/*-
 * Copyright 1996-1998 John D. Polstra.
 * 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 ``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 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.
 *
 * $FreeBSD$
 */

#include <sys/param.h>
#include <sys/mman.h>
#include <sys/stat.h>

#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "debug.h"
#include "rtld.h"

static Elf_Ehdr *get_elf_header(int, const char *);
static int convert_flags(int); /* Elf flags -> mmap flags */

/*
 * Map a shared object into memory.  The "fd" argument is a file descriptor,
 * which must be open on the object and positioned at its beginning.
 * The "path" argument is a pathname that is used only for error messages.
 *
 * The return value is a pointer to a newly-allocated Obj_Entry structure
 * for the shared object.  Returns NULL on failure.
 */
Obj_Entry *
map_object(int fd, const char *path, const struct stat *sb)
{
    Obj_Entry *obj;
    Elf_Ehdr *hdr;
    int i;
    Elf_Phdr *phdr;
    Elf_Phdr *phlimit;
    Elf_Phdr **segs;
    int nsegs;
    Elf_Phdr *phdyn;
    Elf_Phdr *phinterp;
    Elf_Phdr *phtls;
    caddr_t mapbase;
    caddr_t shlib_base;
    size_t mapsize;
    Elf_Addr base_vaddr;
    Elf_Addr base_vlimit;
    caddr_t base_addr;
    Elf_Off data_offset;
    Elf_Addr data_vaddr;
    Elf_Addr data_vlimit;
    caddr_t data_addr;
    int data_prot;
    int data_flags;
    Elf_Addr clear_vaddr;
    caddr_t clear_addr;
    caddr_t clear_page;
    Elf_Addr phdr_vaddr;
    size_t nclear, phsize;
    Elf_Addr bss_vaddr;
    Elf_Addr bss_vlimit;
    caddr_t bss_addr;
    Elf_Word stack_flags;
    Elf_Addr relro_page;
    size_t relro_size;
    Elf_Addr note_start;
    Elf_Addr note_end;

    hdr = get_elf_header(fd, path);
    if (hdr == NULL)
        return (NULL);

    if (__ld_sharedlib_base) {
        shlib_base = (void *)(intptr_t)strtoul(__ld_sharedlib_base, NULL, 0);
    } else {
        shlib_base = NULL;
    }

    /*
     * Scan the program header entries, and save key information.
     *
     * We expect that the loadable segments are ordered by load address.
     */
    phdr = (Elf_Phdr *) ((char *)hdr + hdr->e_phoff);
    phsize  = hdr->e_phnum * sizeof (phdr[0]);
    phlimit = phdr + hdr->e_phnum;
    nsegs = -1;
    phdyn = phinterp = phtls = NULL;
    phdr_vaddr = 0;
    relro_page = 0;
    relro_size = 0;
    note_start = 0;
    note_end = 0;
    segs = alloca(sizeof(segs[0]) * hdr->e_phnum);
    stack_flags = RTLD_DEFAULT_STACK_PF_EXEC | PF_R | PF_W;
    while (phdr < phlimit) {
        switch (phdr->p_type) {

        case PT_INTERP:
            phinterp = phdr;
            break;

        case PT_LOAD:
            segs[++nsegs] = phdr;
            if ((segs[nsegs]->p_align & (PAGE_SIZE - 1)) != 0) {
                _rtld_error("%s: PT_LOAD segment %d not page-aligned",
                    path, nsegs);
                goto error;
            }
            break;

        case PT_PHDR:
            phdr_vaddr = phdr->p_vaddr;
            phsize = phdr->p_memsz;
            break;

        case PT_DYNAMIC:
            phdyn = phdr;
            break;

        case PT_TLS:
            phtls = phdr;
            break;

        case PT_GNU_STACK:
            stack_flags = phdr->p_flags;
            break;

        case PT_GNU_RELRO:
            relro_page = phdr->p_vaddr;
            relro_size = phdr->p_memsz;
            break;

        case PT_NOTE:
            if (phdr->p_offset > PAGE_SIZE ||
              phdr->p_offset + phdr->p_filesz > PAGE_SIZE)
                break;
            note_start = (Elf_Addr)(char *)hdr + phdr->p_offset;
            note_end = note_start + phdr->p_filesz;
            break;
        }

        ++phdr;
    }
    if (phdyn == NULL) {
        _rtld_error("%s: object is not dynamically-linked", path);
        goto error;
    }

    if (nsegs < 0) {
        _rtld_error("%s: too few PT_LOAD segments", path);
        goto error;
    }

