gpgme/assuan/assuan-pipe-connect.c

/* assuan-pipe-connect.c - Establish a pipe connection (client) 
 *	Copyright (C) 2001, 2002, 2003 Free Software Foundation, Inc.
 *
 * This file is part of Assuan.
 *
 * Assuan is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * Assuan 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#ifndef HAVE_W32_SYSTEM
#include <sys/wait.h>
#else
#include <windows.h>
#endif

#include "assuan-defs.h"

#ifdef _POSIX_OPEN_MAX
#define MAX_OPEN_FDS _POSIX_OPEN_MAX
#else
#define MAX_OPEN_FDS 20
#endif

#ifdef HAVE_W32_SYSTEM
/* We assume that a HANDLE can be represented by an int which should
   be true for all i386 systems (HANDLE is defined as void *) and
   these are the only systems for which Windows is available.  Further
   we assume that -1 denotes an invalid handle.  */
#define fd_to_handle(a)  ((HANDLE)(a))
#define handle_to_fd(a)  ((int)(a))
#define pid_to_handle(a) ((HANDLE)(a))
#define handle_to_pid(a) ((int)(a))
#endif /*HAVE_W32_SYSTEM*/


/* This should be called to make sure that SIGPIPE gets ignored.  */
static void
fix_signals (void)
{
#ifndef _ASSUAN_NO_FIXED_SIGNALS
#ifndef HAVE_DOSISH_SYSTEM  /* No SIGPIPE for these systems.  */
  static int fixed_signals;

  if (!fixed_signals)
    { 
      struct sigaction act;
        
      sigaction (SIGPIPE, NULL, &act);
      if (act.sa_handler == SIG_DFL)
	{
	  act.sa_handler = SIG_IGN;
	  sigemptyset (&act.sa_mask);
	  act.sa_flags = 0;
	  sigaction (SIGPIPE, &act, NULL);
        }
      fixed_signals = 1;
      /* FIXME: This is not MT safe */
    }
#endif /*HAVE_DOSISH_SYSTEM*/
#endif /*!_ASSUAN_NO_FIXED_SIGNALS*/
}


#ifndef HAVE_W32_SYSTEM
static int
writen (int fd, const char *buffer, size_t length)
{
  while (length)
    {
      int nwritten = write (fd, buffer, length);
      
      if (nwritten < 0)
        {
          if (errno == EINTR)
            continue;
          return -1; /* write error */
        }
      length -= nwritten;
      buffer += nwritten;
    }
  return 0;  /* okay */
}
#endif

static int
do_finish (assuan_context_t ctx)
{
  if (ctx->inbound.fd != -1)
    {
      _assuan_close (ctx->inbound.fd);
      ctx->inbound.fd = -1;
    }
  if (ctx->outbound.fd != -1)
    {
      _assuan_close (ctx->outbound.fd);
      ctx->outbound.fd = -1;
    }
  if (ctx->pid != -1 && ctx->pid)
    {
#ifndef HAVE_W32_SYSTEM
#ifndef _ASSUAN_USE_DOUBLE_FORK
      if (!ctx->flags.no_waitpid)
        waitpid (ctx->pid, NULL, 0); 
      ctx->pid = -1;
#endif
#endif /*!HAVE_W32_SYSTEM*/
    }
  return 0;
}

static void
do_deinit (assuan_context_t ctx)
{
  do_finish (ctx);
}


#ifdef HAVE_W32_SYSTEM
/* Build a command line for use with W32's CreateProcess.  On success
   CMDLINE gets the address of a newly allocated string.  */
static int
build_w32_commandline (char * const *argv, char **cmdline)
{
  int i, n;
  const char *s;
  char *buf, *p;

  *cmdline = NULL;
  n = 0;
  for (i=0; (s=argv[i]); i++)
    {
      n += strlen (s) + 1 + 2;  /* (1 space, 2 quoting */
      for (; *s; s++)
        if (*s == '\"')
          n++;  /* Need to double inner quotes.  */
    }
  n++;

  buf = p = xtrymalloc (n);
  if (!buf)
    return -1;

  for (i=0; argv[i]; i++) 
    {
      if (i)
        p = stpcpy (p, " ");
      if (!*argv[i]) /* Empty string. */
        p = stpcpy (p, "\"\"");
      else if (strpbrk (argv[i], " \t\n\v\f\""))
        {
          p = stpcpy (p, "\"");
          for (s=argv[i]; *s; s++)
            {
              *p++ = *s;
              if (*s == '\"')
                *p++ = *s;
            }
          *p++ = '\"';
          *p = 0;
        }
      else
        p = stpcpy (p, argv[i]);
    }

