std: Fix Windows XP compatibility

This commit enables executables linked against the standard library to run on
Windows XP. There are two main components of this commit:

* APIs not available on XP are shimmed to have a fallback implementation and use
  runtime detection to determine if they are available.
* Mutexes on Windows were reimplemented to use critical sections on XP where
  rwlocks are not available.

The APIs which are not available on XP are:

* SetFileInformationByHandle - this is just used by `File::truncate` and that
  function just returns an error now.
* SetThreadStackGuarantee - this is used by the stack overflow support on
  windows, but if this isn't available then it's just ignored (it seems
  non-critical).
* All condition variable APIs are missing - the shims added for these apis
  simply always panic for now. We may eventually provide a fallback
  implementation, but for now the standard library does not rely on condition
  variables for normal use.
* RWLocks, like condition variables, are missing entirely. The same story for
  condition variables is taken here. These APIs are all now panicking stubs as
  the standard library doesn't rely on RWLocks for normal use.

Currently, as an optimization, we use SRWLOCKs for the standard `sync::Mutex`
implementation on Windows, which is indeed required for normal operation of the
standard library. To allow the standard library to run on XP, this commit
reimplements mutexes on Windows to use SRWLOCK instances *if available* and
otherwise a CriticalSection is used (with some checking for recursive
locking).

With all these changes put together, a 32-bit MSVC-built executable can run on
Windows XP and print "hello world"

Closes #12842
Closes #19992
Closes #24776

1 files changed, 96 insertions, 115 deletions

diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index 3c9b2ef1b98..7f89ea97939 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -13,6 +13,9 @@
 #![allow(bad_style, dead_code, overflowing_literals)]
 
 use libc;
+use libc::{c_uint, c_ulong};
+use libc::{DWORD, BOOL, BOOLEAN, ERROR_CALL_NOT_IMPLEMENTED, LPVOID, HANDLE};
+use libc::{LPCWSTR, LONG};
 
 pub use self::GET_FILEEX_INFO_LEVELS::*;
 pub use self::FILE_INFO_BY_HANDLE_CLASS::*;
@@ -240,7 +243,32 @@ pub struct SYMBOLIC_LINK_REPARSE_BUFFER {
     pub PathBuffer: libc::WCHAR,
 }
 
+pub type PCONDITION_VARIABLE = *mut CONDITION_VARIABLE;
+pub type PSRWLOCK = *mut SRWLOCK;
+pub type ULONG = c_ulong;
+pub type ULONG_PTR = c_ulong;
+
+#[repr(C)]
+pub struct CONDITION_VARIABLE { pub ptr: LPVOID }
+#[repr(C)]
+pub struct SRWLOCK { pub ptr: LPVOID }
+#[repr(C)]
+pub struct CRITICAL_SECTION {
+    CriticalSectionDebug: LPVOID,
+    LockCount: LONG,
+    RecursionCount: LONG,
+    OwningThread: HANDLE,
+    LockSemaphore: HANDLE,
+    SpinCount: ULONG_PTR
+}
+
+pub const CONDITION_VARIABLE_INIT: CONDITION_VARIABLE = CONDITION_VARIABLE {
+    ptr: 0 as *mut _,
+};
+pub const SRWLOCK_INIT: SRWLOCK = SRWLOCK { ptr: 0 as *mut _ };
+
 #[link(name = "ws2_32")]
+#[link(name = "userenv")]
 extern "system" {
     pub fn WSAStartup(wVersionRequested: libc::WORD,
                       lpWSAData: LPWSADATA) -> libc::c_int;
@@ -295,115 +323,13 @@ extern "system" {
     pub fn CancelIo(hFile: libc::HANDLE) -> libc::BOOL;
     pub fn CancelIoEx(hFile: libc::HANDLE,
                       lpOverlapped: libc::LPOVERLAPPED) -> libc::BOOL;
-}
-
-pub mod compat {
-    use prelude::v1::*;
 
-    use ffi::CString;
-    use libc::types::os::arch::extra::{LPCWSTR, HMODULE, LPCSTR, LPVOID};
-    use sync::atomic::{AtomicUsize, Ordering};
+    pub fn InitializeCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
+    pub fn EnterCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
+    pub fn TryEnterCriticalSection(CriticalSection: *mut CRITICAL_SECTION) -> BOOLEAN;
+    pub fn LeaveCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
+    pub fn DeleteCriticalSection(CriticalSection: *mut CRITICAL_SECTION);
 
