/* pinfo.cc: process table support

   Copyright 1996, 1997, 1998, 2000 Cygnus Solutions.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <stdlib.h>
#include <time.h>
#include <errno.h>
#include <limits.h>
#include "fhandler.h"
#include "dtable.h"
#include "cygerrno.h"
#include "sync.h"
#include "sigproc.h"
#include "pinfo.h"
#include "cygwin_version.h"
#include "perprocess.h"
#include "environ.h"
#include "security.h"
#include <assert.h>
#include <ntdef.h>
#include "ntdll.h"

static char NO_COPY pinfo_dummy[sizeof(pinfo)] = {0};

pinfo NO_COPY myself ((_pinfo *)&pinfo_dummy);	// Avoid myself != NULL checks

HANDLE hexec_proc = NULL;

void __stdcall
pinfo_fixup_after_fork ()
{
  if (hexec_proc)
    CloseHandle (hexec_proc);

  if (!DuplicateHandle (hMainProc, hMainProc, hMainProc, &hexec_proc, 0,
			TRUE, DUPLICATE_SAME_ACCESS))
    {
      system_printf ("couldn't save current process handle %p, %E", hMainProc);
      hexec_proc = NULL;
    }
}

/* Initialize the process table.
   This is done once when the dll is first loaded.  */

void __stdcall
set_myself (pid_t pid, HANDLE h)
{
  DWORD winpid = GetCurrentProcessId ();
  if (pid == 1)
    pid = cygwin_pid (winpid);
  myself.init (pid, 1, h);
  myself->dwProcessId = winpid;
  myself->process_state |= PID_IN_USE;
  myself->start_time = time (NULL); /* Register our starting time. */

  char buf[30];
  __small_sprintf (buf, "cYg%8x %x", _STRACE_INTERFACE_ACTIVATE_ADDR,
		   &strace.active);
  OutputDebugString (buf);

  (void) GetModuleFileName (NULL, myself->progname,
			    sizeof(myself->progname));
  if (strace.active)
    {
      extern char osname[];
      strace.prntf (1, NULL, "**********************************************");
      strace.prntf (1, NULL, "Program name: %s (%d)", myself->progname, myself->pid);
      strace.prntf (1, NULL, "App version:  %d.%d, api: %d.%d",
		       user_data->dll_major, user_data->dll_minor,
		       user_data->api_major, user_data->api_minor);
      strace.prntf (1, NULL, "DLL version:  %d.%d, api: %d.%d",
		       cygwin_version.dll_major, cygwin_version.dll_minor,
		       cygwin_version.api_major, cygwin_version.api_minor);
      strace.prntf (1, NULL, "DLL build:    %s", cygwin_version.dll_build_date);
      strace.prntf (1, NULL, "OS version:   Windows %s", osname);
      strace.prntf (1, NULL, "**********************************************");
    }

  return;
}

/* Initialize the process table entry for the current task.
   This is not called for fork'd tasks, only exec'd ones.  */
void __stdcall
pinfo_init (char **envp, int envc)
{
  if (envp)
    {
      environ_init (envp, envc);
      /* spawn has already set up a pid structure for us so we'll use that */
      myself->process_state |= PID_CYGPARENT;
    }
  else
    {
      /* Invent our own pid.  */

      set_myself (1);
      myself->ppid = 1;
      myself->pgid = myself->sid = myself->pid;
      myself->ctty = -1;
      myself->uid = USHRT_MAX;

      environ_init (NULL, 0);	/* call after myself has been set up */
    }

  debug_printf ("pid %d, pgid %d", myself->pid, myself->pgid);
}

void
_pinfo::exit (UINT n, bool norecord)
{
  if (!norecord)
    process_state = PID_EXITED;

