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/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
process.cpp
A named collection of threads.
*******************************************************************************/
#include <sortix/kernel/platform.h>
#include <sortix/kernel/kthread.h>
#include <sortix/kernel/worker.h>
#include <sortix/kernel/memorymanagement.h>
#include <sortix/signal.h>
#include <sortix/unistd.h>
#include <sortix/fork.h>
#include <sortix/mman.h>
#include <sortix/wait.h>
#include <libmaxsi/error.h>
#include <libmaxsi/memory.h>
#include <libmaxsi/string.h>
#include <libmaxsi/sortedlist.h>
#include <assert.h>
#include "thread.h"
#include "process.h"
#include "device.h"
#include "stream.h"
#include "filesystem.h"
#include "directory.h"
#include "scheduler.h"
#include "initrd.h"
#include "elf.h"
#include "syscall.h"
using namespace Maxsi;
namespace Sortix
{
bool ProcessSegment::Intersects(ProcessSegment* segments)
{
for ( ProcessSegment* tmp = segments; tmp != NULL; tmp = tmp->next )
{
if ( tmp->position < position + size &&
position < tmp->position + tmp->size )
{
return true;
}
}
if ( next ) { return next->Intersects(segments); }
return false;
}
ProcessSegment* ProcessSegment::Fork()
{
ProcessSegment* nextclone = NULL;
if ( next )
{
nextclone = next->Fork();
if ( nextclone == NULL ) { return NULL; }
}
ProcessSegment* clone = new ProcessSegment();
if ( clone == NULL )
{
while ( nextclone != NULL )
{
ProcessSegment* todelete = nextclone;
nextclone = nextclone->next;
delete todelete;
}
return NULL;
}
if ( nextclone )
nextclone->prev = clone;
clone->next = nextclone;
clone->position = position;
clone->size = size;
return clone;
}
Process::Process()
{
addrspace = 0;
segments = NULL;
parent = NULL;
prevsibling = NULL;
nextsibling = NULL;
firstchild = NULL;
zombiechild = NULL;
parentlock = KTHREAD_MUTEX_INITIALIZER;
childlock = KTHREAD_MUTEX_INITIALIZER;
zombiecond = KTHREAD_COND_INITIALIZER;
zombiewaiting = 0;
iszombie = false;
nozombify = false;
firstthread = NULL;
threadlock = KTHREAD_MUTEX_INITIALIZER;
workingdir = NULL;
mmapfrom = 0x80000000UL;
exitstatus = -1;
pid = AllocatePID();
Put(this);
}
Process::~Process()
{
assert(!zombiechild);
assert(!firstchild);
assert(!addrspace);
assert(!segments);
Remove(this);
delete[] workingdir;
}
void Process__OnLastThreadExit(void* user);
void Process::OnThreadDestruction(Thread* thread)
{
assert(thread->process == this);
kthread_mutex_lock(&threadlock);
if ( thread->prevsibling )
thread->prevsibling->nextsibling = thread->nextsibling;
if ( thread->nextsibling )
thread->nextsibling->prevsibling = thread->prevsibling;
if ( thread == firstthread )
firstthread = thread->nextsibling;
if ( firstthread )
firstthread->prevsibling = NULL;
thread->prevsibling = thread->nextsibling = NULL;
bool threadsleft = firstthread;
kthread_mutex_unlock(&threadlock);
// We are called from the threads destructor, let it finish before we
// we handle the situation by killing ourselves.
if ( !threadsleft )
ScheduleDeath();
}
void Process::ScheduleDeath()
{
// All our threads must have exited at this point.
assert(!firstthread);
Worker::Schedule(Process__OnLastThreadExit, this);
}
// Useful for killing a partially constructed process without waiting for
// it to die and garbage collect its zombie. It is not safe to access this
// process after this call as another thread may garbage collect it.
void Process::AbortConstruction()
{
nozombify = true;
ScheduleDeath();
}
void Process__OnLastThreadExit(void* user)
{
return ((Process*) user)->OnLastThreadExit();
}
void Process::OnLastThreadExit()
{
LastPrayer();
}
static void SwitchCurrentAddrspace(addr_t addrspace, void* user)
{
((Thread*) user)->SwitchAddressSpace(addrspace);
}
void Process::LastPrayer()
{
assert(this);
// This must never be called twice.
assert(!iszombie);
// This must be called from a thread using another address space as the
// address space of this process is about to be destroyed.
