libp7/src/stream/streams.c

/* ************************************************************************** */
/*                                       _____           _                    */
/*  handle/streams.c                    |_   _|__  _   _| |__   ___ _   _     */
/*  | Project: libp7                      | |/ _ \| | | | '_ \ / _ \ | | |    */
/*                                        | | (_) | |_| | | | |  __/ |_| |    */
/*  By: thomas <thomas@touhey.fr>         |_|\___/ \__,_|_| |_|\___|\__, |.fr */
/*  Last updated: 2017/01/04 15:01:48                               |___/     */
/*                                                                            */
/* ************************************************************************** */
#include <libp7/internals.h>
#include <string.h>

/* ************************************************************************** */
/*  *nix streams device initialization and callbacks                          */
/* ************************************************************************** */
#ifdef __linux__
# include <errno.h>
# include <stdlib.h>
# include <termios.h>
# include <unistd.h>
# include <fcntl.h>
# include <sys/stat.h>

/* the cookie */
# define BUFSIZE 2048
typedef struct {
	int _readfd, _writefd;

	unsigned char _buffer[2048];
	ssize_t _start, _end;
} streams_cookie_t;

/**
 *	p7_streams_read:
 *	Read from a terminal.
 *
 *	@arg	vcookie		the cookie (uncasted).
 *	@arg	data		the data pointer.
 *	@arg	size		the data size.
 *	@arg	timeout		the timeout in milliseconds.
 *	@return				the error code (0 if ok).
 */

static int p7_streams_read(void *vcookie,
	unsigned char *dest, size_t size, unsigned int timeout)
{
	streams_cookie_t *cookie = (streams_cookie_t*)vcookie;
	int fd = cookie->_readfd;
	/* transmit what's already in the buffer */
	if (cookie->_start <= cookie->_end) {
		size_t tocopy = cookie->_end - cookie->_start + 1;
		if (tocopy > size) tocopy = size;

		memcpy(dest, &cookie->_buffer[cookie->_start], tocopy);
		cookie->_start += tocopy;
		dest += tocopy;
		size -= tocopy;
	}

	/* get terminal structure */
	struct termios term;
	if (tcgetattr(cookie->_readfd, &term))
		return (p7_error_nocalc);

	/* set timeout */
	term.c_cc[VTIME] = timeout / 100; /* deciseconds are expected! */
	tcsetattr(cookie->_readfd, TCSANOW, &term);

	/* main receiving loop */
	while (size) {
		/* receive */
		ssize_t recv = read(fd, cookie->_buffer, BUFSIZE);

		/* check error */
		if (recv < 0) switch (errno) {
			case ENODEV: case EIO:
				return (p7_error_nocalc);
			default:
				logr_fatal("error was %d: %s", errno, strerror(errno));
				return (p7_error_unknown);
		}

		/* get the current size to copy */
		size_t tocopy = (size_t)recv;
		if (tocopy > size) tocopy = size;

		/* copy to destination */
		memcpy(dest, cookie->_buffer, tocopy);
		dest += tocopy;
		size -= tocopy;

		/* correct start and end points */
		cookie->_start = tocopy;
		cookie->_end = (size_t)recv - 1;
	}

	/* no error */
	return (0);
}

/**
 *	p7_streams_write:
 *	Write to a terminal.
 *
 *	@arg	vcookie		the cookie (uncasted)
 *	@arg	data		the source.
 *	@arg	size		the source size.
 *	@return				the error (0 if ok).
 */

static int p7_streams_write(void *vcookie,
	const unsigned char *data, size_t size)
{
	streams_cookie_t *cookie = (streams_cookie_t*)vcookie;
	int fd = cookie->_writefd;

	/* set timeout */
	struct termios term;
	if (!tcgetattr(cookie->_writefd, &term)) {
		term.c_cc[VTIME] = 0;
		term.c_cc[VMIN] = 0;
		tcsetattr(cookie->_writefd, TCSANOW, &term);
	}

	/* send */
	while (size) {
		ssize_t wr = write(fd, data, size);
		if (wr < 0) break;
		size -= (size_t)wr;
	}

	/* be sure it's written, or check the error */
	if (size || tcdrain(fd)) switch (errno) {
		case ENODEV:
			return (p7_error_nocalc);
		default:
			logr_fatal("errno was %d: %s", errno, strerror(errno));
			return (p7_error_unknown);
	}

	/* no error! */
	return (0);
}

/**
 *	p7_streams_setcomm:
 *	Set the communication status.
 *
 *	@arg	vcookie		the cookie (uncasted).
 *	@arg	speed		the speed.
 *	@arg	parity		the parity.
 *	@arg	stopbits	the number of stop bits.
 *	@return				the error code (0 if ok).
 */

static int p7_streams_setcomm(void *vcookie,
	int speed, int parity, int stopbits)
{
	streams_cookie_t *cookie = (streams_cookie_t*)vcookie;