  *cmdline= buf;
  return 0;
}
#endif /*HAVE_W32_SYSTEM*/


#ifdef HAVE_W32_SYSTEM
/* Create pipe where one end end is inheritable.  */
static int
create_inheritable_pipe (int filedes[2], int for_write)
{
  HANDLE r, w, h;
  SECURITY_ATTRIBUTES sec_attr;

  memset (&sec_attr, 0, sizeof sec_attr );
  sec_attr.nLength = sizeof sec_attr;
  sec_attr.bInheritHandle = FALSE;
    
  if (!CreatePipe (&r, &w, &sec_attr, 0))
    {
      _assuan_log_printf ("CreatePipe failed: %s\n", w32_strerror (-1));
      return -1;
    }

  if (!DuplicateHandle (GetCurrentProcess(), for_write? r : w,
                        GetCurrentProcess(), &h, 0,
                        TRUE, DUPLICATE_SAME_ACCESS ))
    {
      _assuan_log_printf ("DuplicateHandle failed: %s\n", w32_strerror (-1));
      CloseHandle (r);
      CloseHandle (w);
      return -1;
    }
  if (for_write)
    {
      CloseHandle (r);
      r = h;
    }
  else
    {
      CloseHandle (w);
      w = h;
    }

  filedes[0] = handle_to_fd (r);
  filedes[1] = handle_to_fd (w);
  return 0;
}
#endif /*HAVE_W32_SYSTEM*/


/* Connect to a server over a pipe, creating the assuan context and
   returning it in CTX.  The server filename is NAME, the argument
   vector in ARGV.  FD_CHILD_LIST is a -1 terminated list of file
   descriptors not to close in the child.  ATFORK is called in the
   child right after the fork; ATFORKVALUE is passed as the first
   argument and 0 is passed as the second argument. The ATFORK
   function should only act if the second value is 0. */
assuan_error_t
assuan_pipe_connect2 (assuan_context_t *ctx,
                      const char *name, char *const argv[],
                      int *fd_child_list,
                      void (*atfork) (void *opaque, int reserved),
                      void *atforkvalue)
{
#ifdef HAVE_W32_SYSTEM
  assuan_error_t err;
  int rp[2];
  int wp[2];
  char mypidstr[50];
  char *cmdline;
  SECURITY_ATTRIBUTES sec_attr;
  PROCESS_INFORMATION pi = 
    {
      NULL,      /* Returns process handle.  */
      0,         /* Returns primary thread handle.  */
      0,         /* Returns pid.  */
      0          /* Returns tid.  */
    };
  STARTUPINFO si;
  int fd, *fdp;
  HANDLE nullfd = INVALID_HANDLE_VALUE;

  if (!ctx || !name || !argv || !argv[0])
    return ASSUAN_Invalid_Value;

  fix_signals ();

  sprintf (mypidstr, "%lu", (unsigned long)getpid ());

  /* Build the command line.  */
  if (build_w32_commandline (argv, &cmdline))
    return ASSUAN_Out_Of_Core;

  /* Create thew two pipes. */
  if (create_inheritable_pipe (rp, 0))
    {
      xfree (cmdline);
      return ASSUAN_General_Error;
    }
  
  if (create_inheritable_pipe (wp, 1))
    {
      CloseHandle (fd_to_handle (rp[0]));
      CloseHandle (fd_to_handle (rp[1]));
      xfree (cmdline);
      return ASSUAN_General_Error;
    }

  
  err = _assuan_new_context (ctx);
  if (err)
    {
      CloseHandle (fd_to_handle (rp[0]));
      CloseHandle (fd_to_handle (rp[1]));
      CloseHandle (fd_to_handle (wp[0]));
      CloseHandle (fd_to_handle (wp[1]));
      xfree (cmdline);
      return ASSUAN_General_Error;
    }

  (*ctx)->pipe_mode = 1;
  (*ctx)->inbound.fd  = rp[0];  /* Our inbound is read end of read pipe. */
  (*ctx)->outbound.fd = wp[1];  /* Our outbound is write end of write pipe. */
  (*ctx)->deinit_handler = do_deinit;
  (*ctx)->finish_handler = do_finish;


  /* fixme: Actually we should set the "_assuan_pipe_connect_pid" env
     variable.  However this requires us to write a full environment
     handler, because the strings are expected in sorted order.  The
     suggestion given in the MS Reference Library, to save the old
     value, changeit, create proces and restore it, is not thread
     safe.  */

  /* Start the process.  */
  memset (&sec_attr, 0, sizeof sec_attr );
  sec_attr.nLength = sizeof sec_attr;
  sec_attr.bInheritHandle = FALSE;
  
  memset (&si, 0, sizeof si);
  si.cb = sizeof (si);
  si.dwFlags = STARTF_USESTDHANDLES;
  si.hStdInput  = fd_to_handle (wp[0]);
  si.hStdOutput = fd_to_handle (rp[1]);