Thread* curthread = CurrentThread();
assert(curthread->process != this);
// This can't be called if the process is still alive.
assert(!firstthread);
// We need to temporarily reload the correct addrese space of the dying
// process such that we can unmap and free its memory.
addr_t prevaddrspace = curthread->SwitchAddressSpace(addrspace);
ResetAddressSpace();
descriptors.Reset();
// Destroy the address space and safely switch to the replacement
// address space before things get dangerous.
Memory::DestroyAddressSpace(prevaddrspace,
SwitchCurrentAddrspace,
curthread);
addrspace = 0;
// Init is nice and will gladly raise our orphaned children and zombies.
Process* init = Scheduler::GetInitProcess();
assert(init);
kthread_mutex_lock(&childlock);
while ( firstchild )
{
ScopedLock firstchildlock(&firstchild->parentlock);
ScopedLock initlock(&init->childlock);
Process* process = firstchild;
firstchild = process->nextsibling;
process->parent = init;
process->prevsibling = NULL;
process->nextsibling = init->firstchild;
if ( init->firstchild )
init->firstchild->prevsibling = process;
init->firstchild = process;
}
// Since we have no more children (they are with init now), we don't
// have to worry about new zombie processes showing up, so just collect
// those that are left. Then we satisfiy the invariant !zombiechild that
// applies on process termination.
bool hadzombies = zombiechild;
while ( zombiechild )
{
ScopedLock zombiechildlock(&zombiechild->parentlock);
ScopedLock initlock(&init->childlock);
Process* zombie = zombiechild;
zombiechild = zombie->nextsibling;
zombie->prevsibling = NULL;
zombie->nextsibling = init->zombiechild;
if ( init->zombiechild )
init->zombiechild->prevsibling = zombie;
init->zombiechild = zombie;
}
kthread_mutex_unlock(&childlock);
if ( hadzombies )
init->NotifyNewZombies();
iszombie = true;
bool zombify = !nozombify;
// This class instance will be destroyed by our parent process when it
// has received and acknowledged our death.
kthread_mutex_lock(&parentlock);
if ( parent )
parent->NotifyChildExit(this, zombify);
kthread_mutex_unlock(&parentlock);
// If nobody is waiting for us, then simply commit suicide.
if ( !zombify )
delete this;
}
void Process::ResetAddressSpace()
{
assert(Memory::GetAddressSpace() == addrspace);
ProcessSegment* tmp = segments;
while ( tmp != NULL )
{
Memory::UnmapRange(tmp->position, tmp->size);
ProcessSegment* todelete = tmp;
tmp = tmp->next;
delete todelete;
}
segments = NULL;
}
void Process::NotifyChildExit(Process* child, bool zombify)
{
kthread_mutex_lock(&childlock);
if ( child->prevsibling )
child->prevsibling->nextsibling = child->nextsibling;
if ( child->nextsibling )
child->nextsibling->prevsibling = child->prevsibling;
if ( firstchild == child )
firstchild = child->nextsibling;
if ( firstchild )
firstchild->prevsibling = NULL;
if ( zombify )
{
if ( zombiechild )
zombiechild->prevsibling = child;
child->prevsibling = NULL;
child->nextsibling = zombiechild;
zombiechild = child;
}
kthread_mutex_unlock(&childlock);
if ( zombify )
NotifyNewZombies();
}
void Process::NotifyNewZombies()
{
ScopedLock lock(&childlock);
// TODO: Send SIGCHLD here?
if ( zombiewaiting )
kthread_cond_broadcast(&zombiecond);
}
pid_t Process::Wait(pid_t thepid, int* status, int options)
{
// TODO: Process groups are not supported yet.
