/*-
* Copyright (c) 2006 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 <ar.h>
#include <assert.h>
#include <ctype.h>
#include "libelf.h"
#include <stdlib.h>
#include <string.h>
#include "_libelf.h"
#define LIBELF_NALLOC_SIZE 16
/*
* `ar' archive handling.
*
* `ar' archives start with signature `ARMAG'. Each archive member is
* preceded by a header containing meta-data for the member. This
* header is described in <ar.h> (struct ar_hdr). The header always
* starts on an even address. File data is padded with "\n"
* characters to keep this invariant.
*
* Special considerations for `ar' archives:
*
* The `ar' header only has space for a 16 character file name. File
* names are terminated with a '/', so this effectively leaves 15
* characters for the actual file name. In order to accomodate longer
* file names, names may be stored in a separate 'string table' and
* referenced indirectly by a member header. The string table itself
* appears as an archive member with name "// ". An indirect file name
* in an `ar' header matches the pattern "/[0-9]*". The digits form a
* decimal number that corresponds to a byte offset into the string
* table where the actual file name of the object starts. Strings in
* the string table are padded to start on even addresses.
*
* Archives may also have a symbol table (see ranlib(1)), mapping
* program symbols to object files inside the archive. A symbol table
* uses a file name of "/ " in its archive header. The symbol table
* is structured as:
* - a 4-byte count of entries stored as a binary value, MSB first
* - 'n' 4-byte offsets, stored as binary values, MSB first
* - 'n' NUL-terminated strings, for ELF symbol names, stored unpadded.
*
* If the symbol table and string table are is present in an archive
* they must be the very first objects and in that order.
*/
/*
* Convert a string bounded by `start' and `start+sz' (exclusive) to a
* number in the specified base.
*/
static int
_libelf_ar_get_number(char *s, size_t sz, int base, size_t *ret)
{
int c, v;
size_t r;
char *e;
assert(base <= 10);
e = s + sz;
/* skip leading blanks */
for (;s < e && (c = *s) == ' '; s++)
;
r = 0L;
for (;s < e; s++) {
if ((c = *s) == ' ')
break;
if (c < '0' || c > '9')
return (0);
v = c - '0';
if (v >= base) /* Illegal digit. */
break;
r *= base;
r += v;
}
*ret = r;
return (1);
}
/*
* Retrieve a string from a name field. If `rawname' is set, leave
* ar(1) control characters in.
*/
static char *
_libelf_ar_get_string(const char *buf, size_t bufsize, int rawname)
{
const char *q;
char *r;
size_t sz;
if (rawname)
sz = bufsize + 1;
else {
/* Skip back over trailing blanks. */
for (q = buf + bufsize - 1; q >= buf && *q == ' '; --q)
;
if (q < buf) {
/*
* If the input buffer only had blanks in it,
* return a zero-length string.
*/
buf = "";
sz = 1;
} else {
/*
* Remove the trailing '/' character, but only
* if the name isn't one of the special names
* "/" and "//".
*/
if (q > buf + 1 ||
(q == (buf + 1) && *buf != '/'))
q--;
sz = q - buf + 2; /* Space for a trailing NUL. */
}
}
if ((r = malloc(sz)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
(void) strncpy(r, buf, sz);
r[sz - 1] = '\0';
return (r);
}
/*
* Retrieve the full name of the archive member.
*/
static char *
_libelf_ar_get_name(char *buf, size_t bufsize, Elf *e)
{
char c, *q, *r, *s;
size_t len;
size_t offset;
assert(e->e_kind == ELF_K_AR);
if (buf[0] == '/' && (c = buf[1]) >= '0' && c <= '9') {
/*
* The value in field ar_name is a decimal offset into
* the archive string table where the actual name
* resides.
*/
if (_libelf_ar_get_number(buf + 1, bufsize - 1, 10,
&offset) == 0) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
if (offset > e->e_u.e_ar.e_rawstrtabsz) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
s = q = e->e_u.e_ar.e_rawstrtab + offset;
r = e->e_u.e_ar.e_rawstrtab + e->e_u.e_ar.e_rawstrtabsz;
for (s = q; s < r && *s != '/'; s++)
;
len = s - q + 1; /* space for the trailing NUL */
if ((s = malloc(len)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
(void) strncpy(s, q, len);
s[len - 1] = '\0';
return (s);
}
/*
* Normal 'name'
*/
return (_libelf_ar_get_string(buf, bufsize, 0));
}
Elf_Arhdr *
_libelf_ar_gethdr(Elf *e)
{
Elf *parent;
struct ar_hdr *arh;
Elf_Arhdr *eh;
size_t n;
if ((parent = e->e_parent) == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
arh = (struct ar_hdr *) ((uintptr_t) e->e_rawfile - sizeof(struct ar_hdr));
assert((uintptr_t) arh >= (uintptr_t) parent->e_rawfile + SARMAG);
assert((uintptr_t) arh <= (uintptr_t) parent->e_rawfile + parent->e_rawsize -
sizeof(struct ar_hdr));
if ((eh = malloc(sizeof(Elf_Arhdr))) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
e->e_arhdr = eh;
eh->ar_name = eh->ar_rawname = NULL;
if ((eh->ar_name = _libelf_ar_get_name(arh->ar_name, sizeof(arh->ar_name),
parent)) == NULL)
goto error;
if (_libelf_ar_get_number(arh->ar_uid, sizeof(arh->ar_uid), 10, &n) == 0)
goto error;
eh->ar_uid = (uid_t) n;
if (_libelf_ar_get_number(arh->ar_gid, sizeof(arh->ar_gid), 10, &n) == 0)
goto error;
eh->ar_gid = (gid_t) n;
if (_libelf_ar_get_number(arh->ar_mode, sizeof(arh->ar_mode), 8, &n) == 0)
goto error;
eh->ar_mode = (mode_t) n;
if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, &n) == 0)
goto error;
eh->ar_size = n;
if ((eh->ar_rawname = _libelf_ar_get_string(arh->ar_name,
sizeof(arh->ar_name), 1)) == NULL)
goto error;
return (eh);
error:
if (eh) {
if (eh->ar_name)
free(eh->ar_name);
if (eh->ar_rawname)
free(eh->ar_rawname);
free(eh);
}
e->e_arhdr = NULL;
return (NULL);
}
Elf *
_libelf_ar_open_member(int fd, Elf_Cmd c, Elf *elf)
{
Elf *e;
off_t next;
struct ar_hdr *arh;
size_t sz;
assert(elf->e_kind == ELF_K_AR);
next = elf->e_u.e_ar.e_next;
/*
* `next' is only set to zero by elf_next() when the last
* member of an archive is processed.
