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llvm-project/llvm/lib/Support/Unix/Program.inc

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//===- llvm/Support/Unix/Program.cpp -----------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Unix specific portion of the Program class.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
//=== WARNING: Implementation here must contain only generic UNIX code that
//=== is guaranteed to work on *all* UNIX variants.
//===----------------------------------------------------------------------===//
#include "Unix.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/FileSystem.h"
#include <llvm/Config/config.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#if HAVE_SYS_RESOURCE_H
#include <sys/resource.h>
#endif
#if HAVE_SIGNAL_H
#include <signal.h>
#endif
#if HAVE_FCNTL_H
#include <fcntl.h>
#endif
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_POSIX_SPAWN
#include <spawn.h>
#if !defined(__APPLE__)
extern char **environ;
#else
#include <crt_externs.h> // _NSGetEnviron
#endif
#endif
namespace llvm {
using namespace sys;
// This function just uses the PATH environment variable to find the program.
std::string
sys::FindProgramByName(const std::string& progName) {
// Check some degenerate cases
if (progName.length() == 0) // no program
return "";
std::string temp = progName;
// Use the given path verbatim if it contains any slashes; this matches
// the behavior of sh(1) and friends.
if (progName.find('/') != std::string::npos)
return temp;
// At this point, the file name is valid and does not contain slashes. Search
// for it through the directories specified in the PATH environment variable.
// Get the path. If its empty, we can't do anything to find it.
const char *PathStr = getenv("PATH");
if (PathStr == 0)
return "";
// Now we have a colon separated list of directories to search; try them.
size_t PathLen = strlen(PathStr);
while (PathLen) {
// Find the first colon...
const char *Colon = std::find(PathStr, PathStr+PathLen, ':');
// Check to see if this first directory contains the executable...
SmallString<128> FilePath(PathStr,Colon);
sys::path::append(FilePath, progName);
if (sys::fs::can_execute(Twine(FilePath)))
return FilePath.str(); // Found the executable!
// Nope it wasn't in this directory, check the next path in the list!
PathLen -= Colon-PathStr;
PathStr = Colon;
// Advance past duplicate colons
while (*PathStr == ':') {
PathStr++;
PathLen--;
}
}
return "";
}
static bool RedirectIO(const StringRef *Path, int FD, std::string* ErrMsg) {
if (Path == 0) // Noop
return false;
std::string File;
if (Path->empty())
// Redirect empty paths to /dev/null
File = "/dev/null";
else
File = *Path;
// Open the file
int InFD = open(File.c_str(), FD == 0 ? O_RDONLY : O_WRONLY|O_CREAT, 0666);
if (InFD == -1) {
MakeErrMsg(ErrMsg, "Cannot open file '" + File + "' for "
+ (FD == 0 ? "input" : "output"));
return true;
}
// Install it as the requested FD
if (dup2(InFD, FD) == -1) {
MakeErrMsg(ErrMsg, "Cannot dup2");
close(InFD);
return true;
}
close(InFD); // Close the original FD
return false;
}
#ifdef HAVE_POSIX_SPAWN
static bool RedirectIO_PS(const StringRef *Path, int FD, std::string *ErrMsg,
posix_spawn_file_actions_t *FileActions) {
if (Path == 0) // Noop
return false;
std::string File;
if (Path->empty())
// Redirect empty paths to /dev/null
File = "/dev/null";
else
File = *Path;
if (int Err = posix_spawn_file_actions_addopen(
FileActions, FD, File.c_str(),
FD == 0 ? O_RDONLY : O_WRONLY | O_CREAT, 0666))
return MakeErrMsg(ErrMsg, "Cannot dup2", Err);
return false;
}
#endif
static void TimeOutHandler(int Sig) {
}
static void SetMemoryLimits (unsigned size)
{
#if HAVE_SYS_RESOURCE_H && HAVE_GETRLIMIT && HAVE_SETRLIMIT
struct rlimit r;
__typeof__ (r.rlim_cur) limit = (__typeof__ (r.rlim_cur)) (size) * 1048576;
// Heap size
getrlimit (RLIMIT_DATA, &r);
r.rlim_cur = limit;
setrlimit (RLIMIT_DATA, &r);
#ifdef RLIMIT_RSS
// Resident set size.
getrlimit (RLIMIT_RSS, &r);
r.rlim_cur = limit;
setrlimit (RLIMIT_RSS, &r);
#endif
#ifdef RLIMIT_AS // e.g. NetBSD doesn't have it.
