procps/watch.c

/*
 * watch -- execute a program repeatedly, displaying output fullscreen
 *
 * Based on the original 1991 'watch' by Tony Rems <rembo@unisoft.com>
 * (with mods and corrections by Francois Pinard).
 *
 * Substantially reworked, new features (differences option, SIGWINCH
 * handling, unlimited command length, long line handling) added Apr
 * 1999 by Mike Coleman <mkc@acm.org>.
 *
 * Changes by Albert Cahalan, 2002-2003.
 * stderr handling, exec, and beep option added by Morty Abzug, 2008
 * Unicode Support added by Jarrod Lowe <procps@rrod.net> in 2009.
 */

#include "config.h"
#include "proc/procps.h"
#include <ctype.h>
#include <errno.h>
#include <errno.h>
#include <getopt.h>
#include <locale.h>
#include <locale.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <termios.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>
#ifdef WITH_WATCH8BIT
#include <wchar.h>
#include <ncursesw/ncurses.h>
#else
#include <ncurses.h>
#endif	/* WITH_WATCH8BIT */

#ifdef FORCE_8BIT
#undef isprint
#define isprint(x) ( (x>=' '&&x<='~') || (x>=0xa0) )
#endif

static int curses_started = 0;
static int height = 24, width = 80;
static int screen_size_changed = 0;
static int first_screen = 1;
static int show_title = 2;	/* number of lines used, 2 or 0 */
static int precise_timekeeping = 0;

#define min(x,y) ((x) > (y) ? (y) : (x))
#define MAX_ANSIBUF 10

static void __attribute__ ((__noreturn__))
    usage(FILE * out)
{
	fprintf(out,
		"\nUsage: %s [options] command\n"
		"\nOptions:\n", program_invocation_short_name);
	fprintf(out,
		"  -b, --beep             beep if command has a non-zero exit\n"
		"  -c, --color            interpret ANSI color sequences\n"
		"  -e, --errexit          exit if command has a non-zero exit\n"
		"  -f, --differences      highlight changes between updates\n"
		"  -n, --interval <secs>  seconds to wait between updates\n"
		"  -p, --precise          attempt run command in precise intervals\n"
		"  -t, --no-title         turn off header\n"
		"  -x, --exec             pass command to exec instead of \"sh -c\"\n"
		"  -h, --help             display this help text\n"
		"  -v, --version          display version information and exit\n");
	fprintf(out, "\nFor more information see watch(1).\n");

	exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
}

static void init_ansi_colors(void)
{
	int i;
	short ncurses_colors[] = {
		COLOR_BLACK, COLOR_RED, COLOR_GREEN, COLOR_YELLOW, COLOR_BLUE,
		COLOR_MAGENTA, COLOR_CYAN, COLOR_WHITE
	};

	for (i = 0; i < 8; i++)
		init_pair(i + 1, ncurses_colors[i], -1);
}

static void set_ansi_attribute(const int attrib)
{
	switch (attrib) {
	case -1:
		return;
	case 0:
		standend();
		return;
	case 1:
		attrset(A_BOLD);
		return;
	}
	if (attrib >= 30 && attrib <= 37) {
		color_set(attrib - 29, NULL);
		return;
	}
}

static void process_ansi(FILE * fp)
{
	int i, c, num1, num2;
	char buf[MAX_ANSIBUF];
	char *nextnum;

	c = getc(fp);
	if (c != '[') {
		ungetc(c, fp);
		return;
	}
	for (i = 0; i < MAX_ANSIBUF; i++) {
		c = getc(fp);
		/* COLOUR SEQUENCE ENDS in 'm' */
		if (c == 'm') {
			buf[i] = '\0';
			break;
		}
		if (c < '0' && c > '9' && c != ';') {
			while (--i >= 0)
				ungetc(buf[i], fp);
			return;
		}
		buf[i] = (char)c;
	}
	num1 = strtol(buf, &nextnum, 10);
	if (nextnum != buf && nextnum[0] != '\0')
		num2 = strtol(nextnum + 1, NULL, 10);
	else
		num2 = -1;
	set_ansi_attribute(num1);
	set_ansi_attribute(num2);
}

static void __attribute__ ((__noreturn__)) do_exit(int status)
{
	if (curses_started)
		endwin();
	exit(status);
}