if ( thepid < -1 || thepid == 0 ) { Error::Set(ENOSYS); return -1; }
ScopedLock lock(&childlock);
// A process can only wait if it has children.
if ( !firstchild && !zombiechild ) { Error::Set(ECHILD); return -1; }
// Processes can only wait for their own children to exit.
if ( 0 < thepid )
{
// TODO: This is a slow but multithread safe way to verify that the
// target process has the correct parent.
bool found = false;
for ( Process* p = firstchild; !found && p; p = p->nextsibling )
if ( p->pid == thepid )
found = true;
for ( Process* p = zombiechild; !found && p; p = p->nextsibling )
if ( p->pid == thepid )
found = true;
if ( !found ) { Error::Set(ECHILD); return -1; }
}
Process* zombie = NULL;
while ( !zombie )
{
for ( zombie = zombiechild; zombie; zombie = zombie->nextsibling )
if ( thepid == -1 || thepid == zombie->pid )
break;
if ( zombie )
break;
if ( options & WNOHANG )
return 0;
zombiewaiting++;
unsigned long r = kthread_cond_wait_signal(&zombiecond, &childlock);
zombiewaiting--;
if ( !r ) { Error::Set(EINTR); return -1; }
}
if ( zombie->prevsibling )
zombie->prevsibling->nextsibling = zombie->nextsibling;
if ( zombie->nextsibling )
zombie->nextsibling->prevsibling = zombie->prevsibling;
if ( zombiechild == zombie )
zombiechild = zombie->nextsibling;
if ( zombiechild )
zombiechild->prevsibling = NULL;
thepid = zombie->pid;
int exitstatus = zombie->exitstatus;
if ( exitstatus < 0 )
exitstatus = W_EXITCODE(128 + SIGKILL, SIGKILL);
// TODO: Validate that status is a valid user-space int!
if ( status )
*status = exitstatus;
// And so, the process was fully deleted.
delete zombie;
return thepid;
}
pid_t SysWait(pid_t pid, int* status, int options)
{
return CurrentProcess()->Wait(pid, status, options);
}
void Process::Exit(int status)
{
ScopedLock lock(&threadlock);
// Status codes can only contain 8 bits according to ISO C and POSIX.
if ( exitstatus == -1 )
exitstatus = W_EXITCODE(status & 0xFF, 0);
// Broadcast SIGKILL to all our threads which will begin our long path
// of process termination. We simply can't stop the threads as they may
// be running in kernel mode doing dangerous stuff. This thread will be
// destroyed by SIGKILL once the system call returns.
for ( Thread* t = firstthread; t; t = t->nextsibling )
t->DeliverSignal(SIGKILL);
}
void SysExit(int status)
{
CurrentProcess()->Exit(status);
}
bool Process::DeliverSignal(int signum)
{
// TODO: How to handle signals that kill the process?
if ( firstthread )
return firstthread->DeliverSignal(signum);
Error::Set(EINIT);
return false;
}
void Process::AddChildProcess(Process* child)
{
ScopedLock mylock(&childlock);
ScopedLock itslock(&child->parentlock);
assert(!child->parent);
assert(!child->nextsibling);
assert(!child->prevsibling);
child->parent = this;
child->nextsibling = firstchild;
child->prevsibling = NULL;
if ( firstchild )
firstchild->prevsibling = child;
firstchild = child;
}
Process* Process::Fork()
{
assert(CurrentProcess() == this);
Process* clone = new Process;
if ( !clone ) { return NULL; }
ProcessSegment* clonesegments = NULL;
// Fork the segment list.
if ( segments )
{
clonesegments = segments->Fork();
if ( clonesegments == NULL ) { delete clone; return NULL; }
}
// Fork address-space here and copy memory.
clone->addrspace = Memory::Fork();
if ( !clone->addrspace )
{
// Delete the segment list, since they are currently bogus.
