freebsd-nq/lib/libc/gen/nlist.c

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)nlist.c	8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/file.h>

#include <errno.h>
#include <a.out.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>

#define _NLIST_DO_AOUT

#ifdef _NLIST_DO_ELF
#include <elf.h>
#endif

int __fdnlist		__P((int, struct nlist *));
int __aout_fdnlist	__P((int, struct nlist *));
int __elf_fdnlist	__P((int, struct nlist *));

int
nlist(name, list)
	const char *name;
	struct nlist *list;
{
	int fd, n;

	fd = open(name, O_RDONLY, 0);
	if (fd < 0)
		return (-1);
	n = __fdnlist(fd, list);
	(void)close(fd);
	return (n);
}

static struct nlist_handlers {
	int	(*fn) __P((int fd, struct nlist *list));
} nlist_fn[] = {
#ifdef _NLIST_DO_AOUT
	{ __aout_fdnlist },
#endif
#ifdef _NLIST_DO_ELF
	{ __elf_fdnlist },
#endif
};

int
__fdnlist(fd, list)
	register int fd;
	register struct nlist *list;
{
	int n = -1, i;

	for (i = 0; i < sizeof(nlist_fn) / sizeof(nlist_fn[0]); 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)

#ifdef _NLIST_DO_AOUT
int
__aout_fdnlist(fd, list)
	register int fd;
	register struct nlist *list;
{
	register struct nlist *p, *symtab;
	register caddr_t strtab, a_out_mmap;
	register off_t stroff, symoff;
	register u_long symsize;
	register int nent;
	struct exec * exec;
	struct stat st;

	/* check that file is at least as large as struct exec! */
	if ((fstat(fd, &st) < 0) || (st.st_size < sizeof(struct exec)))
		return (-1);

	/* Check for files too large to mmap. */
	if (st.st_size > SIZE_T_MAX) {
		errno = EFBIG;
		return (-1);
	}

	/*
	 * Map the whole a.out file into our address space.
	 * We then find the string table withing this area.
	 * We do not just mmap the string table, as it probably
	 * does not start at a page boundary - we save ourselves a
	 * lot of nastiness by mmapping the whole file.
	 *
	 * 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).
	 */
	a_out_mmap = mmap(NULL, (size_t)st.st_size, PROT_READ, MAP_PRIVATE, fd, (off_t)0);
	if (a_out_mmap == MAP_FAILED)
		return (-1);

	exec = (struct exec *)a_out_mmap;
	if (N_BADMAG(*exec)) {
		munmap(a_out_mmap, (size_t)st.st_size);
		return (-1);
	}

	symoff = N_SYMOFF(*exec);
	symsize = exec->a_syms;
	stroff = symoff + symsize;

	/* find the string table in our mmapped area */
	strtab = a_out_mmap + stroff;
	symtab = (struct nlist *)(a_out_mmap + symoff);

	/*
	 * 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;
	}

	while (symsize > 0) {
		register int soff;

		symsize-= sizeof(struct nlist);
		soff = symtab->n_un.n_strx;


		if (soff != 0 && (symtab->n_type & N_STAB) == 0)
			for (p = list; !ISLAST(p); p++)
				if (!strcmp(&strtab[soff], p->n_un.n_name)) {
					p->n_value = symtab->n_value;
					p->n_type = symtab->n_type;
					p->n_desc = symtab->n_desc;
					p->n_other = symtab->n_other;
					if (--nent <= 0)
						break;
				}
		symtab++;
	}
	munmap(a_out_mmap, (size_t)st.st_size);
	return (nent);
}
#endif

#ifdef _NLIST_DO_ELF
/*
 * __elf_is_okay__ - Determine if ehdr really
 * is ELF and valid for the target platform.
 *
 * WARNING:  This is NOT a ELF ABI function and
 * as such it's use should be restricted.
 */
int
__elf_is_okay__(ehdr)
	register Elf32_Ehdr *ehdr;
{
	register int retval = 0;
	/*
	 * We need to check magic, class size, endianess,
	 * and version before we look at the rest of the
	 * Elf32_Ehdr structure.  These few elements are
	 * represented in a machine independant 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(fd, list)
	register int fd;
	register struct nlist *list;
{
	register struct nlist *p;
	register caddr_t strtab;
	register Elf32_Off symoff = 0, symstroff = 0;
	register Elf32_Word symsize = 0, symstrsize = 0;
	register Elf32_Sword nent, cc, i;
	Elf32_Sym sbuf[1024];
	Elf32_Sym *s;
	Elf32_Ehdr ehdr;
	Elf32_Shdr *shdr = NULL;
	Elf32_Word shdr_size;
	struct stat st;

	/* Make sure obj is OK */
	if (lseek(fd, (off_t)0, SEEK_SET) == -1 ||
	    read(fd, &ehdr, sizeof(Elf32_Ehdr)) != sizeof(Elf32_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 */
	shdr = (Elf32_Shdr *)mmap(NULL, (size_t)shdr_size,
				  PROT_READ, 0, fd, (off_t) ehdr.e_shoff);
	if (shdr == (Elf32_Shdr *)-1)
		return (-1);

	/*
	 * 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;
		}
	}

	/* Flush the section header table */
	munmap((caddr_t)shdr, shdr_size);

	/* Check for files too large to mmap. */
	if (symstrsize > SIZE_T_MAX) {
		errno = EFBIG;
		return (-1);
	}
	/*
	 * 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).
	 */
	strtab = mmap(NULL, (size_t)symstrsize, PROT_READ, 0, fd,
		      (off_t) symstroff);
	if (strtab == (char *)-1)
		return (-1);

	/*
	 * 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. */
	/* ELFism - dunno if stripped by looking at header */
	if (symoff == 0)
		goto done;
		
	if (lseek(fd, (off_t) symoff, SEEK_SET) == -1) {
		nent = -1;
		goto done;
	}

	while (symsize > 0) {
		cc = MIN(symsize, sizeof(sbuf));
		if (read(fd, sbuf, cc) != cc)
			break;
		symsize -= cc;
		for (s = sbuf; cc > 0; ++s, cc -= sizeof(*s)) {
			register int soff = s->st_name;

			if (soff == 0)
				continue;
			for (p = list; !ISLAST(p); p++) {
				if ((p->n_un.n_name[0] == '_' &&
				     !strcmp(&strtab[soff], p->n_un.n_name+1))
				    || !strcmp(&strtab[soff], p->n_un.n_name)) {
					p->n_value = s->st_value;

					/* XXX - type conversion */
					/*	 is pretty rude. */
					switch(ELF32_ST_TYPE(s->st_info)) {
						case STT_NOTYPE:
							p->n_type = N_UNDF;
							break;
						case STT_OBJECT:
							p->n_type = N_DATA;
							break;
						case STT_FUNC:
							p->n_type = N_TEXT;
							break;
						case STT_FILE:
							p->n_type = N_FN;
							break;
					}
					if (ELF32_ST_BIND(s->st_info) ==
					    STB_LOCAL)
						p->n_type = N_EXT;
					p->n_desc = 0;
					p->n_other = 0;
					if (--nent <= 0)
						break;
				}
			}
		}
	}
  done:
	munmap(strtab, symstrsize);

	return (nent);
}
#endif /* _NLIST_DO_ELF */