1 //===-- llvm/System/DynamicLibrary.h - Portable Dynamic Library -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Reid Spencer and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the sys::DynamicLibrary class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_SYSTEM_DYNAMIC_LIBRARY_H
15 #define LLVM_SYSTEM_DYNAMIC_LIBRARY_H
17 #include "llvm/System/Path.h"
18 #include "llvm/System/IncludeFile.h"
24 /// This class provides a portable interface to dynamic libraries which also
25 /// might be known as shared libraries, shared objects, dynamic shared
26 /// objects, or dynamic link libraries. Regardless of the terminology or the
27 /// operating system interface, this class provides a portable interface that
28 /// allows dynamic libraries to be loaded and and searched for externally
29 /// defined symbols. This is typically used to provide "plug-in" support.
30 /// It also allows for symbols to be defined which don't live in any library,
31 /// but rather the main program itself, useful on Windows where the main
32 /// executable cannot be searched.
34 /// @brief Portable dynamic library abstraction.
35 class DynamicLibrary {
36 /// @name Constructors
39 /// Construct a DynamicLibrary that represents the currently executing
40 /// program. The program must have been linked with -export-dynamic or
41 /// -dlopen self for this to work. Any symbols retrieved with the
42 /// GetAddressOfSymbol function will refer to the program not to any
44 /// @throws std::string indicating why the program couldn't be opened.
45 /// @brief Open program as dynamic library.
48 /// After destruction, the symbols of the library will no longer be
49 /// available to the program. It is important to make sure the lifespan
50 /// of a DynamicLibrary exceeds the lifetime of the pointers returned
51 /// by the GetAddressOfSymbol otherwise the program may walk off into
52 /// uncharted territory.
53 /// @see GetAddressOfSymbol.
54 /// @brief Closes the DynamicLibrary
61 /// This function allows a library to be loaded without instantiating a
62 /// DynamicLibrary object. Consequently, it is marked as being permanent
63 /// and will only be unloaded when the program terminates. This returns
64 /// false on success or returns true and fills in *ErrMsg on failure.
65 /// @brief Open a dynamic library permanently.
66 static bool LoadLibraryPermanently(const char* filename,
67 std::string *ErrMsg = 0);
69 /// This function will search through all previously loaded dynamic
70 /// libraries for the symbol \p symbolName. If it is found, the addressof
71 /// that symbol is returned. If not, null is returned. Note that this will
72 /// search permanently loaded libraries (LoadLibraryPermanently) as well
73 /// as ephemerally loaded libraries (constructors).
74 /// @throws std::string on error.
75 /// @brief Search through libraries for address of a symbol
76 static void* SearchForAddressOfSymbol(const char* symbolName);
78 /// @brief Convenience function for C++ophiles.
79 static void* SearchForAddressOfSymbol(const std::string& symbolName) {
80 return SearchForAddressOfSymbol(symbolName.c_str());
83 /// This functions permanently adds the symbol \p symbolName with the
84 /// value \p symbolValue. These symbols are searched before any
86 /// @brief Add searchable symbol/value pair.
87 static void AddSymbol(const char* symbolName, void *symbolValue);
89 /// @brief Convenience function for C++ophiles.
90 static void AddSymbol(const std::string& symbolName, void *symbolValue) {
91 AddSymbol(symbolName.c_str(), symbolValue);
98 /// Looks up a \p symbolName in the DynamicLibrary and returns its address
99 /// if it exists. If the symbol does not exist, returns (void*)0.
100 /// @returns the address of the symbol or 0.
101 /// @brief Get the address of a symbol in the DynamicLibrary.
102 void* GetAddressOfSymbol(const char* symbolName);
104 /// @brief Convenience function for C++ophiles.
105 void* GetAddressOfSymbol(const std::string& symbolName) {
106 return GetAddressOfSymbol(symbolName.c_str());
110 /// @name Implementation
113 void* handle; // Opaque handle for information about the library
115 DynamicLibrary(const DynamicLibrary&); ///< Do not implement
116 DynamicLibrary& operator=(const DynamicLibrary&); ///< Do not implement
120 } // End sys namespace
121 } // End llvm namespace
123 FORCE_DEFINING_FILE_TO_BE_LINKED(SystemDynamicLibrary)
125 #endif // LLVM_SYSTEM_DYNAMIC_LIBRARY_H