1 // compressed_output.cc -- manage compressed output sections for gold
3 // Copyright 2007, 2008 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.
29 #include "parameters.h"
31 #include "compressed_output.h"
36 // Compress UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns true
37 // if it successfully compressed, false if it failed for any reason
38 // (including not having zlib support in the library). If it returns
39 // true, it allocates memory for the compressed data using new, and
40 // sets *COMPRESSED_DATA and *COMPRESSED_SIZE to appropriate values.
41 // It also writes a header before COMPRESSED_DATA: 4 bytes saying
42 // "ZLIB", and 8 bytes indicating the uncompressed size, in big-endian
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
];
58 if (parameters
->options().optimize() >= 1)
63 int rc
= compress2(reinterpret_cast<Bytef
*>(*compressed_data
) + header_size
,
65 reinterpret_cast<const Bytef
*>(uncompressed_data
),
70 memcpy(*compressed_data
, "ZLIB", 4);
71 elfcpp::Swap_unaligned
<64, true>::writeval(*compressed_data
+ 4,
73 *compressed_size
+= header_size
;
78 delete[] *compressed_data
;
79 *compressed_data
= NULL
;
84 #else // !defined(HAVE_ZLIB_H)
87 zlib_compress(const unsigned char*, unsigned long,
88 unsigned char**, unsigned long*)
93 #endif // !defined(HAVE_ZLIB_H)
95 // Class Output_compressed_section.
97 // Set the final data size of a compressed section. This is where
98 // we actually compress the section data.
101 Output_compressed_section::set_final_data_size()
103 off_t uncompressed_size
= this->postprocessing_buffer_size();
105 // (Try to) compress the data.
106 unsigned long compressed_size
;
107 unsigned char* uncompressed_data
= this->postprocessing_buffer();
109 // At this point the contents of all regular input sections will
110 // have been copied into the postprocessing buffer, and relocations
111 // will have been applied. Now we need to copy in the contents of
112 // anything other than a regular input section.
113 this->write_to_postprocessing_buffer();
115 bool success
= false;
116 if (strcmp(this->options_
->compress_debug_sections(), "zlib") == 0)
117 success
= zlib_compress(uncompressed_data
, uncompressed_size
,
118 &this->data_
, &compressed_size
);
121 // This converts .debug_foo to .zdebug_foo
122 this->new_section_name_
= std::string(".z") + (this->name() + 1);
123 this->set_name(this->new_section_name_
.c_str());
124 this->set_data_size(compressed_size
);
128 gold_warning(_("not compressing section data: zlib error"));
129 gold_assert(this->data_
== NULL
);
130 this->set_data_size(uncompressed_size
);
134 // Write out a compressed section. If we couldn't compress, we just
135 // write it out as normal, uncompressed data.
138 Output_compressed_section::do_write(Output_file
* of
)
140 off_t offset
= this->offset();
141 off_t data_size
= this->data_size();
142 unsigned char* view
= of
->get_output_view(offset
, data_size
);
143 if (this->data_
== NULL
)
144 memcpy(view
, this->postprocessing_buffer(), data_size
);
146 memcpy(view
, this->data_
, data_size
);
147 of
->write_output_view(offset
, data_size
, view
);
150 } // End namespace gold.
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