Move/rename firmware extractor tools.
[sigrok-util.git] / firmware / saleae-logic16 / parseelf.py
1 #!/usr/bin/python3
2 ##
3 ## This file is part of the sigrok-util project.
4 ##
5 ## Copyright (C) 2013 Marcus Comstedt <marcus@mc.pp.se>
6 ##
7 ## This program is free software; you can redistribute it and/or modify
8 ## it under the terms of the GNU General Public License as published by
9 ## the Free Software Foundation; either version 3 of the License, or
10 ## (at your option) any later version.
11 ##
12 ## This program is distributed in the hope that it will be useful,
13 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
14 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 ## GNU General Public License for more details.
16 ##
17 ## You should have received a copy of the GNU General Public License
18 ## along with this program; if not, see <http://www.gnu.org/licenses/>.
19 ##
20
21 import struct
22
23 class elf:
24
25     def read_struct(this, struct_fmt, struct_fields):
26         fmt = this.elf_endianprefix+str.translate(struct_fmt, this.elf_format);
27         fields = struct.unpack(fmt, this.file.read(struct.calcsize(fmt)))
28         return dict(zip(struct_fields, fields))
29
30     def read_ehdr(this):
31         return this.read_struct('16sHHWNNNWHHHHHH',
32                                 ('e_ident', 'e_type', 'e_machine', 'e_version',
33                                  'e_entry', 'e_phoff', 'e_shoff', 'e_flags',
34                                  'e_ehsize', 'e_phentsize', 'e_phnum',
35                                  'e_shentsize', 'e_shnum', 'e_shstrndx'))
36
37     def read_shdr(this):
38         return this.read_struct('WWNNNNWWNN',
39                                 ('sh_name', 'sh_type', 'sh_flags', 'sh_addr',
40                                  'sh_offset', 'sh_size', 'sh_link', 'sh_info',
41                                  'sh_addralign', 'sh_entsize'))
42
43     def read_section(this, shdr):
44         this.file.seek(shdr['sh_offset'])
45         return this.file.read(shdr['sh_size'])
46
47     def get_name(this, name, strtab=None):
48         strtab = strtab or this.strtab
49         nul = strtab.find(b'\0', name)
50         if nul < 0:
51             return bytes.decode(strtab[name:])
52         else:
53             return bytes.decode(strtab[name:nul])
54
55     def find_section(this, name):
56         for section in this.shdrs:
57             if this.get_name(section['sh_name']) == name:
58                 return section
59         raise KeyError(name)
60
61     def parse_symbol(this):
62         if this.elf_wordsize == 64:
63             return this.read_struct('WBBHNX', 
64                                     ('st_name', 'st_info', 'st_other',
65                                      'st_shndx', 'st_value', 'st_size'))
66         else:
67             return this.read_struct('WNWBBH', 
68                                     ('st_name', 'st_value', 'st_size',
69                                      'st_info', 'st_other', 'st_shndx'))
70
71     def parse_symbols(this, symsecname, strsecname):
72         try:
73             symsechdr = this.find_section(symsecname)
74             strsechdr = this.find_section(strsecname)
75         except KeyError:
76             return {}
77         strsec = this.read_section(strsechdr)
78         this.file.seek(symsechdr['sh_offset'])
79         syms = [this.parse_symbol() for i in
80                 range(0, symsechdr['sh_size'] // symsechdr['sh_entsize'])]
81         return {this.get_name(sym['st_name'], strsec): sym for sym in syms}
82
83     def address_to_offset(this, addr):
84         for section in this.shdrs:
85             if (section['sh_addr'] <= addr and
86                 section['sh_addr']+section['sh_size'] > addr):
87                 return section['sh_offset']+(addr-section['sh_addr'])
88         raise IndexError('address out of range')
89
90     def load_symbol(this, sym):
91         this.file.seek(this.address_to_offset(sym['st_value']))
92         return this.file.read(sym['st_size'])
93
94     def __init__(this, filename):
95         this.file = open(filename, 'rb')
96         magic = this.file.read(16)
97
98         if magic[:4] != b'\x7fELF':
99             raise Exception("ELF signature not found")
100
101         if magic[4] == 1:
102             this.elf_wordsize = 32
103             nativeint = 'Ii'
104         elif magic[4] == 2:
105             this.elf_wordsize = 64
106             nativeint = 'Qq'
107         else:
108             raise Exception("Invalid ELF file class")
109
110         if magic[5] == 1:
111             this.elf_endianprefix = '<'
112         elif magic[5] == 2:
113             this.elf_endianprefix = '>'
114         else:
115             raise Exception("Invalid ELF data encoding")
116
117         this.elf_format = str.maketrans('HWwXxNn', 'HIiQq'+nativeint)
118
119         this.file.seek(0)
120         this.ehdr = this.read_ehdr()
121         this.file.seek(this.ehdr['e_shoff'])
122         this.shdrs = [this.read_shdr() for i in range(this.ehdr['e_shnum'])]
123
124         this.strtab = this.read_section(this.shdrs[this.ehdr['e_shstrndx']])
125
126         this.symtab = this.parse_symbols('.symtab', '.strtab')
127         this.dynsym = this.parse_symbols('.dynsym', '.dynstr')
128
129     def __del__(this):
130         try:
131             this.file.close()
132         except AttributeError:
133             pass