| /* Return string pointer from string section. |
| Copyright (C) 1998-2002, 2004, 2008, 2009, 2015 Red Hat, Inc. |
| This file is part of elfutils. |
| Contributed by Ulrich Drepper <drepper@redhat.com>, 1998. |
| |
| This file is free software; you can redistribute it and/or modify |
| it under the terms of either |
| |
| * the GNU Lesser General Public License as published by the Free |
| Software Foundation; either version 3 of the License, or (at |
| your option) any later version |
| |
| or |
| |
| * the GNU General Public License as published by the Free |
| Software Foundation; either version 2 of the License, or (at |
| your option) any later version |
| |
| or both in parallel, as here. |
| |
| elfutils is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received copies of the GNU General Public License and |
| the GNU Lesser General Public License along with this program. If |
| not, see <http://www.gnu.org/licenses/>. */ |
| |
| #ifdef HAVE_CONFIG_H |
| # include <config.h> |
| #endif |
| |
| #include <libelf.h> |
| #include <stdbool.h> |
| #include <stddef.h> |
| |
| #include "libelfP.h" |
| |
| |
| static void * |
| get_zdata (Elf_Scn *strscn) |
| { |
| size_t zsize, zalign; |
| void *zdata = __libelf_decompress_elf (strscn, &zsize, &zalign); |
| if (zdata == NULL) |
| return NULL; |
| |
| strscn->zdata_base = zdata; |
| strscn->zdata_size = zsize; |
| strscn->zdata_align = zalign; |
| |
| return zdata; |
| } |
| |
| static bool validate_str (const char *str, size_t from, size_t to) |
| { |
| #if HAVE_DECL_MEMRCHR |
| return memrchr (&str[from], '\0', to - from) != NULL; |
| #else |
| do { |
| if (to <= from) |
| return false; |
| |
| to--; |
| } while (str[to]); |
| |
| return true; |
| #endif |
| } |
| |
| char * |
| elf_strptr (Elf *elf, size_t idx, size_t offset) |
| { |
| if (elf == NULL) |
| return NULL; |
| |
| if (elf->kind != ELF_K_ELF) |
| { |
| __libelf_seterrno (ELF_E_INVALID_HANDLE); |
| return NULL; |
| } |
| |
| rwlock_rdlock (elf->lock); |
| |
| char *result = NULL; |
| Elf_Scn *strscn; |
| |
| /* Find the section in the list. */ |
| Elf_ScnList *runp = (elf->class == ELFCLASS32 |
| || (offsetof (struct Elf, state.elf32.scns) |
| == offsetof (struct Elf, state.elf64.scns)) |
| ? &elf->state.elf32.scns : &elf->state.elf64.scns); |
| while (1) |
| { |
| if (idx < runp->max) |
| { |
| if (idx < runp->cnt) |
| strscn = &runp->data[idx]; |
| else |
| { |
| __libelf_seterrno (ELF_E_INVALID_INDEX); |
| goto out; |
| } |
| break; |
| } |
| |
| idx -= runp->max; |
| |
| runp = runp->next; |
| if (runp == NULL) |
| { |
| __libelf_seterrno (ELF_E_INVALID_INDEX); |
| goto out; |
| } |
| } |
| |
| size_t sh_size = 0; |
| if (elf->class == ELFCLASS32) |
| { |
| Elf32_Shdr *shdr = strscn->shdr.e32 ?: __elf32_getshdr_rdlock (strscn); |
| if (unlikely (shdr->sh_type != SHT_STRTAB)) |
| { |
| /* This is no string section. */ |
| __libelf_seterrno (ELF_E_INVALID_SECTION); |
| goto out; |
| } |
| |
| if ((shdr->sh_flags & SHF_COMPRESSED) == 0) |
| sh_size = shdr->sh_size; |
| else |
| { |
| if (strscn->zdata_base == NULL && get_zdata (strscn) == NULL) |
| goto out; |
