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1 | // compressed_output.h -- compressed output sections for gold -*- C++ -*- |
2 | ||
3 | // Copyright 2007 Free Software Foundation, Inc. | |
4 | // Written by Ian Lance Taylor <iant@google.com>. | |
5 | ||
6 | // This file is part of gold. | |
7 | ||
8 | // This program is free software; you can redistribute it and/or modify | |
9 | // it under the terms of the GNU General Public License as published by | |
10 | // the Free Software Foundation; either version 3 of the License, or | |
11 | // (at your option) any later version. | |
12 | ||
13 | // This program is distributed in the hope that it will be useful, | |
14 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | // GNU General Public License for more details. | |
17 | ||
18 | // You should have received a copy of the GNU General Public License | |
19 | // along with this program; if not, write to the Free Software | |
20 | // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, | |
21 | // MA 02110-1301, USA. | |
22 | ||
23 | // We support compressing .debug_* sections on output. (And, | |
24 | // potentially one day, other sections.) This is a form of | |
25 | // relaxation. This file adds support for merging and emitting the | |
26 | // compressed sections. | |
27 | ||
28 | #ifndef GOLD_COMPRESSED_OUTPUT_H | |
29 | #define GOLD_COMPRESSED_OUTPUT_H | |
30 | ||
31 | #include <string> | |
32 | #include <vector> | |
33 | ||
34 | #include "output.h" | |
35 | #include "merge.h" | |
36 | ||
37 | namespace gold | |
38 | { | |
39 | ||
40 | class General_options; | |
41 | ||
42 | // This is used for compressing a section before emitting it in the | |
43 | // output file. This only works for unloaded sections, since it | |
44 | // assumes the final section contents are available at | |
45 | // set_final_data_size() time. For loaded sections (those that end up | |
46 | // in segments), this is not true; relocations are applied after | |
47 | // set_final_data_size() is called. However, for unloaded sections, | |
48 | // we can -- and do -- postpone calling finalize_data_size() until | |
49 | // after relocations are applies. | |
50 | ||
51 | class Output_compressed_section_data : public Output_section_data | |
52 | { | |
53 | public: | |
54 | Output_compressed_section_data(uint64_t addralign, | |
55 | const General_options& options) | |
56 | : Output_section_data(addralign), options_(options), data_(NULL) | |
57 | { } | |
58 | ||
59 | protected: | |
60 | // Add an input section. | |
61 | bool | |
62 | do_add_input_section(Relobj* object, unsigned int shndx); | |
63 | ||
64 | // Set the final data size. | |
65 | void | |
66 | set_final_data_size(); | |
67 | ||
68 | // Change the name of the output section to reflect it's compressed. | |
69 | const char* | |
70 | do_modified_output_section_name(const char* name); | |
71 | ||
72 | // Write the data to the file. | |
73 | void | |
74 | do_write(Output_file*); | |
75 | ||
76 | private: | |
77 | struct Object_entry | |
78 | { | |
79 | Relobj* object; | |
80 | unsigned int shndx; | |
81 | const unsigned char* contents; | |
82 | off_t length; | |
83 | ||
84 | Object_entry(Relobj* o, unsigned int s) | |
85 | : object(o), shndx(s), contents(NULL), length(0) | |
86 | { } | |
87 | }; | |
88 | ||
89 | const General_options& options_; | |
90 | std::vector<Object_entry> objects_; | |
91 | char* data_; | |
92 | std::string new_section_name_; | |
93 | }; | |
94 | ||
95 | // This is a special case for when the output section is a string | |
96 | // section and does not have any relocations to apply to it. | |
97 | ||
98 | template<typename Char_type> | |
99 | class Output_compressed_string : public Output_merge_string<Char_type> | |
100 | { | |
101 | public: | |
102 | Output_compressed_string(uint64_t addralign, | |
103 | const General_options& options) | |
104 | : Output_merge_string<Char_type>(addralign), | |
105 | options_(options), compressed_data_(NULL) | |
106 | { } | |
107 | ||
108 | ~Output_compressed_string() | |
109 | { delete[] compressed_data_; } | |
110 | ||
111 | protected: | |
112 | // Add an input section. | |
113 | bool | |
114 | do_add_input_section(Relobj* object, unsigned int shndx); | |
115 | ||
116 | // Set the final data size. Also compresses the buffer. | |
117 | void | |
118 | set_final_data_size(); | |
119 | ||
120 | // Change the name of the output section to reflect it's compressed. | |
121 | const char* | |
122 | do_modified_output_section_name(const char* name); | |
123 | ||
124 | // Write the data to the file. | |
125 | void | |
126 | do_write(Output_file*); | |
127 | ||
128 | private: | |
129 | const General_options& options_; | |
130 | char* compressed_data_; | |
131 | // This is just a buffer to store the section name in "permanent" storage. | |
132 | std::string new_section_name_; | |
133 | }; | |
134 | ||
135 | } // End namespace gold. | |
136 | ||
137 | #endif // !defined(GOLD_COMPRESSED_OUTPUT_H) |