/*

 * update.c - implementation of the elf_update(3) function.

 * Copyright (C) 1995 - 2006 Michael Riepe

 * 

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 * 

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 * 

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <private.h>

#ifndef lint

static const char rcsid[] = "@(#) $Id: update.c,v 1.32 2006/07/07 22:15:50 michael Exp $";

#endif /* lint */

#include <errno.h>

#if HAVE_MMAP

#include <sys/mman.h>

#endif /* HAVE_MMAP */

static const unsigned short __encoding = ELFDATA2LSB + (ELFDATA2MSB << 8);

#define native_encoding (*(unsigned char*)&__encoding)

#define rewrite(var,val,f)	\

    do{if((var)!=(val)){(var)=(val);(f)|=ELF_F_DIRTY;}}while(0)

#define align(var,val)		\

    do{if((val)>1){(var)+=(val)-1;(var)-=(var)%(val);}}while(0)

#undef max

#define max(a,b)		((a)>(b)?(a):(b))

static off_t

scn_data_layout(Elf_Scn *scn, unsigned v, unsigned type, size_t *algn, unsigned *flag) {

    Elf *elf = scn->s_elf;

    Elf_Data *data;

    int layout = (elf->e_elf_flags & ELF_F_LAYOUT) == 0;

    size_t scn_align = 1;

    size_t len = 0;

    Scn_Data *sd;

    size_t fsize;

    if (!(sd = scn->s_data_1)) {

	/* no data in section */

	*algn = scn_align;

	return (off_t)len;

    }

    /* load data from file, if any */

    if (!(data = elf_getdata(scn, NULL))) {

	return (off_t)-1;

    }

    elf_assert(data == &sd->sd_data);

    for (; sd; sd = sd->sd_link) {

	elf_assert(sd->sd_magic == DATA_MAGIC);

	elf_assert(sd->sd_scn == scn);

	if (!valid_version(sd->sd_data.d_version)) {

	    return (off_t)-1;

	}

	fsize = sd->sd_data.d_size;

	if (fsize && type != SHT_NOBITS && valid_type(sd->sd_data.d_type)) {

	    if (elf->e_class == ELFCLASS32) {

		fsize = _elf32_xltsize(&sd->sd_data, v, ELFDATA2LSB, 1);

	    }

#if __LIBELF64

	    else if (elf->e_class == ELFCLASS64) {

		fsize = _elf64_xltsize(&sd->sd_data, v, ELFDATA2LSB, 1);

	    }

#endif /* __LIBELF64 */

	    else {

		elf_assert(valid_class(elf->e_class));

		seterr(ERROR_UNIMPLEMENTED);

		return (off_t)-1;

	    }

	    if (fsize == (size_t)-1) {

		return (off_t)-1;

	    }

	}

	if (layout) {

	    align(len, sd->sd_data.d_align);

	    scn_align = max(scn_align, sd->sd_data.d_align);

	    rewrite(sd->sd_data.d_off, (off_t)len, sd->sd_data_flags);

	    len += fsize;

	}

	else {

	    len = max(len, sd->sd_data.d_off + fsize);

	}

	*flag |= sd->sd_data_flags;

    }

    *algn = scn_align;

    return (off_t)len;

}

static size_t

scn_entsize(const Elf *elf, unsigned version, unsigned stype) {

    Elf_Type type;

    switch ((type = _elf_scn_type(stype))) {

	case ELF_T_BYTE:

	    return 0;

	case ELF_T_VDEF:

	case ELF_T_VNEED:

	    return 0;	/* What else can I do?  Thank you, Sun! */

	default:

	    return _fsize(elf->e_class, version, type);

    }

}

static off_t

_elf32_layout(Elf *elf, unsigned *flag) {

    int layout = (elf->e_elf_flags & ELF_F_LAYOUT) == 0;

    Elf32_Ehdr *ehdr = (Elf32_Ehdr*)elf->e_ehdr;

    size_t off = 0;

    unsigned version;

    unsigned encoding;

    size_t align_addr;

    size_t entsize;

    unsigned phnum;

    unsigned shnum;

    Elf_Scn *scn;

    *flag = elf->e_elf_flags | elf->e_phdr_flags;

    if ((version = ehdr->e_version) == EV_NONE) {

	version = EV_CURRENT;

    }

    if (!valid_version(version)) {

	seterr(ERROR_UNKNOWN_VERSION);

	return -1;

    }

    if ((encoding = ehdr->e_ident[EI_DATA]) == ELFDATANONE) {

	encoding = native_encoding;

