gpgme/src/posix-io.c

/* posix-io.c - Posix I/O functions
   Copyright (C) 2000 Werner Koch (dd9jn)
   Copyright (C) 2001, 2002, 2004, 2005, 2007, 2010 g10 Code GmbH

   This file is part of GPGME.
 
   GPGME 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.
   
   GPGME 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, see <http://www.gnu.org/licenses/>.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#include <sys/wait.h>
#ifdef HAVE_SYS_UIO_H
# include <sys/uio.h>
#endif
#include <ctype.h>
#include <sys/resource.h>

#include "util.h"
#include "priv-io.h"
#include "sema.h"
#include "ath.h"
#include "debug.h"


void
_gpgme_io_subsystem_init (void)
{
  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);
    }
}


/* Write the printable version of FD to the buffer BUF of length
   BUFLEN.  The printable version is the representation on the command
   line that the child process expects.  */
int
_gpgme_io_fd2str (char *buf, int buflen, int fd)
{
  return snprintf (buf, buflen, "%d", fd);
}


/* The table to hold notification handlers.  We use a linear search
   and extend the table as needed.  */
struct notify_table_item_s
{
  int fd;  /* -1 indicates an unused entry.  */
  _gpgme_close_notify_handler_t handler;
  void *value;
};
typedef struct notify_table_item_s *notify_table_item_t;

static notify_table_item_t notify_table;
static size_t notify_table_size;
DEFINE_STATIC_LOCK (notify_table_lock);



int
_gpgme_io_read (int fd, void *buffer, size_t count)
{
  int nread;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_read", fd,
	      "buffer=%p, count=%u", buffer, count);

  do
    {
      nread = _gpgme_ath_read (fd, buffer, count);
    }
  while (nread == -1 && errno == EINTR);

  TRACE_LOGBUF (buffer, nread);
  return TRACE_SYSRES (nread);
}


int
_gpgme_io_write (int fd, const void *buffer, size_t count)
{
  int nwritten;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_write", fd,
	      "buffer=%p, count=%u", buffer, count);
  TRACE_LOGBUF (buffer, count);

  do
    {
      nwritten = _gpgme_ath_write (fd, buffer, count);
    }
  while (nwritten == -1 && errno == EINTR);

  return TRACE_SYSRES (nwritten);
}


int
_gpgme_io_pipe (int filedes[2], int inherit_idx)
{
  int saved_errno;
  int err;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_pipe", filedes,
	      "inherit_idx=%i (GPGME uses it for %s)",
	      inherit_idx, inherit_idx ? "reading" : "writing");

  err = pipe (filedes);
  if (err < 0)
    return TRACE_SYSRES (err);

  /* FIXME: Should get the old flags first.  */
  err = fcntl (filedes[1 - inherit_idx], F_SETFD, FD_CLOEXEC);
  saved_errno = errno;
  if (err < 0)
    {
      close (filedes[0]);
      close (filedes[1]);
    }
  errno = saved_errno;
  if (err)
    return TRACE_SYSRES (err);

  return TRACE_SUC2 ("read=0x%x, write=0x%x", filedes[0], filedes[1]);
}


int
_gpgme_io_close (int fd)
{
  int res;
  _gpgme_close_notify_handler_t handler = NULL;
  void *handler_value;
  int idx;

  TRACE_BEG (DEBUG_SYSIO, "_gpgme_io_close", fd);

  if (fd == -1)
    {
      errno = EINVAL;
      return TRACE_SYSRES (-1);
    }

  /* First call the notify handler.  */
  LOCK (notify_table_lock);
  for (idx=0; idx < notify_table_size; idx++)
    {
      if (notify_table[idx].fd == fd)
        {
	  handler       = notify_table[idx].handler;
	  handler_value = notify_table[idx].value;
	  notify_table[idx].handler = NULL;
	  notify_table[idx].value = NULL;
	  notify_table[idx].fd = -1; /* Mark slot as free.  */
          break;
        }
    }
  UNLOCK (notify_table_lock);
  if (handler)
    {
      TRACE_LOG2 ("invoking close handler %p/%p", handler, handler_value);
      handler (fd, handler_value);
    }

