external/bsd/libelf/dist/elf_scn.c

   1 /*      $NetBSD: elf_scn.c,v 1.4 2009/12/20 23:23:46 thorpej Exp $      */
   2
   3 /*-
   4  * Copyright (c) 2006 Joseph Koshy
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  */
  28
  29 #include <sys/cdefs.h>
  30 /* __FBSDID("$FreeBSD: src/lib/libelf/elf_scn.c,v 1.2.10.1.2.1 2009/10/25 01:10:29 kensmith Exp $"); */
  31
  32 #include <assert.h>
  33 #include <errno.h>
  34 #include <gelf.h>
  35 #include <libelf.h>
  36 #include <stddef.h>
  37 #include <stdlib.h>
  38 #include <limits.h>
  39
  40 #include "_libelf.h"
  41
  42 /*
  43  * Load an ELF section table and create a list of Elf_Scn structures.
  44  */
  45 static int
  46 _libelf_load_scn(Elf *e, void *ehdr)
  47 {
  48         int ec, swapbytes;
  49         size_t fsz, i, shnum;
  50         uint64_t shoff;
  51         char *src;
  52         Elf32_Ehdr *eh32;
  53         Elf64_Ehdr *eh64;
  54         Elf_Scn *scn;
  55         void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
  56
  57         assert(e != NULL);
  58         assert(ehdr != NULL);
  59         assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0);
  60
  61 #define CHECK_EHDR(E,EH)        do {                            \
  62                 if (fsz != (EH)->e_shentsize ||                 \
  63                     shoff + fsz * shnum > e->e_rawsize) {       \
  64                         LIBELF_SET_ERROR(HEADER, 0);            \
  65                         return (0);                             \
  66                 }                                               \
  67         } while (/*CONSTCOND*/0)
  68
  69         ec = e->e_class;
  70         fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
  71         assert(fsz > 0);
  72
  73         shnum = e->e_u.e_elf.e_nscn;
  74
  75         if (ec == ELFCLASS32) {
  76                 eh32 = (Elf32_Ehdr *) ehdr;
  77                 shoff = (uint64_t) eh32->e_shoff;
  78                 CHECK_EHDR(e, eh32);
  79         } else {
  80                 eh64 = (Elf64_Ehdr *) ehdr;
  81                 shoff = eh64->e_shoff;
  82                 CHECK_EHDR(e, eh64);
  83         }
  84
  85         xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
  86
  87         swapbytes = e->e_byteorder != _libelf_host_byteorder();
  88         if (shoff > SSIZE_MAX) {
  89                 LIBELF_SET_ERROR(HEADER, 0);
  90                 return (0);
  91         }
  92         src = e->e_rawfile + (ssize_t)shoff;
  93
  94         /*
  95          * If the file is using extended numbering then section #0
  96          * would have already been read in.
  97          */
  98
  99         i = 0;
 100         if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
 101                 assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) ==
 102                     STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next));
 103
 104                 i = 1;
 105                 src += fsz;
 106         }
 107
 108         for (; i < shnum; i++, src += fsz) {
 109                 if ((scn = _libelf_allocate_scn(e, i)) == NULL)
 110                         return (0);
 111
 112                 (*xlator)((void *) &scn->s_shdr, src, (size_t) 1, swapbytes);
 113
 114                 if (ec == ELFCLASS32) {
 115                         scn->s_offset = scn->s_rawoff =
 116                             scn->s_shdr.s_shdr32.sh_offset;
 117                         scn->s_size = scn->s_shdr.s_shdr32.sh_size;
 118                 } else {
 119                         scn->s_offset = scn->s_rawoff =
 120                             scn->s_shdr.s_shdr64.sh_offset;
 121                         scn->s_size = scn->s_shdr.s_shdr64.sh_size;
 122                 }
 123         }
 124
 125         e->e_flags |= LIBELF_F_SHDRS_LOADED;
 126
 127         return (1);
 128 }
 129
 130
 131 Elf_Scn *
 132 elf_getscn(Elf *e, size_t index)
 133 {
 134         int ec;
 135         void *ehdr;
 136         Elf_Scn *s;
 137
 138         if (e == NULL || e->e_kind != ELF_K_ELF ||
 139             ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64)) {
 140                 LIBELF_SET_ERROR(ARGUMENT, 0);
 141                 return (NULL);
 142         }
 143
 144         if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
 145                 return (NULL);
 146
 147         if (e->e_cmd != ELF_C_WRITE &&
 148             (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
 149             _libelf_load_scn(e, ehdr) == 0)
 150                 return (NULL);
 151
 152         STAILQ_FOREACH(s, &e->e_u.e_elf.e_scn, s_next)
 153                 if (s->s_ndx == index)
 154                         return (s);
 155
 156         LIBELF_SET_ERROR(ARGUMENT, 0);
 157         return (NULL);
 158 }
 159
 160 size_t
 161 elf_ndxscn(Elf_Scn *s)
 162 {
 163         if (s == NULL) {
 164                 LIBELF_SET_ERROR(ARGUMENT, 0);
 165                 return (SHN_UNDEF);
 166         }
 167         return (s->s_ndx);
 168 }
 169
 170 Elf_Scn *
 171 elf_newscn(Elf *e)
 172 {
 173         int ec;
 174         void *ehdr;
 175         Elf_Scn *scn;
 176
 177         if (e == NULL || e->e_kind != ELF_K_ELF) {
 178                 LIBELF_SET_ERROR(ARGUMENT, 0);
 179                 return (NULL);
 180         }
 181
 182         if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
 183                 LIBELF_SET_ERROR(CLASS, 0);
 184                 return (NULL);
 185         }
 186
 187         if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
 188                 return (NULL);
 189
 190         /*
 191          * The application may be asking for a new section descriptor
 192          * on an ELF object opened with ELF_C_RDWR or ELF_C_READ.  We
 193          * need to bring in the existing section information before
 194          * appending a new one to the list.
 195          *
 196          * Per the ELF(3) API, an application is allowed to open a
 197          * file using ELF_C_READ, mess with its internal structure and
 198          * use elf_update(...,ELF_C_NULL) to compute its new layout.
 199          */
 200         if (e->e_cmd != ELF_C_WRITE &&
 201             (e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
 202             _libelf_load_scn(e, ehdr) == 0)
 203                 return (NULL);
 204
 205         if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
 206                 assert(e->e_u.e_elf.e_nscn == 0);
 207                 if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) ==
 208                     NULL)
 209                         return (NULL);
 210                 e->e_u.e_elf.e_nscn++;
 211         }
 212
 213         assert(e->e_u.e_elf.e_nscn > 0);
 214
 215         if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL)
 216                 return (NULL);
 217
 218         e->e_u.e_elf.e_nscn++;
 219
 220         (void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY);
 221
 222         return (scn);
 223 }
 224
 225 Elf_Scn *
 226 elf_nextscn(Elf *e, Elf_Scn *s)
 227 {
 228         if (e == NULL || (e->e_kind != ELF_K_ELF) ||
 229             (s && s->s_elf != e)) {
 230                 LIBELF_SET_ERROR(ARGUMENT, 0);
 231                 return (NULL);
 232         }
 233
 234         return (s == NULL ? elf_getscn(e, (size_t) 1) :
 235             STAILQ_NEXT(s, s_next));
 236 }