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
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
|
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>symbol versioning - Notes</title>
<!-- Custom HTML head -->
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff" />
<link rel="icon" href="../favicon.svg">
<link rel="shortcut icon" href="../favicon.png">
<link rel="stylesheet" href="../css/variables.css">
<link rel="stylesheet" href="../css/general.css">
<link rel="stylesheet" href="../css/chrome.css">
<link rel="stylesheet" href="../css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
<link rel="stylesheet" href="../fonts/fonts.css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="../highlight.css">
<link rel="stylesheet" href="../tomorrow-night.css">
<link rel="stylesheet" href="../ayu-highlight.css">
<!-- Custom theme stylesheets -->
</head>
<body>
<!-- Provide site root to javascript -->
<script type="text/javascript">
var path_to_root = "../";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script type="text/javascript">
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') && theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
</script>
<!-- Set the theme before any content is loaded, prevents flash -->
<script type="text/javascript">
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item expanded affix "><a href="../intro.html">Introduction</a></li><li class="chapter-item expanded "><a href="../tools/index.html"><strong aria-hidden="true">1.</strong> Tools</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../tools/zsh.html"><strong aria-hidden="true">1.1.</strong> zsh</a></li><li class="chapter-item expanded "><a href="../tools/bash.html"><strong aria-hidden="true">1.2.</strong> bash</a></li><li class="chapter-item expanded "><a href="../tools/fish.html"><strong aria-hidden="true">1.3.</strong> fish</a></li><li class="chapter-item expanded "><a href="../tools/tmux.html"><strong aria-hidden="true">1.4.</strong> tmux</a></li><li class="chapter-item expanded "><a href="../tools/git.html"><strong aria-hidden="true">1.5.</strong> git</a></li><li class="chapter-item expanded "><a href="../tools/awk.html"><strong aria-hidden="true">1.6.</strong> awk</a></li><li class="chapter-item expanded "><a href="../tools/emacs.html"><strong aria-hidden="true">1.7.</strong> emacs</a></li><li class="chapter-item expanded "><a href="../tools/gpg.html"><strong aria-hidden="true">1.8.</strong> gpg</a></li><li class="chapter-item expanded "><a href="../tools/gdb.html"><strong aria-hidden="true">1.9.</strong> gdb</a></li><li class="chapter-item expanded "><a href="../tools/gdbserver.html"><strong aria-hidden="true">1.10.</strong> gdbserver</a></li><li class="chapter-item expanded "><a href="../tools/radare2.html"><strong aria-hidden="true">1.11.</strong> radare2</a></li><li class="chapter-item expanded "><a href="../tools/qemu.html"><strong aria-hidden="true">1.12.</strong> qemu</a></li><li class="chapter-item expanded "><a href="../tools/pacman.html"><strong aria-hidden="true">1.13.</strong> pacman</a></li><li class="chapter-item expanded "><a href="../tools/dot.html"><strong aria-hidden="true">1.14.</strong> dot</a></li></ol></li><li class="chapter-item expanded "><a href="../monitor/index.html"><strong aria-hidden="true">2.</strong> Resource analysis & monitor</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../monitor/lsof.html"><strong aria-hidden="true">2.1.</strong> lsof</a></li><li class="chapter-item expanded "><a href="../monitor/ss.html"><strong aria-hidden="true">2.2.