newlib-cygwin/winsup/cygwin/shared.cc

/* shared.cc: shared data area support.

   Copyright 1996, 1997, 1998, 1999, 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 <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <grp.h>
#include <pwd.h>
#include "winsup.h"

#define SHAREDVER (unsigned)(cygwin_version.api_major << 16 | \
		   cygwin_version.api_minor)

shared_info NO_COPY *cygwin_shared = NULL;

/* The handle of the shared data area.  */
HANDLE cygwin_shared_h = NULL;

/* General purpose security attribute objects for global use. */
SECURITY_ATTRIBUTES NO_COPY sec_none;
SECURITY_ATTRIBUTES NO_COPY sec_none_nih;
SECURITY_ATTRIBUTES NO_COPY sec_all;
SECURITY_ATTRIBUTES NO_COPY sec_all_nih;

char * __stdcall
shared_name (const char *str, int num)
{
  static NO_COPY char buf[MAX_PATH] = {0};
  char envbuf[6];

  __small_sprintf (buf, "%s.%s.%d", cygwin_version.shared_id, str, num);
  if (GetEnvironmentVariable("CYGWIN_TESTING", envbuf, 5))
    strcat(buf, cygwin_version.dll_build_date);
  return buf;
}

/* Open the shared memory map.  */
static void __stdcall
open_shared_file_map ()
{
  cygwin_shared = (shared_info *) open_shared ("shared",
					       cygwin_shared_h,
					       sizeof (*cygwin_shared),
					       (void *)0xa000000);
  ProtectHandle (cygwin_shared);
}

void * __stdcall
open_shared (const char *name, HANDLE &shared_h, DWORD size, void *addr)
{
  void *shared;

  if (!shared_h)
    {
      char *mapname;
      if (!name)
	mapname = NULL;
      else
	{
	  mapname = shared_name (name, 0);
	  shared_h = OpenFileMappingA (FILE_MAP_READ | FILE_MAP_WRITE,
				       TRUE, mapname);
	}
      if (!shared_h &&
	  !(shared_h = CreateFileMappingA ((HANDLE) 0xffffffff,
					   &sec_all,
					   PAGE_READWRITE,
					   0,
					   size,
					   mapname)))
	api_fatal ("CreateFileMappingA, %E.  Terminating.");
    }

  shared = (shared_info *) MapViewOfFileEx (shared_h,
				       FILE_MAP_READ | FILE_MAP_WRITE,
				       0, 0, 0, addr);

  if (!shared)
    {
      /* Probably win95, so try without specifying the address.  */
      shared = (shared_info *) MapViewOfFileEx (shared_h,
				       FILE_MAP_READ|FILE_MAP_WRITE,
				       0,0,0,0);
    }

  if (!shared)
    api_fatal ("MapViewOfFileEx, %E.  Terminating.");

  debug_printf ("name %s, shared %p, h %p", name, shared, shared_h);

  /* FIXME: I couldn't find anywhere in the documentation a note about
     whether the memory is initialized to zero.  The code assumes it does
     and since this part seems to be working, we'll leave it as is.  */
  return shared;
}

void
shared_info::initialize ()
{
  /* Ya, Win32 provides a way for a dll to watch when it's first loaded.
     We may eventually want to use it but for now we have this.  */
  if (inited)
    {
      if (inited != SHAREDVER)
	api_fatal ("shared region is corrupted.  inited %x", inited);
      return;
    }

  /* Initialize the mount table.  */
  mount.init ();

  /* Initialize the process table.  */
  p.init ();

  /* Initialize the queue of deleted files.  */
  delqueue.init ();

  /* Initialize tty table.  */
  tty.init ();

  /* Fetch misc. registry entries.  */

  reg_key reg (KEY_READ, NULL);

  /* Note that reserving a huge amount of heap space does not result in
  swapping since we are not committing it. */
  /* FIXME: We should not be restricted to a fixed size heap no matter
  what the fixed size is. */

  heap_chunk_in_mb = reg.get_int ("heap_chunk_in_mb", 128);
  if (heap_chunk_in_mb < 4)
    {
      heap_chunk_in_mb = 4;
      reg.set_int ("heap_chunk_in_mb", heap_chunk_in_mb);
    }

  inited = SHAREDVER;
}

void __stdcall
shared_init ()
{
  open_shared_file_map ();

  cygwin_shared->initialize ();
}

void __stdcall
shared_terminate ()
{
  if (cygwin_shared_h)
    ForceCloseHandle (cygwin_shared_h);
}

unsigned
shared_info::heap_chunk_size ()
{
  return heap_chunk_in_mb << 20;
}

/* For apps that wish to access the shared data.  */

shared_info *
cygwin_getshared ()
{
  return cygwin_shared;
}

/*
 * Function to return a common SECURITY_DESCRIPTOR * that
 * allows all access.
 */

static NO_COPY SECURITY_DESCRIPTOR *null_sdp = 0;

