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