diff options
| -rw-r--r-- | src/librustc_metadata/dynamic_lib.rs | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/src/librustc_metadata/dynamic_lib.rs b/src/librustc_metadata/dynamic_lib.rs index 6867097d372..b49a1456046 100644 --- a/src/librustc_metadata/dynamic_lib.rs +++ b/src/librustc_metadata/dynamic_lib.rs @@ -107,11 +107,26 @@ mod dl { handle: *mut u8, symbol: *const libc::c_char, ) -> Result<*mut u8, String> { + // HACK(#74469): On some platforms, users observed foreign code + // (specifically libc) invoking `dlopen`/`dlsym` in parallel with the + // functions in this module. This is problematic because, according to + // the POSIX API documentation, `dlerror` must be called to determine + // whether `dlsym` succeeded. Unlike `dlopen`, a NULL return value may + // indicate a successfully resolved symbol with an address of zero. + // + // Because symbols with address zero shouldn't occur in practice, we + // treat them as errors on platforms with misbehaving libc + // implementations. + const DLSYM_NULL_IS_ERROR: bool = cfg!(target_os = "illumos"); + let mut dlerror = error::lock(); - // Flush `dlerror` since we need to use it to determine whether the subsequent call to - // `dlsym` is successful. - dlerror.clear(); + // No need to flush `dlerror` if we aren't using it to determine whether + // the subsequent call to `dlsym` succeeded. If an error occurs, any + // stale value will be overwritten. + if !DLSYM_NULL_IS_ERROR { + dlerror.clear(); + } let ret = libc::dlsym(handle as *mut libc::c_void, symbol) as *mut u8; @@ -121,7 +136,12 @@ mod dl { return Ok(ret); } - dlerror.get().map(|()| ret) + match dlerror.get() { + Ok(()) if DLSYM_NULL_IS_ERROR => Err("Unknown error".to_string()), + Ok(()) => Ok(ret), + + Err(msg) => Err(msg), + } } pub(super) unsafe fn close(handle: *mut u8) { |