DescriptorUtils_noexcept.cpp

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* Copyright (C) 2005, Quest Software, Inc. All rights reserved.
* Copyright (C) 2006, Novell, Inc. All rights reserved.
* 
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*       nor Novell, Inc., 
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*       specific prior written permission.
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// THIS CODE MUST NOT THROW EXCEPTIONS.  IT IS ALSO HIGHLY PREFERRED THAT
// IT NOT RELY ON ANY LIBRARY OTHER THAN STANDARD SYSTEM LIBRARIES AND THE
// STANDARD C++ LIBRARY, AS IT IS USED IN libowcprivman, AND WE WANT TO AVOID
// LINKING OTHER LIBRARIES IN WITH libowcprivman.

#include "blocxx/BLOCXX_config.h"
#include "blocxx/DescriptorUtils_noexcept.hpp"
#include "blocxx/AutoDescriptor.hpp"

#include <cstring>
#include <sys/types.h>
#ifdef BLOCXX_HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifndef BLOCXX_WIN32
#include <sys/uio.h>
#else
#include "blocxx/WinProcessUtils.hpp"
#endif

namespace BLOCXX_NAMESPACE
{

namespace
{
   char const MAGIC_CHAR = '\xa5';

   AutoDescriptor copy_error(char * dst, size_t dstsz, char const * src)
   {
      std::strncpy(dst, src, dstsz);
      dst[dstsz - 1] = '\0';
      return AutoDescriptor();
   }
}


#ifdef BLOCXX_WIN32

int passDescriptor(Descriptor streamPipe, Descriptor descriptor, ProcId targetProcessHd)
{
   if (streamPipe == BLOCXX_INVALID_HANDLE)
   {
      return -1;
   }

   DWORD targetProcessId = WinUtils::getProcessIdNT(targetProcessHd);

   DWORD rc = -1;
   HANDLE dupDescriptor = INVALID_HANDLE_VALUE;
   HANDLE hProcess = targetProcessId == 0 ? GetCurrentProcess() : OpenProcess(PROCESS_ALL_ACCESS, FALSE, targetProcessId);

   BOOL fSuccess = DuplicateHandle(GetCurrentProcess(), descriptor,
      hProcess, &dupDescriptor, 0,
      FALSE, DUPLICATE_SAME_ACCESS);

   CloseHandle(hProcess);

   if (!fSuccess)
   {
      return -1;
   }

   OVERLAPPED ovl;
   ZeroMemory(&ovl, sizeof(OVERLAPPED));
   
   fSuccess = WriteFile(streamPipe, &dupDescriptor, sizeof(long), &rc, &ovl);

   if (!fSuccess)
   {
      DWORD lastError = GetLastError();

      if (lastError != ERROR_IO_INCOMPLETE && lastError != ERROR_IO_PENDING)
      {
         SetLastError(lastError);
         return -1;
      }
      else 
      {
         DWORD waitFlag = WaitForSingleObject(streamPipe, INFINITE);

         if (waitFlag == WAIT_OBJECT_0)
         {
            GetOverlappedResult(streamPipe, &ovl, &rc, FALSE);
         }
         else
         {
            return -1;
         }
      }
   }

   return rc;
}

AutoDescriptor receiveDescriptor(Descriptor streamPipe, char * errbuf, size_t bufsz)
{
   long desc;
   DWORD rc = -1;
   BOOL bSuccess = FALSE;

   if (streamPipe != BLOCXX_INVALID_HANDLE)
   {
      OVERLAPPED ovl;
      ZeroMemory(&ovl, sizeof(OVERLAPPED));

      bSuccess = ReadFile(streamPipe, &desc, sizeof(long), &rc, &ovl);

      if (!bSuccess)
      {
         DWORD lastError = GetLastError();

         if (lastError != ERROR_IO_INCOMPLETE && lastError != ERROR_IO_PENDING)
         {
            SetLastError(lastError);
            return copy_error(errbuf, bufsz, "ReadFile() failed");
         }
         else
         {
            DWORD waitFlag = WaitForSingleObject(streamPipe, INFINITE);

            if (waitFlag == WAIT_OBJECT_0)
            {
               GetOverlappedResult(streamPipe, &ovl, &rc, FALSE);
            }
            else
            {
               return copy_error(errbuf, bufsz, "WaitForSingleObject() failed");
            }
         }
      }

      return AutoDescriptor(reinterpret_cast<HANDLE>(desc));
   }

   return copy_error(errbuf, bufsz, "receiveDescriptor() error");
}

#else

int passDescriptor(Descriptor streamPipe, Descriptor descriptor, ProcId targetProcessId)
{
   struct msghdr msg;
   ::memset(&msg, 0, sizeof(msg));
   struct iovec iov[1];
   ::memset(iov, 0, sizeof(iov[0]));

