1 // compressed_output.cc -- manage compressed debug sections for gold
3 // Copyright (C) 2007-2015 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.
25 #include "parameters.h"
27 #include "compressed_output.h"
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
42 zlib_compress(const unsigned char* uncompressed_data
,
43 unsigned long uncompressed_size
,
44 unsigned char** compressed_data
,
45 unsigned long* compressed_size
)
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
];
52 if (parameters
->options().optimize() >= 1)
57 int rc
= compress2(reinterpret_cast<Bytef
*>(*compressed_data
) + header_size
,
59 reinterpret_cast<const Bytef
*>(uncompressed_data
),
64 memcpy(*compressed_data
, "ZLIB", 4);
65 elfcpp::Swap_unaligned
<64, true>::writeval(*compressed_data
+ 4,
67 *compressed_size
+= header_size
;
72 delete[] *compressed_data
;
73 *compressed_data
= NULL
;
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.
85 zlib_decompress(const unsigned char* compressed_data
,
86 unsigned long compressed_size
,
87 unsigned char* uncompressed_data
,
88 unsigned long uncompressed_size
)
93 /* It is possible the section consists of several compressed
94 buffers concatenated together, so we uncompress in a loop. */
98 strm
.avail_in
= compressed_size
;
99 strm
.next_in
= const_cast<Bytef
*>(compressed_data
);
100 strm
.avail_out
= uncompressed_size
;
102 rc
= inflateInit(&strm
);
103 while (strm
.avail_in
> 0)
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
)
112 rc
= inflateReset(&strm
);
114 rc
= inflateEnd(&strm
);
115 if (rc
!= Z_OK
|| strm
.avail_out
!= 0)
121 // Read the compression header of a compressed debug section and return
122 // the uncompressed size.
125 get_uncompressed_size(const unsigned char* compressed_data
,
126 section_size_type compressed_size
)
128 const unsigned int zlib_header_size
= 12;
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
),
136 return elfcpp::Swap_unaligned
<64, true>::readval(compressed_data
+ 4);
140 // Decompress a compressed debug section directly into the output file.
143 decompress_input_section(const unsigned char* compressed_data
,
144 unsigned long compressed_size
,
145 unsigned char* uncompressed_data
,
146 unsigned long uncompressed_size
)
148 const unsigned int zlib_header_size
= 12;
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
),
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
,
168 // Class Output_compressed_section.
170 // Set the final data size of a compressed section. This is where
171 // we actually compress the section data.
174 Output_compressed_section::set_final_data_size()
176 off_t uncompressed_size
= this->postprocessing_buffer_size();
178 // (Try to) compress the data.
179 unsigned long compressed_size
;
180 unsigned char* uncompressed_data
= this->postprocessing_buffer();
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();
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
);
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
);
201 gold_warning(_("not compressing section data: zlib error"));
202 gold_assert(this->data_
== NULL
);
203 this->set_data_size(uncompressed_size
);
207 // Write out a compressed section. If we couldn't compress, we just
208 // write it out as normal, uncompressed data.
211 Output_compressed_section::do_write(Output_file
* of
)
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
);
219 memcpy(view
, this->data_
, data_size
);
220 of
->write_output_view(offset
, data_size
, view
);
223 } // End namespace gold.