| //===-- Intercept.cpp - System function interception routines -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // If a function call occurs to an external function, the JIT is designed to use |
| // the dynamic loader interface to find a function to call. This is useful for |
| // calling system calls and library functions that are not available in LLVM. |
| // Some system calls, however, need to be handled specially. For this reason, |
| // we intercept some of them here and use our own stubs to handle them. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "VM.h" |
| #include "Support/DynamicLinker.h" |
| #include <iostream> |
| |
| namespace llvm { |
| |
| // AtExitHandlers - List of functions to call when the program exits, |
| // registered with the atexit() library function. |
| static std::vector<void (*)()> AtExitHandlers; |
| |
| /// runAtExitHandlers - Run any functions registered by the program's |
| /// calls to atexit(3), which we intercept and store in |
| /// AtExitHandlers. |
| /// |
| void VM::runAtExitHandlers() { |
| while (!AtExitHandlers.empty()) { |
| void (*Fn)() = AtExitHandlers.back(); |
| AtExitHandlers.pop_back(); |
| Fn(); |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Function stubs that are invoked instead of certain library calls |
| //===----------------------------------------------------------------------===// |
| |
| // NoopFn - Used if we have nothing else to call... |
| static void NoopFn() {} |
| |
| // jit_exit - Used to intercept the "exit" library call. |
| static void jit_exit(int Status) { |
| VM::runAtExitHandlers(); // Run atexit handlers... |
| exit(Status); |
| } |
| |
| // jit_atexit - Used to intercept the "atexit" library call. |
| static int jit_atexit(void (*Fn)(void)) { |
| AtExitHandlers.push_back(Fn); // Take note of atexit handler... |
| return 0; // Always successful |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // |
| /// getPointerToNamedFunction - This method returns the address of the specified |
| /// function by using the dynamic loader interface. As such it is only useful |
| /// for resolving library symbols, not code generated symbols. |
| /// |
| void *VM::getPointerToNamedFunction(const std::string &Name) { |
| // Check to see if this is one of the functions we want to intercept... |
| if (Name == "exit") return (void*)&jit_exit; |
| if (Name == "atexit") return (void*)&jit_atexit; |
| |
| // If it's an external function, look it up in the process image... |
| void *Ptr = GetAddressOfSymbol(Name); |
| if (Ptr == 0) { |
| std::cerr << "WARNING: Cannot resolve fn '" << Name |
| << "' using a dummy noop function instead!\n"; |
| Ptr = (void*)NoopFn; |
| } |
| |
| return Ptr; |
| } |
| |
| } // End llvm namespace |