| sh_size = strscn->zdata_size; |
| } |
| |
| if (unlikely (offset >= sh_size)) |
| { |
| /* The given offset is too big, it is beyond this section. */ |
| __libelf_seterrno (ELF_E_OFFSET_RANGE); |
| goto out; |
| } |
| } |
| else |
| { |
| Elf64_Shdr *shdr = strscn->shdr.e64 ?: __elf64_getshdr_rdlock (strscn); |
| if (unlikely (shdr == NULL || shdr->sh_type != SHT_STRTAB)) |
| { |
| /* This is no string section. */ |
| __libelf_seterrno (ELF_E_INVALID_SECTION); |
| goto out; |
| } |
| |
| if ((shdr->sh_flags & SHF_COMPRESSED) == 0) |
| sh_size = shdr->sh_size; |
| else |
| { |
| if (strscn->zdata_base == NULL && get_zdata (strscn) == NULL) |
| goto out; |
| sh_size = strscn->zdata_size; |
| } |
| |
| if (unlikely (offset >= sh_size)) |
| { |
| /* The given offset is too big, it is beyond this section. */ |
| __libelf_seterrno (ELF_E_OFFSET_RANGE); |
| goto out; |
| } |
| } |
| |
| if (strscn->rawdata_base == NULL && ! strscn->data_read) |
| { |
| rwlock_unlock (elf->lock); |
| rwlock_wrlock (elf->lock); |
| if (strscn->rawdata_base == NULL && ! strscn->data_read |
| /* Read the section data. */ |
| && __libelf_set_rawdata_wrlock (strscn) != 0) |
| goto out; |
| } |
| |
| if (unlikely (strscn->zdata_base != NULL)) |
| { |
| /* Make sure the string is NUL terminated. Start from the end, |
| which very likely is a NUL char. */ |
| if (likely (validate_str (strscn->zdata_base, offset, sh_size))) |
| result = &strscn->zdata_base[offset]; |
| else |
| __libelf_seterrno (ELF_E_INVALID_INDEX); |
| } |
| else if (likely (strscn->data_list_rear == NULL)) |
| { |
| // XXX The above is currently correct since elf_newdata will |
| // make sure to convert the rawdata into the datalist if |
| // necessary. But it would be more efficient to keep the rawdata |
| // unconverted and only then iterate over the rest of the (newly |
| // added data) list. Note that when the ELF file is mmapped |
| // rawdata_base can be set while rawdata.d hasn't been |
| // initialized yet (when data_read is zero). So we cannot just |
| // look at the rawdata.d.d_size. |
| |
| /* Make sure the string is NUL terminated. Start from the end, |
| which very likely is a NUL char. */ |
| if (likely (validate_str (strscn->rawdata_base, offset, sh_size))) |
| result = &strscn->rawdata_base[offset]; |
| else |
| __libelf_seterrno (ELF_E_INVALID_INDEX); |
| } |
| else |
| { |
| /* This is a file which is currently created. Use the list of |
| data blocks. */ |
| struct Elf_Data_List *dl = &strscn->data_list; |
| while (dl != NULL) |
| { |
| if (offset >= (size_t) dl->data.d.d_off |
| && offset < dl->data.d.d_off + dl->data.d.d_size) |
| { |
| /* Make sure the string is NUL terminated. Start from |
| the end, which very likely is a NUL char. */ |
| if (likely (validate_str ((char *) dl->data.d.d_buf, |
| offset - dl->data.d.d_off, |
| dl->data.d.d_size))) |
| result = ((char *) dl->data.d.d_buf |
| + (offset - dl->data.d.d_off)); |
| else |
| __libelf_seterrno (ELF_E_INVALID_INDEX); |
| break; |
| } |
| |
| dl = dl->next; |
| } |
| } |
| |
| out: |
| rwlock_unlock (elf->lock); |
| |
| return result; |
| } |
| INTDEF(elf_strptr) |