    }

    if (!valid_encoding(encoding)) {

	seterr(ERROR_UNKNOWN_ENCODING);

	return -1;

    }

    entsize = _fsize(ELFCLASS32, version, ELF_T_EHDR);

    elf_assert(entsize);

    rewrite(ehdr->e_ehsize, entsize, elf->e_ehdr_flags);

    off = entsize;

    align_addr = _fsize(ELFCLASS32, version, ELF_T_ADDR);

    elf_assert(align_addr);

    if ((phnum = elf->e_phnum)) {

	entsize = _fsize(ELFCLASS32, version, ELF_T_PHDR);

	elf_assert(entsize);

	if (layout) {

	    align(off, align_addr);

	    rewrite(ehdr->e_phoff, off, elf->e_ehdr_flags);

	    off += phnum * entsize;

	}

	else {

	    off = max(off, ehdr->e_phoff + phnum * entsize);

	}

    }

    else {

	entsize = 0;

	if (layout) {

	    rewrite(ehdr->e_phoff, 0, elf->e_ehdr_flags);

	}

    }

    if (phnum >= PN_XNUM) {

	Elf_Scn *scn = elf->e_scn_1;

	Elf32_Shdr *shdr = &scn->s_shdr32;

	elf_assert(scn);

	elf_assert(scn->s_index == 0);

	rewrite(shdr->sh_info, phnum, scn->s_shdr_flags);

	*flag |= scn->s_shdr_flags;

	phnum = PN_XNUM;

    }

    rewrite(ehdr->e_phnum, phnum, elf->e_ehdr_flags);

    rewrite(ehdr->e_phentsize, entsize, elf->e_ehdr_flags);

    for (scn = elf->e_scn_1, shnum = 0; scn; scn = scn->s_link, ++shnum) {

	Elf32_Shdr *shdr = &scn->s_shdr32;

	size_t scn_align = 1;

	off_t len;

	elf_assert(scn->s_index == shnum);

	*flag |= scn->s_scn_flags;

	if (scn->s_index == SHN_UNDEF) {

	    rewrite(shdr->sh_entsize, 0, scn->s_shdr_flags);

	    if (layout) {

		rewrite(shdr->sh_offset, 0, scn->s_shdr_flags);

		rewrite(shdr->sh_size, 0, scn->s_shdr_flags);

		rewrite(shdr->sh_addralign, 0, scn->s_shdr_flags);

	    }

	    *flag |= scn->s_shdr_flags;

	    continue;

	}

	if (shdr->sh_type == SHT_NULL) {

	    *flag |= scn->s_shdr_flags;

	    continue;

	}

	len = scn_data_layout(scn, version, shdr->sh_type, &scn_align, flag);

	if (len == -1) {

	    return -1;

	}

	/*

	 * Never override the program's choice.

	 */

	if (shdr->sh_entsize == 0) {

	    entsize = scn_entsize(elf, version, shdr->sh_type);

	    if (entsize > 1) {

		rewrite(shdr->sh_entsize, entsize, scn->s_shdr_flags);

	    }

	}

	if (layout) {

	    align(off, scn_align);

	    rewrite(shdr->sh_offset, off, scn->s_shdr_flags);

	    rewrite(shdr->sh_size, (size_t)len, scn->s_shdr_flags);

	    rewrite(shdr->sh_addralign, scn_align, scn->s_shdr_flags);

	    if (shdr->sh_type != SHT_NOBITS) {

		off += (size_t)len;

	    }

	}

	else if ((size_t)len > shdr->sh_size) {

	    seterr(ERROR_SCN2SMALL);

	    return -1;

	}

	else {

	    Elf_Scn *scn2;

	    size_t end1, end2;

	    end1 = shdr->sh_offset;

	    if (shdr->sh_type != SHT_NOBITS) {

		end1 += shdr->sh_size;

	    }

	    if (shdr->sh_offset < off) {

		/*

		 * check for overlapping sections

		 */

		for (scn2 = elf->e_scn_1; scn2; scn2 = scn2->s_link) {

		    if (scn2 == scn) {

			break;

		    }

		    end2 = scn2->s_shdr32.sh_offset;

		    if (scn2->s_shdr32.sh_type != SHT_NOBITS) {

			end2 += scn2->s_shdr32.sh_size;

		    }

		    if (end1 > scn2->s_shdr32.sh_offset

		     && end2 > shdr->sh_offset) {

			seterr(ERROR_SCN_OVERLAP);

			return -1;

