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Date: Tue, 11 Jan 2022 12:50:33 +0100
From: Ilia K <>
Subject: Cannot dlopen() an already loaded shared library by its SONAME name


It turns out that `dlopen()` in musl cannot find the already loaded shared
library using the library soname from the dynamic section, unlike glibc.
Here is a simple demo app:
# cat main.c
#include <dlfcn.h>
#include <stdio.h>

#define SOMELIB_DIR  "/root/dlopen_file_name_test/somelib/"
#define SOMELIB_NAME ""

int main() {
    void* library_handle = dlopen(SOMELIB_DIR SOMELIB_NAME, RTLD_LAZY |
    printf("dlopen first load: %p\n", library_handle);

        void* library_handle2 = dlopen(SOMELIB_DIR SOMELIB_NAME, RTLD_LAZY
        printf("dlopen by file path: %p\n", library_handle2);
        if (library_handle2) dlclose(library_handle2);

        void* library_handle3 = dlopen(SOMELIB_NAME, RTLD_LAZY |
RTLD_LOCAL);  // RTLD_NOLOAD doesn't work either
        printf("dlopen by file name: %p %s\n", library_handle3,
library_handle3 ? NULL : dlerror());
        if (library_handle3) dlclose(library_handle3);

    if (library_handle) dlclose(library_handle);
    return 0;
# cat somelib.c
int somelib_func() { return 0; }
# cat Makefile
        mkdir -p somelib
        gcc -shared somelib.c -Wl,-soname, -o
        gcc main.c -o main -ldl

Compile & run:
# make
mkdir -p somelib
gcc -shared somelib.c -Wl,-soname, -o somelib/
gcc main.c -o main -ldl
# ./main
dlopen first load: 0x7f06a28a4ca0
dlopen by file path: 0x7f06a28a4ca0
dlopen by file name: 0 Error loading shared library No such
file or directory

Do you have any plans to support it?

- Ilia

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