1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
|
// compressed_output.cc -- manage compressed debug sections for gold
// Copyright (C) 2007-2015 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
#include "gold.h"
#include <zlib.h>
#include "parameters.h"
#include "options.h"
#include "compressed_output.h"
namespace gold
{
// Compress UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns true
// if it successfully compressed, false if it failed for any reason
// (including not having zlib support in the library). If it returns
// true, it allocates memory for the compressed data using new, and
// sets *COMPRESSED_DATA and *COMPRESSED_SIZE to appropriate values.
// It also writes a header before COMPRESSED_DATA: 4 bytes saying
// "ZLIB", and 8 bytes indicating the uncompressed size, in big-endian
// order.
static bool
zlib_compress(const unsigned char* uncompressed_data,
unsigned long uncompressed_size,
unsigned char** compressed_data,
unsigned long* compressed_size)
{
const int header_size = 12;
*compressed_size = uncompressed_size + uncompressed_size / 1000 + 128;
*compressed_data = new unsigned char[*compressed_size + header_size];
int compress_level;
if (parameters->options().optimize() >= 1)
compress_level = 9;
else
compress_level = 1;
int rc = compress2(reinterpret_cast<Bytef*>(*compressed_data) + header_size,
compressed_size,
reinterpret_cast<const Bytef*>(uncompressed_data),
uncompressed_size,
compress_level);
if (rc == Z_OK)
{
memcpy(*compressed_data, "ZLIB", 4);
elfcpp::Swap_unaligned<64, true>::writeval(*compressed_data + 4,
uncompressed_size);
*compressed_size += header_size;
return true;
}
else
{
delete[] *compressed_data;
*compressed_data = NULL;
return false;
}
}
// Decompress COMPRESSED_DATA of size COMPRESSED_SIZE, into a buffer
// UNCOMPRESSED_DATA of size UNCOMPRESSED_SIZE. Returns TRUE if it
// decompressed successfully, false if it failed. The buffer, of
// appropriate size, is provided by the caller, and is typically part
// of the memory-mapped output file.
static bool
zlib_decompress(const unsigned char* compressed_data,
unsigned long compressed_size,
unsigned char* uncompressed_data,
unsigned long uncompressed_size)
{
z_stream strm;
int rc;
/* It is possible the section consists of several compressed
buffers concatenated together, so we uncompress in a loop. */
strm.zalloc = NULL;
strm.zfree = NULL;
strm.opaque = NULL;
strm.avail_in = compressed_size;
strm.next_in = const_cast<Bytef*>(compressed_data);
strm.avail_out = uncompressed_size;
rc = inflateInit(&strm);
while (strm.avail_in > 0)
{
if (rc != Z_OK)
return false;
strm.next_out = ((Bytef*) uncompressed_data
+ (uncompressed_size - strm.avail_out));
rc = inflate(&strm, Z_FINISH);
if (rc != Z_STREAM_END)
return false;
rc = inflateReset(&strm);
}
rc = inflateEnd(&strm);
if (rc != Z_OK || strm.avail_out != 0)
return false;
return true;
}
// Read the compression header of a compressed debug section and return
// the uncompressed size.
uint64_t
get_uncompressed_size(const unsigned char* compressed_data,
section_size_type compressed_size)
{
const unsigned int zlib_header_size = 12;
/* Verify the compression header. Currently, we support only zlib
compression, so it should be "ZLIB" followed by the uncompressed
section size, 8 bytes in big-endian order. */
if (compressed_size >= zlib_header_size
&& strncmp(reinterpret_cast<const char*>(compressed_data),
"ZLIB", 4) == 0)
return elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4);
return -1ULL;
}
// Decompress a compressed debug section directly into the output file.
bool
decompress_input_section(const unsigned char* compressed_data,
unsigned long compressed_size,
unsigned char* uncompressed_data,
unsigned long uncompressed_size,
int size,
bool big_endian,
elfcpp::Elf_Xword sh_flags)
{
if ((sh_flags & elfcpp::SHF_COMPRESSED) != 0)
{
unsigned int compression_header_size;
if (size == 32)
{
compression_header_size = elfcpp::Elf_sizes<32>::chdr_size;
if (big_endian)
{
elfcpp::Chdr<32, true> chdr(compressed_data);
if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB)
return false;
}
else
{
elfcpp::Chdr<32, false> chdr(compressed_data);
if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB)
return false;
}
}
else if (size == 64)
{
compression_header_size = elfcpp::Elf_sizes<64>::chdr_size;
if (big_endian)
{
elfcpp::Chdr<64, true> chdr(compressed_data);
if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB)
return false;
}
else
{
elfcpp::Chdr<64, false> chdr(compressed_data);
if (chdr.get_ch_type() != elfcpp::ELFCOMPRESS_ZLIB)
return false;
}
}
else
gold_unreachable();
return zlib_decompress(compressed_data + compression_header_size,
compressed_size - compression_header_size,
uncompressed_data,
uncompressed_size);
}
const unsigned int zlib_header_size = 12;
/* Verify the compression header. Currently, we support only zlib
compression, so it should be "ZLIB" followed by the uncompressed
section size, 8 bytes in big-endian order. */
if (compressed_size >= zlib_header_size
&& strncmp(reinterpret_cast<const char*>(compressed_data),
"ZLIB", 4) == 0)
{
unsigned long uncompressed_size_check =
elfcpp::Swap_unaligned<64, true>::readval(compressed_data + 4);
gold_assert(uncompressed_size_check == uncompressed_size);
return zlib_decompress(compressed_data + zlib_header_size,
compressed_size - zlib_header_size,
uncompressed_data,
uncompressed_size);
}
return false;
}
// Class Output_compressed_section.
// Set the final data size of a compressed section. This is where
// we actually compress the section data.
void
Output_compressed_section::set_final_data_size()
{
off_t uncompressed_size = this->postprocessing_buffer_size();
// (Try to) compress the data.
unsigned long compressed_size;
unsigned char* uncompressed_data = this->postprocessing_buffer();
// At this point the contents of all regular input sections will
// have been copied into the postprocessing buffer, and relocations
// will have been applied. Now we need to copy in the contents of
// anything other than a regular input section.
this->write_to_postprocessing_buffer();
bool success = false;
if (strcmp(this->options_->compress_debug_sections(), "zlib") == 0)
success = zlib_compress(uncompressed_data, uncompressed_size,
&this->data_, &compressed_size);
if (success)
{
// This converts .debug_foo to .zdebug_foo
this->new_section_name_ = std::string(".z") + (this->name() + 1);
this->set_name(this->new_section_name_.c_str());
this->set_data_size(compressed_size);
}
else
{
gold_warning(_("not compressing section data: zlib error"));
gold_assert(this->data_ == NULL);
this->set_data_size(uncompressed_size);
}
}
// Write out a compressed section. If we couldn't compress, we just
// write it out as normal, uncompressed data.
void
Output_compressed_section::do_write(Output_file* of)
{
off_t offset = this->offset();
off_t data_size = this->data_size();
unsigned char* view = of->get_output_view(offset, data_size);
if (this->data_ == NULL)
memcpy(view, this->postprocessing_buffer(), data_size);
else
memcpy(view, this->data_, data_size);
of->write_output_view(offset, data_size, view);
}
} // End namespace gold.
|