/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* Copyright (c) 1989, 1993
* The Regents of the University of California. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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 <sys/cdefs.h>
__SCCSID("@(#)nlist.c 8.1 (Berkeley) 6/4/93");
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <arpa/inet.h>
#include <errno.h>
#include <a.out.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"
#include <machine/elf.h>
#include <elf-hints.h>
int __fdnlist(int, struct nlist *);
int __elf_fdnlist(int, struct nlist *);
int __elf_is_okay__(Elf_Ehdr *);
int
nlist(const char *name, struct nlist *list)
{
int fd, n;
fd = _open(name, O_RDONLY | O_CLOEXEC, 0);
if (fd < 0)
return (-1);
n = __fdnlist(fd, list);
(void)_close(fd);
return (n);
}
static struct nlist_handlers {
int (*fn)(int fd, struct nlist *list);
} nlist_fn[] = {
{ __elf_fdnlist },
};
int
__fdnlist(int fd, struct nlist *list)
{
int n = -1;
unsigned int i;
for (i = 0; i < nitems(nlist_fn); i++) {
n = (nlist_fn[i].fn)(fd, list);
if (n != -1)
break;
}
return (n);
}
#define ISLAST(p) (p->n_un.n_name == 0 || p->n_un.n_name[0] == 0)
static void elf_sym_to_nlist(struct nlist *, Elf_Sym *, Elf_Shdr *, int);
/*
* __elf_is_okay__ - Determine if ehdr really
* is ELF and valid for the target platform.
*
* WARNING: This is NOT an ELF ABI function and
* as such its use should be restricted.
*/
int
__elf_is_okay__(Elf_Ehdr *ehdr)
{
int retval = 0;
/*
* We need to check magic, class size, endianess,
* and version before we look at the rest of the
* Elf_Ehdr structure. These few elements are
* represented in a machine independent fashion.
*/
if (IS_ELF(*ehdr) &&
ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS &&
ehdr->e_ident[EI_DATA] == ELF_TARG_DATA &&
ehdr->e_ident[EI_VERSION] == ELF_TARG_VER) {
/* Now check the machine dependant header */
if (ehdr->e_machine == ELF_TARG_MACH &&
ehdr->e_version == ELF_TARG_VER)
retval = 1;
}
return retval;
}
int
__elf_fdnlist(int fd, struct nlist *list)
{
struct nlist *p;
Elf_Off symoff = 0, symstroff = 0;
Elf_Size symsize = 0, symstrsize = 0;
Elf_Ssize cc, i;
int nent = -1;
int errsave;
Elf_Sym sbuf[1024];
Elf_Sym *s;
Elf_Ehdr ehdr;
char *strtab = NULL;
Elf_Shdr *shdr = NULL;
Elf_Size shdr_size;
void *base;
struct stat st;
/* Make sure obj is OK */
if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
_read(fd, &ehdr, sizeof(Elf_Ehdr)) != sizeof(Elf_Ehdr) ||
!__elf_is_okay__(&ehdr) ||
_fstat(fd, &st) < 0)
return (-1);
/* calculate section header table size */
shdr_size = ehdr.e_shentsize * ehdr.e_shnum;
/* Make sure it's not too big to mmap */
if (shdr_size > SIZE_T_MAX) {
errno = EFBIG;
return (-1);
}
/* mmap section header table */
base = mmap(NULL, (size_t)shdr_size, PROT_READ, MAP_PRIVATE, fd,
(off_t)ehdr.e_shoff);
if (base == MAP_FAILED)
return (-1);
shdr = (Elf_Shdr *)base;
/*
* Find the symbol table entry and it's corresponding
* string table entry. Version 1.1 of the ABI states
* that there is only one symbol table but that this
* could change in the future.
*/
for (i = 0; i < ehdr.e_shnum; i++) {
if (shdr[i].sh_type == SHT_SYMTAB) {
symoff = shdr[i].sh_offset;
symsize = shdr[i].sh_size;
symstroff = shdr[shdr[i].sh_link].sh_offset;
symstrsize = shdr[shdr[i].sh_link].sh_size;
break;
}
}
/* Check for files too large to mmap. */
if (symstrsize > SIZE_T_MAX) {
errno = EFBIG;
goto done;
}
/*
* Map string table into our address space. This gives us
* an easy way to randomly access all the strings, without
* making the memory allocation permanent as with malloc/free
* (i.e., munmap will return it to the system).
*/
base = mmap(NULL, (size_t)symstrsize, PROT_READ, MAP_PRIVATE, fd,
(off_t)symstroff);
if (base == MAP_FAILED)
goto done;
strtab = (char *)base;
/*
* clean out any left-over information for all valid entries.
* Type and value defined to be 0 if not found; historical
* versions cleared other and desc as well. Also figure out
* the largest string length so don't read any more of the
* string table than we have to.
*
* XXX clearing anything other than n_type and n_value violates
* the semantics given in the man page.
*/
nent = 0;
for (p = list; !ISLAST(p); ++p) {
p->n_type = 0;
p->n_other = 0;
p->n_desc = 0;
p->n_value = 0;
++nent;
}
/* Don't process any further if object is stripped. */
if (symoff == 0)
goto done;
if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
nent = -1;
goto done;
}
while (symsize > 0 && nent > 0) {
cc = MIN(symsize, sizeof(sbuf));
if (_read(fd, sbuf, cc) != cc)
break;
symsize -= cc;
for (s = sbuf; cc > 0 && nent > 0; ++s, cc -= sizeof(*s)) {
char *name;
struct nlist *p;
name = strtab + s->st_name;
if (name[0] == '\0')
continue;
for (p = list; !ISLAST(p); p++) {
if ((p->n_un.n_name[0] == '_' &&
strcmp(name, p->n_un.n_name+1) == 0)
|| strcmp(name, p->n_un.n_name) == 0) {
elf_sym_to_nlist(p, s, shdr,
ehdr.e_shnum);
if (--nent <= 0)
break;
}
}
}
}
done:
errsave = errno;
if (strtab != NULL)
munmap(strtab, symstrsize);
if (shdr != NULL)
munmap(shdr, shdr_size);
errno = errsave;
return (nent);
}
/*
* Convert an Elf_Sym into an nlist structure. This fills in only the
* n_value and n_type members.
*/
static void
elf_sym_to_nlist(struct nlist *nl, Elf_Sym *s, Elf_Shdr *shdr, int shnum)
{
nl->n_value = s->st_value;
switch (s->st_shndx) {
case SHN_UNDEF:
case SHN_COMMON:
nl->n_type = N_UNDF;
break;
case SHN_ABS:
nl->n_type = ELF_ST_TYPE(s->st_info) == STT_FILE ?
N_FN : N_ABS;
break;
default:
if (s->st_shndx >= shnum)
nl->n_type = N_UNDF;
else {
Elf_Shdr *sh = shdr + s->st_shndx;
nl->n_type = sh->sh_type == SHT_PROGBITS ?
(sh->sh_flags & SHF_WRITE ? N_DATA : N_TEXT) :
(sh->sh_type == SHT_NOBITS ? N_BSS : N_UNDF);
}
break;
}
if (ELF_ST_BIND(s->st_info) == STB_GLOBAL ||
ELF_ST_BIND(s->st_info) == STB_WEAK)
nl->n_type |= N_EXT;
}
