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    <p>If on Linux, with a good Linux file system (e.g. ext3 or ext4 or btrfs), you could update a shared library (e.g. <code>libfoo.so</code>) within a process and program (e.g. <code>bar</code>) using it (e.g. <code>dlopen</code>-ing that <code>libfoo.so</code>)</p> <p>You'll have preferably</p> <ol> <li>to <a href="http://linux.die.net/man/2/rename" rel="nofollow noreferrer">rename(2)</a> the old <code>libfoo.so</code> to e.g. <code>libfoo-old.so</code></li> <li>to <a href="http://linux.die.net/man/3/dlopen" rel="nofollow noreferrer">dlopen(3)</a> the new version of <code>libfoo.so</code></li> <li>to <code>dlsym</code> what you want inside it</li> <li>to perhaps <a href="http://linux.die.net/man/3/dlclose" rel="nofollow noreferrer">dlclose(3)</a> the old <code>dlopen</code>-ed handle to the old version; you can only do that if no active call frame points into the <code>libfoo-old.so</code> (otherwise your program will crash when returning into such call frames).</li> <li>to <a href="http://linux.die.net/man/2/unlink" rel="nofollow noreferrer">unlink(2)</a> the <code>libfoo-old.so</code> if needed</li> </ol> <p>(you could avoid <code>rename</code> and you could even <code>unlink</code> an active <code>dlopen</code>-ed library; the kernel would remove it if no further directory entry or process file descriptor points to it; I won't recommend that, e.g. to ease the debugging of potential <code>core</code> dumps).</p> <p>A simpler, but more "leaking" alternative, is to never <code>dlclose</code>. In practice, a program can <code>dlopen</code> many dozen of thousands <code>*.so</code> without fear. See my old <a href="http://starynkevitch.net/Basile/manydl.c" rel="nofollow noreferrer">manydl.c</a> example.</p> <p>Read also about <a href="https://en.wikipedia.org/wiki/Dynamic_software_updating" rel="nofollow noreferrer">dynamic software updating</a>.</p>
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    1. POCan a C/C++ linux shared library auto-update by overwriting its own file on disk to a newer version?
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    1. USBasile Starynkevitch
    1. USBasile Starynkevitch
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      1. VTUpMod
    1. COHmm, this requires the program to have knowledge of the update right? I want a much more low-tec solution: Library checks if there is newer version, downloads it, rewrites itself.
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      1. USKarthik
    2. COIt can be the library itself. But then, I don't think it can replace itself in each occurrence of running processes using that library. The replacement would be effective only for the next run of the programs.
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      1. USBasile Starynkevitch
 

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