| 1 | // compressed_output.cc -- manage compressed debug sections for gold |
| 2 | |
| 3 | // Copyright (C) 2007-2015 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 | #include "gold.h" |
| 24 | #include <zlib.h> |
| 25 | #include "parameters.h" |
| 26 | #include "options.h" |
| 27 | #include "compressed_output.h" |
| 28 | |
| 29 | namespace gold |
| 30 | { |
| 31 | |
| 32 | // Compress UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns true |
| 33 | // if it successfully compressed, false if it failed for any reason |
| 34 | // (including not having zlib support in the library). If it returns |
| 35 | // true, it allocates memory for the compressed data using new, and |
| 36 | // sets *COMPRESSED_DATA and *COMPRESSED_SIZE to appropriate values. |
| 37 | // It also writes a header before COMPRESSED_DATA: 4 bytes saying |
| 38 | // "ZLIB", and 8 bytes indicating the uncompressed size, in big-endian |
| 39 | // order. |
| 40 | |
| 41 | static bool |
| 42 | zlib_compress(const unsigned char* uncompressed_data, |
| 43 | unsigned long uncompressed_size, |
| 44 | unsigned char** compressed_data, |
| 45 | unsigned long* compressed_size) |
| 46 | { |
| 47 | const int header_size = 12; |
| 48 | *compressed_size = uncompressed_size + uncompressed_size / 1000 + 128; |
| 49 | *compressed_data = new unsigned char[*compressed_size + header_size]; |
| 50 | |
| 51 | int compress_level; |
| 52 | if (parameters->options().optimize() >= 1) |
| 53 | compress_level = 9; |
| 54 | else |
| 55 | compress_level = 1; |
| 56 | |
| 57 | int rc = compress2(reinterpret_cast<Bytef*>(*compressed_data) + header_size, |
| 58 | compressed_size, |
| 59 | reinterpret_cast<const Bytef*>(uncompressed_data), |
| 60 | uncompressed_size, |
| 61 | compress_level); |
| 62 | if (rc == Z_OK) |
| 63 | { |
| 64 | memcpy(*compressed_data, "ZLIB", 4); |
| 65 | elfcpp::Swap_unaligned<64, true>::writeval(*compressed_data + 4, |
| 66 | uncompressed_size); |
| 67 | *compressed_size += header_size; |
| 68 | return true; |
| 69 | } |
| 70 | else |
| 71 | { |
| 72 | delete[] *compressed_data; |
| 73 | *compressed_data = NULL; |
| 74 | return false; |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | // Decompress COMPRESSED_DATA of size COMPRESSED_SIZE, into a buffer |
| 79 | // UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns TRUE if it |
| 80 | // decompressed successfully, false if it failed. The buffer, of |
| 81 | // appropriate size, is provided by the caller, and is typically part |
| 82 | // of the memory-mapped output file. |
| 83 | |
| 84 | static bool |
| 85 | zlib_decompress(const unsigned char* compressed_data, |
| 86 | unsigned long compressed_size, |
| 87 | unsigned char* uncompressed_data, |
| 88 | unsigned long uncompressed_size) |
| 89 | { |
| 90 | z_stream strm; |
| 91 | int rc; |
| 92 | |
| 93 | /* It is possible the section consists of several compressed |
| 94 | buffers concatenated together, so we uncompress in a loop. */ |
| 95 | strm.zalloc = NULL; |
| 96 | strm.zfree = NULL; |
| 97 | strm.opaque = NULL; |
| 98 | strm.avail_in = compressed_size; |
| 99 | strm.next_in = const_cast<Bytef*>(compressed_data); |
| 100 | strm.avail_out = uncompressed_size; |
| 101 | |
| 102 | rc = inflateInit(&strm); |
| 103 | while (strm.avail_in > 0) |
| 104 | { |
| 105 | if (rc != Z_OK) |
| 106 | return false; |
| 107 | strm.next_out = ((Bytef*) uncompressed_data |
| 108 | + (uncompressed_size - strm.avail_out)); |
| 109 | rc = inflate(&strm, Z_FINISH); |
| 110 | if (rc != Z_STREAM_END) |
| 111 | return false; |
| 112 | rc = inflateReset(&strm); |
| 113 | } |
| 114 | rc = inflateEnd(&strm); |
| 115 | if (rc != Z_OK || strm.avail_out != 0) |
| 116 | return false; |
| 117 | |
| 118 | return true; |
| 119 | } |
| 120 | |
| 121 | // Read the compression header of a compressed debug section and return |
| 122 | // the uncompressed size. |
| 123 | |
| 124 | uint64_t |
| 125 | get_uncompressed_size(const unsigned char* compressed_data, |
| 126 | section_size_type compressed_size) |