// Don't set virtual memory limit if built with any Sanitizer. They need 80Tb
// of virtual memory for shadow memory mapping.
#if !LLVM_MEMORY_SANITIZER_BUILD && !LLVM_ADDRESS_SANITIZER_BUILD
// Virtual memory.
getrlimit (RLIMIT_AS, &r);
r.rlim_cur = limit;
setrlimit (RLIMIT_AS, &r);
#endif
#endif
#endif
}
}
static bool Execute(void **Data, StringRef Program, const char **args,
const char **envp, const StringRef **redirects,
unsigned memoryLimit, std::string *ErrMsg) {
// If this OS has posix_spawn and there is no memory limit being implied, use
// posix_spawn. It is more efficient than fork/exec.
#ifdef HAVE_POSIX_SPAWN
if (memoryLimit == 0) {
posix_spawn_file_actions_t FileActionsStore;
posix_spawn_file_actions_t *FileActions = 0;
if (redirects) {
FileActions = &FileActionsStore;
posix_spawn_file_actions_init(FileActions);
// Redirect stdin/stdout.
if (RedirectIO_PS(redirects[0], 0, ErrMsg, FileActions) ||
RedirectIO_PS(redirects[1], 1, ErrMsg, FileActions))
return false;
if (redirects[1] == 0 || redirects[2] == 0 ||
*redirects[1] != *redirects[2]) {
// Just redirect stderr
if (RedirectIO_PS(redirects[2], 2, ErrMsg, FileActions)) return false;
} else {
// If stdout and stderr should go to the same place, redirect stderr
// to the FD already open for stdout.
if (int Err = posix_spawn_file_actions_adddup2(FileActions, 1, 2))
return !MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout", Err);
}
}
if (!envp)
#if !defined(__APPLE__)
envp = const_cast<const char **>(environ);
#else
// environ is missing in dylibs.
envp = const_cast<const char **>(*_NSGetEnviron());
#endif
// Explicitly initialized to prevent what appears to be a valgrind false
// positive.
pid_t PID = 0;
int Err = posix_spawn(&PID, Program.str().c_str(), FileActions, /*attrp*/0,
const_cast<char **>(args), const_cast<char **>(envp));
if (FileActions)
posix_spawn_file_actions_destroy(FileActions);
if (Err)
return !MakeErrMsg(ErrMsg, "posix_spawn failed", Err);
if (Data)
*Data = reinterpret_cast<void*>(PID);
return true;
}
#endif
// Create a child process.
int child = fork();
switch (child) {
// An error occurred: Return to the caller.
case -1:
MakeErrMsg(ErrMsg, "Couldn't fork");
return false;
// Child process: Execute the program.
case 0: {
// Redirect file descriptors...
if (redirects) {
// Redirect stdin
if (RedirectIO(redirects[0], 0, ErrMsg)) { return false; }
// Redirect stdout
if (RedirectIO(redirects[1], 1, ErrMsg)) { return false; }
if (redirects[1] && redirects[2] &&
*(redirects[1]) == *(redirects[2])) {
// If stdout and stderr should go to the same place, redirect stderr
// to the FD already open for stdout.
if (-1 == dup2(1,2)) {
MakeErrMsg(ErrMsg, "Can't redirect stderr to stdout");
return false;
}
} else {
// Just redirect stderr
if (RedirectIO(redirects[2], 2, ErrMsg)) { return false; }
}
}
// Set memory limits
if (memoryLimit!=0) {
SetMemoryLimits(memoryLimit);
}
// Execute!
std::string PathStr = Program;
if (envp != 0)
execve(PathStr.c_str(),
const_cast<char **>(args),
const_cast<char **>(envp));
else
execv(PathStr.c_str(),
const_cast<char **>(args));
// If the execve() failed, we should exit. Follow Unix protocol and
// return 127 if the executable was not found, and 126 otherwise.
// Use _exit rather than exit so that atexit functions and static
// object destructors cloned from the parent process aren't
// redundantly run, and so that any data buffered in stdio buffers
// cloned from the parent aren't redundantly written out.