  /* FIXME:  There is a potential race between an execed process and its
     parent here.  I hated to add a mutex just for this, though.  */
  struct rusage r;
  fill_rusage (&r, hMainProc);
  add_rusage (&rusage_self, &r);

  sigproc_printf ("Calling ExitProcess %d", n);
  ExitProcess (n);
}

void
pinfo::init (pid_t n, DWORD flag, HANDLE in_h)
{
  if (n == myself->pid)
    {
      procinfo = myself;
      destroy = 0;
      h = NULL;
      return;
    }

  int createit = flag & (PID_IN_USE | PID_EXECED);
  for (int i = 0; i < 10; i++)
    {
      int created;
      char mapname[MAX_PATH];
      __small_sprintf (mapname, "cygpid.%x", n);

      int mapsize;
      if (flag & PID_EXECED)
	mapsize = PINFO_REDIR_SIZE;
      else
	mapsize = sizeof (_pinfo);

      if (in_h)
	{
	  h = in_h;
	  created = 0;
	}
      else if (!createit)
	{
	  h = OpenFileMappingA (FILE_MAP_READ | FILE_MAP_WRITE, FALSE, mapname);
	  created = 0;
	}
      else
	{
	  h = CreateFileMapping ((HANDLE) 0xffffffff, &sec_all_nih,
				  PAGE_READWRITE, 0, mapsize, mapname);
	  created = h && GetLastError () != ERROR_ALREADY_EXISTS;
	}

      if (!h)
	{
	  if (createit)
	    __seterrno ();
	  procinfo = NULL;
	  return;
	}

      procinfo = (_pinfo *) MapViewOfFile (h, FILE_MAP_READ | FILE_MAP_WRITE, 0, 0, 0);
      ProtectHandle1 (h, pinfo_shared_handle);

      if ((procinfo->process_state & PID_INITIALIZING) && (flag & PID_NOREDIR))
	{
	  release ();
	  set_errno (ENOENT);
	  return;
	}

      if (procinfo->process_state & PID_EXECED)
	{
	  assert (!i);
	  pid_t realpid = procinfo->pid;
	  debug_printf ("execed process windows pid %d, cygwin pid %d", n, realpid);
	  if (realpid == n)
	    api_fatal ("retrieval of execed process info for pid %d failed due to recursion.", n);
	  n = realpid;
	  release ();
	  continue;
	}

	/* In certain rare, pathological cases, it is possible for the shared
	   memory region to exist for a while after a process has exited.  This
	   should only be a brief occurrence, so rather than introduce some kind
	   of locking mechanism, just loop.  FIXME: I'm sure I'll regret doing it
	   this way at some point.  */
      if (i < 9 && !created && createit && (procinfo->process_state & PID_EXITED))
	{
	  Sleep (5);
	  release ();
	  continue;
	}

      if (!created)
	/* nothing */;
      else if (!(flag & PID_EXECED))
	procinfo->pid = n;
      else
	{
	  procinfo->pid = myself->pid;
	  procinfo->process_state |= PID_IN_USE | PID_EXECED;
	}
      break;
    }
  destroy = 1;
}

void
pinfo::release ()
{
  if (h)
    {
#ifdef DEBUGGING
      if (((DWORD) procinfo & 0x77000000) == 0x61000000) try_to_debug ();
#endif
      UnmapViewOfFile (procinfo);
      procinfo = NULL;
      ForceCloseHandle1 (h, pinfo_shared_handle);
      h = NULL;
    }
}

/* DOCTOOL-START

<sect1 id="func-cygwin-winpid-to-pid">
  <title>cygwin_winpid_to_pid</title>

  <funcsynopsis>
    <funcdef>extern "C" pid_t
      <function>cygwin_winpid_to_pid</function>
      </funcdef>
      <paramdef>int <parameter>winpid</parameter></paramdef>
  </funcsynopsis>

  <para>Given a windows pid, converts to the corresponding Cygwin
pid, if any.  Returns -1 if windows pid does not correspond to
a cygwin pid.</para>
  <example>
    <title>Example use of cygwin_winpid_to_pid</title>
    <programlisting>
      extern "C" cygwin_winpid_to_pid (int winpid);
      pid_t mypid;
      mypid = cygwin_winpid_to_pid (windows_pid);
    </programlisting>
  </example>
</sect1>