| 127 | { |
| 128 | const unsigned int zlib_header_size = 12; |
| 129 | |
| 130 | /* Verify the compression header. Currently, we support only zlib |
| 131 | compression, so it should be "ZLIB" followed by the uncompressed |
| 132 | section size, 8 bytes in big-endian order. */ |
| 133 | if (compressed_size >= zlib_header_size |
| 134 | && strncmp(reinterpret_cast<const char*>(compressed_data), |
| 135 | "ZLIB", 4) == 0) |
| 136 | return elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4); |
| 137 | return -1ULL; |
| 138 | } |
| 139 | |
| 140 | // Decompress a compressed debug section directly into the output file. |
| 141 | |
| 142 | bool |
| 143 | decompress_input_section(const unsigned char* compressed_data, |
| 144 | unsigned long compressed_size, |
| 145 | unsigned char* uncompressed_data, |
| 146 | unsigned long uncompressed_size) |
| 147 | { |
| 148 | const unsigned int zlib_header_size = 12; |
| 149 | |
| 150 | /* Verify the compression header. Currently, we support only zlib |
| 151 | compression, so it should be "ZLIB" followed by the uncompressed |
| 152 | section size, 8 bytes in big-endian order. */ |
| 153 | if (compressed_size >= zlib_header_size |
| 154 | && strncmp(reinterpret_cast<const char*>(compressed_data), |
| 155 | "ZLIB", 4) == 0) |
| 156 | { |
| 157 | unsigned long uncompressed_size_check = |
| 158 | elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4); |
| 159 | gold_assert(uncompressed_size_check == uncompressed_size); |
| 160 | return zlib_decompress(compressed_data + zlib_header_size, |
| 161 | compressed_size - zlib_header_size, |
| 162 | uncompressed_data, |
| 163 | uncompressed_size); |
| 164 | } |
| 165 | return false; |
| 166 | } |
| 167 | |
| 168 | // Class Output_compressed_section. |
| 169 | |
| 170 | // Set the final data size of a compressed section. This is where |
| 171 | // we actually compress the section data. |
| 172 | |
| 173 | void |
| 174 | Output_compressed_section::set_final_data_size() |
| 175 | { |
| 176 | off_t uncompressed_size = this->postprocessing_buffer_size(); |
| 177 | |
| 178 | // (Try to) compress the data. |
| 179 | unsigned long compressed_size; |
| 180 | unsigned char* uncompressed_data = this->postprocessing_buffer(); |
| 181 | |
| 182 | // At this point the contents of all regular input sections will |
| 183 | // have been copied into the postprocessing buffer, and relocations |
| 184 | // will have been applied. Now we need to copy in the contents of |
| 185 | // anything other than a regular input section. |
| 186 | this->write_to_postprocessing_buffer(); |
| 187 | |
| 188 | bool success = false; |
| 189 | if (strcmp(this->options_->compress_debug_sections(), "zlib") == 0) |
| 190 | success = zlib_compress(uncompressed_data, uncompressed_size, |
| 191 | &this->data_, &compressed_size); |
| 192 | if (success) |
| 193 | { |
| 194 | // This converts .debug_foo to .zdebug_foo |
| 195 | this->new_section_name_ = std::string(".z") + (this->name() + 1); |
| 196 | this->set_name(this->new_section_name_.c_str()); |
| 197 | this->set_data_size(compressed_size); |
| 198 | } |
| 199 | else |
| 200 | { |
| 201 | gold_warning(_("not compressing section data: zlib error")); |
| 202 | gold_assert(this->data_ == NULL); |
| 203 | this->set_data_size(uncompressed_size); |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | // Write out a compressed section. If we couldn't compress, we just |
| 208 | // write it out as normal, uncompressed data. |
| 209 | |
| 210 | void |
| 211 | Output_compressed_section::do_write(Output_file* of) |
| 212 | { |
| 213 | off_t offset = this->offset(); |
| 214 | off_t data_size = this->data_size(); |
| 215 | unsigned char* view = of->get_output_view(offset, data_size); |
| 216 | if (this->data_ == NULL) |
| 217 | memcpy(view, this->postprocessing_buffer(), data_size); |
| 218 | else |
| 219 | memcpy(view, this->data_, data_size); |
| 220 | of->write_output_view(offset, data_size, view); |
| 221 | } |
| 222 | |
| 223 | } // End namespace gold. |