_exit(errno == ENOENT ? 127 : 126);
}
// Parent process: Break out of the switch to do our processing.
default:
break;
}
if (Data)
*Data = reinterpret_cast<void*>(child);
return true;
}
static int Wait(void *&Data, StringRef Program, unsigned secondsToWait,
std::string *ErrMsg) {
#ifdef HAVE_SYS_WAIT_H
struct sigaction Act, Old;
assert(Data && "invalid pid to wait on, process not started?");
// Install a timeout handler. The handler itself does nothing, but the simple
// fact of having a handler at all causes the wait below to return with EINTR,
// unlike if we used SIG_IGN.
if (secondsToWait) {
memset(&Act, 0, sizeof(Act));
Act.sa_handler = TimeOutHandler;
sigemptyset(&Act.sa_mask);
sigaction(SIGALRM, &Act, &Old);
alarm(secondsToWait);
}
// Parent process: Wait for the child process to terminate.
int status;
uint64_t pid = reinterpret_cast<uint64_t>(Data);
pid_t child = static_cast<pid_t>(pid);
while (waitpid(pid, &status, 0) != child)
if (secondsToWait && errno == EINTR) {
// Kill the child.
kill(child, SIGKILL);
// Turn off the alarm and restore the signal handler
alarm(0);
sigaction(SIGALRM, &Old, 0);
// Wait for child to die
if (wait(&status) != child)
MakeErrMsg(ErrMsg, "Child timed out but wouldn't die");
else
MakeErrMsg(ErrMsg, "Child timed out", 0);
return -2; // Timeout detected
} else if (errno != EINTR) {
MakeErrMsg(ErrMsg, "Error waiting for child process");
return -1;
}
// We exited normally without timeout, so turn off the timer.
if (secondsToWait) {
alarm(0);
sigaction(SIGALRM, &Old, 0);
}
// Return the proper exit status. Detect error conditions
// so we can return -1 for them and set ErrMsg informatively.
int result = 0;
if (WIFEXITED(status)) {
result = WEXITSTATUS(status);
#ifdef HAVE_POSIX_SPAWN
// The posix_spawn child process returns 127 on any kind of error.
// Following the POSIX convention for command-line tools (which posix_spawn
// itself apparently does not), check to see if the failure was due to some
// reason other than the file not existing, and return 126 in this case.
bool Exists;
if (result == 127 && !llvm::sys::fs::exists(Program, Exists) && Exists)
result = 126;
#endif
if (result == 127) {
if (ErrMsg)
*ErrMsg = llvm::sys::StrError(ENOENT);
return -1;
}
if (result == 126) {
if (ErrMsg)
*ErrMsg = "Program could not be executed";
return -1;
}
} else if (WIFSIGNALED(status)) {
if (ErrMsg) {
*ErrMsg = strsignal(WTERMSIG(status));
#ifdef WCOREDUMP
if (WCOREDUMP(status))
*ErrMsg += " (core dumped)";
#endif
}
// Return a special value to indicate that the process received an unhandled
// signal during execution as opposed to failing to execute.
return -2;
}
return result;
#else
if (ErrMsg)
*ErrMsg = "Program::Wait is not implemented on this platform yet!";
return -1;
#endif
}
namespace llvm {
error_code sys::ChangeStdinToBinary(){
// Do nothing, as Unix doesn't differentiate between text and binary.
return make_error_code(errc::success);
}
error_code sys::ChangeStdoutToBinary(){
// Do nothing, as Unix doesn't differentiate between text and binary.
return make_error_code(errc::success);
}
error_code sys::ChangeStderrToBinary(){
// Do nothing, as Unix doesn't differentiate between text and binary.
return make_error_code(errc::success);
}
bool llvm::sys::argumentsFitWithinSystemLimits(ArrayRef<const char*> Args) {
static long ArgMax = sysconf(_SC_ARG_MAX);
// System says no practical limit.
if (ArgMax == -1)
return true;
// Conservatively account for space required by environment variables.
ArgMax /= 2;
size_t ArgLength = 0;
for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
I != E; ++I) {
ArgLength += strlen(*I) + 1;
if (ArgLength > size_t(ArgMax)) {
return false;
}
}
return true;
}
}
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