blocxx
dlSharedLibraryLoader.cpp
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2* Copyright (C) 2005, Vintela, Inc. All rights reserved.
3* Copyright (C) 2006, Novell, Inc. All rights reserved.
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32
33
38#include "blocxx/BLOCXX_config.h"
39#if defined(BLOCXX_USE_DL)
42#include "blocxx/Format.hpp"
44#include <dlfcn.h>
45
46namespace BLOCXX_NAMESPACE
47{
48
49namespace
50{
51 GlobalString COMPONENT_NAME = BLOCXX_GLOBAL_STRING_INIT("blocxx.dlSharedLibraryLoader");
52}
55dlSharedLibraryLoader::loadSharedLibrary(const String& filename) const
56{
57 // There is a reason to use RTLD_NOW. If some symbols can't be resolved because
58 // the shared library is built incorrectly or missing some symbols or something,
59 // then using RTLD_NOW will cause dlopen() to fail, and then the error can be detected
60 // and handled. If RTLD_LAZY is specified, dlopen() won't fail, but when code is
61 // executed that tries to use an unresolvable symbol, that will cause a segfault.
62 // RTLD_GLOBAL is necessary for proper exception and rtti support with gcc.
63 // See http://gcc.gnu.org/faq.html#dso, so even though it may cause symbol conflicts,
64 // we have to live with it.
65 void* libhandle = dlopen(filename.c_str(), RTLD_NOW | RTLD_GLOBAL);
66
67 String first_error = dlerror();
68 String second_error;
69
70#if defined(BLOCXX_USE_FAKE_LIBS)
71 // This section, if it determines that a library is fake, will attempt
72 // to load NULL (which, on most dlopen platforms should return a handle
73 // to the main executable). This handle can be used just like any
74 // other, assuming that the main executable was linked with the proper
75 // export flags (--export-dynamic on linux, -bexpall on AIX, etc.).
76 if ( !libhandle )
77 {
78 if ( dlSharedLibrary::isFakeLibrary(filename) )
79 {
80 libhandle = dlopen(NULL, RTLD_NOW | RTLD_GLOBAL);
81
82 if ( !libhandle )
83 {
84 second_error = dlerror();
85 }
86 }
87 }
88#endif /* defined(BLOCXX_USE_FAKE_LIBS) */
89 if (libhandle)
90 {
91 return SharedLibraryRef( new dlSharedLibrary(libhandle,
92 filename));
93 }
94 else
95 {
96 Logger logger(COMPONENT_NAME);
97 BLOCXX_LOG_ERROR(logger, Format("dlSharedLibraryLoader::loadSharedLibrary "
98 "dlopen returned NULL. Error is: %1", first_error));
99 if ( !second_error.empty() )
100 {
101 BLOCXX_LOG_ERROR(logger, Format("dlSharedLibraryLoader::loadSharedLibrary (fakelib) "
102 "dlopen returned NULL. Error is: %1", second_error));
103 }
104 return SharedLibraryRef( 0 );
105 }
106}
107
111{
112 return SharedLibraryLoaderRef(new dlSharedLibraryLoader);
113}
115dlSharedLibraryLoader::~dlSharedLibraryLoader()
116{
117}
118
119} // end namespace BLOCXX_NAMESPACE
120
121#endif // BLOCXX_USE_DL
#define BLOCXX_GLOBAL_STRING_INIT(str)
#define BLOCXX_LOG_ERROR(logger, message)
Log message to logger with the Error level.
Definition Logger.hpp:433
static SharedLibraryLoaderRef createSharedLibraryLoader()
Taken from RFC 1321.
LazyGlobal< String, char const *const > GlobalString
class BLOCXX_COMMON_API Logger
Definition CommonFwd.hpp:63
IntrusiveReference< SharedLibrary > SharedLibraryRef
IntrusiveReference< SharedLibraryLoader > SharedLibraryLoaderRef