ProcessSegment* tmp = clonesegments;
while ( tmp != NULL )
{
ProcessSegment* todelete = tmp;
tmp = tmp->next;
delete todelete;
}
delete clone; return NULL;
}
// Now it's too late to clean up here, if anything goes wrong, we simply
// ask the process to commit suicide before it goes live.
clone->segments = clonesegments;
// Remember the relation to the child process.
AddChildProcess(clone);
bool failure = false;
if ( !descriptors.Fork(&clone->descriptors) )
failure = true;
clone->mmapfrom = mmapfrom;
clone->workingdir = NULL;
if ( workingdir && !(clone->workingdir = String::Clone(workingdir)) )
failure = true;
// If the proces creation failed, ask the process to commit suicide and
// not become a zombie, as we don't wait for it to exit. It will clean
// up all the above resources and delete itself.
if ( failure )
{
clone->AbortConstruction();
return NULL;
}
return clone;
}
void Process::ResetForExecute()
{
// TODO: Delete all threads and their stacks.
ResetAddressSpace();
}
int Process::Execute(const char* programname, const uint8_t* program,
size_t programsize, int argc, const char* const* argv,
int envc, const char* const* envp,
CPU::InterruptRegisters* regs)
{
assert(CurrentProcess() == this);
addr_t entry = ELF::Construct(CurrentProcess(), program, programsize);
if ( !entry ) { return -1; }
// TODO: This may be an ugly hack!
// TODO: Move this to x86/process.cpp.
addr_t stackpos = CurrentThread()->stackpos + CurrentThread()->stacksize;
// Alright, move argv onto the new stack! First figure out exactly how
// big argv actually is.
addr_t argvpos = stackpos - sizeof(char*) * (argc+1);
char** stackargv = (char**) argvpos;
size_t argvsize = 0;
for ( int i = 0; i < argc; i++ )
{
size_t len = String::Length(argv[i]) + 1;
argvsize += len;
char* dest = ((char*) argvpos) - argvsize;
stackargv[i] = dest;
Maxsi::Memory::Copy(dest, argv[i], len);
}
stackargv[argc] = NULL;
if ( argvsize % 16UL ) { argvsize += 16 - (argvsize % 16UL); }
// And then move envp onto the stack.
addr_t envppos = argvpos - argvsize - sizeof(char*) * (envc+1);
char** stackenvp = (char**) envppos;
size_t envpsize = 0;
for ( int i = 0; i < envc; i++ )
{
size_t len = String::Length(envp[i]) + 1;
envpsize += len;
char* dest = ((char*) envppos) - envpsize;
stackenvp[i] = dest;
Maxsi::Memory::Copy(dest, envp[i], len);
}
stackenvp[envc] = NULL;
if ( envpsize % 16UL ) { envpsize += 16 - (envpsize % 16UL); }
stackpos = envppos - envpsize;
descriptors.OnExecute();
ExecuteCPU(argc, stackargv, envc, stackenvp, stackpos, entry, regs);
return 0;
}
DevBuffer* OpenProgramImage(const char* progname, const char* wd, const char* path)
{
char* abs = Directory::MakeAbsolute("/", progname);
if ( !abs ) { Error::Set(ENOMEM); return NULL; }
// TODO: Use O_EXEC here!
