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Add beginning of an ELF parser.
2006-08-15 Soren Sandmann <sandmann@redhat.com> Add beginning of an ELF parser. * binparser.[ch]: New files * elfparser.[ch]: New files * testelf.c: New file * Makefile.am (testelf_SOURCES): Add new testelf program.
This commit is contained in:
Soren Sandmann
committed by
Søren Sandmann Pedersen
Søren Sandmann Pedersen
parent
bde3d8a537
commit
2bc2e3658d
458
elfparser.c
Normal file
458
elfparser.c
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@ -0,0 +1,458 @@
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#include <string.h>
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#include <elf.h>
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#include "binparser.h"
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#include "elfparser.h"
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typedef struct SymbolTable SymbolTable;
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struct SymbolTable
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{
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};
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struct ElfSym
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{
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};
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struct ElfParser
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{
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BinParser *parser;
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BinFormat *header;
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BinFormat *strtab_format;
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BinFormat *shn_entry;
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BinFormat *sym_format;
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gsize strtab_offset;
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gsize str_table;
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};
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static void make_formats (ElfParser *parser,
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gboolean is_64,
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gboolean is_big_endian);
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#if 0
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BinFormat *str_tab = bin_field_new_string ("string", make_string());
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gsize offset = find_it();
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#endif
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#if 0
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static void
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parse_elf (const guchar *data,
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gsize length)
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{
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gboolean is_64, is_big_endian;
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BinFormat *elf_header;
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BinFormat *shn_entry;
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BinParser *parser;
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BinParser *sh_parser;
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BinFormat *sym;
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int i;
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find_elf_type (data, length, &is_64, &is_big_endian);
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parser = bin_parser_new (data, length);
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bin_parser_begin (parser, elf_header, 0);
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g_print ("section header offset: %u\n",
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bin_parser_get_uint ("e_shoff"));
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g_print ("There are %llu sections\n",
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bin_parser_get_uint (parser, "e_shnum"));
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}
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#endif
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static const char *
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elf_lookup_string (ElfParser *parser, int offset)
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{
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const char *result;
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/* This function has a midleading name. In reality
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* it only looks up in the section header table
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*/
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bin_parser_begin (parser->parser,
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NULL, parser->strtab_offset + offset);
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result = bin_parser_get_string (parser->parser);
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bin_parser_end (parser->parser);
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return result;
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}
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static gboolean
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find_elf_type (const guchar *data, gsize length,
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gboolean *is_64, gboolean *is_be)
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{
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/* FIXME: this function should be able to return an error */
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if (length < EI_NIDENT)
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return FALSE;
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/* 32 or 64? */
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if (data[EI_CLASS] == ELFCLASS32)
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{
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*is_64 = FALSE;
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}
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else if (data[EI_CLASS] == ELFCLASS64)
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{
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*is_64 = TRUE;
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}
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else
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{
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/* FIXME: set_error */
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return FALSE;
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}
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/* big or little endian? */
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if (data[EI_DATA] == ELFDATA2LSB)
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{
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*is_be = FALSE;
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}
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else if (data[EI_DATA] == ELFDATA2MSB)
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{
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*is_be = TRUE;
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}
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else
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{
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/* FIXME: set error */
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return FALSE;
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}
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g_print ("This elf file is %s %s\n",
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*is_64? "64 bit" : "32 bit",
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*is_be? "big endiann" : "little endian");
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return TRUE;
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}
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static BinField *
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make_word (gboolean is_64)
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{
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if (is_64)
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return bin_field_new_uint64 ();
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else
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return bin_field_new_uint32 ();
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}
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static void
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dump_symbol_table (ElfParser *parser,
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gsize offset,
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gsize size)
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{
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int i;
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if (!parser->str_table)
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{
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g_print ("no string table\n");
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return;
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}
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g_print ("dumping symbol table at %d\n", offset);
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bin_parser_begin (parser->parser, parser->sym_format, offset);
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for (i = 0; i < 200; ++i)
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{
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guint64 idx;
