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