</strong> ss</a></li><li class="chapter-item expanded "><a href="../monitor/pidstat.html"><strong aria-hidden="true">2.3.</strong> pidstat</a></li><li class="chapter-item expanded "><a href="../monitor/pgrep.html"><strong aria-hidden="true">2.4.</strong> pgrep</a></li><li class="chapter-item expanded "><a href="../monitor/pmap.html"><strong aria-hidden="true">2.5.</strong> pmap</a></li><li class="chapter-item expanded "><a href="../monitor/pstack.html"><strong aria-hidden="true">2.6.</strong> pstack</a></li></ol></li><li class="chapter-item expanded "><a href="../trace_profile/index.html"><strong aria-hidden="true">3.</strong> Trace and Profile</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../trace_profile/strace.html"><strong aria-hidden="true">3.1.</strong> strace</a></li><li class="chapter-item expanded "><a href="../trace_profile/ltrace.html"><strong aria-hidden="true">3.2.</strong> ltrace</a></li><li class="chapter-item expanded "><a href="../trace_profile/perf.html"><strong aria-hidden="true">3.3.</strong> perf</a></li><li class="chapter-item expanded "><a href="../trace_profile/oprofile.html"><strong aria-hidden="true">3.4.</strong> OProfile</a></li><li class="chapter-item expanded "><a href="../trace_profile/time.html"><strong aria-hidden="true">3.5.</strong> time</a></li></ol></li><li class="chapter-item expanded "><a href="../binary/index.html"><strong aria-hidden="true">4.</strong> Binary</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../binary/od.html"><strong aria-hidden="true">4.1.</strong> od</a></li><li class="chapter-item expanded "><a href="../binary/xxd.html"><strong aria-hidden="true">4.2.</strong> xxd</a></li><li class="chapter-item expanded "><a href="../binary/readelf.html"><strong aria-hidden="true">4.3.</strong> readelf</a></li><li class="chapter-item expanded "><a href="../binary/objdump.html"><strong aria-hidden="true">4.4.</strong> objdump</a></li><li class="chapter-item expanded "><a href="../binary/nm.html"><strong aria-hidden="true">4.5.</strong> nm</a></li></ol></li><li class="chapter-item expanded "><a href="../development/index.html"><strong aria-hidden="true">5.</strong> Development</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../development/c++filt.html"><strong aria-hidden="true">5.1.</strong> c++filt</a></li><li class="chapter-item expanded "><a href="../development/c++.html"><strong aria-hidden="true">5.2.</strong> c++</a></li><li class="chapter-item expanded "><a href="../development/glibc.html"><strong aria-hidden="true">5.3.</strong> glibc</a></li><li class="chapter-item expanded "><a href="../development/gcc.html"><strong aria-hidden="true">5.4.</strong> gcc</a></li><li class="chapter-item expanded "><a href="../development/make.html"><strong aria-hidden="true">5.5.</strong> make</a></li><li class="chapter-item expanded "><a href="../development/ld.so.html"><strong aria-hidden="true">5.6.</strong> ld.so</a></li><li class="chapter-item expanded "><a href="../development/symbolver.html" class="active"><strong aria-hidden="true">5.7.</strong> symbol versioning</a></li><li class="chapter-item expanded "><a href="../development/python.html"><strong aria-hidden="true">5.8.</strong> python</a></li></ol></li><li class="chapter-item expanded "><a href="../linux/index.html"><strong aria-hidden="true">6.</strong> Linux</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../linux/systemd.html"><strong aria-hidden="true">6.1.</strong> systemd</a></li><li class="chapter-item expanded "><a href="../linux/coredump.html"><strong aria-hidden="true">6.2.</strong> coredump</a></li><li class="chapter-item expanded "><a href="../linux/ptrace_scope.html"><strong aria-hidden="true">6.3.