  /* Dup stderr to /dev/null unless it is in the list of FDs to be
     passed to the child. */
  fd = fileno (stderr);
  fdp = fd_child_list;
  if (fdp)
    {
      for (; *fdp != -1 && *fdp != fd; fdp++)
        ;
    }
  if (!fdp || *fdp == -1)
    {
      nullfd = CreateFile ("nul", GENERIC_WRITE,
                           FILE_SHARE_READ | FILE_SHARE_WRITE,
                           NULL, OPEN_EXISTING, 0, NULL);
      if (nullfd == INVALID_HANDLE_VALUE)
        {
          _assuan_log_printf ("can't open `nul': %s\n", w32_strerror (-1));
          CloseHandle (fd_to_handle (rp[0]));
          CloseHandle (fd_to_handle (rp[1]));
          CloseHandle (fd_to_handle (wp[0]));
          CloseHandle (fd_to_handle (wp[1]));
          xfree (cmdline);
          _assuan_release_context (*ctx); 
          return -1;
        }
      si.hStdError = nullfd;
    }
  else
    si.hStdError = fd_to_handle (_get_osfhandle (fd));


  /* Note: We inherit all handles flagged as inheritable.  This seems
     to be a security flaw but there seems to be no way of selecting
     handles to inherit. */
  /*   _assuan_log_printf ("CreateProcess, path=`%s' cmdline=`%s'\n", */
  /*                       name, cmdline); */
  if (!CreateProcess (name,                 /* Program to start.  */
                      cmdline,              /* Command line arguments.  */
                      &sec_attr,            /* Process security attributes.  */
                      &sec_attr,            /* Thread security attributes.  */
                      TRUE,                 /* Inherit handles.  */
                      (CREATE_DEFAULT_ERROR_MODE
                       | GetPriorityClass (GetCurrentProcess ())
                       | CREATE_SUSPENDED), /* Creation flags.  */
                      NULL,                 /* Environment.  */
                      NULL,                 /* Use current drive/directory.  */
                      &si,                  /* Startup information. */
                      &pi                   /* Returns process information.  */
                      ))
    {
      _assuan_log_printf ("CreateProcess failed: %s\n", w32_strerror (-1));
      CloseHandle (fd_to_handle (rp[0]));
      CloseHandle (fd_to_handle (rp[1]));
      CloseHandle (fd_to_handle (wp[0]));
      CloseHandle (fd_to_handle (wp[1]));
      if (nullfd != INVALID_HANDLE_VALUE)
        CloseHandle (nullfd);
      xfree (cmdline);
      _assuan_release_context (*ctx); 
      return ASSUAN_General_Error;
    }
  xfree (cmdline);
  cmdline = NULL;
  if (nullfd != INVALID_HANDLE_VALUE)
    {
      CloseHandle (nullfd);
      nullfd = INVALID_HANDLE_VALUE;
    }

  CloseHandle (fd_to_handle (rp[1]));
  CloseHandle (fd_to_handle (wp[0]));

  /*   _assuan_log_printf ("CreateProcess ready: hProcess=%p hThread=%p" */
  /*                       " dwProcessID=%d dwThreadId=%d\n", */
  /*                       pi.hProcess, pi.hThread, */
  /*                       (int) pi.dwProcessId, (int) pi.dwThreadId); */

  ResumeThread (pi.hThread);
  CloseHandle (pi.hThread); 
  (*ctx)->pid = 0;  /* We don't use the PID. */
  CloseHandle (pi.hProcess); /* We don't need to wait for the process. */

#else /*!HAVE_W32_SYSTEM*/
  assuan_error_t err;
  int rp[2];
  int wp[2];
  char mypidstr[50];

  if (!ctx || !name || !argv || !argv[0])
    return ASSUAN_Invalid_Value;

  fix_signals ();

  sprintf (mypidstr, "%lu", (unsigned long)getpid ());

  if (pipe (rp) < 0)
    return ASSUAN_General_Error;

  if (pipe (wp) < 0)
    {
      close (rp[0]);
      close (rp[1]);
      return ASSUAN_General_Error;
    }
  
  err = _assuan_new_context (ctx);
  if (err)
    {
      close (rp[0]);
      close (rp[1]);
      close (wp[0]);
      close (wp[1]);
      return err;
    }
  (*ctx)->pipe_mode = 1;
  (*ctx)->inbound.fd  = rp[0];  /* Our inbound is read end of read pipe. */
  (*ctx)->outbound.fd = wp[1];  /* Our outbound is write end of write pipe. */
  (*ctx)->deinit_handler = do_deinit;
  (*ctx)->finish_handler = do_finish;

