Ulrich Drepper | b08d5a8 | 2005-07-26 05:00:05 +0000 | [diff] [blame] | 1 | /* Create descriptor from ELF descriptor for processing file. |
| 2 | Copyright (C) 2002, 2003, 2004, 2005 Red Hat, Inc. |
| 3 | Written by Ulrich Drepper <drepper@redhat.com>, 2002. |
| 4 | |
| 5 | This program is Open Source software; you can redistribute it and/or |
| 6 | modify it under the terms of the Open Software License version 1.0 as |
| 7 | published by the Open Source Initiative. |
| 8 | |
| 9 | You should have received a copy of the Open Software License along |
| 10 | with this program; if not, you may obtain a copy of the Open Software |
| 11 | License version 1.0 from http://www.opensource.org/licenses/osl.php or |
| 12 | by writing the Open Source Initiative c/o Lawrence Rosen, Esq., |
| 13 | 3001 King Ranch Road, Ukiah, CA 95482. */ |
| 14 | |
| 15 | #ifdef HAVE_CONFIG_H |
| 16 | # include <config.h> |
| 17 | #endif |
| 18 | |
| 19 | #include <stdbool.h> |
| 20 | #include <stddef.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <string.h> |
| 23 | #include <unistd.h> |
| 24 | #include <sys/stat.h> |
| 25 | |
| 26 | #include "libdwP.h" |
| 27 | |
| 28 | |
| 29 | /* Section names. */ |
| 30 | static const char dwarf_scnnames[IDX_last][17] = |
| 31 | { |
| 32 | [IDX_debug_info] = ".debug_info", |
| 33 | [IDX_debug_abbrev] = ".debug_abbrev", |
| 34 | [IDX_debug_aranges] = ".debug_aranges", |
| 35 | [IDX_debug_line] = ".debug_line", |
| 36 | [IDX_debug_frame] = ".debug_frame", |
| 37 | [IDX_eh_frame] = ".eh_frame", |
| 38 | [IDX_debug_loc] = ".debug_loc", |
| 39 | [IDX_debug_pubnames] = ".debug_pubnames", |
| 40 | [IDX_debug_str] = ".debug_str", |
| 41 | [IDX_debug_funcnames] = ".debug_funcnames", |
| 42 | [IDX_debug_typenames] = ".debug_typenames", |
| 43 | [IDX_debug_varnames] = ".debug_varnames", |
| 44 | [IDX_debug_weaknames] = ".debug_weaknames", |
| 45 | [IDX_debug_macinfo] = ".debug_macinfo", |
| 46 | [IDX_debug_ranges] = ".debug_ranges" |
| 47 | }; |
| 48 | #define ndwarf_scnnames (sizeof (dwarf_scnnames) / sizeof (dwarf_scnnames[0])) |
| 49 | |
| 50 | |
| 51 | static void |
| 52 | check_section (Dwarf *result, GElf_Ehdr *ehdr, Elf_Scn *scn, bool inscngrp) |
| 53 | { |
| 54 | GElf_Shdr shdr_mem; |
| 55 | GElf_Shdr *shdr; |
| 56 | |
| 57 | /* Get the section header data. */ |
| 58 | shdr = gelf_getshdr (scn, &shdr_mem); |
| 59 | if (shdr == NULL) |
| 60 | /* This should never happen. If it does something is |
| 61 | wrong in the libelf library. */ |
| 62 | abort (); |
| 63 | |
| 64 | |
| 65 | /* Make sure the section is part of a section group only iff we |
| 66 | really need it. If we are looking for the global (= non-section |
| 67 | group debug info) we have to ignore all the info in section |
| 68 | groups. If we are looking into a section group we cannot look at |
| 69 | a section which isn't part of the section group. */ |
| 70 | if (! inscngrp && (shdr->sh_flags & SHF_GROUP) != 0) |
| 71 | /* Ignore the section. */ |
| 72 | return; |
| 73 | |
| 74 | |
