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int main() { __res_maybe_init(); // now expects GLIBC_PRIVATE version return 0; }
The error undefined symbol --res-maybe-init version glibc-private typically indicates a or a linking issue with a custom or mismatched glibc. This symbol is not public ; it’s a private glibc resolver symbol used internally for thread-safe resolver initialization. undefined symbol --res-maybe-init version glibc-private
But for a , use a direct linker undefined reference : The actual fix for such an error (if
undefined symbol: __res_maybe_init@GLIBC_PRIVATE This is not a real-world fix — it’s a reproduction of the error. The actual fix for such an error (if encountered in real code) is to avoid relying on glibc private symbols and link against the correct public resolver API (e.g., res_ninit , __res_init with appropriate feature test macros). int main() { __res_maybe_init()
Compile and link (the error appears at link time or runtime depending on -z lazy ):
// provoke_glibc_private_undef.c void __res_maybe_init(void) __attribute__((weak)); void __res_maybe_init(void) {} // Trick: force reference to the PRIVATE version asm(".symver __res_maybe_init, __res_maybe_init@GLIBC_PRIVATE");