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[binutils.git] / gold / compressed_output.cc
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1 // compressed_output.cc -- manage compressed debug sections for gold
3 // Copyright 2007, 2008, 2010 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
23 #include "gold.h"
25 #ifdef HAVE_ZLIB_H
26 #include <zlib.h>
27 #endif
29 #include "parameters.h"
30 #include "options.h"
31 #include "compressed_output.h"
33 namespace gold
36 #ifdef HAVE_ZLIB_H
38 // Compress UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns true
39 // if it successfully compressed, false if it failed for any reason
40 // (including not having zlib support in the library). If it returns
41 // true, it allocates memory for the compressed data using new, and
42 // sets *COMPRESSED_DATA and *COMPRESSED_SIZE to appropriate values.
43 // It also writes a header before COMPRESSED_DATA: 4 bytes saying
44 // "ZLIB", and 8 bytes indicating the uncompressed size, in big-endian
45 // order.
47 static bool
48 zlib_compress(const unsigned char* uncompressed_data,
49 unsigned long uncompressed_size,
50 unsigned char** compressed_data,
51 unsigned long* compressed_size)
53 const int header_size = 12;
54 *compressed_size = uncompressed_size + uncompressed_size / 1000 + 128;
55 *compressed_data = new unsigned char[*compressed_size + header_size];
57 int compress_level;
58 if (parameters->options().optimize() >= 1)
59 compress_level = 9;
60 else
61 compress_level = 1;
63 int rc = compress2(reinterpret_cast<Bytef*>(*compressed_data) + header_size,
64 compressed_size,
65 reinterpret_cast<const Bytef*>(uncompressed_data),
66 uncompressed_size,
67 compress_level);
68 if (rc == Z_OK)
70 memcpy(*compressed_data, "ZLIB", 4);
71 elfcpp::Swap_unaligned<64, true>::writeval(*compressed_data + 4,
72 uncompressed_size);
73 *compressed_size += header_size;
74 return true;
76 else
78 delete[] *compressed_data;
79 *compressed_data = NULL;
80 return false;
84 // Decompress COMPRESSED_DATA of size COMPRESSED_SIZE, into a buffer
85 // UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns TRUE if it
86 // decompressed successfully, false if it failed. The buffer, of
87 // appropriate size, is provided by the caller, and is typically part
88 // of the memory-mapped output file.
90 static bool
91 zlib_decompress(const unsigned char* compressed_data,
92 unsigned long compressed_size,
93 unsigned char* uncompressed_data,
94 unsigned long uncompressed_size)
96 z_stream strm;
97 int rc;
99 /* It is possible the section consists of several compressed
100 buffers concatenated together, so we uncompress in a loop. */
101 strm.zalloc = NULL;
102 strm.zfree = NULL;
103 strm.opaque = NULL;
104 strm.avail_in = compressed_size;
105 strm.next_in = const_cast<Bytef*>(compressed_data);
106 strm.avail_out = uncompressed_size;
108 rc = inflateInit(&strm);
109 while (strm.avail_in > 0)
111 if (rc != Z_OK)
112 return false;
113 strm.next_out = ((Bytef*) uncompressed_data
114 + (uncompressed_size - strm.avail_out));
115 rc = inflate(&strm, Z_FINISH);
116 if (rc != Z_STREAM_END)
117 return false;
118 rc = inflateReset(&strm);
120 rc = inflateEnd(&strm);
121 if (rc != Z_OK || strm.avail_out != 0)
122 return false;
124 return true;
127 #else // !defined(HAVE_ZLIB_H)
129 static bool
130 zlib_compress(const unsigned char*, unsigned long,
131 unsigned char**, unsigned long*)
133 return false;
136 static bool
137 zlib_decompress(const unsigned char*, unsigned long,
138 unsigned char*, unsigned long)
140 return false;
143 #endif // !defined(HAVE_ZLIB_H)
145 // Read the compression header of a compressed debug section and return
146 // the uncompressed size.
148 uint64_t
149 get_uncompressed_size(const unsigned char* compressed_data,
150 section_size_type compressed_size)
152 const unsigned int zlib_header_size = 12;
154 /* Verify the compression header. Currently, we support only zlib
155 compression, so it should be "ZLIB" followed by the uncompressed
156 section size, 8 bytes in big-endian order. */
157 if (compressed_size >= zlib_header_size
158 && strncmp(reinterpret_cast<const char*>(compressed_data),
159 "ZLIB", 4) == 0)
160 return elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4);
161 return -1ULL;
164 // Decompress a compressed debug section directly into the output file.
166 bool
167 decompress_input_section(const unsigned char* compressed_data,
168 unsigned long compressed_size,
169 unsigned char* uncompressed_data,
170 unsigned long uncompressed_size)
172 const unsigned int zlib_header_size = 12;
174 /* Verify the compression header. Currently, we support only zlib
175 compression, so it should be "ZLIB" followed by the uncompressed
176 section size, 8 bytes in big-endian order. */
177 if (compressed_size >= zlib_header_size
178 && strncmp(reinterpret_cast<const char*>(compressed_data),
179 "ZLIB", 4) == 0)
181 unsigned long uncompressed_size_check =
182 elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4);
183 gold_assert(uncompressed_size_check == uncompressed_size);
184 return zlib_decompress(compressed_data + zlib_header_size,
185 compressed_size - zlib_header_size,
186 uncompressed_data,
187 uncompressed_size);
189 return false;
192 // Class Output_compressed_section.
194 // Set the final data size of a compressed section. This is where
195 // we actually compress the section data.
197 void
198 Output_compressed_section::set_final_data_size()
200 off_t uncompressed_size = this->postprocessing_buffer_size();
202 // (Try to) compress the data.
203 unsigned long compressed_size;
204 unsigned char* uncompressed_data = this->postprocessing_buffer();
206 // At this point the contents of all regular input sections will
207 // have been copied into the postprocessing buffer, and relocations
208 // will have been applied. Now we need to copy in the contents of
209 // anything other than a regular input section.
210 this->write_to_postprocessing_buffer();
212 bool success = false;
213 if (strcmp(this->options_->compress_debug_sections(), "zlib") == 0)
214 success = zlib_compress(uncompressed_data, uncompressed_size,
215 &this->data_, &compressed_size);
216 if (success)
218 // This converts .debug_foo to .zdebug_foo
219 this->new_section_name_ = std::string(".z") + (this->name() + 1);
220 this->set_name(this->new_section_name_.c_str());
221 this->set_data_size(compressed_size);
223 else
225 gold_warning(_("not compressing section data: zlib error"));
226 gold_assert(this->data_ == NULL);
227 this->set_data_size(uncompressed_size);
231 // Write out a compressed section. If we couldn't compress, we just
232 // write it out as normal, uncompressed data.
234 void
235 Output_compressed_section::do_write(Output_file* of)
237 off_t offset = this->offset();
238 off_t data_size = this->data_size();
239 unsigned char* view = of->get_output_view(offset, data_size);
240 if (this->data_ == NULL)
241 memcpy(view, this->postprocessing_buffer(), data_size);
242 else
243 memcpy(view, this->data_, data_size);
244 of->write_output_view(offset, data_size, view);
247 } // End namespace gold.