Device* dev = FileSystem::Open(abs, O_RDONLY, 0);
delete[] abs;
if ( !dev ) { return NULL; }
if ( !dev->IsType(Device::BUFFER) ) { Error::Set(EACCES); dev->Unref(); return NULL; }
return (DevBuffer*) dev;
}
int SysExecVE(const char* _filename, char* const _argv[], char* const _envp[])
{
char* filename;
int argc;
int envc;
char** argv;
char** envp;
DevBuffer* dev;
uintmax_t needed;
size_t sofar;
size_t count;
uint8_t* buffer;
int result = -1;
Process* process = CurrentProcess();
CPU::InterruptRegisters regs;
Maxsi::Memory::Set(&regs, 0, sizeof(regs));
filename = String::Clone(_filename);
if ( !filename ) { goto cleanup_done; }
for ( argc = 0; _argv && _argv[argc]; argc++ );
for ( envc = 0; _envp && _envp[envc]; envc++ );
argv = new char*[argc+1];
if ( !argv ) { goto cleanup_filename; }
Maxsi::Memory::Set(argv, 0, sizeof(char*) * (argc+1));
for ( int i = 0; i < argc; i++ )
{
argv[i] = String::Clone(_argv[i]);
if ( !argv[i] ) { goto cleanup_argv; }
}
envp = new char*[envc+1];
if ( !envp ) { goto cleanup_argv; }
envc = envc;
Maxsi::Memory::Set(envp, 0, sizeof(char*) * (envc+1));
for ( int i = 0; i < envc; i++ )
{
envp[i] = String::Clone(_envp[i]);
if ( !envp[i] ) { goto cleanup_envp; }
}
dev = OpenProgramImage(filename, process->workingdir, "/bin");
if ( !dev ) { goto cleanup_envp; }
dev->Refer(); // TODO: Rules of GC may change soon.
needed = dev->Size();
if ( SIZE_MAX < needed ) { Error::Set(ENOMEM); goto cleanup_dev; }
if ( !dev->IsReadable() ) { Error::Set(EBADF); goto cleanup_dev; }
count = needed;
buffer = new uint8_t[count];
if ( !buffer ) { goto cleanup_dev; }
sofar = 0;
while ( sofar < count )
{
ssize_t bytesread = dev->Read(buffer + sofar, count - sofar);
if ( bytesread < 0 ) { goto cleanup_buffer; }
if ( bytesread == 0 ) { Error::Set(EEOF); return -1; }
sofar += bytesread;
}
result = process->Execute(filename, buffer, count, argc, argv, envc,
envp, &regs);
cleanup_buffer:
delete[] buffer;
cleanup_dev:
dev->Unref();
cleanup_envp:
for ( int i = 0; i < envc; i++) { delete[] envp[i]; }
delete[] envp;
cleanup_argv:
for ( int i = 0; i < argc; i++) { delete[] argv[i]; }
delete[] argv;
cleanup_filename:
delete[] filename;
cleanup_done:
if ( !result ) { CPU::LoadRegisters(&regs); }
return result;
}
pid_t SysTFork(int flags, tforkregs_t* regs)
{
if ( Signal::IsPending() ) { Error::Set(EINTR); return -1; }
// TODO: Properly support tfork(2).
if ( flags != SFFORK ) { Error::Set(ENOSYS); return -1; }
CPU::InterruptRegisters cpuregs;
InitializeThreadRegisters(&cpuregs, regs);
// TODO: Is it a hack to create a new kernel stack here?
Thread* curthread = CurrentThread();
uint8_t* newkernelstack = new uint8_t[curthread->kernelstacksize];
if ( !newkernelstack ) { return -1; }
Process* clone = CurrentProcess()->Fork();
if ( !clone ) { delete[] newkernelstack; return -1; }
// If the thread could not be created, make the process commit suicide
// in a manner such that we don't wait for its zombie.
Thread* thread = CreateKernelThread(clone, &cpuregs);
if ( !thread )
{
clone->AbortConstruction();
return -1;
}
thread->kernelstackpos = (addr_t) newkernelstack;
thread->kernelstacksize = curthread->kernelstacksize;
thread->kernelstackmalloced = true;
thread->stackpos = curthread->stackpos;
thread->stacksize = curthread->stacksize;
thread->sighandler = curthread->sighandler;
StartKernelThread(thread);
return clone->pid;
}
pid_t SysGetPID()
{
return CurrentProcess()->pid;
}
pid_t Process::GetParentProcessId()
{
ScopedLock lock(&parentlock);
if( !parent )
return 0;
return parent->pid;
}
pid_t SysGetParentPID()
{
return CurrentProcess()->GetParentProcessId();
}
pid_t nextpidtoallocate;
kthread_mutex_t pidalloclock;
pid_t Process::AllocatePID()
{
ScopedLock lock(&pidalloclock);
return nextpidtoallocate++;
}
// TODO: This is not thread safe.
