1 /*

     2  * newscn.c - implementation of the elf_newscn(3) function.

     3  * Copyright (C) 1995 - 2006 Michael Riepe

     4  * 

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

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

     7  * License as published by the Free Software Foundation; either

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

     9  * 

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

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

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

    13  * Library General Public License for more details.

    14  * 

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

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

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

    18  */

    19 

    20 #include <private.h>

    21 

    22 #ifndef lint

    23 static const char rcsid[] = "@(#) $Id: newscn.c,v 1.12 2006/07/07 22:17:01 michael Exp $";

    24 #endif /* lint */

    25 

    26 int

    27 _elf_update_shnum(Elf *elf, size_t shnum) {

    28     size_t extshnum = 0;

    29     Elf_Scn *scn;

    30 

    31     elf_assert(elf);

    32     elf_assert(elf->e_ehdr);

    33     scn = elf->e_scn_1;

    34     elf_assert(scn);

    35     elf_assert(scn->s_index == 0);

    36     if (shnum >= SHN_LORESERVE) {

    37 	extshnum = shnum;

    38 	shnum = 0;

    39     }

    40     if (elf->e_class == ELFCLASS32) {

    41 	((Elf32_Ehdr*)elf->e_ehdr)->e_shnum = shnum;

    42 	scn->s_shdr32.sh_size = extshnum;

    43     }

    44 #if __LIBELF64

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

    46 	((Elf64_Ehdr*)elf->e_ehdr)->e_shnum = shnum;

    47 	scn->s_shdr64.sh_size = extshnum;

    48     }

    49 #endif /* __LIBELF64 */

    50     else {

    51 	if (valid_class(elf->e_class)) {

    52 	    seterr(ERROR_UNIMPLEMENTED);

    53 	}

    54 	else {

    55 	    seterr(ERROR_UNKNOWN_CLASS);

    56 	}

    57 	return -1;

    58     }

    59     elf->e_ehdr_flags |= ELF_F_DIRTY;

    60     scn->s_shdr_flags |= ELF_F_DIRTY;

    61     return 0;

    62 }

    63 

    64 static Elf_Scn*

    65 _makescn(Elf *elf, size_t index) {

    66     Elf_Scn *scn;

    67 

    68     elf_assert(elf);

    69     elf_assert(elf->e_magic == ELF_MAGIC);

    70     elf_assert(elf->e_ehdr);

    71     elf_assert(_elf_scn_init.s_magic == SCN_MAGIC);

    72     if (!(scn = (Elf_Scn*)malloc(sizeof(*scn)))) {

    73 	seterr(ERROR_MEM_SCN);

    74 	return NULL;

    75     }

    76     *scn = _elf_scn_init;

    77     scn->s_elf = elf;

    78     scn->s_scn_flags = ELF_F_DIRTY;

    79     scn->s_shdr_flags = ELF_F_DIRTY;

    80     scn->s_freeme = 1;

    81     scn->s_index = index;

    82     return scn;

    83 }

    84 

    85 Elf_Scn*

    86 _elf_first_scn(Elf *elf) {

    87     Elf_Scn *scn;

    88 

    89     elf_assert(elf);

    90     elf_assert(elf->e_magic == ELF_MAGIC);

    91     if ((scn = elf->e_scn_1)) {

    92 	return scn;

    93     }

    94     if ((scn = _makescn(elf, 0))) {

    95 	elf->e_scn_1 = elf->e_scn_n = scn;

    96 	if (_elf_update_shnum(elf, 1)) {

    97 	    free(scn);

    98 	    elf->e_scn_1 = elf->e_scn_n = scn = NULL;

    99 	}

   100     }

   101     return scn;

   102 }

   103 

   104 static Elf_Scn*

   105 _buildscn(Elf *elf) {

   106     Elf_Scn *scn;

   107 

   108     if (!_elf_first_scn(elf)) {

   109 	return NULL;

   110     }

   111     scn = elf->e_scn_n;

   112     elf_assert(scn);

   113     if (!(scn = _makescn(elf, scn->s_index + 1))) {

   114 	return NULL;

   115     }

   116     if (_elf_update_shnum(elf, scn->s_index + 1)) {

   117 	free(scn);

   118 	return NULL;

   119     }

   120     elf->e_scn_n = elf->e_scn_n->s_link = scn;

   121     return scn;

   122 }

   123 

   124 Elf_Scn*

   125 elf_newscn(Elf *elf) {

   126     Elf_Scn *scn;

   127 

   128     if (!elf) {

   129 	return NULL;

   130     }

   131     elf_assert(elf->e_magic == ELF_MAGIC);

   132     if (!elf->e_readable && !elf->e_ehdr) {

   133 	seterr(ERROR_NOEHDR);

   134     }

   135     else if (elf->e_kind != ELF_K_ELF) {

   136 	seterr(ERROR_NOTELF);

   137     }

   138     else if (!elf->e_ehdr && !_elf_cook(elf)) {

   139 	return NULL;

   140     }

   141     else if ((scn = _buildscn(elf))) {

   142 	return scn;

   143     }

   144     return NULL;

   145 }