minix/lib/libelf/libelf_ar.c

462 lines
12 KiB
C
Raw Normal View History

2011-05-21 19:11:59 +02:00
/*-
* Copyright (c) 2006,2008,2010 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 <sys/cdefs.h>
#include <assert.h>
#include <ctype.h>
#include <libelf.h>
#include <stdlib.h>
#include <string.h>
#include "_libelf.h"
#include "_libelf_ar.h"
LIBELF_VCSID("$Id$");
#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:
*
* There are two variants of the `ar' archive format: traditional BSD
* and SVR4. These differ in the way long file names are treated, and
* in the layout of the archive symbol table.
*
* The `ar' header only has space for a 16 character file name.
*
* In the SVR4 format, file names are terminated with a '/', so this
* effectively leaves 15 characters for the actual file name. Longer
* file names stored in a separate 'string table' and referenced
* indirectly from the name field. 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.
*
* In the BSD format, file names can be upto 16 characters. File
* names shorter than 16 characters are padded to 16 characters using
* (ASCII) space characters. File names with embedded spaces and file
* names longer than 16 characters are stored immediately after the
* archive header and the name field set to a special indirect name
* matching the pattern "#1/[0-9]+". The digits form a decimal number
* that corresponds to the actual length of the file name following
* the archive header. The content of the archive member immediately
* follows the file name, and the size field of the archive member
* holds the sum of the sizes of the member and of the appended file
* name.
*
* Archives may also have a symbol table (see ranlib(1)), mapping
* program symbols to object files inside the archive.
*
* In the SVR4 format, 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.
*
* In the BSD format, the symbol table uses a file name of "__.SYMDEF".
* It is structured as two parts:
* - The first part is an array of "ranlib" structures preceded by
* the size of the array in bytes. Each "ranlib" structure
* describes one symbol. Each structure contains an offset into
* the string table for the symbol name, and a file offset into the
* archive for the member defining the symbol.
* - The second part is a string table containing NUL-terminated
* strings, preceded by the size of the string table in bytes.
*
* If the symbol table and string table are is present in an archive
* they must be the very first objects and in that order.
*/
/*
* Retrieve an archive header descriptor.
*/
Elf_Arhdr *
_libelf_ar_gethdr(Elf *e)
{
Elf *parent;
char *namelen;
Elf_Arhdr *eh;
size_t n, nlen;
struct ar_hdr *arh;
if ((parent = e->e_parent) == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
assert((e->e_flags & LIBELF_F_AR_HEADER) == 0);
arh = (struct ar_hdr *) (uintptr_t) e->e_hdr.e_rawhdr;
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_hdr.e_arhdr = eh;
e->e_flags |= LIBELF_F_AR_HEADER;
eh->ar_name = eh->ar_rawname = NULL;
if ((eh->ar_name = _libelf_ar_get_translated_name(arh, 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;
/*
* Get the true size of the member if extended naming is being used.
*/
if (IS_EXTENDED_BSD_NAME(arh->ar_name)) {
namelen = arh->ar_name +
LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE;
if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) -
LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nlen) == 0)
goto error;
n -= nlen;
}
eh->ar_size = n;
if ((eh->ar_rawname = _libelf_ar_get_raw_name(arh)) == NULL)
goto error;
eh->ar_flags = 0;
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_flags &= ~LIBELF_F_AR_HEADER;
e->e_hdr.e_rawhdr = (char *) arh;
return (NULL);
}
Elf *
_libelf_ar_open_member(int fd, Elf_Cmd c, Elf *elf)
{
Elf *e;
char *member, *namelen;
size_t nsz, sz;
off_t next;
struct ar_hdr *arh;
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);
/*
* Retrieve the size of the member.
*/
if (_libelf_ar_get_number(arh->ar_size, sizeof(arh->ar_size), 10,
&sz) == 0) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
/*
* Adjust the size field for members in BSD archives using
* extended naming.