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bin_parser_index (parser->parser, i);
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idx = bin_parser_get_uint (parser->parser, "st_name");
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const char *result;
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gsize size;
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#if 0
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g_print ("addr: %p\n", bin_parser_get_address (parser->parser, "st_name"));
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#endif
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#if 0
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g_print ("idx: %d\n", idx);
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#endif
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size = bin_parser_get_uint (parser->parser, "st_size");
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bin_parser_begin (parser->parser,
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NULL, parser->str_table + idx);
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result = bin_parser_get_string (parser->parser);
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bin_parser_end (parser->parser);
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g_print ("%d symbol: size: %d, %s.\n",
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i, size, result);
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}
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bin_parser_end (parser->parser);
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}
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ElfParser *
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elf_parser_new (const guchar *data, gsize length)
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{
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ElfParser *parser;
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gboolean is_64, is_big_endian;
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int n_sections;
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int section_name_table;
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int i;
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if (!find_elf_type (data, length, &is_64, &is_big_endian))
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{
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/* FIXME: set error */
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return NULL;
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}
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parser = g_new0 (ElfParser, 1);
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parser->parser = bin_parser_new (data, length);
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make_formats (parser, is_64, is_big_endian);
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bin_parser_begin (parser->parser, parser->header, 0);
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n_sections =
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bin_parser_get_uint (parser->parser, "e_shnum");
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section_name_table =
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bin_parser_get_uint (parser->parser, "e_shstrndx");
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bin_parser_begin (
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parser->parser, parser->shn_entry,
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bin_parser_get_uint (parser->parser, "e_shoff"));
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bin_parser_index (parser->parser, section_name_table);
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parser->strtab_offset =
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bin_parser_get_uint (parser->parser, "sh_offset");
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for (i = 0; i < n_sections; ++i)
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{
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const char *name;
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int offset;
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bin_parser_index (parser->parser, i);
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offset = bin_parser_get_uint (parser->parser, "sh_name");
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name = elf_lookup_string (parser, offset);
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if (strcmp (name, ".strtab") == 0)
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{
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parser->str_table = bin_parser_get_uint (
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parser->parser, "sh_offset");
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}
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}
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for (i = 0; i < n_sections; ++i)
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{
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const char *name;
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int offset;
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const char *type;
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bin_parser_index (parser->parser, i);
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offset = bin_parser_get_uint (parser->parser, "sh_name");
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name = elf_lookup_string (parser, offset);
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switch (bin_parser_get_uint (parser->parser, "sh_type"))
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{
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case SHT_NULL:
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type = "undefined";
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break;
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case SHT_PROGBITS:
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type = "progbits";
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break;
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case SHT_SYMTAB:
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type = "symbol table";
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dump_symbol_table (
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parser,
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bin_parser_get_uint (parser->parser, "sh_offset"),
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bin_parser_get_uint (parser->parser, "sh_size"));
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break;
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case SHT_STRTAB:
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type = "string table";
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break;
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case SHT_RELA:
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type = "relocations with explicit addends";
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break;
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case SHT_HASH:
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type = "symbol hash table";
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break;
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case SHT_DYNAMIC:
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type = "Information for dynamic linking";
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break;
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case SHT_NOTE:
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type = "note";
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break;
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case SHT_NOBITS:
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type = "nobits";
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break;
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case SHT_REL:
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type = "relocations without explicit addends";
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break;
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case SHT_SHLIB:
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type = "reserved with unspecified semantics";
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break;
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case SHT_DYNSYM:
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type = "dynamic symbols";
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break;
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case SHT_LOPROC:
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type = "loproc";
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break;
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case SHT_HIPROC:
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type = "hiproc";
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break;
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case SHT_LOUSER:
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type = "louser:";
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break;
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case SHT_HIUSER:
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type = "hiuser";
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break;
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default:
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type = "<unknown>";
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break;
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}
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g_print ("%s [%s] (%d)\n", name, type, offset);
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}
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bin_parser_end (parser->parser);
