DynamicLibrary.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
1//===-- DynamicLibrary.cpp - Runtime link/load libraries --------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This header file implements the operating system DynamicLibrary concept.
11//
12// FIXME: This file leaks ExplicitSymbols and OpenedHandles!
13//
14//===----------------------------------------------------------------------===//
15
16#include "llvm/Support/DynamicLibrary.h"
17#include "llvm-c/Support.h"
18#include "llvm/ADT/DenseSet.h"
19#include "llvm/ADT/StringMap.h"
20#include "llvm/Config/config.h"
21#include "llvm/Support/ManagedStatic.h"
22#include "llvm/Support/Mutex.h"
23#include <cstdio>
24#include <cstring>
25
26// Collection of symbol name/value pairs to be searched prior to any libraries.
27static llvm::ManagedStatic<llvm::StringMap<void *> > ExplicitSymbols;
28static llvm::ManagedStatic<llvm::sys::SmartMutex<true> > SymbolsMutex;
29
30void llvm::sys::DynamicLibrary::AddSymbol(StringRef symbolName,
31                                          void *symbolValue) {
32  SmartScopedLock<true> lock(*SymbolsMutex);
33  (*ExplicitSymbols)[symbolName] = symbolValue;
34}
35
36char llvm::sys::DynamicLibrary::Invalid = 0;
37
38#ifdef LLVM_ON_WIN32
39
40#include "Windows/DynamicLibrary.inc"
41
42#else
43
44#if HAVE_DLFCN_H
45#include <dlfcn.h>
46using namespace llvm;
47using namespace llvm::sys;
48
49//===----------------------------------------------------------------------===//
50//=== WARNING: Implementation here must contain only TRULY operating system
51//===          independent code.
52//===----------------------------------------------------------------------===//
53
54static DenseSet<void *> *OpenedHandles = nullptr;
55
56DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *filename,
57                                                   std::string *errMsg) {
58  SmartScopedLock<true> lock(*SymbolsMutex);
59
60  void *handle = dlopen(filename, RTLD_LAZY|RTLD_GLOBAL);
61  if (!handle) {
62    if (errMsg) *errMsg = dlerror();
63    return DynamicLibrary();
64  }
65
66#ifdef __CYGWIN__
67  // Cygwin searches symbols only in the main
68  // with the handle of dlopen(NULL, RTLD_GLOBAL).
69  if (!filename)
70    handle = RTLD_DEFAULT;
71#endif
72
73  if (!OpenedHandles)
74    OpenedHandles = new DenseSet<void *>();
75
76  // If we've already loaded this library, dlclose() the handle in order to
77  // keep the internal refcount at +1.
78  if (!OpenedHandles->insert(handle).second)
79    dlclose(handle);
80
81  return DynamicLibrary(handle);
82}
83
84void *DynamicLibrary::getAddressOfSymbol(const char *symbolName) {
85  if (!isValid())
86    return nullptr;
87  return dlsym(Data, symbolName);
88}
89
90#else
91
92using namespace llvm;
93using namespace llvm::sys;
94
95DynamicLibrary DynamicLibrary::getPermanentLibrary(const char *filename,
96                                                   std::string *errMsg) {
97  if (errMsg) *errMsg = "dlopen() not supported on this platform";
98  return DynamicLibrary();
99}
100
101void *DynamicLibrary::getAddressOfSymbol(const char *symbolName) {
102  return NULL;
103}
104
105#endif
106
107namespace llvm {
108void *SearchForAddressOfSpecialSymbol(const char* symbolName);
109}
110
111void* DynamicLibrary::SearchForAddressOfSymbol(const char *symbolName) {
112  SmartScopedLock<true> Lock(*SymbolsMutex);
113
114  // First check symbols added via AddSymbol().
115  if (ExplicitSymbols.isConstructed()) {
116    StringMap<void *>::iterator i = ExplicitSymbols->find(symbolName);
117
118    if (i != ExplicitSymbols->end())
119      return i->second;
120  }
121
122#if HAVE_DLFCN_H
123  // Now search the libraries.
124  if (OpenedHandles) {
125    for (DenseSet<void *>::iterator I = OpenedHandles->begin(),
126         E = OpenedHandles->end(); I != E; ++I) {
127      //lt_ptr ptr = lt_dlsym(*I, symbolName);
128      void *ptr = dlsym(*I, symbolName);
129      if (ptr) {
130        return ptr;
131      }
132    }
133  }
134#endif
135
136  if (void *Result = llvm::SearchForAddressOfSpecialSymbol(symbolName))
137    return Result;
138
139// This macro returns the address of a well-known, explicit symbol
140#define EXPLICIT_SYMBOL(SYM) \
141   if (!strcmp(symbolName, #SYM)) return &SYM
142
143// On linux we have a weird situation. The stderr/out/in symbols are both
144// macros and global variables because of standards requirements. So, we
145// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
146#if defined(__linux__) and !defined(__ANDROID__)
147  {
148    EXPLICIT_SYMBOL(stderr);
149    EXPLICIT_SYMBOL(stdout);
150    EXPLICIT_SYMBOL(stdin);
151  }
152#else
153  // For everything else, we want to check to make sure the symbol isn't defined
154  // as a macro before using EXPLICIT_SYMBOL.
155  {
156#ifndef stdin
157    EXPLICIT_SYMBOL(stdin);
158#endif
159#ifndef stdout
160    EXPLICIT_SYMBOL(stdout);
161#endif
162#ifndef stderr
163    EXPLICIT_SYMBOL(stderr);
164#endif
165  }
166#endif
167#undef EXPLICIT_SYMBOL
168
169  return nullptr;
170}
171
172#endif // LLVM_ON_WIN32
173
174//===----------------------------------------------------------------------===//
175// C API.
176//===----------------------------------------------------------------------===//
177
178LLVMBool LLVMLoadLibraryPermanently(const char* Filename) {
179  return llvm::sys::DynamicLibrary::LoadLibraryPermanently(Filename);
180}
181