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Chris Lattner6701a862003-05-14 13:26:47 +00001//===-- Intercept.cpp - System function interception routines -------------===//
John Criswellb576c942003-10-20 19:43:21 +00002//
3// The LLVM Compiler Infrastructure
4//
5// This file was developed by the LLVM research group and is distributed under
6// the University of Illinois Open Source License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
Chris Lattner6701a862003-05-14 13:26:47 +00009//
10// If a function call occurs to an external function, the JIT is designed to use
Brian Gaeke322cdb22003-10-10 17:02:42 +000011// the dynamic loader interface to find a function to call. This is useful for
Chris Lattner6701a862003-05-14 13:26:47 +000012// calling system calls and library functions that are not available in LLVM.
13// Some system calls, however, need to be handled specially. For this reason,
14// we intercept some of them here and use our own stubs to handle them.
15//
16//===----------------------------------------------------------------------===//
17
18#include "VM.h"
Brian Gaeke322cdb22003-10-10 17:02:42 +000019#include "Support/DynamicLinker.h"
Chris Lattner1b722162003-05-14 13:27:36 +000020#include <iostream>
Chris Lattner6701a862003-05-14 13:26:47 +000021
Brian Gaeked0fde302003-11-11 22:41:34 +000022namespace llvm {
23
Brian Gaeke70975ee2003-09-05 18:42:01 +000024// AtExitHandlers - List of functions to call when the program exits,
25// registered with the atexit() library function.
26static std::vector<void (*)()> AtExitHandlers;
Chris Lattner22080f92003-05-14 13:53:40 +000027
Brian Gaeke70975ee2003-09-05 18:42:01 +000028/// runAtExitHandlers - Run any functions registered by the program's
29/// calls to atexit(3), which we intercept and store in
30/// AtExitHandlers.
31///
Chris Lattner22080f92003-05-14 13:53:40 +000032void VM::runAtExitHandlers() {
Brian Gaeke70975ee2003-09-05 18:42:01 +000033 while (!AtExitHandlers.empty()) {
34 void (*Fn)() = AtExitHandlers.back();
35 AtExitHandlers.pop_back();
Chris Lattner22080f92003-05-14 13:53:40 +000036 Fn();
37 }
38}
39
Chris Lattner6701a862003-05-14 13:26:47 +000040//===----------------------------------------------------------------------===//
Brian Gaeke70975ee2003-09-05 18:42:01 +000041// Function stubs that are invoked instead of certain library calls
Chris Lattner6701a862003-05-14 13:26:47 +000042//===----------------------------------------------------------------------===//
43
44// NoopFn - Used if we have nothing else to call...
45static void NoopFn() {}
46
Brian Gaeke70975ee2003-09-05 18:42:01 +000047// jit_exit - Used to intercept the "exit" library call.
Chris Lattner6701a862003-05-14 13:26:47 +000048static void jit_exit(int Status) {
Brian Gaeke70975ee2003-09-05 18:42:01 +000049 VM::runAtExitHandlers(); // Run atexit handlers...
Chris Lattner22080f92003-05-14 13:53:40 +000050 exit(Status);
Chris Lattner6701a862003-05-14 13:26:47 +000051}
52
Brian Gaeke70975ee2003-09-05 18:42:01 +000053// jit_atexit - Used to intercept the "atexit" library call.
Chris Lattner6701a862003-05-14 13:26:47 +000054static int jit_atexit(void (*Fn)(void)) {
Brian Gaeke70975ee2003-09-05 18:42:01 +000055 AtExitHandlers.push_back(Fn); // Take note of atexit handler...
Chris Lattner22080f92003-05-14 13:53:40 +000056 return 0; // Always successful
Chris Lattner6701a862003-05-14 13:26:47 +000057}
58
59//===----------------------------------------------------------------------===//
60//
61/// getPointerToNamedFunction - This method returns the address of the specified
Brian Gaeke322cdb22003-10-10 17:02:42 +000062/// function by using the dynamic loader interface. As such it is only useful
63/// for resolving library symbols, not code generated symbols.
Chris Lattner6701a862003-05-14 13:26:47 +000064///
65void *VM::getPointerToNamedFunction(const std::string &Name) {
66 // Check to see if this is one of the functions we want to intercept...
Chris Lattner1b722162003-05-14 13:27:36 +000067 if (Name == "exit") return (void*)&jit_exit;
Chris Lattner22080f92003-05-14 13:53:40 +000068 if (Name == "atexit") return (void*)&jit_atexit;
Chris Lattner6701a862003-05-14 13:26:47 +000069
70 // If it's an external function, look it up in the process image...
Brian Gaeke322cdb22003-10-10 17:02:42 +000071 void *Ptr = GetAddressOfSymbol(Name);
Chris Lattner6701a862003-05-14 13:26:47 +000072 if (Ptr == 0) {
73 std::cerr << "WARNING: Cannot resolve fn '" << Name
74 << "' using a dummy noop function instead!\n";
75 Ptr = (void*)NoopFn;
76 }
77
78 return Ptr;
79}
Brian Gaeked0fde302003-11-11 22:41:34 +000080
81} // End llvm namespace