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bin_parser_end (parser->parser);
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return parser;
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}
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static const char *
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get_string (BinParser *parser,
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gsize table,
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gsize offset)
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{
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const char *result = NULL;
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bin_parser_begin (parser, NULL, table + offset);
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result = bin_parser_get_string (parser);
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bin_parser_end (parser);
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return result;
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}
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static gssize
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find_section (ElfParser *parser,
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const char *name)
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{
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int n_sections;
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int section_name_table;
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int section_headers_offset;
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int section_name_table_offset;
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BinParser *bparser = parser->parser;
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int i;
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gssize result;
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bin_parser_begin (parser->parser, parser->header, 0);
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n_sections = bin_parser_get_uint (bparser, "e_shnum");
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section_name_table = bin_parser_get_uint (bparser, "e_shstrndx");
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section_headers_offset = bin_parser_get_uint (bparser, "e_shoff");
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bin_parser_begin (bparser, parser->shn_entry, section_headers_offset);
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bin_parser_index (bparser, section_name_table);
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section_name_table_offset = bin_parser_get_uint (bparser, "sh_offset");
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result = -1;
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for (i = 0; i < n_sections; ++i)
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{
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const char *section_name;
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gsize name_offset;
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bin_parser_index (bparser, i);
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name_offset = bin_parser_get_uint (bparser, "sh_name");
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section_name = get_string (
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bparser, section_name_table_offset, name_offset);
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if (strcmp (section_name, name) == 0)
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{
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result = bin_parser_get_uint (bparser, "sh_offset");
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goto out;
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}
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}
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out:
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bin_parser_end (bparser);
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g_print ("found %s at %d\n", name, result);
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return result;
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}
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const ElfSym *
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elf_parser_lookup_symbol (ElfParser *parser,
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gulong address)
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{
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gssize symtab_offset = find_section (parser, ".symtab");
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gssize strtab_offset = find_section (parser, ".strtab");
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gssize dynsym_offset = find_section (parser, ".dynsym");
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gssize dynstr_offset = find_section (parser, ".dynstr");
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return NULL;
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}
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static void
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make_formats (ElfParser *parser, gboolean is_64, gboolean is_big_endian)
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{
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parser->header = bin_format_new (
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is_big_endian,
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"e_ident", bin_field_new_fixed_array (EI_NIDENT, 1),
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"e_type", bin_field_new_uint16 (),
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"e_machine", bin_field_new_uint16 (),
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"e_version", bin_field_new_uint32 (),
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"e_entry", make_word (is_64),
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"e_phoff", make_word (is_64),
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"e_shoff", make_word (is_64),
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"e_flags", bin_field_new_uint32 (),
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"e_ehsize", bin_field_new_uint16 (),
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"e_phentsize", bin_field_new_uint16 (),
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"e_phnum", bin_field_new_uint16 (),
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"e_shentsize", bin_field_new_uint16 (),
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"e_shnum", bin_field_new_uint16 (),
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"e_shstrndx", bin_field_new_uint16 (),
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NULL);
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parser->shn_entry = bin_format_new (
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is_big_endian,
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"sh_name", bin_field_new_uint32 (),
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"sh_type", bin_field_new_uint32 (),
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"sh_flags", make_word (is_64),
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"sh_addr", make_word (is_64),
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"sh_offset", make_word (is_64),
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"sh_size", make_word (is_64),
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"sh_link", bin_field_new_uint32 (),
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"sh_info", bin_field_new_uint32 (),
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"sh_addralign", make_word (is_64),
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"sh_entsize", make_word (is_64),
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NULL);
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if (is_64)
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{
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parser->sym_format = bin_format_new (
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is_big_endian,
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"st_name", bin_field_new_uint32 (),
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"st_info", bin_field_new_uint8 (),
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"st_other", bin_field_new_uint8 (),
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"st_shndx", bin_field_new_uint16 (),
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"st_value", bin_field_new_uint64 (),
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"st_size", bin_field_new_uint64 (),
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NULL);
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}
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else
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{
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parser->sym_format = bin_format_new (
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is_big_endian,
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"st_name", bin_field_new_uint32 (),
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"st_value", bin_field_new_uint32 (),
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"st_size", bin_field_new_uint32 (),
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"st_info", bin_field_new_uint8 (),
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"st_other", bin_field_new_uint8 (),
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"st_shndx", bin_field_new_uint16 (),
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NULL);
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}
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}
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