Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 446 insertions, 0 deletions

diff --git a/vendor/libloading/src/os/unix/mod.rs b/vendor/libloading/src/os/unix/mod.rs
new file mode 100644
index 000000000..fd0777eab
--- /dev/null
+++ b/vendor/libloading/src/os/unix/mod.rs
@@ -0,0 +1,446 @@
+// A hack for docs.rs to build documentation that has both windows and linux documentation in the
+// same rustdoc build visible.
+#[cfg(all(libloading_docs, not(unix)))]
+mod unix_imports {}
+#[cfg(any(not(libloading_docs), unix))]
+mod unix_imports {
+    pub(super) use std::os::unix::ffi::OsStrExt;
+}
+
+pub use self::consts::*;
+use self::unix_imports::*;
+use std::ffi::{CStr, OsStr};
+use std::os::raw;
+use std::{fmt, marker, mem, ptr};
+use util::{cstr_cow_from_bytes, ensure_compatible_types};
+
+mod consts;
+
+// dl* family of functions did not have enough thought put into it.
+//
+// Whole error handling scheme is done via setting and querying some global state, therefore it is
+// not safe to use dynamic library loading in MT-capable environment at all. Only in POSIX 2008+TC1
+// a thread-local state was allowed for `dlerror`, making the dl* family of functions MT-safe.
+//
+// In practice (as of 2020-04-01) most of the widely used targets use a thread-local for error
+// state and have been doing so for a long time. Regardless the comments in this function shall
+// remain as a documentation for the future generations.
+fn with_dlerror<T, F>(wrap: fn(crate::error::DlDescription) -> crate::Error, closure: F)
+-> Result<T, Option<crate::Error>>
+where F: FnOnce() -> Option<T> {
+    // We used to guard all uses of dl* functions with our own mutex. This made them safe to use in
+    // MT programs provided the only way a program used dl* was via this library. However, it also
+    // had a number of downsides or cases where it failed to handle the problems. For instance,
+    // if any other library called `dlerror` internally concurrently with `libloading` things would
+    // still go awry.
+    //
+    // On platforms where `dlerror` is still MT-unsafe, `dlsym` (`Library::get`) can spuriously
+    // succeed and return a null pointer for a symbol when the actual symbol look-up operation
+    // fails. Instances where the actual symbol _could_ be `NULL` are platform specific. For
+    // instance on GNU glibc based-systems (an excerpt from dlsym(3)):
+    //
+    // > The value of a symbol returned by dlsym() will never be NULL if the shared object is the
+    // > result of normal compilation,  since  a  global  symbol is never placed at the NULL
+    // > address. There are nevertheless cases where a lookup using dlsym() may return NULL as the
+    // > value of a symbol. For example, the symbol value may be  the  result of a GNU indirect
+    // > function (IFUNC) resolver function that returns NULL as the resolved value.
+
+    // While we could could call `dlerror` here to clear the previous error value, only the `dlsym`
+    // call depends on it being cleared beforehand and only in some cases too. We will instead
+    // clear the error inside the dlsym binding instead.
+    //
+    // In all the other cases, clearing the error here will only be hiding misuse of these bindings
+    // or a bug in implementation of dl* family of functions.
+    closure().ok_or_else(|| unsafe {
+        // This code will only get executed if the `closure` returns `None`.
+        let error = dlerror();
+        if error.is_null() {
+            // In non-dlsym case this may happen when there’re bugs in our bindings or there’s
+            // non-libloading user of libdl; possibly in another thread.
+            None
+        } else {
+            // You can’t even rely on error string being static here; call to subsequent dlerror
+            // may invalidate or overwrite the error message. Why couldn’t they simply give up the
+            // ownership over the message?
+            // TODO: should do locale-aware conversion here. OTOH Rust doesn’t seem to work well in
+            // any system that uses non-utf8 locale, so I doubt there’s a problem here.
+            let message = CStr::from_ptr(error).into();
+            Some(wrap(crate::error::DlDescription(message)))
+            // Since we do a copy of the error string above, maybe we should call dlerror again to
+            // let libdl know it may free its copy of the string now?
+        }
+    })
+}
+
+/// A platform-specific counterpart of the cross-platform [`Library`](crate::Library).
+pub struct Library {
+    handle: *mut raw::c_void
+}
+
+unsafe impl Send for Library {}
+
+// That being said... this section in the volume 2 of POSIX.1-2008 states:
+//
+// > All functions defined by this volume of POSIX.1-2008 shall be thread-safe, except that the
+// > following functions need not be thread-safe.
+//
+// With notable absence of any dl* function other than dlerror in the list. By “this volume”
+// I suppose they refer precisely to the “volume 2”. dl* family of functions are specified
+// by this same volume, so the conclusion is indeed that dl* functions are required by POSIX
+// to be thread-safe. Great!