  /* Then do the close.  */    
  res = close (fd);
  return TRACE_SYSRES (res);
}


int
_gpgme_io_set_close_notify (int fd, _gpgme_close_notify_handler_t handler,
			    void *value)
{
  int res = 0;
  int idx;

  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_set_close_notify", fd,
	      "close_handler=%p/%p", handler, value);

  assert (fd != -1);
  
  LOCK (notify_table_lock);
  for (idx=0; idx < notify_table_size; idx++)
    if (notify_table[idx].fd == -1)
      break;
  if (idx == notify_table_size)
    {
      /* We need to increase the size of the table.  The approach we
         take is straightforward to minimize the risk of bugs.  */
      notify_table_item_t newtbl;
      size_t newsize = notify_table_size + 64;

      newtbl = calloc (newsize, sizeof *newtbl);
      if (!newtbl)
        {
          res = -1;
          goto leave;
        }
      for (idx=0; idx < notify_table_size; idx++)
        newtbl[idx] = notify_table[idx];
      for (; idx < newsize; idx++)
        {
          newtbl[idx].fd = -1;
          newtbl[idx].handler = NULL;
          newtbl[idx].value = NULL;
        }
      free (notify_table);
      notify_table = newtbl;
      idx = notify_table_size;
      notify_table_size = newsize;
    }
  notify_table[idx].fd = fd;
  notify_table[idx].handler = handler;
  notify_table[idx].value = value;
  
 leave:
  UNLOCK (notify_table_lock);

  return TRACE_SYSRES (res);
}


int
_gpgme_io_set_nonblocking (int fd)
{
  int flags;
  int res;
  TRACE_BEG (DEBUG_SYSIO, "_gpgme_io_set_nonblocking", fd);

  flags = fcntl (fd, F_GETFL, 0);
  if (flags == -1)
    return TRACE_SYSRES (-1);
  flags |= O_NONBLOCK;
  res = fcntl (fd, F_SETFL, flags);
  return TRACE_SYSRES (res);
}


static long int
get_max_fds (void)
{
  char *source = NULL;
  long int fds = -1;
  int rc;

#ifdef RLIMIT_NOFILE
  {
    struct rlimit rl;
    rc = getrlimit (RLIMIT_NOFILE, &rl);
    if (rc == 0)
      {
	source = "RLIMIT_NOFILE";
	fds = rl.rlim_max;
      }
  }
#endif
#ifdef RLIMIT_OFILE
  if (fds == -1)
    {
      struct rlimit rl;
      rc = getrlimit (RLIMIT_OFILE, &rl);
      if (rc == 0)
	{
	  source = "RLIMIT_OFILE";
	  fds = rl.rlim_max;
	}
    }
#endif
#ifdef _SC_OPEN_MAX
  if (fds == -1)
    {
      long int scres;
      scres = sysconf (_SC_OPEN_MAX);
      if (scres >= 0)
	{
	  source = "_SC_OPEN_MAX";
	  return scres;
	}
    }
#endif
#ifdef OPEN_MAX
  if (fds == -1)
    {
      source = "OPEN_MAX";
      fds = OPEN_MAX;
    }
#endif

#if !defined(RLIMIT_NOFILE) && !defined(RLIMIT_OFILE) \
  && !defined(_SC_OPEN_MAX) && !defined(OPEN_MAX)
#warning "No known way to get the maximum number of file descriptors."
#endif
  if (fds == -1)
    {
      source = "arbitrary";
      /* Arbitrary limit.  */
      fds = 1024;
    }

  TRACE2 (DEBUG_SYSIO, "gpgme:max_fds", 0, "max fds=%i (%s)", fds, source);
  return fds;
}


int
_gpgme_io_waitpid (int pid, int hang, int *r_status, int *r_signal)
{
  int status;