</strong> ptrace_scope</a></li><li class="chapter-item expanded "><a href="../linux/cryptsetup.html"><strong aria-hidden="true">6.4.</strong> cryptsetup</a></li><li class="chapter-item expanded "><a href="../linux/swap.html"><strong aria-hidden="true">6.5.</strong> swap</a></li></ol></li><li class="chapter-item expanded "><a href="../network/index.html"><strong aria-hidden="true">7.</strong> Network</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../network/tcpdump.html"><strong aria-hidden="true">7.1.</strong> tcpdump</a></li></ol></li><li class="chapter-item expanded "><a href="../arch/index.html"><strong aria-hidden="true">8.</strong> Arch</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../arch/x86_64.html"><strong aria-hidden="true">8.1.</strong> x86_64</a></li><li class="chapter-item expanded "><a href="../arch/arm64.html"><strong aria-hidden="true">8.2.</strong> arm64</a></li><li class="chapter-item expanded "><a href="../arch/armv7.html"><strong aria-hidden="true">8.3.</strong> armv7</a></li><li class="chapter-item expanded "><a href="../arch/riscv.html"><strong aria-hidden="true">8.4.</strong> riscv</a></li></ol></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
</nav>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar-hover-placeholder"></div>
<div id="menu-bar" class="menu-bar sticky bordered">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</button>
</div>
<h1 class="menu-title">Notes</h1>
<div class="right-buttons">
<a href="../print.html" title="Print this book" aria-label="Print this book">
<i id="print-button" class="fa fa-print"></i>
</a>
<a href="https://github.com/johannst/notes" title="Git repository" aria-label="Git repository">
<i id="git-repository-button" class="fa fa-github"></i>
</a>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script type="text/javascript">
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<main>
<h1 id="elf-symbol-versioning"><a class="header" href="#elf-symbol-versioning">ELF Symbol Versioning</a></h1>
<p>The <a href="https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/symversion.html">ELF symbol versioning</a> mechanism allows to attach version
information to symbols.
This can be used to express symbol version requirements or to provide certain
symbols multiple times in the same ELF file with different versions (eg for
backwards compatibility).</p>
<p>The <code>libpthread.so</code> library is an example which provides the
<code>pthread_cond_wait</code> symbol multiple times but in different versions.
With readelf the version of the symbol can be seen after the <code>@</code>.</p>
<pre><code class="language-bash">> readelf -W --dyn-syms /lib/libpthread.so
Symbol table '.dynsym' contains 342 entries:
Num: Value Size Type Bind Vis Ndx Name
...
141: 0000f080 696 FUNC GLOBAL DEFAULT 16 pthread_cond_wait@@GLIBC_2.3.2
142: 00010000 111 FUNC GLOBAL DEFAULT 16 pthread_cond_wait@GLIBC_2.2.5
</code></pre>
<p>The <code>@@</code> denotes the <strong>default symbol version</strong> which will be used during
static linking against the library.
The following dump shows that the <code>tmp</code> program linked against <code>lpthread</code> will
depend on the symbol version <code>GLIBC_2.3.2</code>, which is the default version.</p>
<pre><code class="language-bash">> echo "#include <pthread.h>
int main() {
return pthread_cond_wait(0,0);
}" | gcc -o tmp -xc - -lpthread;
readelf -W --dyn-syms tmp | grep pthread_cond_wait;
Symbol table '.dynsym' contains 7 entries:
Num: Value Size Type Bind Vis Ndx Name
...
