1 | #if defined(__ELF__) && !defined(__FreeBSD__) |
2 | |
3 | #include <Common/Elf.h> |
4 | #include <Common/Exception.h> |
5 | |
6 | #include <string.h> |
7 | |
8 | |
9 | namespace DB |
10 | { |
11 | |
12 | namespace ErrorCodes |
13 | { |
14 | extern const int CANNOT_PARSE_ELF; |
15 | } |
16 | |
17 | |
18 | Elf::Elf(const std::string & path) |
19 | : in(path, 0) |
20 | { |
21 | /// Check if it's an elf. |
22 | elf_size = in.buffer().size(); |
23 | if (elf_size < sizeof(ElfEhdr)) |
24 | throw Exception("The size of supposedly ELF file is too small" , ErrorCodes::CANNOT_PARSE_ELF); |
25 | |
26 | mapped = in.buffer().begin(); |
27 | header = reinterpret_cast<const ElfEhdr *>(mapped); |
28 | |
29 | if (memcmp(header->e_ident, "\x7F" "ELF" , 4) != 0) |
30 | throw Exception("The file is not ELF according to magic" , ErrorCodes::CANNOT_PARSE_ELF); |
31 | |
32 | /// Get section header. |
33 | ElfOff = header->e_shoff; |
34 | uint16_t = header->e_shnum; |
35 | |
36 | if (!section_header_offset |
37 | || !section_header_num_entries |
38 | || section_header_offset + section_header_num_entries * sizeof(ElfShdr) > elf_size) |
39 | throw Exception("The ELF is truncated (section header points after end of file)" , ErrorCodes::CANNOT_PARSE_ELF); |
40 | |
41 | section_headers = reinterpret_cast<const ElfShdr *>(mapped + section_header_offset); |
42 | |
43 | /// The string table with section names. |
44 | auto section_names_strtab = findSection([&](const Section & section, size_t idx) |
45 | { |
46 | return section.header.sh_type == SHT_STRTAB && header->e_shstrndx == idx; |
47 | }); |
48 | |
49 | if (!section_names_strtab) |
50 | throw Exception("The ELF doesn't have string table with section names" , ErrorCodes::CANNOT_PARSE_ELF); |
51 | |
52 | ElfOff section_names_offset = section_names_strtab->header.sh_offset; |
53 | if (section_names_offset >= elf_size) |
54 | throw Exception("The ELF is truncated (section names string table points after end of file)" , ErrorCodes::CANNOT_PARSE_ELF); |
55 | |
56 | section_names = reinterpret_cast<const char *>(mapped + section_names_offset); |
57 | } |
58 | |
59 | |
60 | Elf::Section::Section(const ElfShdr & , const Elf & elf_) |
61 | : header(header_), elf(elf_) |
62 | { |
63 | } |
64 | |
65 | |
66 | bool Elf::iterateSections(std::function<bool(const Section & section, size_t idx)> && pred) const |
67 | { |
68 | for (size_t idx = 0; idx < header->e_shnum; ++idx) |
69 | { |
70 | Section section(section_headers[idx], *this); |
71 | |
72 | /// Sections spans after end of file. |
73 | if (section.header.sh_offset + section.header.sh_size > elf_size) |
74 | continue; |
75 | |
76 | if (pred(section, idx)) |
77 | return true; |
78 | } |
79 | return false; |
80 | } |
81 | |
82 | |
83 | std::optional<Elf::Section> Elf::findSection(std::function<bool(const Section & section, size_t idx)> && pred) const |
84 | { |
85 | std::optional<Elf::Section> result; |
86 | |
87 | iterateSections([&](const Section & section, size_t idx) |
88 | { |
89 | if (pred(section, idx)) |
90 | { |
91 | result.emplace(section); |
92 | return true; |
93 | } |
94 | return false; |
95 | }); |
96 | |
97 | return result; |
98 | } |
99 | |
100 | |
101 | std::optional<Elf::Section> Elf::findSectionByName(const char * name) const |
102 | { |
103 | return findSection([&](const Section & section, size_t) { return 0 == strcmp(name, section.name()); }); |
104 | } |
105 | |
106 | |
107 | const char * Elf::Section::name() const |
108 | { |
109 | if (!elf.section_names) |
110 | throw Exception("Section names are not initialized" , ErrorCodes::CANNOT_PARSE_ELF); |
111 | |
112 | /// TODO buffer overflow is possible, we may need to check strlen. |
113 | return elf.section_names + header.sh_name; |
114 | } |
115 | |
116 | |
117 | const char * Elf::Section::begin() const |
118 | { |
119 | return elf.mapped + header.sh_offset; |
120 | } |
121 | |
122 | const char * Elf::Section::end() const |
123 | { |
124 | return begin() + size(); |
125 | } |
126 | |
127 | size_t Elf::Section::size() const |
128 | { |
129 | return header.sh_size; |
130 | } |
131 | |
132 | } |
133 | |
134 | #endif |
135 | |