  *r_status = 0;
  *r_signal = 0;
  if (_gpgme_ath_waitpid (pid, &status, hang? 0 : WNOHANG) == pid)
    {
      if (WIFSIGNALED (status))
	{
	  *r_status = 4; /* Need some value here.  */
	  *r_signal = WTERMSIG (status);
	}
      else if (WIFEXITED (status))
	*r_status = WEXITSTATUS (status);
      else
	*r_status = 4; /* Oops.  */
      return 1;
    }
  return 0;
}


/* Returns 0 on success, -1 on error.  */
int
_gpgme_io_spawn (const char *path, char *const argv[], unsigned int flags,
		 struct spawn_fd_item_s *fd_list,
		 void (*atfork) (void *opaque, int reserved),
		 void *atforkvalue, pid_t *r_pid)
{
  pid_t pid;
  int i;
  int status;
  int signo;

  (void)flags;

  TRACE_BEG1 (DEBUG_SYSIO, "_gpgme_io_spawn", path,
	      "path=%s", path);
  i = 0;
  while (argv[i])
    {
      TRACE_LOG2 ("argv[%2i] = %s", i, argv[i]);
      i++;
    }
  for (i = 0; fd_list[i].fd != -1; i++)
    if (fd_list[i].dup_to == -1)
      TRACE_LOG2 ("fd[%i] = 0x%x", i, fd_list[i].fd);
    else
      TRACE_LOG3 ("fd[%i] = 0x%x -> 0x%x", i, fd_list[i].fd, fd_list[i].dup_to);

  pid = fork ();
  if (pid == -1) 
    return TRACE_SYSRES (-1);

  if (!pid)
    {
      /* Intermediate child to prevent zombie processes.  */
      if ((pid = fork ()) == 0)
	{
	  int max_fds = get_max_fds ();
	  int fd;

	  /* Child.  */
	  int seen_stdin = 0;
	  int seen_stderr = 0;

	  if (atfork)
	    atfork (atforkvalue, 0);

	  /* First close all fds which will not be inherited.  */
	  for (fd = 0; fd < max_fds; fd++)
	    {
	      for (i = 0; fd_list[i].fd != -1; i++)
		if (fd_list[i].fd == fd)
		  break;
	      if (fd_list[i].fd == -1)
		close (fd);
	    }

	  /* And now dup and close those to be duplicated.  */
	  for (i = 0; fd_list[i].fd != -1; i++)
	    {
	      int child_fd;
	      int res;

	      if (fd_list[i].dup_to != -1)
		child_fd = fd_list[i].dup_to;
	      else
		child_fd = fd_list[i].fd;

	      if (child_fd == 0)
		seen_stdin = 1;
	      else if (child_fd == 2)
		seen_stderr = 1;

	      if (fd_list[i].dup_to == -1)
		continue;

	      res = dup2 (fd_list[i].fd, fd_list[i].dup_to);
	      if (res < 0)
		{
#if 0
		  /* FIXME: The debug file descriptor is not
		     dup'ed anyway, so we can't see this.  */
		  TRACE_LOG1 ("dup2 failed in child: %s\n",
			      strerror (errno));
#endif
		  _exit (8);
		}

