1/* Create new, empty section data. 2 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2015 Red Hat, Inc. 3 This file is part of elfutils. 4 Contributed by Ulrich Drepper <drepper@redhat.com>, 1998. 5 6 This file is free software; you can redistribute it and/or modify 7 it under the terms of either 8 9 * the GNU Lesser General Public License as published by the Free 10 Software Foundation; either version 3 of the License, or (at 11 your option) any later version 12 13 or 14 15 * the GNU General Public License as published by the Free 16 Software Foundation; either version 2 of the License, or (at 17 your option) any later version 18 19 or both in parallel, as here. 20 21 elfutils is distributed in the hope that it will be useful, but 22 WITHOUT ANY WARRANTY; without even the implied warranty of 23 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 24 General Public License for more details. 25 26 You should have received copies of the GNU General Public License and 27 the GNU Lesser General Public License along with this program. If 28 not, see <http://www.gnu.org/licenses/>. */ 29 30#ifdef HAVE_CONFIG_H 31# include <config.h> 32#endif 33 34#include <stddef.h> 35#include <stdlib.h> 36 37#include "libelfP.h" 38 39 40Elf_Data * 41elf_newdata (Elf_Scn *scn) 42{ 43 Elf_Data_List *result = NULL; 44 45 if (scn == NULL) 46 return NULL; 47 48 if (unlikely (scn->index == 0)) 49 { 50 /* It is not allowed to add something to the 0th section. */ 51 __libelf_seterrno (ELF_E_NOT_NUL_SECTION); 52 return NULL; 53 } 54 55 if (scn->elf->class == ELFCLASS32 56 || (offsetof (struct Elf, state.elf32.ehdr) 57 == offsetof (struct Elf, state.elf64.ehdr)) 58 ? scn->elf->state.elf32.ehdr == NULL 59 : scn->elf->state.elf64.ehdr == NULL) 60 { 61 __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR); 62 return NULL; 63 } 64 65 rwlock_wrlock (scn->elf->lock); 66 67 /* data_read is set when data has been read from the ELF image or 68 when a new section has been created by elf_newscn. If data has 69 been read from the ELF image, then rawdata_base will point to raw 70 data. If data_read has been set by elf_newscn, then rawdata_base 71 will be NULL. data_list_rear will be set by elf_getdata if the 72 data has been converted, or by this function, elf_newdata, when 73 new data has been added. 74 75 Currently elf_getdata and elf_update rely on the fact that when 76 data_list_read is not NULL all they have to do is walk the data 77 list. They will ignore any (unread) raw data in that case. 78 79 So we need to make sure the data list is setup if there is 80 already data available. */ 81 if (scn->data_read 82 && scn->rawdata_base != NULL 83 && scn->data_list_rear == NULL) 84 __libelf_set_data_list_rdlock (scn, 1); 85 86 if (scn->data_read && scn->data_list_rear == NULL) 87 { 88 /* This means the section was created by the user and this is the 89 first data. */ 90 result = &scn->data_list; 91 result->flags = ELF_F_DIRTY; 92 } 93 else 94 { 95 /* It would be more efficient to create new data without 96 reading/converting the data from the file. But then we 97 have to remember this. Currently elf_getdata and 98 elf_update rely on the fact that they don't have to 99 load/convert any data if data_list_rear is set. */ 100 if (scn->data_read == 0) 101 { 102 if (__libelf_set_rawdata_wrlock (scn) != 0) 103 /* Something went wrong. The error value is already set. */ 104 goto out; 105 __libelf_set_data_list_rdlock (scn, 1); 106 } 107 108 /* Create a new, empty data descriptor. */ 109 result = calloc (1, sizeof (Elf_Data_List)); 110 if (result == NULL) 111 { 112 __libelf_seterrno (ELF_E_NOMEM); 113 goto out; 114 } 115 116 result->flags = ELF_F_DIRTY | ELF_F_MALLOCED; 117 } 118 119 /* Set the predefined values. */ 120 result->data.d.d_version = EV_CURRENT; 121 122 result->data.s = scn; 123 124 /* Add to the end of the list. */ 125 if (scn->data_list_rear != NULL) 126 scn->data_list_rear->next = result; 127 128 scn->data_list_rear = result; 129 130 out: 131 rwlock_unlock (scn->elf->lock); 132 133 /* Please note that the following is thread safe and is also defined 134 for RESULT == NULL since it still return NULL. */ 135 return &result->data.d; 136} 137