		    }

		}

	    }

	    if (off < end1) {

		off = end1;

	    }

	}

	*flag |= scn->s_shdr_flags;

    }

    if (shnum) {

	entsize = _fsize(ELFCLASS32, version, ELF_T_SHDR);

	elf_assert(entsize);

	if (layout) {

	    align(off, align_addr);

	    rewrite(ehdr->e_shoff, off, elf->e_ehdr_flags);

	    off += shnum * entsize;

	}

	else {

	    off = max(off, ehdr->e_shoff + shnum * entsize);

	}

    }

    else {

	entsize = 0;

	if (layout) {

	    rewrite(ehdr->e_shoff, 0, elf->e_ehdr_flags);

	}

    }

    if (shnum >= SHN_LORESERVE) {

	Elf_Scn *scn = elf->e_scn_1;

	Elf32_Shdr *shdr = &scn->s_shdr32;

	elf_assert(scn->s_index == 0);

	rewrite(shdr->sh_size, shnum, scn->s_shdr_flags);

	*flag |= scn->s_shdr_flags;

	shnum = 0;

    }

    rewrite(ehdr->e_shnum, shnum, elf->e_ehdr_flags);

    rewrite(ehdr->e_shentsize, entsize, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG0], ELFMAG0, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG1], ELFMAG1, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG2], ELFMAG2, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG3], ELFMAG3, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_CLASS], ELFCLASS32, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_DATA], encoding, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_VERSION], version, elf->e_ehdr_flags);

    rewrite(ehdr->e_version, version, elf->e_ehdr_flags);

    *flag |= elf->e_ehdr_flags;

    return off;

}

#if __LIBELF64

static off_t

_elf64_layout(Elf *elf, unsigned *flag) {

    int layout = (elf->e_elf_flags & ELF_F_LAYOUT) == 0;

    Elf64_Ehdr *ehdr = (Elf64_Ehdr*)elf->e_ehdr;

    size_t off = 0;

    unsigned version;

    unsigned encoding;

    size_t align_addr;

    size_t entsize;

    unsigned phnum;

    unsigned shnum;

    Elf_Scn *scn;

    *flag = elf->e_elf_flags | elf->e_phdr_flags;

    if ((version = ehdr->e_version) == EV_NONE) {

	version = EV_CURRENT;

    }

    if (!valid_version(version)) {

	seterr(ERROR_UNKNOWN_VERSION);

	return -1;

    }

    if ((encoding = ehdr->e_ident[EI_DATA]) == ELFDATANONE) {

	encoding = native_encoding;

    }

    if (!valid_encoding(encoding)) {

	seterr(ERROR_UNKNOWN_ENCODING);

	return -1;

    }

    entsize = _fsize(ELFCLASS64, version, ELF_T_EHDR);

    elf_assert(entsize);

    rewrite(ehdr->e_ehsize, entsize, elf->e_ehdr_flags);

    off = entsize;

    align_addr = _fsize(ELFCLASS64, version, ELF_T_ADDR);

    elf_assert(align_addr);

    if ((phnum = elf->e_phnum)) {

	entsize = _fsize(ELFCLASS64, version, ELF_T_PHDR);

	elf_assert(entsize);

	if (layout) {

	    align(off, align_addr);

	    rewrite(ehdr->e_phoff, off, elf->e_ehdr_flags);

	    off += phnum * entsize;

	}

	else {

	    off = max(off, ehdr->e_phoff + phnum * entsize);

	}

    }

    else {

	entsize = 0;

	if (layout) {

	    rewrite(ehdr->e_phoff, 0, elf->e_ehdr_flags);

	}

    }

    if (phnum >= PN_XNUM) {

	Elf_Scn *scn = elf->e_scn_1;

	Elf32_Shdr *shdr = &scn->s_shdr32;

	/* modify first section header, too! */

	elf_assert(scn);

	elf_assert(scn->s_index == 0);

	rewrite(shdr->sh_info, phnum, scn->s_shdr_flags);

	*flag |= scn->s_shdr_flags;

	phnum = PN_XNUM;

    }

    rewrite(ehdr->e_phnum, phnum, elf->e_ehdr_flags);

    rewrite(ehdr->e_phentsize, entsize, elf->e_ehdr_flags);

    for (scn = elf->e_scn_1, shnum = 0; scn; scn = scn->s_link, ++shnum) {

	Elf64_Shdr *shdr = &scn->s_shdr64;

	size_t scn_align = 1;

	off_t len;

	elf_assert(scn->s_index == shnum);