  /* FIXME: For GPGME we should better use _gpgme_io_spawn.  The PID
     stored here is actually soon useless.  */
  (*ctx)->pid = fork ();
  if ((*ctx)->pid < 0)
    {
      close (rp[0]);
      close (rp[1]);
      close (wp[0]);
      close (wp[1]);
      _assuan_release_context (*ctx); 
      return ASSUAN_General_Error;
    }

  if ((*ctx)->pid == 0)
    {
#ifdef _ASSUAN_USE_DOUBLE_FORK      
      pid_t pid;

      if ((pid = fork ()) == 0)
#endif
	{
          int i, n;
          char errbuf[512];
          int *fdp;
          
          if (atfork)
            atfork (atforkvalue, 0);

          /* Dup handles to stdin/stdout. */
          if (rp[1] != STDOUT_FILENO)
            {
              if (dup2 (rp[1], STDOUT_FILENO) == -1)
                {
                  _assuan_log_printf ("dup2 failed in child: %s\n",
                                      strerror (errno));
                  _exit (4);
                }
            }
          if (wp[0] != STDIN_FILENO)
            {
              if (dup2 (wp[0], STDIN_FILENO) == -1)
                {
                  _assuan_log_printf ("dup2 failed in child: %s\n",
                                      strerror (errno));
                  _exit (4);
                }
            }

          /* Dup stderr to /dev/null unless it is in the list of FDs to be
             passed to the child. */
          fdp = fd_child_list;
          if (fdp)
            {
              for (; *fdp != -1 && *fdp != STDERR_FILENO; fdp++)
                ;
            }
          if (!fdp || *fdp == -1)
            {
              int fd = open ("/dev/null", O_WRONLY);
              if (fd == -1)
                {
                  _assuan_log_printf ("can't open `/dev/null': %s\n",
                                      strerror (errno));
                  _exit (4);
                }
              if (dup2 (fd, STDERR_FILENO) == -1)
                {
                  _assuan_log_printf ("dup2(dev/null, 2) failed: %s\n",
                                      strerror (errno));
                  _exit (4);
                }
            }


          /* Close all files which will not be duped and are not in the
             fd_child_list. */
          n = sysconf (_SC_OPEN_MAX);
          if (n < 0)
            n = MAX_OPEN_FDS;
          for (i=0; i < n; i++)
            {
              if ( i == STDIN_FILENO || i == STDOUT_FILENO
                   || i == STDERR_FILENO)
                continue;
              fdp = fd_child_list;
              if (fdp)
                {
                  while (*fdp != -1 && *fdp != i)
                    fdp++;
                }

              if (!(fdp && *fdp != -1))
                close(i);
            }
          errno = 0;

          /* We store our parents pid in the environment so that the
             execed assuan server is able to read the actual pid of the
             client.  The server can't use getppid becuase it might have
             been double forked before the assuan server has been
             initialized. */
          setenv ("_assuan_pipe_connect_pid", mypidstr, 1);

          execv (name, argv); 
          /* oops - use the pipe to tell the parent about it */
          snprintf (errbuf, sizeof(errbuf)-1,
                    "ERR %d can't exec `%s': %.50s\n",
                    ASSUAN_Problem_Starting_Server, name, strerror (errno));
          errbuf[sizeof(errbuf)-1] = 0;
          writen (1, errbuf, strlen (errbuf));
          _exit (4);
        }
#ifdef _ASSUAN_USE_DOUBLE_FORK
      if (pid == -1)
	_exit (1);
      else
	_exit (0);
#endif
    }

#ifdef _ASSUAN_USE_DOUBLE_FORK
  waitpid ((*ctx)->pid, NULL, 0);
  (*ctx)->pid = -1;
#endif

  close (rp[1]);
  close (wp[0]);

#endif /*!HAVE_W32_SYSTEM*/

  /* initial handshake */
  {
    int okay, off;

    err = _assuan_read_from_server (*ctx, &okay, &off);
    if (err)
      _assuan_log_printf ("can't connect server: %s\n",
                          assuan_strerror (err));
    else if (okay != 1)
      {
	_assuan_log_printf ("can't connect server: `%s'\n",
                            (*ctx)->inbound.line);
	err = ASSUAN_Connect_Failed;
      }
  }

  if (err)
    {
      assuan_disconnect (*ctx);
      *ctx = NULL;
    }

  return err;
}


/* Connect to a server over a pipe, creating the assuan context and
   returning it in CTX.  The server filename is NAME, the argument
   vector in ARGV.  FD_CHILD_LIST is a -1 terminated list of file
   descriptors not to close in the child.  */
assuan_error_t
assuan_pipe_connect (assuan_context_t *ctx, const char *name, char *const argv[],
		     int *fd_child_list)
{
  return assuan_pipe_connect2 (ctx, name, argv, fd_child_list, NULL, NULL);
}