mirror of
https://github.com/yugr/Implib.so
synced 2026-06-08 18:33:41 +00:00
Yury Gribov
34 lines
1.2 KiB
Markdown
34 lines
1.2 KiB
Markdown
Sometimes you may want to reduce public interface of existing closed-source shared library (e.g. if it's a third-party lib which erroneously exports too many unrelated symbols).
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To achieve this you can generate a wrapper with limited number of symbols and override the callback which loads the library to use `dlmopen` instead of `dlopen` (and thus does not pollute the global namespace):
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```
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$ cat mysymbols.txt
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foo
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bar
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$ cat mycallback.c
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#define _GNU_SOURCE
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#include <dlfcn.h>
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#include <stdio.h>
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#include <stdlib.h>
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#ifdef __cplusplus
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extern "C"
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#endif
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// Dlopen callback that loads library to dedicated namespace
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void *mycallback(const char *lib_name) {
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void *h = dlmopen(LM_ID_NEWLM, lib_name, RTLD_LAZY | RTLD_DEEPBIND);
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if (h)
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return h;
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fprintf(stderr, "dlmopen failed: %s\n", dlerror());
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exit(1);
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}
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$ implib-gen.py --dlopen-callback=mycallback --symbol-list=mysymbols.txt libxyz.so
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$ ... # Link your app with libxyz.tramp.S, libxyz.init.c and mycallback.c
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```
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Similar approach can be used if you want to provide a common interface for several libraries with partially intersecting interfaces (see [this example](tests/multilib/run.sh) for more details).
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