    /*
     * Map the entire address space of the object, to stake out our
     * contiguous region, and to establish the base address for relocation.
     */
    base_vaddr = trunc_page(segs[0]->p_vaddr);
    base_vlimit = round_page(segs[nsegs]->p_vaddr + segs[nsegs]->p_memsz);
    mapsize = base_vlimit - base_vaddr;
    base_addr = (caddr_t) base_vaddr;

    if (base_addr == NULL && shlib_base) {
        size_t limit = 1024 * 256 * 1024;
        size_t offset;

        for (offset = 0; offset < limit; offset += 256 * 1024) {
                mapbase = mmap(shlib_base + offset, mapsize,
                               PROT_NONE,
                               MAP_ANON | MAP_PRIVATE | MAP_NOCORE |
                               MAP_TRYFIXED,
                               -1, 0);
                if (mapbase != MAP_FAILED)
                        break;
        }
    } else {
        mapbase = mmap(base_addr, mapsize,
                       PROT_NONE,
                       MAP_ANON | MAP_PRIVATE | MAP_NOCORE,
                       -1, 0);
    }
    if (mapbase == (caddr_t) -1) {
        _rtld_error("%s: mmap of entire address space failed: %s",
          path, rtld_strerror(errno));
        goto error;
    }
    if (base_addr != NULL && mapbase != base_addr) {
        _rtld_error("%s: mmap returned wrong address: wanted %p, got %p",
          path, base_addr, mapbase);
        goto error1;
    }

    for (i = 0; i <= nsegs; i++) {
        /* Overlay the segment onto the proper region. */
        data_offset = trunc_page(segs[i]->p_offset);
        data_vaddr = trunc_page(segs[i]->p_vaddr);
        data_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_filesz);
        data_addr = mapbase + (data_vaddr - base_vaddr);
        data_prot = convert_prot(segs[i]->p_flags);
        data_flags = convert_flags(segs[i]->p_flags) | MAP_FIXED;
        if (mmap(data_addr, data_vlimit - data_vaddr, data_prot,
          data_flags, fd, data_offset) == (caddr_t) -1) {
            _rtld_error("%s: mmap of data failed: %s", path,
                rtld_strerror(errno));
            goto error1;
        }

        /* Do BSS setup */
        if (segs[i]->p_filesz != segs[i]->p_memsz) {

            /* Clear any BSS in the last page of the segment. */
            clear_vaddr = segs[i]->p_vaddr + segs[i]->p_filesz;
            clear_addr = mapbase + (clear_vaddr - base_vaddr);
            clear_page = mapbase + (trunc_page(clear_vaddr) - base_vaddr);

            if ((nclear = data_vlimit - clear_vaddr) > 0) {
                /* Make sure the end of the segment is writable */
                if ((data_prot & PROT_WRITE) == 0 && -1 ==
                     mprotect(clear_page, PAGE_SIZE, data_prot|PROT_WRITE)) {
                        _rtld_error("%s: mprotect failed: %s", path,
                            rtld_strerror(errno));
                        goto error1;
                }

                memset(clear_addr, 0, nclear);

                /*
                 * reset the data protection back, enable the segment to be
                 * coredumped since we modified it.
                 */
                if ((data_prot & PROT_WRITE) == 0) {
                    madvise(clear_page, PAGE_SIZE, MADV_CORE);
                    mprotect(clear_page, PAGE_SIZE, data_prot);
                }
            }

            /* Overlay the BSS segment onto the proper region. */
            bss_vaddr = data_vlimit;
            bss_vlimit = round_page(segs[i]->p_vaddr + segs[i]->p_memsz);
            bss_addr = mapbase +  (bss_vaddr - base_vaddr);
            if (bss_vlimit > bss_vaddr) {       /* There is something to do */
                if (mmap(bss_addr, bss_vlimit - bss_vaddr, data_prot,
                    data_flags | MAP_ANON, -1, 0) == (caddr_t)-1) {
                    _rtld_error("%s: mmap of bss failed: %s", path,
                        rtld_strerror(errno));
                    goto error1;
                }
            }
        }

        if (phdr_vaddr == 0 && data_offset <= hdr->e_phoff &&
          (data_vlimit - data_vaddr + data_offset) >=
          (hdr->e_phoff + hdr->e_phnum * sizeof (Elf_Phdr))) {
            phdr_vaddr = data_vaddr + hdr->e_phoff - data_offset;
        }
    }

    obj = obj_new();
    if (sb != NULL) {
        obj->dev = sb->st_dev;
        obj->ino = sb->st_ino;
    }
    obj->mapbase = mapbase;
    obj->mapsize = mapsize;
    obj->textsize = round_page(segs[0]->p_vaddr + segs[0]->p_memsz) -
      base_vaddr;
    obj->vaddrbase = base_vaddr;
    obj->relocbase = mapbase - base_vaddr;
    obj->dynamic = (const Elf_Dyn *) (obj->relocbase + phdyn->p_vaddr);
    if (hdr->e_entry != 0)
        obj->entry = (caddr_t) (obj->relocbase + hdr->e_entry);
    if (phdr_vaddr != 0) {
        obj->phdr = (const Elf_Phdr *) (obj->relocbase + phdr_vaddr);
    } else {
        obj->phdr = malloc(phsize);
        if (obj->phdr == NULL) {
            obj_free(obj);
            _rtld_error("%s: cannot allocate program header", path);
            goto error1;
        }
        memcpy((char *)obj->phdr, (char *)hdr + hdr->e_phoff, phsize);
        obj->phdr_alloc = true;
    }
    obj->phsize = phsize;
    if (phinterp != NULL)
        obj->interp = (const char *) (obj->relocbase + phinterp->p_vaddr);
    if (phtls != NULL) {
        tls_dtv_generation++;
        obj->tlsindex = ++tls_max_index;
        obj->tlssize = phtls->p_memsz;
        obj->tlsalign = phtls->p_align;
        obj->tlsinitsize = phtls->p_filesz;
        obj->tlsinit = mapbase + phtls->p_vaddr;
    }
    obj->stack_flags = stack_flags;
    if (relro_size) {
        obj->relro_page = obj->relocbase + trunc_page(relro_page);
        obj->relro_size = round_page(relro_size);
    }
    if (note_start < note_end)
       digest_notes(obj, note_start, note_end);
    munmap(hdr, PAGE_SIZE);
    return (obj);