#ifdef BLOCXX_HAVE_MSGHDR_MSG_CONTROL

// We need the newer CMSG_LEN() and CMSG_SPACE() macros, but few
// implementations support them today.  These two macros really need
// an ALIGN() macro, but each implementation does this differently.
#ifndef CMSG_LEN
#define CMSG_LEN(size)      (sizeof(struct cmsghdr) + (size))
#endif

#ifndef CMSG_SPACE
#define CMSG_SPACE(size)    (sizeof(struct cmsghdr) + (size))
#endif

   union {
     struct cmsghdr cm;
     char control[CMSG_SPACE(sizeof(int))];
   } control_un;
   ::memset(&control_un, 0, sizeof(control_un));
   struct cmsghdr * cmptr;

   msg.msg_control = control_un.control;
   msg.msg_controllen = sizeof(control_un.control);

   cmptr = CMSG_FIRSTHDR(&msg);
   cmptr->cmsg_len = CMSG_LEN(sizeof(int));
   cmptr->cmsg_level = SOL_SOCKET;
   cmptr->cmsg_type = SCM_RIGHTS;
   *(reinterpret_cast<int *>(CMSG_DATA(cmptr))) = descriptor;
#else

#ifdef BLOCXX_NCR
   void *temp_cast = &descriptor;
   msg.msg_accrights = static_cast<caddr_t>(temp_cast);
#else
   msg.msg_accrights = static_cast<caddr_t>(&descriptor);
#endif

   msg.msg_accrightslen = sizeof(int);
#endif

   msg.msg_name = 0;
   msg.msg_namelen = 0;

   char dummy[1] = { MAGIC_CHAR };
   iov[0].iov_base = dummy;
   iov[0].iov_len = 1;
   msg.msg_iov = iov;
   msg.msg_iovlen = 1;

   return ::sendmsg(streamPipe, &msg, 0);
}

AutoDescriptor receiveDescriptor(Descriptor streamPipe, char * errbuf, size_t bufsz)
{
   struct msghdr msg;
   struct iovec iov[1];

   msg = msghdr(); // zero-init to make valgrind happy
#ifdef BLOCXX_HAVE_MSGHDR_MSG_CONTROL
   union {
     struct cmsghdr cm;
     char control[CMSG_SPACE(sizeof(int))];
   } control_un;

   msg.msg_control = control_un.control;
   msg.msg_controllen = sizeof(control_un.control);
#else
   int   newfd = -1;

#ifdef BLOCXX_NCR
   void *temp_cast = &newfd;
   msg.msg_accrights = static_cast<caddr_t>(temp_cast);
#else
   msg.msg_accrights = static_cast<caddr_t>(&newfd);
#endif

   msg.msg_accrightslen = sizeof(int);
#endif

   msg.msg_name = 0;
   msg.msg_namelen = 0;

   char dummy[1] = { '\x7F' };
   iov[0].iov_base = dummy;
   iov[0].iov_len = 1;
   msg.msg_iov = iov;
   msg.msg_iovlen = 1;

   ssize_t  n = ::recvmsg(streamPipe, &msg, 0);
   if (n == 0)
   {
      return copy_error(errbuf, bufsz,
         "unexpected end of input when receiving handle");
   }
   if (n < 0)
   {
      return copy_error(errbuf, bufsz, "recvmsg() failed");
   }
   if (n != 1)
   {
      return copy_error(errbuf, bufsz, "received more than 1 byte.");
   }
   if (dummy[0] != MAGIC_CHAR)
   {
      return copy_error(errbuf, bufsz, "bad magic char when receiving handle");
   }


#ifdef BLOCXX_HAVE_MSGHDR_MSG_CONTROL
   struct cmsghdr * cmptr = CMSG_FIRSTHDR(&msg);
   if (!cmptr)
   {
      return copy_error(errbuf, bufsz,
         "missing control message when receiving handle");
   }
   // as far as I can tell, HP-UX is just broken and sets cmptr->cmsg_len to 12. Things work anyway.
#if !defined (BLOCXX_HPUX)
   if (cmptr->cmsg_len != CMSG_LEN(sizeof(int)))
   {
      return copy_error(errbuf, bufsz,
         "cmptr->cmsg_len != CMSG_LEN(sizeof(int)) when receiving handle");
   }
#endif
   if (cmptr->cmsg_level != SOL_SOCKET)
   {
      return copy_error(errbuf, bufsz,
         "control level != SOL_SOCKET when receiving handle");
   }
   if (cmptr->cmsg_type != SCM_RIGHTS)
   {
      return copy_error(errbuf, bufsz,
         "control type != SCM_RIGHTS when receiving handle");
   }
   return AutoDescriptor(*(reinterpret_cast<int *>(CMSG_DATA(cmptr))));
#else
   if (msg.msg_accrightslen != sizeof(int))
   {
      return copy_error(errbuf, bufsz,
         "bad control message when receiving handle");
   }
   return AutoDescriptor(newfd);
#endif
}

#endif


} // end namespace BLOCXX_NAMESPACE