   DOCTOOL-END */

extern "C" pid_t
cygwin_winpid_to_pid (int winpid)
{
  pinfo p (winpid);
  if (p)
    return p->pid;

  set_errno (ESRCH);
  return (pid_t) -1;
}

#include <tlhelp32.h>

typedef DWORD (WINAPI * ENUMPROCESSES) (DWORD* &, DWORD &);
typedef HANDLE (WINAPI * CREATESNAPSHOT) (DWORD, DWORD);
typedef BOOL (WINAPI * PROCESSWALK) (HANDLE, LPPROCESSENTRY32);
typedef BOOL (WINAPI * CLOSESNAPSHOT) (HANDLE);

static NO_COPY CREATESNAPSHOT myCreateToolhelp32Snapshot = NULL;
static NO_COPY PROCESSWALK myProcess32First = NULL;
static NO_COPY PROCESSWALK myProcess32Next  = NULL;
static DWORD WINAPI enum_init (DWORD* &, DWORD&);

static NO_COPY ENUMPROCESSES myEnumProcesses = enum_init;

#define slop_pidlist 200
#define size_pidlist(i) (sizeof (pidlist[0]) * ((i) + 1))

static DWORD WINAPI
EnumProcessesNT (DWORD* &pidlist, DWORD &npidlist)
{
  static DWORD szprocs = 0;
  static SYSTEM_PROCESSES *procs;

  DWORD nelem = 0;
  if (!szprocs)
    procs = (SYSTEM_PROCESSES *) malloc (szprocs = 200 * sizeof (*procs));

  NTSTATUS res;
  for (;;)
    {
      res = ZwQuerySystemInformation (SystemProcessesAndThreadsInformation,
				      procs, szprocs, NULL);
      if (res == 0)
	break;

      if (res == STATUS_INFO_LENGTH_MISMATCH)
	procs =  (SYSTEM_PROCESSES *)realloc (procs, szprocs += 200 * sizeof (*procs));
      else
	{
	  system_printf ("error %p reading system process information", res);
	  return 0;
	}
    }

  SYSTEM_PROCESSES *px = procs;
  for (;;)
    {
      if (nelem >= npidlist)
	{
	  npidlist += slop_pidlist;
	  pidlist = (DWORD *) realloc (pidlist, size_pidlist (npidlist));
	}
      pidlist[nelem++] = cygwin_pid (px->ProcessId);
      if (!px->NextEntryDelta)
	break;
      px = (SYSTEM_PROCESSES *) ((char *) px + px->NextEntryDelta);
    }

  return nelem;
}

static DWORD WINAPI
EnumProcesses9x (DWORD* &pidlist, DWORD &npidlist)
{
  DWORD nelem = 0;

  HANDLE h = myCreateToolhelp32Snapshot (TH32CS_SNAPPROCESS, 0);
  if (!h)
    {
      system_printf ("Couldn't create process snapshot, %E");
      return 0;
    }

  PROCESSENTRY32 proc;
  proc.dwSize = sizeof (proc);

  if (myProcess32First(h, &proc))
    do
      {
	if (nelem >= npidlist)
	  {
	    npidlist += slop_pidlist;
	    pidlist = (DWORD *) realloc (pidlist, size_pidlist (npidlist));
	  }
	pidlist[nelem++] = cygwin_pid (proc.th32ProcessID);
      }
    while (myProcess32Next (h, &proc));

  CloseHandle (h);
  return nelem;
}

void
winpids::init ()
{
  npids = myEnumProcesses (pidlist, npidlist);
  pidlist[npids] = 0;
}

static DWORD WINAPI
enum_init (DWORD* &pidlist, DWORD& npidlist)
{
  HINSTANCE h;
  if (os_being_run == winNT)
    myEnumProcesses = EnumProcessesNT;
  else
    {
      h = GetModuleHandle("kernel32.dll");
      myCreateToolhelp32Snapshot = (CREATESNAPSHOT)
		  GetProcAddress(h, "CreateToolhelp32Snapshot");
      myProcess32First = (PROCESSWALK)
	      GetProcAddress(h, "Process32First");
      myProcess32Next  = (PROCESSWALK)
	      GetProcAddress(h, "Process32Next");
      if (!myCreateToolhelp32Snapshot || !myProcess32First || !myProcess32Next)
	{
	  system_printf ("Couldn't find toolhelp processes, %E");
	  return 0;
	}

      myEnumProcesses = EnumProcesses9x;
    }

  return myEnumProcesses (pidlist, npidlist);
}