2: 00000000 0 FUNC GLOBAL DEFAULT UND pthread_cond_wait@GLIBC_2.3.2 (2)
</code></pre>
<blockquote>
<p>Only <strong>one</strong> symbol can be annotated as the <code>@@</code> default version.</p>
</blockquote>
<p>Using the <code>--version-info</code> flag with readelf, more details on the symbol
version info compiled into the <code>tmp</code> ELF file can be obtained.</p>
<ul>
<li>The <code>.gnu.version</code> section contains the version definition for each symbol in
the <code>.dynsym</code> section. <code>pthread_cond_wait</code> is at index <code>2</code> in the <code>.dynsym</code>
section, the corresponding symbol version is at index <code>2</code> in the
<code>.gnu.version</code> section.</li>
<li>The <code>.gnu.version_r</code> section contains symbol version requirements per shared
library dependency (<code>DT_NEEDED</code> dynamic entry).</li>
</ul>
<pre><code class="language-bash">> readelf -W --version-info --dyn-syms tmp
Symbol table '.dynsym' contains 7 entries:
Num: Value Size Type Bind Vis Ndx Name
0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
1: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_deregisterTMCloneTable
2: 0000000000000000 0 FUNC GLOBAL DEFAULT UND pthread_cond_wait@GLIBC_2.3.2 (2)
3: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __libc_start_main@GLIBC_2.2.5 (3)
4: 0000000000000000 0 NOTYPE WEAK DEFAULT UND __gmon_start__
5: 0000000000000000 0 NOTYPE WEAK DEFAULT UND _ITM_registerTMCloneTable
6: 0000000000000000 0 FUNC WEAK DEFAULT UND __cxa_finalize@GLIBC_2.2.5 (3)
Version symbols section '.gnu.version' contains 7 entries:
Addr: 0x0000000000000534 Offset: 0x000534 Link: 6 (.dynsym)
000: 0 (*local*) 0 (*local*) 2 (GLIBC_2.3.2) 3 (GLIBC_2.2.5)
004: 0 (*local*) 0 (*local*) 3 (GLIBC_2.2.5)
Version needs section '.gnu.version_r' contains 2 entries:
Addr: 0x0000000000000548 Offset: 0x000548 Link: 7 (.dynstr)
000000: Version: 1 File: libc.so.6 Cnt: 1
0x0010: Name: GLIBC_2.2.5 Flags: none Version: 3
0x0020: Version: 1 File: libpthread.so.0 Cnt: 1
0x0030: Name: GLIBC_2.3.2 Flags: none Version: 2
</code></pre>
<p>The gnu dynamic linker allows to inspect the version processing during runtime
by setting the <code>LD_DEBUG</code> environment variable accordingly.</p>
<pre><code class="language-text"># version: Display version dependencies.
> LD_DEBUG=versions ./tmp
717904: checking for version `GLIBC_2.2.5' in file /usr/lib/libc.so.6 [0] required by file ./tmp [0]
717904: checking for version `GLIBC_2.3.2' in file /usr/lib/libpthread.so.0 [0] required by file ./tmp [0]
...
# symbols : Display symbol table processing.
# bindings: Display information about symbol binding.
> LD_DEBUG=symbols,bindings ./tmp
...
718123: symbol=pthread_cond_wait; lookup in file=./tmp [0]
718123: symbol=pthread_cond_wait; lookup in file=/usr/lib/libpthread.so.0 [0]
718123: binding file ./tmp [0] to /usr/lib/libpthread.so.0 [0]: normal symbol `pthread_cond_wait' [GLIBC_2.3.2]
</code></pre>
<h2 id="example-version-script"><a class="header" href="#example-version-script">Example: version script</a></h2>
<p>The following shows an example C++ library <code>libfoo</code> which provides the same
symbol multiple times but in different versions.</p>
<pre><code class="language-cpp">// file: libfoo.cc
#include<stdio.h>
// Bind function symbols to version nodes.
//
// ..@ -> Is the unversioned symbol.
// ..@@.. -> Is the default symbol.
__asm__(".symver func_v0,func@");
__asm__(".symver func_v1,func@LIB_V1");
__asm__(".symver func_v2,func@@LIB_V2");
extern "C" {
void func_v0() { puts("func_v0"); }
void func_v1() { puts("func_v1"); }
void func_v2() { puts("func_v2"); }
}
__asm__(".symver _Z11func_cpp_v1i,_Z8func_cppi@LIB_V1");
__asm__(".symver _Z11func_cpp_v2i,_Z8func_cppi@@LIB_V2");
void func_cpp_v1(int) { puts("func_cpp_v1"); }
void func_cpp_v2(int) { puts("func_cpp_v2"); }
void func_cpp(int) { puts("func_cpp_v2"); }
</code></pre>
<p>Version script for <code>libfoo</code> which defines which symbols for which versions are
exported from the ELF file.</p>
<pre><code class="language-ld"># file: libfoo.ver
LIB_V1 {
global:
func;
extern "C++" {
"func_cpp(int)";
};
local:
*;
};
LIB_V2 {
global:
func;
extern "C++" {
"func_cpp(int)";
};
} LIB_V1;
</code></pre>
<blockquote>
<p>The <strong>local:</strong> section in <code>LIB_V1</code> is a catch all, that matches any symbol
not explicitly specified, and defines that the symbol is local and therefore
not exported from the ELF file.</p>
</blockquote>
<p>The library <code>libfoo</code> can be linked with the version definitions in <code>libfoo.ver</code>
by passing the version script to the linker with the <code>--version-script</code> flag.</p>
<pre><code class="language-bash">> g++ -shared -fPIC -o libfoo.so libfoo.cc -Wl,--version-script=libfoo.ver
> readelf -W --dyn-syms libfoo.so | c++filt
Symbol table '.dynsym' contains 14 entries:
Num: Value Size Type Bind Vis Ndx Name
...