+//
+// See for more details:
+//
+//  * https://github.com/nagisa/rust_libloading/pull/17
+//  * http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_09_01
+unsafe impl Sync for Library {}
+
+impl Library {
+    /// Find and eagerly load a shared library (module).
+    ///
+    /// If the `filename` contains a [path separator], the `filename` is interpreted as a `path` to
+    /// a file. Otherwise, platform-specific algorithms are employed to find a library with a
+    /// matching file name.
+    ///
+    /// This is equivalent to <code>[Library::open](filename, [RTLD_LAZY] | [RTLD_LOCAL])</code>.
+    ///
+    /// [path separator]: std::path::MAIN_SEPARATOR
+    ///
+    /// # Safety
+    ///
+    /// When a library is loaded, initialisation routines contained within the library are executed.
+    /// For the purposes of safety, the execution of these routines is conceptually the same calling an
+    /// unknown foreign function and may impose arbitrary requirements on the caller for the call
+    /// to be sound.
+    ///
+    /// Additionally, the callers of this function must also ensure that execution of the
+    /// termination routines contained within the library is safe as well. These routines may be
+    /// executed when the library is unloaded.
+    #[inline]
+    pub unsafe fn new<P: AsRef<OsStr>>(filename: P) -> Result<Library, crate::Error> {
+        Library::open(Some(filename), RTLD_LAZY | RTLD_LOCAL)
+    }
+
+    /// Load the `Library` representing the current executable.
+    ///
+    /// [`Library::get`] calls of the returned `Library` will look for symbols in following
+    /// locations in order:
+    ///
+    /// 1. The original program image;
+    /// 2. Any executable object files (e.g. shared libraries) loaded at program startup;
+    /// 3. Any executable object files loaded at runtime (e.g. via other `Library::new` calls or via
+    ///    calls to the `dlopen` function).
+    ///
+    /// Note that the behaviour of a `Library` loaded with this method is different from that of
+    /// Libraries loaded with [`os::windows::Library::this`].
+    ///
+    /// This is equivalent to <code>[Library::open](None, [RTLD_LAZY] | [RTLD_LOCAL])</code>.
+    ///
+    /// [`os::windows::Library::this`]: crate::os::windows::Library::this
+    #[inline]
+    pub fn this() -> Library {
+        unsafe {
+            // SAFE: this does not load any new shared library images, no danger in it executing
+            // initialiser routines.
+            Library::open(None::<&OsStr>, RTLD_LAZY | RTLD_LOCAL).expect("this should never fail")
+        }
+    }
+
+    /// Find and load an executable object file (shared library).
+    ///
+    /// See documentation for [`Library::this`] for further description of the behaviour
+    /// when the `filename` is `None`. Otherwise see [`Library::new`].
+    ///
+    /// Corresponds to `dlopen(filename, flags)`.
+    ///
+    /// # Safety
+    ///
+    /// When a library is loaded, initialisation routines contained within the library are executed.
+    /// For the purposes of safety, the execution of these routines is conceptually the same calling an
+    /// unknown foreign function and may impose arbitrary requirements on the caller for the call
+    /// to be sound.
+    ///
+    /// Additionally, the callers of this function must also ensure that execution of the
+    /// termination routines contained within the library is safe as well. These routines may be
+    /// executed when the library is unloaded.
+    pub unsafe fn open<P>(filename: Option<P>, flags: raw::c_int) -> Result<Library, crate::Error>
+    where P: AsRef<OsStr> {
+        let filename = match filename {
+            None => None,
+            Some(ref f) => Some(cstr_cow_from_bytes(f.as_ref().as_bytes())?),
+        };
+        with_dlerror(|desc| crate::Error::DlOpen { desc }, move || {
+            let result = dlopen(match filename {
+                None => ptr::null(),
+                Some(ref f) => f.as_ptr()
+            }, flags);
+            // ensure filename lives until dlopen completes
+            drop(filename);
+            if result.is_null() {
+                None
+            } else {
+                Some(Library {
+                    handle: result
+                })
+            }
+        }).map_err(|e| e.unwrap_or(crate::Error::DlOpenUnknown))
+    }
+
+    unsafe fn get_impl<T, F>(&self, symbol: &[u8], on_null: F) -> Result<Symbol<T>, crate::Error>
+    where F: FnOnce() -> Result<Symbol<T>, crate::Error>
+    {
+        ensure_compatible_types::<T, *mut raw::c_void>()?;
+        let symbol = cstr_cow_from_bytes(symbol)?;
+        // `dlsym` may return nullptr in two cases: when a symbol genuinely points to a null
+        // pointer or the symbol cannot be found. In order to detect this case a double dlerror
+        // pattern must be used, which is, sadly, a little bit racy.
