| 1 | // compressed_output.cc -- manage compressed debug sections for gold |
| 2 | |
| 3 | // Copyright (C) 2007-2018 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(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 | // Clear the reserved field. |
| 290 | chdr.put_ch_reserved(0); |
| 291 | } |
| 292 | else |
| 293 | { |
| 294 | elfcpp::Chdr_write<64, false> chdr(this->data_); |
| 295 | chdr.put_ch_type(elfcpp::ELFCOMPRESS_ZLIB); |
| 296 | chdr.put_ch_size(uncompressed_size); |
| 297 | chdr.put_ch_addralign(addralign); |
| 298 | // Clear the reserved field. |
| 299 | chdr.put_ch_reserved(0); |
| 300 | } |
| 301 | } |
| 302 | else |
| 303 | gold_unreachable(); |
| 304 | } |
| 305 | else |
| 306 | { |
| 307 | // Write out the zlib header. |
| 308 | memcpy(this->data_, "ZLIB", 4); |
| 309 | elfcpp::Swap_unaligned<64, true>::writeval(this->data_ + 4, |
| 310 | uncompressed_size); |
| 311 | // This converts .debug_foo to .zdebug_foo |
| 312 | this->new_section_name_ = std::string(".z") + (this->name() + 1); |
| 313 | this->set_name(this->new_section_name_.c_str()); |
| 314 | } |
| 315 | this->set_flags(flags); |
| 316 | this->set_data_size(compressed_size); |
| 317 | } |
| 318 | else |
| 319 | { |
| 320 | gold_warning(_("not compressing section data: zlib error")); |
| 321 | gold_assert(this->data_ == NULL); |
| 322 | this->set_data_size(uncompressed_size); |
| 323 | } |
| 324 | } |
| 325 | |
| 326 | // Write out a compressed section. If we couldn't compress, we just |
| 327 | // write it out as normal, uncompressed data. |
| 328 | |
| 329 | void |
| 330 | Output_compressed_section::do_write(Output_file* of) |
| 331 | { |
| 332 | off_t offset = this->offset(); |
| 333 | off_t data_size = this->data_size(); |
| 334 | unsigned char* view = of->get_output_view(offset, data_size); |
| 335 | if (this->data_ == NULL) |
| 336 | memcpy(view, this->postprocessing_buffer(), data_size); |
| 337 | else |
| 338 | memcpy(view, this->data_, data_size); |
| 339 | of->write_output_view(offset, data_size, view); |
| 340 | } |
| 341 | |
| 342 | } // End namespace gold. |