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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-exception6//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(Handles))19 ::dlclose(Handle);20 if (Process != &Invalid)21 ::dlclose(Process);22 23 // llvm_shutdown called, Return to default24 DynamicLibrary::SearchOrder = DynamicLibrary::SO_Linker;25}26 27void *DynamicLibrary::HandleSet::DLOpen(const char *File, std::string *Err) {28 void *Handle = ::dlopen(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 main37 // with the handle of dlopen(NULL, RTLD_GLOBAL).38 if (!File)39 Handle = RTLD_DEFAULT;40#endif41 42 return Handle;43}44 45void DynamicLibrary::HandleSet::DLClose(void *Handle) { ::dlclose(Handle); }46 47void *DynamicLibrary::HandleSet::DLSym(void *Handle, const char *Symbol) {48 return ::dlsym(Handle, Symbol);49}50 51#else // !HAVE_DLOPEN52 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#endif68 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 *)&SYM75 76 // If this is darwin, it has some funky issues, try to solve them here. Some77 // important symbols are marked 'private external' which doesn't allow78 // 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 our86 // runtime support libraries available.87#ifndef __clang__88#ifdef __i386__89 EXPLICIT_SYMBOL(__eprintf);90#endif91#endif92 }93#endif94 95#ifdef __CYGWIN__96 {97 EXPLICIT_SYMBOL(_alloca);98 EXPLICIT_SYMBOL(__main);99 }100#endif101 102#undef EXPLICIT_SYMBOL103 104// This macro returns the address of a well-known, explicit symbol105#define EXPLICIT_SYMBOL(SYM) \106 if (!strcmp(SymbolName, #SYM)) \107 return &SYM108 109// Under glibc we have a weird situation. The stderr/out/in symbols are both110// macros and global variables because of standards requirements. So, we111// 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#else119 // For everything else, we want to check to make sure the symbol isn't defined120 // as a macro before using EXPLICIT_SYMBOL.121 {122#ifndef stdin123 EXPLICIT_SYMBOL(stdin);124#endif125#ifndef stdout126 EXPLICIT_SYMBOL(stdout);127#endif128#ifndef stderr129 EXPLICIT_SYMBOL(stderr);130#endif131 }132#endif133#undef EXPLICIT_SYMBOL134 135 return nullptr;136}137