	*flag |= scn->s_scn_flags;

	if (scn->s_index == SHN_UNDEF) {

	    rewrite(shdr->sh_entsize, 0, scn->s_shdr_flags);

	    if (layout) {

		rewrite(shdr->sh_offset, 0, scn->s_shdr_flags);

		rewrite(shdr->sh_size, 0, scn->s_shdr_flags);

		rewrite(shdr->sh_addralign, 0, scn->s_shdr_flags);

	    }

	    *flag |= scn->s_shdr_flags;

	    continue;

	}

	if (shdr->sh_type == SHT_NULL) {

	    *flag |= scn->s_shdr_flags;

	    continue;

	}

	len = scn_data_layout(scn, version, shdr->sh_type, &scn_align, flag);

	if (len == -1) {

	    return -1;

	}

	/*

	 * Never override the program's choice.

	 */

	if (shdr->sh_entsize == 0) {

	    entsize = scn_entsize(elf, version, shdr->sh_type);

	    if (entsize > 1) {

		rewrite(shdr->sh_entsize, entsize, scn->s_shdr_flags);

	    }

	}

	if (layout) {

	    align(off, scn_align);

	    rewrite(shdr->sh_offset, off, scn->s_shdr_flags);

	    rewrite(shdr->sh_size, (size_t)len, scn->s_shdr_flags);

	    rewrite(shdr->sh_addralign, scn_align, scn->s_shdr_flags);

	    if (shdr->sh_type != SHT_NOBITS) {

		off += (size_t)len;

	    }

	}

	else if ((size_t)len > shdr->sh_size) {

	    seterr(ERROR_SCN2SMALL);

	    return -1;

	}

	else {

	    Elf_Scn *scn2;

	    size_t end1, end2;

	    end1 = shdr->sh_offset;

	    if (shdr->sh_type != SHT_NOBITS) {

		end1 += shdr->sh_size;

	    }

	    if (shdr->sh_offset < off) {

		/*

		 * check for overlapping sections

		 */

		for (scn2 = elf->e_scn_1; scn2; scn2 = scn2->s_link) {

		    if (scn2 == scn) {

			break;

		    }

		    end2 = scn2->s_shdr64.sh_offset;

		    if (scn2->s_shdr64.sh_type != SHT_NOBITS) {

			end2 += scn2->s_shdr64.sh_size;

		    }

		    if (end1 > scn2->s_shdr64.sh_offset

		     && end2 > shdr->sh_offset) {

			seterr(ERROR_SCN_OVERLAP);

			return -1;

		    }

		}

	    }

	    if (off < end1) {

		off = end1;

	    }

	}

	*flag |= scn->s_shdr_flags;

    }

    if (shnum) {

	entsize = _fsize(ELFCLASS64, version, ELF_T_SHDR);

	elf_assert(entsize);

	if (layout) {

	    align(off, align_addr);

	    rewrite(ehdr->e_shoff, off, elf->e_ehdr_flags);

	    off += shnum * entsize;

	}

	else {

	    off = max(off, ehdr->e_shoff + shnum * entsize);

	}

    }

    else {

	entsize = 0;

	if (layout) {

	    rewrite(ehdr->e_shoff, 0, elf->e_ehdr_flags);

	}

    }

    if (shnum >= SHN_LORESERVE) {

	Elf_Scn *scn = elf->e_scn_1;

	Elf64_Shdr *shdr = &scn->s_shdr64;

	elf_assert(scn->s_index == 0);

	rewrite(shdr->sh_size, shnum, scn->s_shdr_flags);

	*flag |= scn->s_shdr_flags;

	shnum = 0;

    }

    rewrite(ehdr->e_shnum, shnum, elf->e_ehdr_flags);

    rewrite(ehdr->e_shentsize, entsize, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG0], ELFMAG0, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG1], ELFMAG1, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG2], ELFMAG2, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_MAG3], ELFMAG3, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_CLASS], ELFCLASS64, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_DATA], encoding, elf->e_ehdr_flags);

    rewrite(ehdr->e_ident[EI_VERSION], version, elf->e_ehdr_flags);

    rewrite(ehdr->e_version, version, elf->e_ehdr_flags);

    *flag |= elf->e_ehdr_flags;

    return off;

}

#endif /* __LIBELF64 */

#define ptrinside(p,a,l)	((p)>=(a)&&(p)<(a)+(l))

#define newptr(p,o,n)		((p)=((p)-(o))+(n))