elf_symtab.c

   1 /*
   2   SPDX-License-Identifier: GPL-2.0-only
   3
   4   Copyright (C) 2009 Red Hat Inc.
   5   Copyright (C) 2009 Arnaldo Carvalho de Melo <acme@redhat.com>
   6 */
   7
   8 #include <malloc.h>
   9 #include <stdio.h>
  10 #include <string.h>
  11
  12 #include "dutil.h"
  13 #include "elf_symtab.h"
  14
  15 #define HASHSYMS__BITS 8
  16 #define HASHSYMS__SIZE (1UL << HASHSYMS__BITS)
  17
  18 struct elf_symtab *elf_symtab__new(const char *name, Elf *elf)
  19 {
  20         size_t symtab_index;
  21
  22         if (name == NULL)
  23                 name = ".symtab";
  24
  25         GElf_Shdr shdr;
  26         Elf_Scn *sec = elf_section_by_name(elf, &shdr, name, &symtab_index);
  27
  28         if (sec == NULL)
  29                 return NULL;
  30
  31         if (gelf_getshdr(sec, &shdr) == NULL)
  32                 return NULL;
  33
  34         struct elf_symtab *symtab = zalloc(sizeof(*symtab));
  35         if (symtab == NULL)
  36                 return NULL;
  37
  38         symtab->name = strdup(name);
  39         if (symtab->name == NULL)
  40                 goto out_delete;
  41
  42         symtab->syms = elf_getdata(sec, NULL);
  43         if (symtab->syms == NULL)
  44                 goto out_free_name;
  45
  46         /*
  47          * This returns extended section index table's
  48          * section index, if it exists.
  49          */
  50         int symtab_xindex = elf_scnshndx(sec);
  51
  52         sec = elf_getscn(elf, shdr.sh_link);
  53         if (sec == NULL)
  54                 goto out_free_name;
  55
  56         symtab->symstrs = elf_getdata(sec, NULL);
  57         if (symtab->symstrs == NULL)
  58                 goto out_free_name;
  59
  60         /*
  61          * The .symtab section has optional extended section index
  62          * table, load its data so it can be used to resolve symbol's
  63          * section index.
  64          **/
  65         if (symtab_xindex > 0) {
  66                 GElf_Shdr shdr_xindex;
  67                 Elf_Scn *sec_xindex;
  68
  69                 sec_xindex = elf_getscn(elf, symtab_xindex);
  70                 if (sec_xindex == NULL)
  71                         goto out_free_name;
  72
  73                 if (gelf_getshdr(sec_xindex, &shdr_xindex) == NULL)
  74                         goto out_free_name;
  75
  76                 /* Extra check to verify it's correct type */
  77                 if (shdr_xindex.sh_type != SHT_SYMTAB_SHNDX)
  78                         goto out_free_name;
  79
  80                 /* Extra check to verify it belongs to the .symtab */
  81                 if (symtab_index != shdr_xindex.sh_link)
  82                         goto out_free_name;
  83
  84                 symtab->syms_sec_idx_table = elf_getdata(elf_getscn(elf, symtab_xindex), NULL);
  85                 if (symtab->syms_sec_idx_table == NULL)
  86                         goto out_free_name;
  87         }
  88
  89         symtab->nr_syms = shdr.sh_size / shdr.sh_entsize;
  90
  91         return symtab;
  92 out_free_name:
  93         zfree(&symtab->name);
  94 out_delete:
  95         free(symtab);
  96         return NULL;
  97 }
  98
  99 void elf_symtab__delete(struct elf_symtab *symtab)
 100 {
 101         if (symtab == NULL)
 102                 return;
 103         zfree(&symtab->name);
 104         free(symtab);
 105 }