/* signal handler */
static void die(int notused __attribute__ ((__unused__)))
{
	do_exit(EXIT_SUCCESS);
}

static void winch_handler(int notused __attribute__ ((__unused__)))
{
	screen_size_changed = 1;
}

static char env_col_buf[24];
static char env_row_buf[24];
static int incoming_cols;
static int incoming_rows;

static void get_terminal_size(void)
{
	struct winsize w;
	if (!incoming_cols) {
		/* have we checked COLUMNS? */
		const char *s = getenv("COLUMNS");
		incoming_cols = -1;
		if (s && *s) {
			long t;
			char *endptr;
			t = strtol(s, &endptr, 0);
			if (!*endptr && (t > 0) && (t < (long)666))
				incoming_cols = (int)t;
			width = incoming_cols;
			snprintf(env_col_buf, sizeof env_col_buf, "COLUMNS=%d",
				 width);
			putenv(env_col_buf);
		}
	}
	if (!incoming_rows) {
		/* have we checked LINES? */
		const char *s = getenv("LINES");
		incoming_rows = -1;
		if (s && *s) {
			long t;
			char *endptr;
			t = strtol(s, &endptr, 0);
			if (!*endptr && (t > 0) && (t < (long)666))
				incoming_rows = (int)t;
			height = incoming_rows;
			snprintf(env_row_buf, sizeof env_row_buf, "LINES=%d",
				 height);
			putenv(env_row_buf);
		}
	}
	if (incoming_cols < 0 || incoming_rows < 0) {
		if (ioctl(2, TIOCGWINSZ, &w) == 0) {
			if (incoming_rows < 0 && w.ws_row > 0) {
				height = w.ws_row;
				snprintf(env_row_buf, sizeof env_row_buf,
					 "LINES=%d", height);
				putenv(env_row_buf);
			}
			if (incoming_cols < 0 && w.ws_col > 0) {
				width = w.ws_col;
				snprintf(env_col_buf, sizeof env_col_buf,
					 "COLUMNS=%d", width);
				putenv(env_col_buf);
			}
		}
	}
}

/* get current time in usec */
typedef unsigned long long watch_usec_t;
#define USECS_PER_SEC (1000000ull)
watch_usec_t get_time_usec()
{
	struct timeval now;
	gettimeofday(&now, NULL);
	return USECS_PER_SEC * now.tv_sec + now.tv_usec;
}

#ifdef WITH_WATCH8BIT
/* read a wide character from a popen'd stream */
#define MAX_ENC_BYTES 16
wint_t my_getwc(FILE * s);
wint_t my_getwc(FILE * s)
{
	/* assuming no encoding ever consumes more than 16 bytes */
	char i[MAX_ENC_BYTES];
	int byte = 0;
	int convert;
	int x;
	wchar_t rval;
	while (1) {
		i[byte] = getc(s);
		if (i[byte] == EOF) {
			return WEOF;
		}
		byte++;
		errno = 0;
		mbtowc(NULL, NULL, 0);
		convert = mbtowc(&rval, i, byte);
		x = errno;
		if (convert > 0) {
			/* legal conversion */
			return rval;
		}
		if (byte == MAX_ENC_BYTES) {
			while (byte > 1) {
				/* at least *try* to fix up */
				ungetc(i[--byte], s);
			}
			errno = -EILSEQ;
			return WEOF;
		}
	}
}
#endif	/* WITH_WATCH8BIT */

int main(int argc, char *argv[])
{
	int optc;
	int option_differences = 0,
	    option_differences_cumulative = 0,
	    option_exec = 0,
	    option_beep = 0,
	    option_color = 0,
	    option_errexit = 0, option_help = 0, option_version = 0;
	double interval = 2;
	char *command;
	char **command_argv;
	int command_length = 0;	/* not including final \0 */
	watch_usec_t next_loop;	/* next loop time in us, used for precise time
				 * keeping only */
#ifdef WITH_WATCH8BIT
	wchar_t *wcommand = NULL;
	int wcommand_columns = 0;	/* not including final \0 */
	int wcommand_characters = 0;	/* not including final \0 */
#endif	/* WITH_WATCH8BIT */

	int pipefd[2];
	int status;
	pid_t child;

	static struct option longopts[] = {
		{"color", no_argument, 0, 'c'},
		{"differences", optional_argument, 0, 'd'},
		{"help", no_argument, 0, 'h'},
		{"interval", required_argument, 0, 'n'},
		{"beep", no_argument, 0, 'b'},
		{"errexit", no_argument, 0, 'e'},
		{"exec", no_argument, 0, 'x'},
		{"precise", no_argument, 0, 'p'},
		{"no-title", no_argument, 0, 't'},
		{"version", no_argument, 0, 'v'},
		{0, 0, 0, 0}
	};

	setlocale(LC_ALL, "");

