/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 *      Copyright (c) 1988 AT&T
 *      All Rights Reserved
 */

#include <ar.h>
#include <stdlib.h>
#include <memory.h>
#include <errno.h>
#include <libelf.h>
#include <sys/mman.h>
#include "decl.h"
#include "member.h"
#include "msg.h"

static const char       armag[] = ARMAG;


/*
 * Initialize archive member
 */
Elf *
_elf_member(int fd, Elf * ref, unsigned flags)
{
        register Elf    *elf;
        Member          *mh;
        size_t          base;

        if (ref->ed_nextoff >= ref->ed_fsz)
                return (0);
        if (ref->ed_fd == -1)           /* disabled */
                fd = -1;
        if (flags & EDF_WRITE) {
                _elf_seterr(EREQ_ARRDWR, 0);
                return (0);
        }
        if (ref->ed_fd != fd) {
                _elf_seterr(EREQ_ARMEMFD, 0);
                return (0);
        }
        if ((_elf_vm(ref, ref->ed_nextoff, sizeof (struct ar_hdr)) !=
            OK_YES) || ((mh = _elf_armem(ref,
            ref->ed_ident + ref->ed_nextoff, ref->ed_fsz)) == 0))
                return (0);

        base = ref->ed_nextoff + sizeof (struct ar_hdr);
        if (ref->ed_fsz - base < mh->m_hdr.ar_size) {
                _elf_seterr(EFMT_ARMEMSZ, 0);
                return (0);
        }
        if ((elf = (Elf *)calloc(1, sizeof (Elf))) == 0) {
                _elf_seterr(EMEM_ELF, errno);
                return (0);
        }
        ++ref->ed_activ;
        elf->ed_parent = ref;
        elf->ed_fd = fd;
        elf->ed_myflags |= flags;
        elf->ed_armem = mh;
        elf->ed_fsz = mh->m_hdr.ar_size;
        elf->ed_baseoff = ref->ed_baseoff + base;
        elf->ed_memoff = base - mh->m_slide;
        elf->ed_siboff = base + elf->ed_fsz + (elf->ed_fsz & 1);
        ref->ed_nextoff = elf->ed_siboff;
        elf->ed_image = ref->ed_image;
        elf->ed_imagesz = ref->ed_imagesz;
        elf->ed_vm = ref->ed_vm;
        elf->ed_vmsz = ref->ed_vmsz;
        elf->ed_ident = ref->ed_ident + base - mh->m_slide;

        /*
         * If this member is the archive string table,
         * we've already altered the bytes.
         */

        if (ref->ed_arstroff == ref->ed_nextoff)
                elf->ed_status = ES_COOKED;
        return (elf);
}


Elf *
_elf_regular(int fd, unsigned flags)            /* initialize regular file */
{
        Elf             *elf;

        if ((elf = (Elf *)calloc(1, sizeof (Elf))) == 0) {
                _elf_seterr(EMEM_ELF, errno);
                return (0);
        }

        elf->ed_fd = fd;
        elf->ed_myflags |= flags;
        if (_elf_inmap(elf) != OK_YES) {
                free(elf);
                return (0);
        }
        return (elf);
}


Elf *
_elf_config(Elf * elf)
{
        char            *base;
        unsigned        encode;

        ELFRWLOCKINIT(&elf->ed_rwlock);

        /*
         * Determine if this is a ELF file.
         */
        base = elf->ed_ident;
        if ((elf->ed_fsz >= EI_NIDENT) &&
            (_elf_vm(elf, (size_t)0, (size_t)EI_NIDENT) == OK_YES) &&
            (base[EI_MAG0] == ELFMAG0) &&
            (base[EI_MAG1] == ELFMAG1) &&
            (base[EI_MAG2] == ELFMAG2) &&
            (base[EI_MAG3] == ELFMAG3)) {
                elf->ed_kind = ELF_K_ELF;
                elf->ed_class = base[EI_CLASS];
                elf->ed_encode = base[EI_DATA];
                if ((elf->ed_version = base[EI_VERSION]) == 0)
                        elf->ed_version = 1;
                elf->ed_identsz = EI_NIDENT;