-    extern "system" {
-        fn GetModuleHandleW(lpModuleName: LPCWSTR) -> HMODULE;
-        fn GetProcAddress(hModule: HMODULE, lpProcName: LPCSTR) -> LPVOID;
-    }
-
-    fn store_func(ptr: &AtomicUsize, module: &str, symbol: &str,
-                  fallback: usize) -> usize {
-        let mut module: Vec<u16> = module.utf16_units().collect();
-        module.push(0);
-        let symbol = CString::new(symbol).unwrap();
-        let func = unsafe {
-            let handle = GetModuleHandleW(module.as_ptr());
-            GetProcAddress(handle, symbol.as_ptr()) as usize
-        };
-        let value = if func == 0 {fallback} else {func};
-        ptr.store(value, Ordering::SeqCst);
-        value
-    }
-
-    /// Macro for creating a compatibility fallback for a Windows function
-    ///
-    /// # Examples
-    /// ```
-    /// compat_fn!(adll32::SomeFunctionW(_arg: LPCWSTR) {
-    ///     // Fallback implementation
-    /// })
-    /// ```
-    ///
-    /// Note that arguments unused by the fallback implementation should not be
-    /// called `_` as they are used to be passed to the real function if
-    /// available.
-    macro_rules! compat_fn {
-        ($module:ident::$symbol:ident($($argname:ident: $argtype:ty),*)
-                                      -> $rettype:ty { $fallback:expr }) => (
-            #[inline(always)]
-            pub unsafe fn $symbol($($argname: $argtype),*) -> $rettype {
-                use sync::atomic::{AtomicUsize, Ordering};
-                use mem;
-
-                static PTR: AtomicUsize = AtomicUsize::new(0);
-
-                fn load() -> usize {
-                    ::sys::c::compat::store_func(&PTR,
-                                                 stringify!($module),
-                                                 stringify!($symbol),
-                                                 fallback as usize)
-                }
-
-                extern "system" fn fallback($($argname: $argtype),*)
-                                            -> $rettype { $fallback }
-
-                let addr = match PTR.load(Ordering::SeqCst) {
-                    0 => load(),
-                    n => n,
-                };
-                let f: extern "system" fn($($argtype),*) -> $rettype =
-                    mem::transmute(addr);
-                f($($argname),*)
-            }
-        )
-    }
-
-    /// Compatibility layer for functions in `kernel32.dll`
-    ///
-    /// Latest versions of Windows this is needed for:
-    ///
-    /// * `CreateSymbolicLinkW`: Windows XP, Windows Server 2003
-    /// * `GetFinalPathNameByHandleW`: Windows XP, Windows Server 2003
-    pub mod kernel32 {
-        use libc::c_uint;
-        use libc::types::os::arch::extra::{DWORD, LPCWSTR, BOOLEAN, HANDLE};
-        use libc::consts::os::extra::ERROR_CALL_NOT_IMPLEMENTED;
-        use sys::c::SetLastError;
-
-        compat_fn! {
-            kernel32::CreateSymbolicLinkW(_lpSymlinkFileName: LPCWSTR,
-                                          _lpTargetFileName: LPCWSTR,
-                                          _dwFlags: DWORD) -> BOOLEAN {
-                unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0 }
-            }
-        }
-
-        compat_fn! {
-            kernel32::GetFinalPathNameByHandleW(_hFile: HANDLE,
-                                                _lpszFilePath: LPCWSTR,
-                                                _cchFilePath: DWORD,
-                                                _dwFlags: DWORD) -> DWORD {
-                unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0 }
-            }
-        }
-
-        compat_fn! {
-            kernel32::SetThreadErrorMode(_dwNewMode: DWORD, _lpOldMode: *mut DWORD) -> c_uint {
-                unsafe { SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0 }
-            }
-        }
-    }
-}
-
-extern "system" {