error1:
    munmap(mapbase, mapsize);
error:
    munmap(hdr, PAGE_SIZE);
    return (NULL);
}

static Elf_Ehdr *
get_elf_header(int fd, const char *path)
{
        Elf_Ehdr *hdr;

        /* DragonFly mmap does not have MAP_PREFAULT_READ */
        hdr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_PRIVATE, fd, 0);
        if (hdr == (Elf_Ehdr *)MAP_FAILED) {
                _rtld_error("%s: read error: %s", path, rtld_strerror(errno));
                return (NULL);
        }

        /* Make sure the file is valid */
        if (!IS_ELF(*hdr)) {
                _rtld_error("%s: invalid file format", path);
                goto error;
        }
        if (hdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
            hdr->e_ident[EI_DATA] != ELF_TARG_DATA) {
                _rtld_error("%s: unsupported file layout", path);
                goto error;
        }
        if (hdr->e_ident[EI_VERSION] != EV_CURRENT ||
            hdr->e_version != EV_CURRENT) {
                _rtld_error("%s: unsupported file version", path);
                goto error;
        }
        if (hdr->e_type != ET_EXEC && hdr->e_type != ET_DYN) {
                _rtld_error("%s: unsupported file type", path);
                goto error;
        }
        if (hdr->e_machine != ELF_TARG_MACH) {
                _rtld_error("%s: unsupported machine", path);
                goto error;
        }

        /*
         * We rely on the program header being in the first page.  This is
         * not strictly required by the ABI specification, but it seems to
         * always true in practice.  And, it simplifies things considerably.
         */
        if (hdr->e_phentsize != sizeof(Elf_Phdr)) {
                _rtld_error(
            "%s: invalid shared object: e_phentsize != sizeof(Elf_Phdr)", path);
                goto error;
        }
        if (hdr->e_phoff + hdr->e_phnum * sizeof(Elf_Phdr) >
            (size_t)PAGE_SIZE) {
                _rtld_error("%s: program header too large", path);
                goto error;
        }
        return (hdr);

error:
        munmap(hdr, PAGE_SIZE);
        return (NULL);
}

void
obj_free(Obj_Entry *obj)
{
    Objlist_Entry *elm;

    if (obj->tls_static)
        free_tls_offset(obj);
    while (obj->needed != NULL) {
        Needed_Entry *needed = obj->needed;
        obj->needed = needed->next;
        free(needed);
    }
    while (!STAILQ_EMPTY(&obj->names)) {
        Name_Entry *entry = STAILQ_FIRST(&obj->names);
        STAILQ_REMOVE_HEAD(&obj->names, link);
        free(entry);
    }
    while (!STAILQ_EMPTY(&obj->dldags)) {
        elm = STAILQ_FIRST(&obj->dldags);
        STAILQ_REMOVE_HEAD(&obj->dldags, link);
        free(elm);
    }
    while (!STAILQ_EMPTY(&obj->dagmembers)) {
        elm = STAILQ_FIRST(&obj->dagmembers);
        STAILQ_REMOVE_HEAD(&obj->dagmembers, link);
        free(elm);
    }
    if (obj->vertab)
        free(obj->vertab);
    if (obj->origin_path)
        free(obj->origin_path);
    if (obj->z_origin)
        free(obj->rpath);
    if (obj->priv)
        free(obj->priv);
    if (obj->path)
        free(obj->path);
    if (obj->phdr_alloc)
        free((void *)obj->phdr);
    free(obj);
}

Obj_Entry *
obj_new(void)
{
    Obj_Entry *obj;

    obj = CNEW(Obj_Entry);
    STAILQ_INIT(&obj->dldags);
    STAILQ_INIT(&obj->dagmembers);
    STAILQ_INIT(&obj->names);
    return obj;
}

/*
 * Given a set of ELF protection flags, return the corresponding protection
 * flags for MMAP.
 */
int
convert_prot(int elfflags)
{
    int prot = 0;
    if (elfflags & PF_R)
        prot |= PROT_READ;
    if (elfflags & PF_W)
        prot |= PROT_WRITE;
    if (elfflags & PF_X)
        prot |= PROT_EXEC;
    return prot;
}

static int
convert_flags(int elfflags)
{
    int flags = MAP_PRIVATE; /* All mappings are private */

    /*
     * Readonly mappings are marked "MAP_NOCORE", because they can be
     * reconstructed by a debugger.
     */
    if (!(elfflags & PF_W))
        flags |= MAP_NOCORE;
    return flags;
}