1 /* Compute simple checksum from permanent parts of the ELF file. 2 Copyright (C) 2002, 2003, 2004 Red Hat, Inc. 3 Written by Ulrich Drepper <drepper@redhat.com>, 2002. 4 5 This program is free software; you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation, version 2. 8 9 This program is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU General Public License for more details. 13 14 You should have received a copy of the GNU General Public License 15 along with this program; if not, write to the Free Software Foundation, 16 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ 17 18 #ifdef HAVE_CONFIG_H 19 # include <config.h> 20 #endif 21 22 #include <assert.h> 23 #include <stdbool.h> 24 #include <stddef.h> 25 #include <string.h> 26 27 #include "gelf.h" 28 #include "libelfP.h" 29 #include "elf-knowledge.h" 30 31 #ifndef LIBELFBITS 32 # define LIBELFBITS 32 33 #endif 34 35 36 /* The SECTION_STRIP_P macro wants to call into libebl which we cannot 37 do and do not have to do here. Provide a dummy replacement. */ 38 #define ebl_debugscn_p(ebl, name) true 39 40 41 #define process_block(crc, data) \ 42 __libelf_crc32 (crc, data->d_buf, data->d_size) 43 44 45 long int 46 elfw2(LIBELFBITS,checksum) (elf) 47 Elf *elf; 48 { 49 size_t shstrndx; 50 Elf_Scn *scn; 51 long int result = 0; 52 unsigned char *ident; 53 bool same_byte_order; 54 55 if (elf == NULL) 56 return -1l; 57 58 /* Find the section header string table. */ 59 if (INTUSE(elf_getshstrndx) (elf, &shstrndx) < 0) 60 { 61 /* This can only happen if the ELF handle is not for real. */ 62 __libelf_seterrno (ELF_E_INVALID_HANDLE); 63 return -1l; 64 } 65 66 /* Determine whether the byte order of the file and that of the host 67 is the same. */ 68 ident = elf->state.ELFW(elf,LIBELFBITS).ehdr->e_ident; 69 same_byte_order = ((ident[EI_DATA] == ELFDATA2LSB 70 && __BYTE_ORDER == __LITTLE_ENDIAN) 71 || (ident[EI_DATA] == ELFDATA2MSB 72 && __BYTE_ORDER == __BIG_ENDIAN)); 73 74 /* Iterate over all sections to find those which are not strippable. */ 75 scn = NULL; 76 while ((scn = INTUSE(elf_nextscn) (elf, scn)) != NULL) 77 { 78 GElf_Shdr shdr_mem; 79 GElf_Shdr *shdr; 80 Elf_Data *data; 81 82 /* Get the section header. */ 83 shdr = INTUSE(gelf_getshdr) (scn, &shdr_mem); 84 if (shdr == NULL) 85 { 86 __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER); 87 return -1l; 88 } 89 90 if (SECTION_STRIP_P (NULL, NULL, NULL, shdr, 91 elf_strptr (elf, shstrndx, shdr->sh_name), 92 true, false)) 93 /* The section can be stripped. Don't use it. */ 94 continue; 95 96 /* To compute the checksum we need to get to the data. For 97 repeatable results we must use the external format. The data 98 we get with 'elf'getdata' might be changed for endianess 99 reasons. Therefore we use 'elf_rawdata' if possible. But 100 this function can fail if the data was constructed by the 101 program. In this case we have to use 'elf_getdata' and 102 eventually convert the data to the external format. */ 103 data = INTUSE(elf_rawdata) (scn, NULL); 104 if (data != NULL) 105 { 106 /* The raw data is available. */ 107 result = process_block (result, data); 108 109 /* Maybe the user added more data. These blocks cannot be 110 read using 'elf_rawdata'. Simply proceed with looking 111 for more data block with 'elf_getdata'. */ 112 } 113 114 /* Iterate through the list of data blocks. */ 115 while ((data = INTUSE(elf_getdata) (scn, data)) != NULL) 116 /* If the file byte order is the same as the host byte order 117 process the buffer directly. If the data is just a stream 118 of bytes which the library will not convert we can use it 119 as well. */ 120 if (likely (same_byte_order) || data->d_type == ELF_T_BYTE) 121 result = process_block (result, data); 122 else 123 { 124 /* Convert the data to file byte order. */ 125 if (INTUSE(elfw2(LIBELFBITS,xlatetof)) (data, data, ident[EI_DATA]) 126 == NULL) 127 return -1l; 128 129 result = process_block (result, data); 130 131 /* And convert it back. */ 132 if (INTUSE(elfw2(LIBELFBITS,xlatetom)) (data, data, ident[EI_DATA]) 133 == NULL) 134 return -1l; 135 } 136 } 137 138 return result; 139 } 140 INTDEF(elfw2(LIBELFBITS,checksum)) 141