	/* get attributes */
	logr_info("Setting terminal properties: %d baud/s, %d stop bits, %s parity",
		speed, stopbits, !parity ? "NONE" : (parity % 2) ? "ODD" : "EVEN");
	struct termios rdterm, wrterm;
	if (tcgetattr(cookie->_readfd, &rdterm)
	 || tcgetattr(cookie->_writefd, &wrterm)) {
		logr_warn("Could not get read or write terminal props, nevermind.");
		return (0);
	}

	/* prepare values */
	speed = (speed == P7_B9600) ? B9600 : B19200;

	/* set attributes */
	cfsetspeed(&rdterm, speed);
	cfsetspeed(&wrterm, speed);
	rdterm.c_cflag &= ~(PARENB | PARODD | CSTOPB);
	rdterm.c_cflag |= (!!parity * PARENB) | (PARODD * (parity % 2))
		| (CSTOPB * (stopbits - 1));
	wrterm.c_cflag &= ~(PARENB | PARODD | CSTOPB);
	wrterm.c_cflag |= (!!parity * PARENB) | (PARODD * (parity % 2))
		| (CSTOPB * (stopbits - 1));

	/* save attributes */
	tcsetattr(cookie->_readfd, TCSADRAIN, &rdterm);
	tcsetattr(cookie->_writefd, TCSADRAIN, &wrterm);

	/* no error */
	return (0);
}

/**
 *	p7_streams_close:
 *	Close the cookie.
 *
 *	@arg	vcookie		the cookie (uncasted).
 *	@return				the error code (0 if ok).
 */

static int p7_streams_close(void *vcookie)
{
	streams_cookie_t *cookie = (streams_cookie_t*)vcookie;
	close(cookie->_readfd);
	close(cookie->_writefd);
	free(cookie);
	return (0);
}

/**
 *	p7_fdinit:
 *	Initialize libp7 with char device.
 *
 *	@arg	handle		the handle to create
 *	@arg	flags		the flags.
 *	@arg	name		the name of the handle.
 *	@arg	readfd		the read file descriptor.
 *	@arg	writefd		the write file descriptor.
 *	@return				the error (0 if ok)
 */

int p7_fdinit(p7_handle_t **handle, unsigned int flags,
	const char *name, int readfd, int writefd)
{
	int err;
	/* check if it's valid devices */
	if (readfd < 0 || writefd < 0)
		return (p7_error_nostream);

	/* get attributes (while checking file descriptors are terminals) */
	struct termios rdterm, wrterm;
	if (tcgetattr(readfd, &rdterm) || tcgetattr(writefd, &wrterm)) {
		logr_fatal("Read or write streams are not terminals, abandon ship!");
		return (p7_error_nochar);
	}

	/* set read thingy attribute */
	cfmakeraw(&rdterm);
	rdterm.c_iflag |= IGNPAR;
	rdterm.c_cflag |= CS8 | CLOCAL | CREAD;
	rdterm.c_cc[VMIN] = 0;
	tcsetattr(readfd, TCSANOW, &rdterm);

	/* set write thingy attribute */
	cfmakeraw(&wrterm);
	wrterm.c_cflag |= CS8 | CLOCAL | CREAD;
	tcsetattr(writefd, TCSANOW, &wrterm);

	/* try to read */
	if (read(readfd, NULL, 0) < 0) {
		err = p7_error_noread;
		goto test_failed;
	} else if (write(writefd, NULL, 0) < 0) {
		err = p7_error_nowrite;
		goto test_failed;
	}

	/* allocate cookie */
	streams_cookie_t *cookie = malloc(sizeof(streams_cookie_t));
	if (!cookie) return (p7_error_alloc);
	*cookie = (streams_cookie_t){
		._readfd = readfd,
		._writefd = writefd,
		._start = 0,
		._end = -1
	};

	/* init for real */
	logr_info("Initializing STREAMS stream with fds: (%d,%d)", readfd, writefd);
	return (p7_sinit(handle, flags, name, (p7_stream_t){
		.cookie = cookie,
		.read = p7_streams_read,
		.write = p7_streams_write,
		.setcomm = p7_streams_setcomm,
		.close = p7_streams_close
	}));

test_failed:
	close(readfd);
	close(writefd);
	return (err);
}

/* ************************************************************************** */
/*  Use a file descriptor on other systems (placebo)                          */
/* ************************************************************************** */
#else
/**
 *	p7_fdinit:
 *	Initialize libp7 with a file descriptor. Placebo.
 *
 *	@arg	handle		the handle to create
 *	@arg	flags		the flags.
 *	@arg	name		the name of the handle.
 *	@arg	readfd		the read file descriptor.
 *	@arg	writefd		the write file descriptor.
 *	@return				the error (0 if ok)
 */

int p7_fdinit(p7_handle_t **handle, unsigned int flags,
	const char *name, int readfd, int writefd)
{
	(void)handle;
	(void)flags;
	(void)name;
	(void)readfd;
	(void)writefd;
	return (p7_error_nocalc);
}

#endif