1//===- Unix/DynamicLibrary.cpp - Unix DL Implementation ---------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file provides the UNIX specific implementation of DynamicLibrary.
10//
11//===----------------------------------------------------------------------===//
12
13#if defined(HAVE_DLOPEN)
14#include <dlfcn.h>
15
16DynamicLibrary::HandleSet::~HandleSet() {
17 // Close the libraries in reverse order.
18 for (void *Handle : llvm::reverse(C&: Handles))
19 ::dlclose(handle: Handle);
20 if (Process != &Invalid)
21 ::dlclose(handle: Process);
22
23 // llvm_shutdown called, Return to default
24 DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;
25}
26
27void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
28 void *Handle = ::dlopen(file: File, RTLD_LAZY | RTLD_GLOBAL);
29 if (!Handle) {
30 if (Err)
31 *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) { ::dlclose(handle: Handle); }
46
47void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
48 return ::dlsym(handle: Handle, name: Symbol);
49}
50
51#else // !HAVE_DLOPEN
52
53DynamicLibrary::HandleSet::~HandleSet() {}
54
55void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {
56 if (Err)
57 *Err = "dlopen() not supported on this platform";
58 return &Invalid;
59}
60
61void DynamicLibrary::HandleSet::DLClose(void *Handle) {}
62
63void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {
64 return nullptr;
65}
66
67#endif
68
69// Must declare the symbols in the global namespace.
70static void *DoSearch(const char *SymbolName) {
71#define EXPLICIT_SYMBOL(SYM) \
72 extern void *SYM; \
73 if (!strcmp(SymbolName, #SYM)) \
74 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)) \
107 return &SYM
108
109// Under glibc we have a weird situation. The stderr/out/in symbols are both
110// macros and global variables because of standards requirements. So, we
111// boldly use the EXPLICIT_SYMBOL macro without checking for a #define first.
112#if defined(__GLIBC__)
113 {
114 EXPLICIT_SYMBOL(stderr);
115 EXPLICIT_SYMBOL(stdout);
116 EXPLICIT_SYMBOL(stdin);
117 }
118#else
119 // For everything else, we want to check to make sure the symbol isn't defined
120 // as a macro before using EXPLICIT_SYMBOL.
121 {
122#ifndef stdin
123 EXPLICIT_SYMBOL(stdin);
124#endif
125#ifndef stdout
126 EXPLICIT_SYMBOL(stdout);
127#endif
128#ifndef stderr
129 EXPLICIT_SYMBOL(stderr);
130#endif
131 }
132#endif
133#undef EXPLICIT_SYMBOL
134
135 return nullptr;
136}
137