| 75 | /* We recognize the DWARF section by their names. This is not very |
| 76 | safe and stable but the best we can do. */ |
| 77 | const char *scnname = elf_strptr (result->elf, ehdr->e_shstrndx, |
| 78 | shdr->sh_name); |
| 79 | if (scnname == NULL) |
| 80 | { |
| 81 | /* The section name must be valid. Otherwise is the ELF file |
| 82 | invalid. */ |
| 83 | __libdw_seterrno (DWARF_E_INVALID_ELF); |
| 84 | free (result); |
| 85 | return; |
| 86 | } |
| 87 | |
| 88 | |
| 89 | /* Recognize the various sections. Most names start with .debug_. */ |
| 90 | size_t cnt; |
| 91 | for (cnt = 0; cnt < ndwarf_scnnames; ++cnt) |
| 92 | if (strcmp (scnname, dwarf_scnnames[cnt]) == 0) |
| 93 | { |
| 94 | /* Found it. Remember where the data is. */ |
| 95 | if (unlikely (result->sectiondata[cnt] != NULL)) |
| 96 | /* A section appears twice. That's bad. We ignore the section. */ |
| 97 | break; |
| 98 | |
| 99 | /* Get the section data. */ |
| 100 | Elf_Data *data = elf_getdata (scn, NULL); |
| 101 | if (data != NULL && data->d_size != 0) |
| 102 | /* Yep, there is actually data available. */ |
| 103 | result->sectiondata[cnt] = data; |
| 104 | |
| 105 | break; |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | |
| 110 | /* Check whether all the necessary DWARF information is available. */ |
| 111 | static Dwarf * |
| 112 | valid_p (Dwarf *result) |
| 113 | { |
| 114 | /* We looked at all the sections. Now determine whether all the |
| 115 | sections with debugging information we need are there. |
| 116 | |
| 117 | XXX Which sections are absolutely necessary? Add tests if |
| 118 | necessary. For now we require only .debug_info. Hopefully this |
| 119 | is correct. */ |
| 120 | if (unlikely (result->sectiondata[IDX_debug_info] == NULL)) |
| 121 | { |
| 122 | __libdw_seterrno (DWARF_E_NO_DWARF); |
| 123 | result = NULL; |
| 124 | } |
| 125 | |
| 126 | return result; |
| 127 | } |
| 128 | |
| 129 | |
| 130 | static Dwarf * |
| 131 | global_read (Dwarf *result, Elf *elf, GElf_Ehdr *ehdr) |
| 132 | { |
| 133 | Elf_Scn *scn = NULL; |
| 134 | |
| 135 | while ((scn = elf_nextscn (elf, scn)) != NULL) |
| 136 | check_section (result, ehdr, scn, false); |
| 137 | |
| 138 | return valid_p (result); |
| 139 | } |
| 140 | |
| 141 | |
| 142 | static Dwarf * |
| 143 | scngrp_read (Dwarf *result, Elf *elf, GElf_Ehdr *ehdr, Elf_Scn *scngrp) |
| 144 | { |
| 145 | /* SCNGRP is the section descriptor for a section group which might |
| 146 | contain debug sections. */ |
| 147 | Elf_Data *data = elf_getdata (scngrp, NULL); |
| 148 | if (data == NULL) |
| 149 | { |
| 150 | /* We cannot read the section content. Fail! */ |
| 151 | free (result); |
| 152 | return NULL; |
| 153 | } |
| 154 | |
| 155 | /* The content of the section is a number of 32-bit words which |
| 156 | represent section indices. The first word is a flag word. */ |
| 157 | Elf32_Word *scnidx = (Elf32_Word *) data->d_buf; |
| 158 | size_t cnt; |
| 159 | for (cnt = 1; cnt * sizeof (Elf32_Word) <= data->d_size; ++cnt) |
| 160 | { |
| 161 | Elf_Scn *scn = elf_getscn (elf, scnidx[cnt]); |