	      close (fd_list[i].fd);
	    }
	  
	  if (! seen_stdin || ! seen_stderr)
	    {
	      fd = open ("/dev/null", O_RDWR);
	      if (fd == -1)
		{
#if 0
		  /* FIXME: The debug file descriptor is not dup'ed
		     anyway, so we can't see this.  */
		  TRACE_LOG1 ("can't open `/dev/null': %s\n",
			      strerror (errno));
#endif
		  _exit (8);
		}
	      /* Make sure that the process has a connected stdin.  */
	      if (! seen_stdin && fd != 0)
		{
		  if (dup2 (fd, 0) == -1)
		    {
#if 0
		  /* FIXME: The debug file descriptor is not dup'ed
		     anyway, so we can't see this.  */
		      TRACE_LOG1 ("dup2(/dev/null, 0) failed: %s\n",
				  strerror (errno));
#endif
		      _exit (8);
		    }
		}
	      if (! seen_stderr && fd != 2)
		if (dup2 (fd, 2) == -1)
		  {
#if 0
		    /* FIXME: The debug file descriptor is not dup'ed
		       anyway, so we can't see this.  */
		    TRACE_LOG1 ("dup2(dev/null, 2) failed: %s\n",
				strerror (errno));
#endif
		    _exit (8);
		  }
	      if (fd != 0 && fd != 2)
		close (fd);
	    }
    
	  execv (path, (char *const *) argv);
	  /* Hmm: in that case we could write a special status code to the
	     status-pipe.  */
#if 0
	  /* FIXME: The debug file descriptor is not dup'ed anyway, so
	     we can't see this.  */
	  TRACE_LOG1 ("exec of `%s' failed\n", path);
#endif
	  _exit (8);
	  /* End child.  */
	}
      if (pid == -1)
	_exit (1);
      else
	_exit (0);
    }

  TRACE_LOG1 ("waiting for child process pid=%i", pid);
  _gpgme_io_waitpid (pid, 1, &status, &signo);
  if (status)
    return TRACE_SYSRES (-1);

  for (i = 0; fd_list[i].fd != -1; i++)
    {
      if (! (flags & IOSPAWN_FLAG_NOCLOSE))
	_gpgme_io_close (fd_list[i].fd);
      /* No handle translation.  */
      fd_list[i].peer_name = fd_list[i].fd;
    }

  if (r_pid)
    *r_pid = pid;

  return TRACE_SYSRES (0);
}


/* Select on the list of fds.  Returns: -1 = error, 0 = timeout or
   nothing to select, > 0 = number of signaled fds.  */
int
_gpgme_io_select (struct io_select_fd_s *fds, size_t nfds, int nonblock)
{
  fd_set readfds;
  fd_set writefds;
  unsigned int i;
  int any;
  int max_fd;
  int n;
  int count;
  /* Use a 1s timeout.  */
  struct timeval timeout = { 1, 0 };
  void *dbg_help = NULL;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_select", fds,
	      "nfds=%u, nonblock=%u", nfds, nonblock);

  FD_ZERO (&readfds);
  FD_ZERO (&writefds);
  max_fd = 0;
  if (nonblock)
    timeout.tv_sec = 0;

  TRACE_SEQ (dbg_help, "select on [ ");

  any = 0;
  for (i = 0; i < nfds; i++)
    {
      if (fds[i].fd == -1) 
	continue;
      if (fds[i].for_read)
	{
	  assert (!FD_ISSET (fds[i].fd, &readfds));
	  FD_SET (fds[i].fd, &readfds);
	  if (fds[i].fd > max_fd)
	    max_fd = fds[i].fd;
	  TRACE_ADD1 (dbg_help, "r0x%x ", fds[i].fd);
	  any = 1;
        }
      else if (fds[i].for_write)
	{
	  assert (!FD_ISSET (fds[i].fd, &writefds));
	  FD_SET (fds[i].fd, &writefds);
	  if (fds[i].fd > max_fd)
	    max_fd = fds[i].fd;
	  TRACE_ADD1 (dbg_help, "w0x%x ", fds[i].fd);
	  any = 1;
        }
      fds[i].signaled = 0;
    }
  TRACE_END (dbg_help, "]"); 
  if (!any)
    return TRACE_SYSRES (0);

  do
    {
      count = _gpgme_ath_select (max_fd + 1, &readfds, &writefds, NULL,
				 &timeout);
    }
  while (count < 0 && errno == EINTR);
  if (count < 0)
    return TRACE_SYSRES (-1);

