1//===- Win32/DynamicLibrary.cpp - Win32 DL Implementation -------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides the Win32 specific implementation of DynamicLibrary.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Support/ConvertUTF.h"
14#include "llvm/Support/Windows/WindowsSupport.h"
15#include "llvm/Support/raw_ostream.h"
16
17#include <psapi.h>
18
19//===----------------------------------------------------------------------===//
20//=== WARNING: Implementation here must contain only Win32 specific code
21//===          and must not be UNIX code.
22//===----------------------------------------------------------------------===//
23
24DynamicLibrary::HandleSet::~HandleSet() {
25  for (void *Handle : llvm::reverse(Handles))
26    FreeLibrary(HMODULE(Handle));
27
28  // 'Process' should not be released on Windows.
29  assert((!Process || Process == this) && "Bad Handle");
30  // llvm_shutdown called, Return to default
31  DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
32}
33
34void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
35  // Create the instance and return it to be the *Process* handle
36  // simillar to dlopen(NULL, RTLD_LAZY|RTLD_GLOBAL)
37  if (!File)
38    return &getGlobals().OpenedHandles;
39
40  SmallVector<wchar_t, MAX_PATH> FileUnicode;
41  if (std::error_code ec = windows::UTF8ToUTF16(File, FileUnicode)) {
42    SetLastError(ec.value());
43    MakeErrMsg(Err, std::string(File) + ": Can't convert to UTF-16");
44    return &DynamicLibrary::Invalid;
45  }
46
47  HMODULE Handle = LoadLibraryW(FileUnicode.data());
48  if (Handle == NULL) {
49    MakeErrMsg(Err, std::string(File) + ": Can't open");
50    return &DynamicLibrary::Invalid;
51  }
52
53  return reinterpret_cast<void *>(Handle);
54}
55
56static DynamicLibrary::HandleSet *IsOpenedHandlesInstance(void *Handle) {
57  DynamicLibrary::HandleSet &Inst = getGlobals().OpenedHandles;
58  return Handle == &Inst ? &Inst : nullptr;
59}
60
61void DynamicLibrary::HandleSet::DLClose(void *Handle) {
62  if (HandleSet *HS = IsOpenedHandlesInstance(Handle))
63    HS->Process = nullptr; // Just drop the *Process* handle.
64  else
65    FreeLibrary((HMODULE)Handle);
66}
67
68static bool GetProcessModules(HANDLE H, DWORD &Bytes, HMODULE *Data = nullptr) {
69  // EnumProcessModules will fail on Windows 64 while some versions of
70  // MingW-32 don't have EnumProcessModulesEx.
71  if (
72#ifdef _WIN64
73      !EnumProcessModulesEx(H, Data, Bytes, &Bytes, LIST_MODULES_64BIT)
74#else
75      !EnumProcessModules(H, Data, Bytes, &Bytes)
76#endif
77  ) {
78    std::string Err;
79    if (MakeErrMsg(&Err, "EnumProcessModules failure"))
80      llvm::errs() << Err << "\n";
81    return false;
82  }
83  return true;
84}
85
86void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
87  HandleSet *HS = IsOpenedHandlesInstance(Handle);
88  if (!HS)
89    return (void *)uintptr_t(GetProcAddress((HMODULE)Handle, Symbol));
90
91  // Could have done a dlclose on the *Process* handle
92  if (!HS->Process)
93    return nullptr;
94
95  // Trials indicate EnumProcessModulesEx is consistantly faster than using
96  // EnumerateLoadedModules64 or CreateToolhelp32Snapshot.
97  //
98  // | Handles | DbgHelp.dll | CreateSnapshot | EnumProcessModulesEx
99  // |=========|=============|========================================
100  // | 37      | 0.0000585 * | 0.0003031      | 0.0000152
101  // | 1020    | 0.0026310 * | 0.0121598      | 0.0002683
102  // | 2084    | 0.0149418 * | 0.0369936      | 0.0005610
103  //
104  // * Not including the load time of Dbghelp.dll (~.005 sec)
105  //
106  // There's still a case to somehow cache the result of EnumProcessModulesEx
107  // across invocations, but the complication of doing that properly...
108  // Possibly using LdrRegisterDllNotification to invalidate the cache?