*/
if (next == (off_t) 0)
return (NULL);
assert((next & 1) == 0);
arh = (struct ar_hdr *) (elf->e_rawfile + next);
if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10, &sz) == 0) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
assert(sz > 0);
arh++; /* skip over archive member header */
if ((e = elf_memory((char *) arh, sz)) == NULL)
return (NULL);
e->e_fd = fd;
e->e_cmd = c;
elf->e_u.e_ar.e_nchildren++;
e->e_parent = elf;
return (e);
}
Elf *
_libelf_ar_open(Elf *e)
{
int i;
char *s, *end;
size_t sz;
struct ar_hdr arh;
e->e_kind = ELF_K_AR;
e->e_u.e_ar.e_nchildren = 0;
e->e_u.e_ar.e_next = (off_t) -1;
/*
* Look for special members.
*/
s = e->e_rawfile + SARMAG;
end = e->e_rawfile + e->e_rawsize;
assert(e->e_rawsize > 0);
/*
* Look for magic names "/ " and "// " in the first two entries
* of the archive.
*/
for (i = 0; i < 2; i++) {
if (s + sizeof(arh) > end) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
(void) memcpy(&arh, s, sizeof(arh));
if (arh.ar_fmag[0] != '`' || arh.ar_fmag[1] != '\n') {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
if (arh.ar_name[0] != '/') /* not a special symbol */
break;
if (_libelf_ar_get_number(arh.ar_size, sizeof(arh.ar_size), 10, &sz) == 0) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
assert(sz > 0);
s += sizeof(arh);
if (arh.ar_name[1] == ' ') { /* "/ " => symbol table */
e->e_u.e_ar.e_rawsymtab = s;
e->e_u.e_ar.e_rawsymtabsz = sz;
} else if (arh.ar_name[1] == '/' && arh.ar_name[2] == ' ') {
/* "// " => string table for long file names */
e->e_u.e_ar.e_rawstrtab = s;
e->e_u.e_ar.e_rawstrtabsz = sz;
}
sz = LIBELF_ADJUST_AR_SIZE(sz);
s += sz;
}
e->e_u.e_ar.e_next = (off_t) (s - e->e_rawfile);
return (e);
}
/*
* An ar(1) symbol table has the following layout:
*
* The first 4 bytes are a binary count of the number of entries in the
* symbol table, stored MSB-first.
*
* Then there are 'n' 4-byte binary offsets, also stored MSB first.
*
* Following this, there are 'n' null-terminated strings.
*/
#define GET_WORD(P, V) do { \
(V) = 0; \
(V) = (P)[0]; (V) <<= 8; \
(V) += (P)[1]; (V) <<= 8; \
(V) += (P)[2]; (V) <<= 8; \
(V) += (P)[3]; \
} while (0)
#define INTSZ 4
Elf_Arsym *
_libelf_ar_process_symtab(Elf *e, size_t *count)
{
size_t n, nentries, off;
Elf_Arsym *symtab, *sym;
char *p, *s, *end;
assert(e != NULL);
assert(count != NULL);
if (e->e_u.e_ar.e_rawsymtabsz < INTSZ) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
p = e->e_u.e_ar.e_rawsymtab;
end = p + e->e_u.e_ar.e_rawsymtabsz;
GET_WORD(p, nentries);
p += INTSZ;
if (nentries == 0 || p + nentries * INTSZ >= end) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
/* Allocate space for a nentries + a sentinel. */
if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries+1))) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
s = p + (nentries * INTSZ); /* start of the string table. */
for (n = nentries, sym = symtab; n > 0; n--) {
off = 0;
GET_WORD(p, off);
sym->as_off = off;
sym->as_hash = elf_hash(s);
sym->as_name = s;
p += INTSZ;
sym++;
for (; s < end && *s++ != '\0';) /* skip to next string */
;
if (s > end) {
LIBELF_SET_ERROR(ARCHIVE, 0);
free(symtab);
return (NULL);
}
}
/* Fill up the sentinel entry. */
sym->as_name = NULL;
sym->as_hash = ~0UL;
sym->as_off = (off_t) 0;
*count = e->e_u.e_ar.e_symtabsz = nentries + 1;
e->e_u.e_ar.e_symtab = symtab;
return (symtab);
}