| 162 | if (scn == NULL) |
| 163 | { |
| 164 | /* A section group refers to a non-existing section. Should |
| 165 | never happen. */ |
| 166 | __libdw_seterrno (DWARF_E_INVALID_ELF); |
| 167 | free (result); |
| 168 | return NULL; |
| 169 | } |
| 170 | |
| 171 | check_section (result, ehdr, scn, true); |
| 172 | } |
| 173 | |
| 174 | return valid_p (result); |
| 175 | } |
| 176 | |
| 177 | |
| 178 | Dwarf * |
| 179 | dwarf_begin_elf (elf, cmd, scngrp) |
| 180 | Elf *elf; |
| 181 | Dwarf_Cmd cmd; |
| 182 | Elf_Scn *scngrp; |
| 183 | { |
| 184 | GElf_Ehdr *ehdr; |
| 185 | GElf_Ehdr ehdr_mem; |
| 186 | |
| 187 | /* Get the ELF header of the file. We need various pieces of |
| 188 | information from it. */ |
| 189 | ehdr = gelf_getehdr (elf, &ehdr_mem); |
| 190 | if (ehdr == NULL) |
| 191 | { |
| 192 | if (elf_kind (elf) != ELF_K_ELF) |
| 193 | __libdw_seterrno (DWARF_E_NOELF); |
| 194 | else |
| 195 | __libdw_seterrno (DWARF_E_GETEHDR_ERROR); |
| 196 | |
| 197 | return NULL; |
| 198 | } |
| 199 | |
| 200 | |
| 201 | /* Default memory allocation size. */ |
| 202 | size_t mem_default_size = sysconf (_SC_PAGESIZE) - 4 * sizeof (void *); |
| 203 | |
| 204 | /* Allocate the data structure. */ |
| 205 | Dwarf *result = (Dwarf *) calloc (1, sizeof (Dwarf) + mem_default_size); |
| 206 | if (result == NULL) |
| 207 | { |
| 208 | __libdw_seterrno (DWARF_E_NOMEM); |
| 209 | return NULL; |
| 210 | } |
| 211 | |
| 212 | /* Fill in some values. */ |
| 213 | if ((BYTE_ORDER == LITTLE_ENDIAN && ehdr->e_ident[EI_DATA] == ELFDATA2MSB) |
| 214 | || (BYTE_ORDER == BIG_ENDIAN && ehdr->e_ident[EI_DATA] == ELFDATA2LSB)) |
| 215 | result->other_byte_order = true; |
| 216 | |
| 217 | result->elf = elf; |
| 218 | |
| 219 | /* Initialize the memory handling. */ |
| 220 | result->mem_default_size = mem_default_size; |
| 221 | result->oom_handler = __libdw_oom; |
| 222 | result->mem_tail = (struct libdw_memblock *) (result + 1); |
| 223 | result->mem_tail->size = (result->mem_default_size |
| 224 | - offsetof (struct libdw_memblock, mem)); |
| 225 | result->mem_tail->remaining = result->mem_tail->size; |
| 226 | result->mem_tail->prev = NULL; |
| 227 | |
| 228 | |
| 229 | if (cmd == DWARF_C_READ || cmd == DWARF_C_RDWR) |
| 230 | { |
| 231 | /* If the caller provides a section group we get the DWARF |
| 232 | sections only from this setion group. Otherwise we search |
| 233 | for the first section with the required name. Further |
| 234 | sections with the name are ignored. The DWARF specification |
| 235 | does not really say this is allowed. */ |
| 236 | if (scngrp == NULL) |
| 237 | return global_read (result, elf, ehdr); |
| 238 | else |
| 239 | return scngrp_read (result, elf, ehdr, scngrp); |
| 240 | } |
| 241 | else if (cmd == DWARF_C_WRITE) |
| 242 | { |
| 243 | __libdw_seterrno (DWARF_E_UNIMPL); |
| 244 | free (result); |
| 245 | return NULL; |
| 246 | } |
| 247 | |
| 248 | __libdw_seterrno (DWARF_E_INVALID_CMD); |
| 249 | free (result); |
| 250 | return NULL; |
| 251 | } |
| 252 | INTDEF(dwarf_begin_elf) |