+        //
+        // We try to leave as little space as possible for this to occur, but we can’t exactly
+        // fully prevent it.
+        match with_dlerror(|desc| crate::Error::DlSym { desc }, || {
+            dlerror();
+            let symbol = dlsym(self.handle, symbol.as_ptr());
+            if symbol.is_null() {
+                None
+            } else {
+                Some(Symbol {
+                    pointer: symbol,
+                    pd: marker::PhantomData
+                })
+            }
+        }) {
+            Err(None) => on_null(),
+            Err(Some(e)) => Err(e),
+            Ok(x) => Ok(x)
+        }
+
+    }
+
+    /// Get a pointer to a function or static variable by symbol name.
+    ///
+    /// The `symbol` may not contain any null bytes, with the exception of the last byte. Providing a
+    /// null terminated `symbol` may help to avoid an allocation.
+    ///
+    /// Symbol is interpreted as-is; no mangling is done. This means that symbols like `x::y` are
+    /// most likely invalid.
+    ///
+    /// # Safety
+    ///
+    /// Users of this API must specify the correct type of the function or variable loaded. Using a
+    /// `Symbol` with a wrong type is undefined.
+    ///
+    /// # Platform-specific behaviour
+    ///
+    /// Implementation of thread local variables is extremely platform specific and uses of such
+    /// variables that work on e.g. Linux may have unintended behaviour on other targets.
+    ///
+    /// On POSIX implementations where the `dlerror` function is not confirmed to be MT-safe (such
+    /// as FreeBSD), this function will unconditionally return an error when the underlying `dlsym`
+    /// call returns a null pointer. There are rare situations where `dlsym` returns a genuine null
+    /// pointer without it being an error. If loading a null pointer is something you care about,
+    /// consider using the [`Library::get_singlethreaded`] call.
+    #[inline(always)]
+    pub unsafe fn get<T>(&self, symbol: &[u8]) -> Result<Symbol<T>, crate::Error> {
+        extern crate cfg_if;
+        cfg_if::cfg_if! {
+            // These targets are known to have MT-safe `dlerror`.
+            if #[cfg(any(
+                target_os = "linux",
+                target_os = "android",
+                target_os = "openbsd",
+                target_os = "macos",
+                target_os = "ios",
+                target_os = "solaris",
+                target_os = "illumos",
+                target_os = "redox",
+                target_os = "fuchsia"
+            ))] {
+                self.get_singlethreaded(symbol)
+            } else {
+                self.get_impl(symbol, || Err(crate::Error::DlSymUnknown))
+            }
+        }
+    }
+
+    /// Get a pointer to function or static variable by symbol name.
+    ///
+    /// The `symbol` may not contain any null bytes, with the exception of the last byte. Providing a
+    /// null terminated `symbol` may help to avoid an allocation.
+    ///
+    /// Symbol is interpreted as-is; no mangling is done. This means that symbols like `x::y` are
+    /// most likely invalid.
+    ///
+    /// # Safety
+    ///
+    /// Users of this API must specify the correct type of the function or variable loaded.
+    ///
+    /// It is up to the user of this library to ensure that no other calls to an MT-unsafe
+    /// implementation of `dlerror` occur during the execution of this function. Failing that, the
+    /// behaviour of this function is not defined.
+    ///
+    /// # Platform-specific behaviour
+    ///
+    /// The implementation of thread-local variables is extremely platform specific and uses of such
+    /// variables that work on e.g. Linux may have unintended behaviour on other targets.
+    #[inline(always)]
+    pub unsafe fn get_singlethreaded<T>(&self, symbol: &[u8]) -> Result<Symbol<T>, crate::Error> {
+        self.get_impl(symbol, || Ok(Symbol {
+            pointer: ptr::null_mut(),
+            pd: marker::PhantomData
+        }))
+    }
+
+    /// Convert the `Library` to a raw handle.
+    ///
+    /// The handle returned by this function shall be usable with APIs which accept handles
+    /// as returned by `dlopen`.
+    pub fn into_raw(self) -> *mut raw::c_void {
+        let handle = self.handle;
+        mem::forget(self);
+        handle
+    }
+
+    /// Convert a raw handle returned by `dlopen`-family of calls to a `Library`.
+    ///
+    /// # Safety
+    ///
+    /// The pointer shall be a result of a successful call of the `dlopen`-family of functions or a
+    /// pointer previously returned by `Library::into_raw` call. It must be valid to call `dlclose`
+    /// with this pointer as an argument.
