1 // compressed_output.cc -- manage compressed debug sections for gold 2 3 // Copyright (C) 2007-2016 Free Software Foundation, Inc. 4 // Written by Ian Lance Taylor <iant (at) 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(int header_size, 43 const unsigned char* uncompressed_data, 44 unsigned long uncompressed_size, 45 unsigned char** compressed_data, 46 unsigned long* compressed_size) 47 { 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 *compressed_size += header_size; 65 return true; 66 } 67 else 68 { 69 delete[] *compressed_data; 70 *compressed_data = NULL; 71 return false; 72 } 73 } 74 75 // Decompress COMPRESSED_DATA of size COMPRESSED_SIZE, into a buffer 76 // UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns TRUE if it 77 // decompressed successfully, false if it failed. The buffer, of 78 // appropriate size, is provided by the caller, and is typically part 79 // of the memory-mapped output file. 80 81 static bool 82 zlib_decompress(const unsigned char* compressed_data, 83 unsigned long compressed_size, 84 unsigned char* uncompressed_data, 85 unsigned long uncompressed_size) 86 { 87 z_stream strm; 88 int rc; 89 90 /* It is possible the section consists of several compressed 91 buffers concatenated together, so we uncompress in a loop. */ 92 strm.zalloc = NULL; 93 strm.zfree = NULL; 94 strm.opaque = NULL; 95 strm.avail_in = compressed_size; 96 strm.next_in = const_cast<Bytef*>(compressed_data); 97 strm.avail_out = uncompressed_size; 98 99 rc = inflateInit(&strm); 100 while (strm.avail_in > 0) 101 { 102 if (rc != Z_OK) 103 return false; 104 strm.next_out = ((Bytef*) uncompressed_data 105 + (uncompressed_size - strm.avail_out)); 106 rc = inflate(&strm, Z_FINISH); 107 if (rc != Z_STREAM_END) 108 return false; 109 rc = inflateReset(&strm); 110 } 111 rc = inflateEnd(&strm); 112 if (rc != Z_OK || strm.avail_out != 0) 113 return false; 114 115 return true; 116 } 117 118 // Read the compression header of a compressed debug section and return 119 // the uncompressed size. 120 121 uint64_t 122 get_uncompressed_size(const unsigned char* compressed_data, 123 section_size_type compressed_size) 124 { 125 const unsigned int zlib_header_size = 12; 126 127 /* Verify the compression header. Currently, we support only zlib 128 compression, so it should be "ZLIB" followed by the uncompressed 129 section size, 8 bytes in big-endian order. */ 130 if (compressed_size >= zlib_header_size 131 && strncmp(reinterpret_cast<const char*>(compressed_data), 132 "ZLIB", 4) == 0) 133 return elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4); 134 return -1ULL; 135 } 136 137 // Decompress a compressed debug section directly into the output file. 138 139 bool 140 decompress_input_section(const unsigned char* compressed_data, 141 unsigned long compressed_size, 142 unsigned char* uncompressed_data, 143 unsigned long uncompressed_size, 144 int size, 145 bool big_endian, 146 elfcpp::Elf_Xword sh_flags) 147 { 148 if ((sh_flags & elfcpp::SHF_COMPRESSED) != 0) 149 { 150 unsigned int compression_header_size; 151 if (size == 32) 152 { 153 compression_header_size = elfcpp::Elf_sizes<32>::chdr_size; 154 if (big_endian) 155 { 156 elfcpp::Chdr<32, true> chdr(compressed_data); 157 if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB) 158 return false; 159 } 160 else 161 { 162 elfcpp::Chdr<32, false> chdr(compressed_data); 163 if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB) 164 return false; 165 } 166 } 167 else if (size == 64) 168 { 169 compression_header_size = elfcpp::Elf_sizes<64>::chdr_size; 170 if (big_endian) 171 { 172 elfcpp::Chdr<64, true> chdr(compressed_data); 173 if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB) 174 return false; 175 } 176 else 177 { 178 elfcpp::Chdr<64, false> chdr(compressed_data); 179 if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB) 180 return false; 181 } 182 } 183 else 184 gold_unreachable(); 185 186 return zlib_decompress(compressed_data + compression_header_size, 187 compressed_size - compression_header_size, 188 uncompressed_data, 189 uncompressed_size); 190 } 191 192 const unsigned int zlib_header_size = 12; 193 194 /* Verify the compression header. Currently, we support only zlib 195 compression, so it should be "ZLIB" followed by the uncompressed 196 section size, 8 bytes in big-endian order. */ 197 if (compressed_size >= zlib_header_size 198 && strncmp(reinterpret_cast<const char*>(compressed_data), 199 "ZLIB", 4) == 0) 200 { 201 unsigned long uncompressed_size_check = 202 elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4); 203 gold_assert(uncompressed_size_check == uncompressed_size); 204 return zlib_decompress(compressed_data + zlib_header_size, 205 compressed_size - zlib_header_size, 206 uncompressed_data, 207 uncompressed_size); 208 } 209 return false; 210 } 211 212 // Class Output_compressed_section. 