DynamicLibrary.inc revision 327952 
1//===- Unix/DynamicLibrary.cpp - Unix DL Implementation ---------*- 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 file provides the UNIX specific implementation of DynamicLibrary.
11//
12//===----------------------------------------------------------------------===//
13
14#if defined(HAVE_DLFCN_H) && defined(HAVE_DLOPEN)
15#include <dlfcn.h>
16
17DynamicLibrary::HandleSet::~HandleSet() {
18  // Close the libraries in reverse order.
19  for (void *Handle : llvm::reverse(Handles))
20    ::dlclose(Handle);
21  if (Process)
22    ::dlclose(Process);
23
24  // llvm_shutdown called, Return to default
25  DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
26}
27
28void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
29  void *Handle = ::dlopen(File, RTLD_LAZY|RTLD_GLOBAL);
30  if (!Handle) {
31    if (Err) *Err = ::dlerror();
32    return &DynamicLibrary::Invalid;
33  }
34
35#ifdef __CYGWIN__
36  // Cygwin searches symbols only in the main
37  // with the handle of dlopen(NULL, RTLD_GLOBAL).
38  if (!File)
39    Handle = RTLD_DEFAULT;
40#endif
41
42  return Handle;
43}
44
45void DynamicLibrary::HandleSet::DLClose(void *Handle) {
46  ::dlclose(Handle);
47}
48
49void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
50  return ::dlsym(Handle, Symbol);
51}
52
53#else // !HAVE_DLOPEN
54
55DynamicLibrary::HandleSet::~HandleSet() {}
56
57void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
58  if (Err) *Err = "dlopen() not supported on this platform";
59  return &Invalid;
60}
61
62void DynamicLibrary::HandleSet::DLClose(void *Handle) {
63}
64
65void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
66  return nullptr;
67}
68
69#endif
70
71// Must declare the symbols in the global namespace.
72static void *DoSearch(const char* SymbolName) {
73#define EXPLICIT_SYMBOL(SYM) \
74   extern void *SYM; if (!strcmp(SymbolName, #SYM)) return (void*)&SYM
75
76  // If this is darwin, it has some funky issues, try to solve them here.  Some
77  // important symbols are marked 'private external' which doesn't allow
78  // SearchForAddressOfSymbol to find them.  As such, we special case them here,
79  // there is only a small handful of them.
80
81#ifdef __APPLE__
82  {
83    // __eprintf is sometimes used for assert() handling on x86.
84    //
85    // FIXME: Currently disabled when using Clang, as we don't always have our
86    // runtime support libraries available.
87#ifndef __clang__
88#ifdef __i386__
89    EXPLICIT_SYMBOL(__eprintf);
90#endif
91#endif
92  }
93#endif
94
95#ifdef __CYGWIN__
96  {
97    EXPLICIT_SYMBOL(_alloca);
98    EXPLICIT_SYMBOL(__main);
99  }
100#endif
101
102#undef EXPLICIT_SYMBOL
103
104// This macro returns the address of a well-known, explicit symbol
105#define EXPLICIT_SYMBOL(SYM) \
106   if (!strcmp(SymbolName, #SYM)) return &SYM
107
108// Under glibc we have a weird situation. The stderr/out/in symbols are both
109// macros and global variables because of standards requirements. So, we
110// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
111#if defined(__GLIBC__)
112  {
113    EXPLICIT_SYMBOL(stderr);
114    EXPLICIT_SYMBOL(stdout);
115    EXPLICIT_SYMBOL(stdin);
116  }
117#else
118  // For everything else, we want to check to make sure the symbol isn't defined
119  // as a macro before using EXPLICIT_SYMBOL.
120  {
121#ifndef stdin
122    EXPLICIT_SYMBOL(stdin);
123#endif
124#ifndef stdout
125    EXPLICIT_SYMBOL(stdout);
126#endif
127#ifndef stderr
128    EXPLICIT_SYMBOL(stderr);
129#endif
130  }
131#endif
132#undef EXPLICIT_SYMBOL
133
134  return nullptr;
135}
136