  TRACE_SEQ (dbg_help, "select OK [ ");
  if (TRACE_ENABLED (dbg_help))
    {
      for (i = 0; i <= max_fd; i++)
	{
	  if (FD_ISSET (i, &readfds))
	    TRACE_ADD1 (dbg_help, "r0x%x ", i);
	  if (FD_ISSET (i, &writefds))
	    TRACE_ADD1 (dbg_help, "w0x%x ", i);
        }
      TRACE_END (dbg_help, "]");
    }
    
  /* The variable N is used to optimize it a little bit.  */
  for (n = count, i = 0; i < nfds && n; i++)
    {
      if (fds[i].fd == -1)
	;
      else if (fds[i].for_read)
	{
	  if (FD_ISSET (fds[i].fd, &readfds))
	    {
	      fds[i].signaled = 1;
	      n--;
            }
        }
      else if (fds[i].for_write)
	{
	  if (FD_ISSET (fds[i].fd, &writefds))
	    {
	      fds[i].signaled = 1;
	      n--;
            }
        }
    }
  return TRACE_SYSRES (count);
}


int
_gpgme_io_recvmsg (int fd, struct msghdr *msg, int flags)
{
  int nread;
  int saved_errno;
  struct iovec *iov;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_recvmsg", fd,
	      "msg=%p, flags=%i", msg, flags);

  nread = 0;
  iov = msg->msg_iov;
  while (iov < msg->msg_iov + msg->msg_iovlen)
    {
      nread += iov->iov_len;
      iov++;
    }
  
  TRACE_LOG1 ("about to receive %d bytes", nread);

  do
    {
      nread = _gpgme_ath_recvmsg (fd, msg, flags);
    }
  while (nread == -1 && errno == EINTR);
  saved_errno = errno;
  if (nread > 0)
    {
      int nr = nread;

      iov = msg->msg_iov;
      while (nr > 0)
	{
	  int len = nr > iov->iov_len ? iov->iov_len : nr;
	  TRACE_LOGBUF (msg->msg_iov->iov_base, len);
	  iov++;
	  nr -= len;
	}
    }
  errno = saved_errno;
  return TRACE_SYSRES (nread);
}


int
_gpgme_io_sendmsg (int fd, const struct msghdr *msg, int flags)
{
  int nwritten;
  struct iovec *iov;
  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_sendmsg", fd,
	      "msg=%p, flags=%i", msg, flags);

  nwritten = 0;
  iov = msg->msg_iov;
  while (iov < msg->msg_iov + msg->msg_iovlen)
    {
      nwritten += iov->iov_len;
      iov++;
    }

  TRACE_LOG1 ("about to receive %d bytes", nwritten);
  iov = msg->msg_iov;
  while (nwritten > 0)
    {
      int len = nwritten > iov->iov_len ? iov->iov_len : nwritten;
      TRACE_LOGBUF (msg->msg_iov->iov_base, len);
      iov++;
      nwritten -= len;
    }

  do
    {
      nwritten = _gpgme_ath_sendmsg (fd, msg, flags);
    }
  while (nwritten == -1 && errno == EINTR);
  return TRACE_SYSRES (nwritten);
}


int
_gpgme_io_dup (int fd)
{
  int new_fd = dup (fd);

  TRACE1 (DEBUG_SYSIO, "_gpgme_io_dup", fd, "new fd==%i", new_fd);

  return new_fd;
}


int
_gpgme_io_socket (int domain, int type, int proto)
{
  int res;

  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_socket", domain,
	      "type=%i, proto=%i", type, proto);

  res = socket (domain, type, proto);

  return TRACE_SYSRES (res);
}


int
_gpgme_io_connect (int fd, struct sockaddr *addr, int addrlen)
{
  int res;

  TRACE_BEG2 (DEBUG_SYSIO, "_gpgme_io_connect", fd,
	      "addr=%p, addrlen=%i", addr, addrlen);

  res = ath_connect (fd, addr, addrlen);

  return TRACE_SYSRES (res);
}