6: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIB_V1
7: 000000000000114b 29 FUNC GLOBAL DEFAULT 13 func_cpp(int)@LIB_V1
8: 0000000000001168 29 FUNC GLOBAL DEFAULT 13 func_cpp(int)@@LIB_V2
9: 0000000000001185 29 FUNC GLOBAL DEFAULT 13 func_cpp(int)@@LIB_V1
10: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIB_V2
11: 0000000000001109 22 FUNC GLOBAL DEFAULT 13 func
12: 000000000000111f 22 FUNC GLOBAL DEFAULT 13 func@LIB_V1
13: 0000000000001135 22 FUNC GLOBAL DEFAULT 13 func@@LIB_V2
</code></pre>
<p>The following program demonstrates how to make use of the different versions:</p>
<pre><code class="language-cpp">// file: main.cc
#include <dlfcn.h>
#include <assert.h>
// Links against default symbol in the lib.so.
extern "C" void func();
int main() {
// Call the default version.
func();
#ifdef _GNU_SOURCE
typedef void (*fnptr)();
// Unversioned lookup.
fnptr fn_v0 = (fnptr)dlsym(RTLD_DEFAULT, "func");
// Version lookup.
fnptr fn_v1 = (fnptr)dlvsym(RTLD_DEFAULT, "func", "LIB_V1");
fnptr fn_v2 = (fnptr)dlvsym(RTLD_DEFAULT, "func", "LIB_V2");
assert(fn_v0 != 0);
assert(fn_v1 != 0);
assert(fn_v2 != 0);
fn_v0();
fn_v1();
fn_v2();
#endif
return 0;
}
</code></pre>
<p>Compiling and running results in:</p>
<pre><code class="language-bash">> g++ -o main main.cc -ldl ./libfoo.so && ./main
func_v2
func_v0
func_v1
func_v2
</code></pre>
<h2 id="references"><a class="header" href="#references">References</a></h2>
<ul>
<li><a href="https://akkadia.org/drepper/symbol-versioning">ELF Symbol Versioning</a></li>
<li><a href="https://sourceware.org/binutils/docs/ld/VERSION.html">Binutils ld: Symbol Versioning</a></li>
<li><a href="https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/symversion.html">LSB: Symbol Versioning</a></li>
<li><a href="https://akkadia.org/drepper/dsohowto.pdf">How To Write Shared Libraries</a></li>
</ul>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="../development/ld.so.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="../development/python.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
<a rel="prev" href="../development/ld.so.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="../development/python.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script type="text/javascript">
window.playground_copyable = true;
</script>
<script src="../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../mark.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../searcher.js" type="text/javascript" charset="utf-8"></script>
<script src="../clipboard.min.js" type="text/javascript" charset="utf-8"></script>
<script src="../highlight.js" type="text/javascript" charset="utf-8"></script>
<script src="../book.js" type="text/javascript" charset="utf-8"></script>
<!-- Custom JS scripts -->
</body>
</html>
|