     // FIXME - pInputControl should be PCONSOLE_READCONSOLE_CONTROL
     pub fn ReadConsoleW(hConsoleInput: libc::HANDLE,
                         lpBuffer: libc::LPVOID,
@@ -447,10 +373,6 @@ extern "system" {
                        lpCreationTime: *const libc::FILETIME,
                        lpLastAccessTime: *const libc::FILETIME,
                        lpLastWriteTime: *const libc::FILETIME) -> libc::BOOL;
-    pub fn SetFileInformationByHandle(hFile: libc::HANDLE,
-                    FileInformationClass: FILE_INFO_BY_HANDLE_CLASS,
-                    lpFileInformation: libc::LPVOID,
-                    dwBufferSize: libc::DWORD) -> libc::BOOL;
     pub fn GetTempPathW(nBufferLength: libc::DWORD,
                         lpBuffer: libc::LPCWSTR) -> libc::DWORD;
     pub fn OpenProcessToken(ProcessHandle: libc::HANDLE,
@@ -483,11 +405,70 @@ extern "system" {
     pub fn SwitchToThread() -> libc::BOOL;
     pub fn Sleep(dwMilliseconds: libc::DWORD);
     pub fn GetProcessId(handle: libc::HANDLE) -> libc::DWORD;
-}
-
-#[link(name = "userenv")]
-extern "system" {
     pub fn GetUserProfileDirectoryW(hToken: libc::HANDLE,
                                     lpProfileDir: libc::LPCWSTR,
                                     lpcchSize: *mut libc::DWORD) -> libc::BOOL;
 }
+
+// Functions that aren't available on Windows XP, but we still use them and just
+// provide some form of a fallback implementation.
+compat_fn! {
+    kernel32:
+
+    pub fn CreateSymbolicLinkW(_lpSymlinkFileName: LPCWSTR,
+                               _lpTargetFileName: LPCWSTR,
+                               _dwFlags: DWORD) -> BOOLEAN {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0
+    }
+    pub fn GetFinalPathNameByHandleW(_hFile: HANDLE,
+                                     _lpszFilePath: LPCWSTR,
+                                     _cchFilePath: DWORD,
+                                     _dwFlags: DWORD) -> DWORD {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0
+    }
+    pub fn SetThreadErrorMode(_dwNewMode: DWORD,
+                              _lpOldMode: *mut DWORD) -> c_uint {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0
+    }
+    pub fn SetThreadStackGuarantee(_size: *mut c_ulong) -> BOOL {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0
+    }
+    pub fn SetFileInformationByHandle(_hFile: HANDLE,
+                    _FileInformationClass: FILE_INFO_BY_HANDLE_CLASS,
+                    _lpFileInformation: LPVOID,
+                    _dwBufferSize: DWORD) -> BOOL {
+        SetLastError(ERROR_CALL_NOT_IMPLEMENTED as DWORD); 0
+    }
+    pub fn SleepConditionVariableSRW(ConditionVariable: PCONDITION_VARIABLE,
+                                     SRWLock: PSRWLOCK,
+                                     dwMilliseconds: DWORD,
+                                     Flags: ULONG) -> BOOL {
+        panic!("condition variables not available")
+    }
+    pub fn WakeConditionVariable(ConditionVariable: PCONDITION_VARIABLE)
+                                 -> () {
+        panic!("condition variables not available")
+    }
+    pub fn WakeAllConditionVariable(ConditionVariable: PCONDITION_VARIABLE)
+                                    -> () {
+        panic!("condition variables not available")
+    }
+    pub fn AcquireSRWLockExclusive(SRWLock: PSRWLOCK) -> () {
+        panic!("rwlocks not available")
+    }
+    pub fn AcquireSRWLockShared(SRWLock: PSRWLOCK) -> () {
+        panic!("rwlocks not available")
+    }
+    pub fn ReleaseSRWLockExclusive(SRWLock: PSRWLOCK) -> () {
+        panic!("rwlocks not available")
+    }
+    pub fn ReleaseSRWLockShared(SRWLock: PSRWLOCK) -> () {
+        panic!("rwlocks not available")
+    }
+    pub fn TryAcquireSRWLockExclusive(SRWLock: PSRWLOCK) -> BOOLEAN {
+        panic!("rwlocks not available")
+    }
+    pub fn TryAcquireSRWLockShared(SRWLock: PSRWLOCK) -> BOOLEAN {
+        panic!("rwlocks not available")
+    }
+}