+    pub unsafe fn from_raw(handle: *mut raw::c_void) -> Library {
+        Library {
+            handle
+        }
+    }
+
+    /// Unload the library.
+    ///
+    /// This method might be a no-op, depending on the flags with which the `Library` was opened,
+    /// what library was opened or other platform specifics.
+    ///
+    /// You only need to call this if you are interested in handling any errors that may arise when
+    /// library is unloaded. Otherwise the implementation of `Drop` for `Library` will close the
+    /// library and ignore the errors were they arise.
+    ///
+    /// The underlying data structures may still get leaked if an error does occur.
+    pub fn close(self) -> Result<(), crate::Error> {
+        let result = with_dlerror(|desc| crate::Error::DlClose { desc }, || {
+            if unsafe { dlclose(self.handle) } == 0 {
+                Some(())
+            } else {
+                None
+            }
+        }).map_err(|e| e.unwrap_or(crate::Error::DlCloseUnknown));
+        // While the library is not free'd yet in case of an error, there is no reason to try
+        // dropping it again, because all that will do is try calling `dlclose` again. only
+        // this time it would ignore the return result, which we already seen failing…
+        std::mem::forget(self);
+        result
+    }
+}
+
+impl Drop for Library {
+    fn drop(&mut self) {
+        unsafe {
+            dlclose(self.handle);
+        }
+    }
+}
+
+impl fmt::Debug for Library {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str(&format!("Library@{:p}", self.handle))
+    }
+}
+
+/// Symbol from a library.
+///
+/// A major difference compared to the cross-platform `Symbol` is that this does not ensure that the
+/// `Symbol` does not outlive the `Library` it comes from.
+pub struct Symbol<T> {
+    pointer: *mut raw::c_void,
+    pd: marker::PhantomData<T>
+}
+
+impl<T> Symbol<T> {
+    /// Convert the loaded `Symbol` into a raw pointer.
+    pub fn into_raw(self) -> *mut raw::c_void {
+        let pointer = self.pointer;
+        mem::forget(self);
+        pointer
+    }
+}
+
+impl<T> Symbol<Option<T>> {
+    /// Lift Option out of the symbol.
+    pub fn lift_option(self) -> Option<Symbol<T>> {
+        if self.pointer.is_null() {
+            None
+        } else {
+            Some(Symbol {
+                pointer: self.pointer,
+                pd: marker::PhantomData,
+            })
+        }
+    }
+}
+
+unsafe impl<T: Send> Send for Symbol<T> {}
+unsafe impl<T: Sync> Sync for Symbol<T> {}
+
+impl<T> Clone for Symbol<T> {
+    fn clone(&self) -> Symbol<T> {
+        Symbol { ..*self }
+    }
+}
+
+impl<T> ::std::ops::Deref for Symbol<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        unsafe {
+            // Additional reference level for a dereference on `deref` return value.
+            &*(&self.pointer as *const *mut _ as *const T)
+        }
+    }
+}
+
+impl<T> fmt::Debug for Symbol<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        unsafe {
+            let mut info = mem::MaybeUninit::<DlInfo>::uninit();
+            if dladdr(self.pointer, info.as_mut_ptr()) != 0 {
+                let info = info.assume_init();
+                if info.dli_sname.is_null() {
+                    f.write_str(&format!("Symbol@{:p} from {:?}",
+                                         self.pointer,
+                                         CStr::from_ptr(info.dli_fname)))
+                } else {
+                    f.write_str(&format!("Symbol {:?}@{:p} from {:?}",
+                                         CStr::from_ptr(info.dli_sname), self.pointer,
+                                         CStr::from_ptr(info.dli_fname)))
+                }
+            } else {
+                f.write_str(&format!("Symbol@{:p}", self.pointer))
+            }
+        }
+    }
+}
+
+// Platform specific things
+#[cfg_attr(any(target_os = "linux", target_os = "android"), link(name="dl"))]
+#[cfg_attr(any(target_os = "freebsd", target_os = "dragonfly"), link(name="c"))]
+extern {
+    fn dlopen(filename: *const raw::c_char, flags: raw::c_int) -> *mut raw::c_void;
+    fn dlclose(handle: *mut raw::c_void) -> raw::c_int;
+    fn dlsym(handle: *mut raw::c_void, symbol: *const raw::c_char) -> *mut raw::c_void;
+    fn dlerror() -> *mut raw::c_char;
+    fn dladdr(addr: *mut raw::c_void, info: *mut DlInfo) -> raw::c_int;
+}
+
+#[repr(C)]
+struct DlInfo {
+  dli_fname: *const raw::c_char,
+  dli_fbase: *mut raw::c_void,
+  dli_sname: *const raw::c_char,
+  dli_saddr: *mut raw::c_void
+}