*/
if (IS_EXTENDED_BSD_NAME(arh->ar_name)) {
namelen = arh->ar_name +
LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE;
if (_libelf_ar_get_number(namelen, sizeof(arh->ar_name) -
LIBELF_AR_BSD_EXTENDED_NAME_PREFIX_SIZE, 10, &nsz) == 0) {
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
member = (char *) (arh + 1) + nsz;
sz -= nsz;
} else
member = (char *) (arh + 1);
if ((e = elf_memory((char *) member, sz)) == NULL)
return (NULL);
e->e_fd = fd;
e->e_cmd = c;
e->e_hdr.e_rawhdr = (char *) arh;
elf->e_u.e_ar.e_nchildren++;
e->e_parent = elf;
return (e);
}
/*
* A BSD-style ar(1) symbol table has the following layout:
*
* - A count of bytes used by the following array of 'ranlib'
* structures, stored as a 'long'.
* - An array of 'ranlib' structures. Each array element is
* two 'long's in size.
* - A count of bytes used for the following symbol table.
* - The symbol table itself.
*/
/*
* A helper macro to read in a 'long' value from the archive. We use
* memcpy() since the source pointer may be misaligned with respect to
* the natural alignment for a C 'long'.
*/
#define GET_LONG(P, V)do { \
memcpy(&(V), (P), sizeof(long)); \
(P) += sizeof(long); \
} while (0)
Elf_Arsym *
_libelf_ar_process_bsd_symtab(Elf *e, size_t *count)
{
Elf_Arsym *symtab, *sym;
unsigned char *end, *p, *p0, *s, *s0;
const unsigned int entrysize = 2 * sizeof(long);
long arraysize, fileoffset, n, nentries, stroffset, strtabsize;
assert(e != NULL);
assert(count != NULL);
assert(e->e_u.e_ar.e_symtab == NULL);
symtab = NULL;
/*
* The BSD symbol table always contains the count fields even
* if there are no entries in it.
*/
if (e->e_u.e_ar.e_rawsymtabsz < 2 * sizeof(long))
goto symtaberror;
p = p0 = (unsigned char *) e->e_u.e_ar.e_rawsymtab;
end = p0 + e->e_u.e_ar.e_rawsymtabsz;
/*
* Retrieve the size of the array of ranlib descriptors and
* check it for validity.
*/
GET_LONG(p, arraysize);
if (p0 + arraysize >= end || (arraysize % entrysize != 0))
goto symtaberror;
/*
* Check the value of the string table size.
*/
s = p + arraysize;
GET_LONG(s, strtabsize);
s0 = s; /* Start of string table. */
if (s0 + strtabsize > end)
goto symtaberror;
nentries = arraysize / entrysize;
/*
* Allocate space for the returned Elf_Arsym array.
*/
if ((symtab = malloc(sizeof(Elf_Arsym) * (nentries + 1))) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
/* Read in symbol table entries. */
for (n = 0, sym = symtab; n < nentries; n++, sym++) {
GET_LONG(p, stroffset);
GET_LONG(p, fileoffset);
s = s0 + stroffset;
if (s >= end)
goto symtaberror;
sym->as_off = fileoffset;
sym->as_hash = elf_hash((char *) s);
sym->as_name = (char *) s;
}
/* Fill up the sentinel entry. */
sym->as_name = NULL;
sym->as_hash = ~0UL;
sym->as_off = (off_t) 0;
/* Remember the processed symbol table. */
e->e_u.e_ar.e_symtab = symtab;
*count = e->e_u.e_ar.e_symtabsz = nentries + 1;
return (symtab);
symtaberror:
if (symtab)
free(symtab);
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}
/*
* An SVR4-style 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_svr4_symtab(Elf *e, size_t *count)
{
size_t n, nentries, off;
Elf_Arsym *symtab, *sym;
unsigned char *p, *s, *end;
assert(e != NULL);
assert(count != NULL);
assert(e->e_u.e_ar.e_symtab == NULL);
symtab = NULL;
if (e->e_u.e_ar.e_rawsymtabsz < INTSZ)
goto symtaberror;
p = (unsigned char *) 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)
goto symtaberror;
/* 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--) {
if (s >= end)
goto symtaberror;
off = 0;
GET_WORD(p, off);
sym->as_off = off;
sym->as_hash = elf_hash((char *) s);
sym->as_name = (char *) s;
p += INTSZ;
sym++;
for (; s < end && *s++ != '\0';) /* skip to next string */
;
}
/* 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);
symtaberror:
if (symtab)
free(symtab);
LIBELF_SET_ERROR(ARCHIVE, 0);
return (NULL);
}