posix-io.c
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	/* 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_stdout = 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 == 1)
	seen_stdout = 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_stdout \|\| !seen_stderr)
	{
	fd = open ("/dev/null", O_RDWR);
	if (fd == -1)
	{
	/* The debug file descriptor is not dup'ed, so we
	can't do a trace output. */
	_exit (8);
	}
	/* Make sure that the process has connected stdin. */
	if (! seen_stdin && fd != 0)
	{
	if (dup2 (fd, 0) == -1)
	_exit (8);
	}
	if (! seen_stdout && fd != 1)
	{
	if (dup2 (fd, 1) == -1)
	_exit (8);
	}
	if (! seen_stderr && fd != 2)
	{
	if (dup2 (fd, 2) == -1)
	_exit (8);
	}
	if (fd != 0 && fd != 1 && fd != 2)
	close (fd);
	}

	execv (path, (char const ) argv);
	/* Hmm: in that case we could write a special status code to the
	status-pipe. */
	_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);
	}

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