109
110  DWORD Bytes = 0;
111  HMODULE Self = HMODULE(GetCurrentProcess());
112  if (!GetProcessModules(Self, Bytes))
113    return nullptr;
114
115  // Get the most recent list in case any modules added/removed between calls
116  // to EnumProcessModulesEx that gets the amount of, then copies the HMODULES.
117  // MSDN is pretty clear that if the module list changes during the call to
118  // EnumProcessModulesEx the results should not be used.
119  std::vector<HMODULE> Handles;
120  do {
121    assert(Bytes && ((Bytes % sizeof(HMODULE)) == 0) &&
122           "Should have at least one module and be aligned");
123    Handles.resize(Bytes / sizeof(HMODULE));
124    if (!GetProcessModules(Self, Bytes, Handles.data()))
125      return nullptr;
126  } while (Bytes != (Handles.size() * sizeof(HMODULE)));
127
128  // Try EXE first, mirroring what dlsym(dlopen(NULL)) does.
129  if (FARPROC Ptr = GetProcAddress(HMODULE(Handles.front()), Symbol))
130    return (void *)uintptr_t(Ptr);
131
132  if (Handles.size() > 1) {
133    // This is different behaviour than what Posix dlsym(dlopen(NULL)) does.
134    // Doing that here is causing real problems for the JIT where msvc.dll
135    // and ucrt.dll can define the same symbols. The runtime linker will choose
136    // symbols from ucrt.dll first, but iterating NOT in reverse here would
137    // mean that the msvc.dll versions would be returned.
138
139    for (auto I = Handles.rbegin(), E = Handles.rend() - 1; I != E; ++I) {
140      if (FARPROC Ptr = GetProcAddress(HMODULE(*I), Symbol))
141        return (void *)uintptr_t(Ptr);
142    }
143  }
144  return nullptr;
145}
146
147// Stack probing routines are in the support library (e.g. libgcc), but we don't
148// have dynamic linking on windows. Provide a hook.
149#define EXPLICIT_SYMBOL(SYM)                                                   \
150  extern "C" {                                                                 \
151  extern void *SYM;                                                            \
152  }
153#define EXPLICIT_SYMBOL2(SYMFROM, SYMTO) EXPLICIT_SYMBOL(SYMTO)
154
155#ifdef _M_IX86
156// Win32 on x86 implements certain single-precision math functions as macros.
157// These functions are not exported by the DLL, but will still be needed
158// for symbol-resolution by the JIT loader. Therefore, this Support libray
159// provides helper functions with the same implementation.
160
161#define INLINE_DEF_SYMBOL1(TYP, SYM)                                           \
162  extern "C" TYP inline_##SYM(TYP _X) { return SYM(_X); }
163#define INLINE_DEF_SYMBOL2(TYP, SYM)                                           \
164  extern "C" TYP inline_##SYM(TYP _X, TYP _Y) { return SYM(_X, _Y); }
165#endif
166
167#include "explicit_symbols.inc"
168
169#undef EXPLICIT_SYMBOL
170#undef EXPLICIT_SYMBOL2
171#undef INLINE_DEF_SYMBOL1
172#undef INLINE_DEF_SYMBOL2
173
174static void *DoSearch(const char *SymbolName) {
175
176#define EXPLICIT_SYMBOL(SYM)                                                   \
177  if (!strcmp(SymbolName, #SYM))                                               \
178    return (void *)&SYM;
179#define EXPLICIT_SYMBOL2(SYMFROM, SYMTO)                                       \
180  if (!strcmp(SymbolName, #SYMFROM))                                           \
181    return (void *)&SYMTO;
182
183#ifdef _M_IX86
184#define INLINE_DEF_SYMBOL1(TYP, SYM)                                           \
185  if (!strcmp(SymbolName, #SYM))                                               \
186    return (void *)&inline_##SYM;
187#define INLINE_DEF_SYMBOL2(TYP, SYM) INLINE_DEF_SYMBOL1(TYP, SYM)
188#endif
189
190  {
191#include "explicit_symbols.inc"
192  }
193
194#undef EXPLICIT_SYMBOL
195#undef EXPLICIT_SYMBOL2
196#undef INLINE_DEF_SYMBOL1
197#undef INLINE_DEF_SYMBOL2
198
199  return nullptr;
200}
201