                /*
                 * Allow writing only if originally specified read only.
                 * This is only necessary if the file must be translating
                 * from one encoding to another.
                 */
                ELFACCESSDATA(encode, _elf_encode)
                if ((elf->ed_vm == 0) && ((elf->ed_myflags & EDF_WRITE) == 0) &&
                    (elf->ed_encode != encode)) {
                        if (mprotect((char *)elf->ed_image, elf->ed_imagesz,
                            PROT_READ|PROT_WRITE) == -1) {
                                _elf_seterr(EIO_VM, errno);
                                return (0);
                        }
                }
                return (elf);
        }

        /*
         * Determine if this is an Archive
         */
        if ((elf->ed_fsz >= SARMAG) &&
            (_elf_vm(elf, (size_t)0, (size_t)SARMAG) == OK_YES) &&
            (memcmp(base, armag, SARMAG) == 0)) {
                _elf_arinit(elf);
                elf->ed_kind = ELF_K_AR;
                elf->ed_identsz = SARMAG;
                return (elf);
        }

        /*
         *      Return a few ident bytes, but not so many that
         *      getident() must read a large file.  512 is arbitrary.
         */

        elf->ed_kind = ELF_K_NONE;
        if ((elf->ed_identsz = elf->ed_fsz) > 512)
                elf->ed_identsz = 512;

        return (elf);
}

Elf *
elf_memory(char *image, size_t sz)
{
        Elf             *elf;
        unsigned        work;

        /*
         * version() no called yet?
         */
        ELFACCESSDATA(work, _elf_work)
        if (work == EV_NONE) {
                _elf_seterr(ESEQ_VER, 0);
                return (0);
        }

        if ((elf = (Elf *)calloc(1, sizeof (Elf))) == 0) {
                _elf_seterr(EMEM_ELF, errno);
                return (0);
        }
        elf->ed_fd = -1;
        elf->ed_myflags |= EDF_READ | EDF_MEMORY;
        elf->ed_image = elf->ed_ident = image;
        elf->ed_imagesz = elf->ed_fsz = elf->ed_identsz = sz;
        elf->ed_kind = ELF_K_ELF;
        elf->ed_class = image[EI_CLASS];
        elf->ed_encode = image[EI_DATA];
        if ((elf->ed_version = image[EI_VERSION]) == 0)
                elf->ed_version = 1;
        elf->ed_identsz = EI_NIDENT;
        elf->ed_activ = 1;
        elf = _elf_config(elf);
        return (elf);
}

/*
 * The following is a private interface between the linkers (ld & ld.so.1)
 * and libelf.
 *
 * elf_begin(0, ELF_C_IMAGE, ref)
 *      Return a new elf_descriptor which uses the memory image from
 *      ref as the base image of the elf file.  Before this elf_begin()
 *      is called an elf_update(ref, ELF_C_WRIMAGE) must have been
 *      done to the ref elf descriptor.
 *      The ELF_C_IMAGE is unique in that modificatino of the Elf structure
 *      is illegal (no elf_new*()) but you can modify the actual
 *      data image of the file in question.
 *
 *      When you are done processing this file you can then perform a
 *      elf_end() on it.
 *
 *      NOTE: if an elf_update(ref, ELF_C_WRITE) is done on the ref Elf
 *              descriptor then the memory image that the ELF_C_IMAGE
 *              is using has been discarded.  The proper calling convention
 *              for this is as follows:
 *
 *      elf1 = elf_begin(fd, ELF_C_WRITE, 0);
 *      ...
 *      elf_update(elf1, ELF_C_WRIMAGE);         build memory image
 *      elf2 = elf_begin(0, ELF_C_IMAGE, elf1);
 *      ...
 *      elf_end(elf2);
 *      elf_updage(elf1, ELF_C_WRITE);          flush memory image to disk
 *      elf_end(elf1);
 *
 *
 * elf_begin(0, ELF_C_IMAGE, 0);
 *      returns a pointer to an elf descriptor as if it were opened
 *      with ELF_C_WRITE except that it has no file descriptor and it
 *      will not create a file.  It's to be used with the command:
 *
 *              elf_update(elf, ELF_C_WRIMAGE)
 *
 *      which will build a memory image instead of a file image.
 *      The memory image is allocated via dynamic memory (malloc) and
 *      can be free with a subsequent call to
 *
 *              elf_update(elf, ELF_C_WRITE)
 *
 *      NOTE: that if elf_end(elf) is called it will not free the
 *              memory image if it is still allocated.  It is then
 *              the callers responsiblity to free it via a call
 *              to free().
 *
 *      Here is a potential calling sequence for this interface:
 *
 *      elf1 = elf_begin(0, ELF_C_IMAGE, 0);
 *      ...
 *      elf_update(elf1, ELF_C_WRIMAGE);        build memory image
 *      elf2 = elf_begin(0, ELF_C_IMAGE, elf1);
 *      ...
 *      image_ptr = elf32_getehdr(elf2);        get pointer to image
 *      elf_end(elf2);
 *      elf_end(elf1);
 *      ...
 *      use image
 *      ...
 *      free(image_ptr);
 */