SECURITY_DESCRIPTOR *__stdcall
get_null_sd ()
{
  static NO_COPY SECURITY_DESCRIPTOR sd;

  if (null_sdp == 0)
    {
      InitializeSecurityDescriptor (&sd, SECURITY_DESCRIPTOR_REVISION);
      SetSecurityDescriptorDacl (&sd, TRUE, 0, FALSE);
      null_sdp = &sd;
    }
  return null_sdp;
}

extern PSID get_admin_sid ();
extern PSID get_system_sid ();
extern PSID get_creator_owner_sid ();

PSECURITY_ATTRIBUTES __stdcall
sec_user (PVOID sa_buf, PSID sid2, BOOL inherit)
{
  if (! sa_buf)
    return inherit ? &sec_none_nih : &sec_none;

  PSECURITY_ATTRIBUTES psa = (PSECURITY_ATTRIBUTES) sa_buf;
  PSECURITY_DESCRIPTOR psd = (PSECURITY_DESCRIPTOR)
                             ((char *) sa_buf + sizeof (*psa));
  PACL acl = (PACL) ((char *) sa_buf + sizeof (*psa) + sizeof (*psd));

  char sid_buf[40];
  PSID sid = (PSID) sid_buf;

  if (myself->psid)
    CopySid (40, sid, myself->psid);
  else if (! lookup_name (getlogin (), myself->logsrv, sid))
    return inherit ? &sec_none_nih : &sec_none;

  size_t acl_len = sizeof (ACL)
                   + 4 * (sizeof (ACCESS_ALLOWED_ACE) - sizeof (DWORD))
                   + GetLengthSid (sid)
                   + GetLengthSid (get_admin_sid ())
                   + GetLengthSid (get_system_sid ())
                   + GetLengthSid (get_creator_owner_sid ());
  if (sid2)
    acl_len += sizeof (ACCESS_ALLOWED_ACE) - sizeof (DWORD)
               + GetLengthSid (sid2);

  if (! InitializeAcl (acl, acl_len, ACL_REVISION))
    debug_printf("InitializeAcl %E");

  if (! AddAccessAllowedAce (acl, ACL_REVISION,
                             SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
                             sid))
    debug_printf("AddAccessAllowedAce(%s) %E", getlogin());

  if (! AddAccessAllowedAce (acl, ACL_REVISION,
                             SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
                             get_admin_sid ()))
    debug_printf("AddAccessAllowedAce(admin) %E");

  if (! AddAccessAllowedAce (acl, ACL_REVISION,
                             SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
                             get_system_sid ()))
    debug_printf("AddAccessAllowedAce(system) %E");

  if (! AddAccessAllowedAce (acl, ACL_REVISION,
                             SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
                             get_creator_owner_sid ()))
    debug_printf("AddAccessAllowedAce(creator_owner) %E");

  if (sid2)
    if (! AddAccessAllowedAce (acl, ACL_REVISION,
                               SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL,
                               sid2))
      debug_printf("AddAccessAllowedAce(sid2) %E");

  if (! InitializeSecurityDescriptor (psd,
                                      SECURITY_DESCRIPTOR_REVISION))
    debug_printf("InitializeSecurityDescriptor %E");

/*
 * Setting the owner lets the created security attribute not work
 * on NT4 SP3 Server. Don't know why, but the function still does
 * what it should do also if the owner isn't set.
*/
#if 0
  if (! SetSecurityDescriptorOwner (psd, sid, FALSE))
    debug_printf("SetSecurityDescriptorOwner %E");
#endif

  if (! SetSecurityDescriptorDacl (psd, TRUE, acl, FALSE))
    debug_printf("SetSecurityDescriptorDacl %E");

  psa->nLength = sizeof (SECURITY_ATTRIBUTES);
  psa->lpSecurityDescriptor = psd;
  psa->bInheritHandle = inherit;
  return psa;
}

SECURITY_ATTRIBUTES *__stdcall
sec_user_nih (PVOID sa_buf, PSID sid2)
{
  return sec_user (sa_buf, sid2, FALSE);
}