/* $NetBSD: libelf_ar.c,v 1.5 2010/02/22 10:48:32 darran Exp $ */ /*- * 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. */ #if HAVE_NBTOOL_CONFIG_H # include "nbtool_config.h" #endif #include /* __FBSDID("$FreeBSD: src/lib/libelf/libelf_ar.c,v 1.3.10.1.2.1 2009/10/25 01:10:29 kensmith Exp $"); */ #include #include #include #include #include #include #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 (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 (/*CONSTCOND*/0) #define INTSZ 4 Elf_Arsym * _libelf_ar_process_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); if (e->e_u.e_ar.e_rawsymtabsz < INTSZ) { LIBELF_SET_ERROR(ARCHIVE, 0); return (NULL); } 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) { 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 = (char *)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); }