view loadtools/tpinterf2.c @ 407:19e5a3e2f9c0

fcup-settime: moved time() retrieval a little closer to the output A fundamental problem with all simple time transfer tools is that there is always some delay between the time retrieval on the source system and that transmitted time being set on the destination, and the resulting time on the destination system is off by that delay amount. This delay cannot be fully eliminated when working in a simple environment like ours, but we should make our best effort to minimize it. In the present case, moving the atinterf_init() call before the time() retrieval should make a teensy-tiny improvement.
author Mychaela Falconia <falcon@freecalypso.org>
date Sat, 11 Aug 2018 21:52:17 +0000
parents e7502631a0f9
children 8d7dcfd9df53
line wrap: on
line source

/*
 * This module provides a more advanced target interface function
 * than tpinterf.c - programmatic capture of target responses,
 * for dumps etc.  It will be linked by fc-loadtool, but not fc-chainload.
 */

#include <sys/types.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <stdlib.h>

extern int errno;

extern int target_fd;

/*
 * This functions reads the serial output from the target until a
 * '=' prompt is received.  All intermediate output is parsed into
 * lines and passed to a callback function.
 *
 * The callback function is called with a pointer to each received
 * line, stored in a buffer ending in NUL, with CRLF stripped.
 * The callback function is expected to return an int.  If the
 * callback return value is negative, this function returns immediately
 * with that negative value.  If the callback return value is positive
 * or zero, it is added to an accumulator.
 *
 * Termination: this function returns when it has received a '=' at
 * the beginning of a line (return value is the callback return
 * accumulator, or 0 if no lines came), if the callback returns a
 * negative value (that value is returned), or if an error is detected
 * within this function (return value -1, and an error message
 * printed on stderr).
 */
tpinterf_capture_output(timeout, callback)
	int timeout;	/* seconds */
	int (*callback)();
{
	char buf[512], *cp;
	char line[1024], *dp = line;
	fd_set fds;
	struct timeval tv;
	int cc, linelen = 0;
	int totout = 0, cbret;

	for (;;) {
		FD_ZERO(&fds);
		FD_SET(target_fd, &fds);
		tv.tv_sec = timeout;
		tv.tv_usec = 0;
		cc = select(target_fd+1, &fds, NULL, NULL, &tv);
		if (cc < 0) {
			if (errno == EINTR)
				continue;
			perror("select");
			return(-1);
		}
		if (cc < 1) {
			fprintf(stderr,
		"error: timeout waiting for \'=\' prompt from target\n");
			return(-1);
		}
		cc = read(target_fd, buf, sizeof buf);
		if (cc <= 0) {
			perror("read after successful select");
			return(-1);
		}
		for (cp = buf; cc; cp++) {
			cc--;
			if (*cp == '=' && !linelen && !cc)
				return(totout);
			if (*cp == '\r')
				continue;
			if (*cp == '\n') {
				*dp = '\0';
				cbret = callback(line);
				if (cbret < 0)
					return(cbret);
				totout += cbret;
				dp = line;
				linelen = 0;
				continue;
			}
			*dp++ = *cp;
			linelen++;
			if (linelen >= sizeof line) {
				fprintf(stderr,
			"error: target response line length exceeds buffer\n");
				return(-1);
			}
		}
	}
}

/* single line response capture mechanism */
/* same line buffer size as in tpinterf_capture_output() */
char target_response_line[1024];

static
oneline_catcher(linein)
	char *linein;
{
	strcpy(target_response_line, linein);
	return(1);
}

tpinterf_capture_output_oneline(timeout)
{
	return tpinterf_capture_output(timeout, oneline_catcher);
}