look at the rest of the
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* Elf_Ehdr structure. These few elements are
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* represented in a machine independent fashion.
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*/
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if (IS_ELF(*ehdr) &&
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ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
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ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
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ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
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/* Now check the machine dependent header */
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if (ehdr->e_machine == ELF_TARG_MACH &&
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ehdr->e_version == ELF_TARG_VER)
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retval = 1;
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}
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return retval;
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}
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/*
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* Convert an Elf_Sym into an nlist structure. This fills in only the
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* n_value and n_type members.
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*/
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static void
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elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
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{
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nl->n_value = s->st_value;
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switch (s->st_shndx) {
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case SHN_UNDEF:
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case SHN_COMMON:
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nl->n_type = N_UNDF;
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break;
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case SHN_ABS:
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nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
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N_FN : N_ABS;
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break;
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default:
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if (s->st_shndx >= shnum)
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nl->n_type = N_UNDF;
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else {
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Elf_Shdr *sh = shdr + s->st_shndx;
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nl->n_type = sh->sh_type == SHT_PROGBITS ?
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(sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
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(sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
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}
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break;
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}
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if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
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ELF_ST_BIND(s->st_info) == STB_WEAK)
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nl->n_type |= N_EXT;
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}
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int
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__fdnlist(int fd, struct nlist *list)
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{
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struct nlist *p;
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Elf_Off symoff = 0, symstroff = 0;
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Elf_Word symsize = 0, symstrsize = 0;
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Elf_Sword cc, i;
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int nent = -1;
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int errsave;
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Elf_Sym sbuf[1024];
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Elf_Sym *s;
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Elf_Ehdr ehdr;
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char *strtab = NULL;
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Elf_Shdr *shdr = NULL;
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Elf_Word shdr_size;
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struct stat st;
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/* Make sure obj is OK */
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if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
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read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
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!__elf_is_okay__(&ehdr) ||
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fstat(fd, &st) < 0)
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return (-1);
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if (ehdr.e_shnum == 0 ||
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ehdr.e_shentsize != sizeof(Elf_Shdr)) {
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errno = ERANGE;
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return (-1);
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}
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/* calculate section header table size */
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shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
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/* Make sure it's not too big to mmap */
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if (shdr_size > SIZE_T_MAX || shdr_size > st.st_size) {
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errno = EFBIG;
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return (-1);
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}
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shdr = malloc((size_t)shdr_size);
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if (shdr == NULL)
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return (-1);
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/* Load section header table. */
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if (pread(fd, shdr, (size_t)shdr_size, (off_t)ehdr.e_shoff) != (ssize_t)shdr_size)
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goto done;
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/*
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* Find the symbol table entry and it's corresponding
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* string table entry. Version 1.1 of the ABI states
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* that there is only one symbol table but that this
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* could change in the future.
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*/
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for (i = 0; i < ehdr.e_shnum; i++) {
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if (shdr[i].sh_type == SHT_SYMTAB) {
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if (shdr[i].sh_link >= ehdr.e_shnum)
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goto done;
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symoff = shdr[i].sh_offset;
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symsize = shdr[i].sh_size;
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symstroff = shdr[shdr[i].sh_link].sh_offset;
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symstrsize = shdr[shdr[i].sh_link].sh_size;
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break;
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}
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}
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/* Check for files too large to mmap. */
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if (symstrsize > SIZE_T_MAX || symstrsize > st.st_size) {
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errno = EFBIG;
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goto done;
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}
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/*
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* Load string table into our address space. This gives us
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* an easy way to randomly access all the strings, without
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* making the memory allocation permanent as with malloc/free
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* (i.e., munmap will return it to the system).
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*/
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strtab = malloc((size_t)symstrsize);
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if (strtab == NULL)
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goto done;
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if (pread(fd, strtab, (size_t)symstrsize, (off_t)symstroff) != (ssize_t)symstrsize)
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goto done;
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/*
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* clean out any left-over information for all valid entries.
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* Type and value defined to be 0 if not found; historical
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* versions cleared other and desc as well. Also figure out
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* the largest string length so don't read any more of the
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* string table than we have to.
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*
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* XXX clearing anything other than n_type and n_value violates
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* the semantics given in the man page.
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*/
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nent = 0;
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for (p = list; !ISLAST(p); ++p) {
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p->n_type = 0;
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p->n_other = 0;
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p->n_desc = 0;
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p->n_value = 0;
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++nent;
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}
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/* Don't process any further if object is stripped. */
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if (symoff == 0)
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goto done;
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if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
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nent = -1;
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goto done;
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}
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while (symsize > 0 && nent > 0) {
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cc = MIN(symsize, sizeof(sbuf));
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if (read(fd, sbuf, cc) != cc)
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break;
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symsize -= cc;
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for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
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char *name;
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Elf_Word size;
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struct nlist *p;
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name = strtab + s->st_name;
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if (name[0] == '\0')
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continue;
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size = symstrsize - s->st_name;
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for (p = list; !ISLAST(p); p++) {
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if ((p->n_un.n_name[0] == '_' &&
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strncmp(name, p->n_un.n_name+1, size) == 0) ||
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strncmp(name, p->n_un.n_name, size) == 0) {
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elf_sym_to_nlist(p, s, shdr,
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ehdr.e_shnum);
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if (--nent <= 0)
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break;
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}
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}
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}
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}
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done:
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errsave = errno;
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free(strtab);
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free(shdr);
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errno = errsave;
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return (nent);
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}
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int
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nlist(const char *name, struct nlist *list)
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{
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int fd, n;
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if (list == NULL) {
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errno = EINVAL;
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return (-1);
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}
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fd = open(name, O_RDONLY, 0);
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if (fd < 0)
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return (-1);
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n = __fdnlist(fd, list);
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(void)close(fd);
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return (n);
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}
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