Elf *
elf_begin(int fd, Elf_Cmd cmd, Elf *ref)
{
        register Elf    *elf;
        unsigned        work;
        unsigned        flags = 0;

        ELFACCESSDATA(work, _elf_work)
        if (work == EV_NONE)    /* version() not called yet */
        {
                _elf_seterr(ESEQ_VER, 0);
                return (0);
        }
        switch (cmd) {
        default:
                _elf_seterr(EREQ_BEGIN, 0);
                return (0);

        case ELF_C_NULL:
                return (0);

        case ELF_C_IMAGE:
                if (ref) {
                        char    *image;
                        size_t  imagesz;
                        ELFRLOCK(ref);
                        if ((image = ref->ed_wrimage) == 0) {
                                _elf_seterr(EREQ_NOWRIMAGE, 0);
                                ELFUNLOCK(ref);
                                return (0);
                        }
                        imagesz = ref->ed_wrimagesz;
                        ELFUNLOCK(ref);
                        return (elf_memory(image, imagesz));
                }
                /* FALLTHROUGH */
        case ELF_C_WRITE:
                if ((elf = (Elf *)calloc(1, sizeof (Elf))) == 0) {
                        _elf_seterr(EMEM_ELF, errno);
                        return (0);
                }
                ELFRWLOCKINIT(&elf->ed_rwlock);
                elf->ed_fd = fd;
                elf->ed_activ = 1;
                elf->ed_myflags |= EDF_WRITE;
                if (cmd == ELF_C_IMAGE)
                        elf->ed_myflags |= EDF_WRALLOC;
                return (elf);
        case ELF_C_RDWR:
                flags = EDF_WRITE | EDF_READ;
                break;

        case ELF_C_READ:
                flags = EDF_READ;
                break;
        }

        /*
         *      A null ref asks for a new file
         *      Non-null ref bumps the activation count
         *              or gets next archive member
         */

        if (ref == 0) {
                if ((elf = _elf_regular(fd, flags)) == 0)
                        return (0);
        } else {
                ELFWLOCK(ref);
                if ((ref->ed_myflags & flags) != flags) {
                        _elf_seterr(EREQ_RDWR, 0);
                        ELFUNLOCK(ref);
                        return (0);
                }
                /*
                 * new activation ?
                 */
                if (ref->ed_kind != ELF_K_AR) {
                        ++ref->ed_activ;
                        ELFUNLOCK(ref);
                        return (ref);
                }
                if ((elf = _elf_member(fd, ref, flags)) == 0) {
                        ELFUNLOCK(ref);
                        return (0);
                }
                ELFUNLOCK(ref);
        }

        elf->ed_activ = 1;
        elf = _elf_config(elf);

        return (elf);
}