213 214 // Set the final data size of a compressed section. This is where 215 // we actually compress the section data. 216 217 void 218 Output_compressed_section::set_final_data_size() 219 { 220 off_t uncompressed_size = this->postprocessing_buffer_size(); 221 222 // (Try to) compress the data. 223 unsigned long compressed_size; 224 unsigned char* uncompressed_data = this->postprocessing_buffer(); 225 226 // At this point the contents of all regular input sections will 227 // have been copied into the postprocessing buffer, and relocations 228 // will have been applied. Now we need to copy in the contents of 229 // anything other than a regular input section. 230 this->write_to_postprocessing_buffer(); 231 232 bool success = false; 233 enum { none, gnu_zlib, gabi_zlib } compress; 234 int compression_header_size = 12; 235 const int size = parameters->target().get_size(); 236 if (strcmp(this->options_->compress_debug_sections(), "zlib-gnu") == 0) 237 compress = gnu_zlib; 238 else if (strcmp(this->options_->compress_debug_sections(), "zlib-gabi") == 0 239 || strcmp(this->options_->compress_debug_sections(), "zlib") == 0) 240 { 241 compress = gabi_zlib; 242 if (size == 32) 243 compression_header_size = elfcpp::Elf_sizes<32>::chdr_size; 244 else if (size == 64) 245 compression_header_size = elfcpp::Elf_sizes<64>::chdr_size; 246 else 247 gold_unreachable(); 248 } 249 else 250 compress = none; 251 if (compress != none) 252 success = zlib_compress(compression_header_size, uncompressed_data, 253 uncompressed_size, &this->data_, 254 &compressed_size); 255 if (success) 256 { 257 elfcpp::Elf_Xword flags = this->flags(); 258 if (compress == gabi_zlib) 259 { 260 // Set the SHF_COMPRESSED bit. 261 flags |= elfcpp::SHF_COMPRESSED; 262 const bool is_big_endian = parameters->target().is_big_endian(); 263 uint64_t addralign = this->addralign(); 264 if (size == 32) 265 { 266 if (is_big_endian) 267 { 268 elfcpp::Chdr_write<32, true> chdr(this->data_); 269 chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB); 270 chdr.put_ch_size(uncompressed_size); 271 chdr.put_ch_addralign(addralign); 272 } 273 else 274 { 275 elfcpp::Chdr_write<32, false> chdr(this->data_); 276 chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB); 277 chdr.put_ch_size(uncompressed_size); 278 chdr.put_ch_addralign(addralign); 279 } 280 } 281 else if (size == 64) 282 { 283 if (is_big_endian) 284 { 285 elfcpp::Chdr_write<64, true> chdr(this->data_); 286 chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB); 287 chdr.put_ch_size(uncompressed_size); 288 chdr.put_ch_addralign(addralign); 289 } 290 else 291 { 292 elfcpp::Chdr_write<64, false> chdr(this->data_); 293 chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB); 294 chdr.put_ch_size(uncompressed_size); 295 chdr.put_ch_addralign(addralign); 296 } 297 } 298 else 299 gold_unreachable(); 300 } 301 else 302 { 303 // Write out the zlib header. 304 memcpy(this->data_, "ZLIB", 4); 305 elfcpp::Swap_unaligned<64, true>::writeval(this->data_ + 4, 306 uncompressed_size); 307 // This converts .debug_foo to .zdebug_foo 308 this->new_section_name_ = std::string(".z") + (this->name() + 1); 309 this->set_name(this->new_section_name_.c_str()); 310 } 311 this->set_flags(flags); 312 this->set_data_size(compressed_size); 313 } 314 else 315 { 316 gold_warning(_("not compressing section data: zlib error")); 317 gold_assert(this->data_ == NULL); 318 this->set_data_size(uncompressed_size); 319 } 320 } 321 322 // Write out a compressed section. If we couldn't compress, we just 323 // write it out as normal, uncompressed data. 324 325 void 326 Output_compressed_section::do_write(Output_file* of) 327 { 328 off_t offset = this->offset(); 329 off_t data_size = this->data_size(); 330 unsigned char* view = of->get_output_view(offset, data_size); 331 if (this->data_ == NULL) 332 memcpy(view, this->postprocessing_buffer(), data_size); 333 else 334 memcpy(view, this->data_, data_size); 335 of->write_output_view(offset, data_size, view); 336 } 337 338 } // End namespace gold. 339