pid_t Process::HackGetForegroundProcess()
{
for ( pid_t i = nextpidtoallocate; 1 <= i; i-- )
{
Process* process = Get(i);
if ( !process )
continue;
if ( process->pid <= 1 )
continue;
if ( process->iszombie )
continue;
return i;
}
return 0;
}
int ProcessCompare(Process* a, Process* b)
{
if ( a->pid < b->pid ) { return -1; }
if ( a->pid > b->pid ) { return 1; }
return 0;
}
int ProcessPIDCompare(Process* a, pid_t pid)
{
if ( a->pid < pid ) { return -1; }
if ( a->pid > pid ) { return 1; }
return 0;
}
SortedList<Process*>* pidlist;
Process* Process::Get(pid_t pid)
{
ScopedLock lock(&pidalloclock);
size_t index = pidlist->Search(ProcessPIDCompare, pid);
if ( index == SIZE_MAX ) { return NULL; }
return pidlist->Get(index);
}
bool Process::Put(Process* process)
{
ScopedLock lock(&pidalloclock);
return pidlist->Add(process);
}
void Process::Remove(Process* process)
{
ScopedLock lock(&pidalloclock);
size_t index = pidlist->Search(process);
assert(index != SIZE_MAX);
pidlist->Remove(index);
}
void* SysSbrk(intptr_t increment)
{
Process* process = CurrentProcess();
ProcessSegment* dataseg = NULL;
for ( ProcessSegment* iter = process->segments; iter; iter = iter->next )
{
if ( !iter->type == SEG_DATA ) { continue; }
if ( dataseg && iter->position < dataseg->position ) { continue; }
dataseg = iter;
}
if ( !dataseg ) { Error::Set(ENOMEM); return (void*) -1UL; }
addr_t currentend = dataseg->position + dataseg->size;
addr_t newend = currentend + increment;
if ( newend < dataseg->position ) { Error::Set(EINVAL); return (void*) -1UL; }
if ( newend < currentend )
{
addr_t unmapfrom = Page::AlignUp(newend);
if ( unmapfrom < currentend )
{
size_t unmapbytes = Page::AlignUp(currentend - unmapfrom);
Memory::UnmapRange(unmapfrom, unmapbytes);
}
}
else if ( currentend < newend )
{
// TODO: HACK: Make a safer way of expanding the data segment
// without segments possibly colliding!
addr_t mapfrom = Page::AlignUp(currentend);
if ( mapfrom < newend )
{
size_t mapbytes = Page::AlignUp(newend - mapfrom);
int prot = PROT_FORK | PROT_READ | PROT_WRITE | PROT_KREAD | PROT_KWRITE;
if ( !Memory::MapRange(mapfrom, mapbytes, prot) )
{
return (void*) -1UL;
}
}
}
dataseg->size += increment;
return (void*) newend;
}
size_t SysGetPageSize()
{
return Page::Size();
}
void Process::Init()
{
Syscall::Register(SYSCALL_EXEC, (void*) SysExecVE);
Syscall::Register(SYSCALL_TFORK, (void*) SysTFork);
Syscall::Register(SYSCALL_GETPID, (void*) SysGetPID);
Syscall::Register(SYSCALL_GETPPID, (void*) SysGetParentPID);
Syscall::Register(SYSCALL_EXIT, (void*) SysExit);
Syscall::Register(SYSCALL_WAIT, (void*) SysWait);
Syscall::Register(SYSCALL_SBRK, (void*) SysSbrk);
Syscall::Register(SYSCALL_GET_PAGE_SIZE, (void*) SysGetPageSize);
pidalloclock = KTHREAD_MUTEX_INITIALIZER;
nextpidtoallocate = 0;
pidlist = new SortedList<Process*>(ProcessCompare);
if ( !pidlist ) { Panic("could not allocate pidlist\n"); }
}
addr_t Process::AllocVirtualAddr(size_t size)
{
return (mmapfrom -= size);
}
}
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