	while ((optc =
		getopt_long(argc, argv, "+bced::hn:pvtx", longopts, (int *)0))
	       != EOF) {
		switch (optc) {
		case 'b':
			option_beep = 1;
			break;
		case 'c':
			option_color = 1;
			break;
		case 'd':
			option_differences = 1;
			if (optarg)
				option_differences_cumulative = 1;
			break;
		case 'e':
			option_errexit = 1;
			break;
		case 't':
			show_title = 0;
			break;
		case 'x':
			option_exec = 1;
			break;
		case 'n':
			{
				char *str;
				interval = strtod(optarg, &str);
				if (!*optarg || *str)
					usage(stderr);
				if (interval < 0.1)
					interval = 0.1;
				if (interval > ~0u / 1000000)
					interval = ~0u / 1000000;
			}
			break;
		case 'p':
			precise_timekeeping = 1;
			break;
		case 'h':
			usage(stdout);
			break;
		case 'v':
			display_version();
			return EXIT_SUCCESS;
		default:
			usage(stderr);
			break;
		}
	}

	if (optind >= argc)
		usage(stderr);

	/* save for later */
	command_argv = &(argv[optind]);

	command = strdup(argv[optind++]);
	command_length = strlen(command);
	for (; optind < argc; optind++) {
		char *endp;
		int s = strlen(argv[optind]);
		/* space and \0 */
		command = realloc(command, command_length + s + 2);
		endp = command + command_length;
		*endp = ' ';
		memcpy(endp + 1, argv[optind], s);
		/* space then string length */
		command_length += 1 + s;
		command[command_length] = '\0';
	}

#ifdef WITH_WATCH8BIT
	/* convert to wide for printing purposes */
	/*mbstowcs(NULL, NULL, 0); */
	wcommand_characters = mbstowcs(NULL, command, 0);
	if (wcommand_characters < 0) {
		fprintf(stderr, "Unicode Handling Error\n");
		exit(EXIT_FAILURE);
	}
	wcommand =
	    (wchar_t *) malloc((wcommand_characters + 1) * sizeof(wcommand));
	if (wcommand == NULL) {
		fprintf(stderr, "Unicode Handling Error (malloc)\n");
		exit(EXIT_FAILURE);
	}
	mbstowcs(wcommand, command, wcommand_characters + 1);
	wcommand_columns = wcswidth(wcommand, -1);
#endif	/* WITH_WATCH8BIT */

	get_terminal_size();

	/* Catch keyboard interrupts so we can put tty back in a sane
	 * state.  */
	signal(SIGINT, die);
	signal(SIGTERM, die);
	signal(SIGHUP, die);
	signal(SIGWINCH, winch_handler);

	/* Set up tty for curses use.  */
	curses_started = 1;
	initscr();
	if (option_color) {
		if (has_colors()) {
			start_color();
			use_default_colors();
			init_ansi_colors();
		} else
			option_color = 0;
	}
	nonl();
	noecho();
	cbreak();

	if (precise_timekeeping)
		next_loop = get_time_usec();

	for (;;) {
		time_t t = time(NULL);
		char *ts = ctime(&t);
		int tsl = strlen(ts);
		char *header;
		FILE *p;
		int x, y;
		int oldeolseen = 1;

		if (screen_size_changed) {
			get_terminal_size();
			resizeterm(height, width);
			clear();
			/* redrawwin(stdscr); */
			screen_size_changed = 0;
			first_screen = 1;
		}

		if (show_title) {
			/*
			 * left justify interval and command, right
			 * justify time, clipping all to fit window
			 * width
			 */
			int hlen = asprintf(&header, "Every %.1fs: ", interval);

			/*
			 * the rules:
			 *   width < tsl : print nothing
			 *   width < tsl + hlen + 1: print ts
			 *   width = tsl + hlen + 1: print header, ts
			 *   width < tsl + hlen + 4: print header, ..., ts
			 *   width < tsl + hlen +    wcommand_columns: print
			 *                           header, truncated wcommand,
			 *                           ..., ts
			 *   width > "": print header, wcomand, ts
			 * this is slightly different from how it used to be
			 */
			if (width >= tsl) {
				if (width >= tsl + hlen + 1) {
					mvaddstr(0, 0, header);
					if (width >= tsl + hlen + 2) {
						if (width < tsl + hlen + 4) {
							mvaddstr(0,
								 width - tsl -
								 4, "...  ");
						} else {
#ifdef WITH_WATCH8BIT
							if (width <
							    tsl + hlen +
							    wcommand_columns) {
								/* print truncated */
								int avail_columns = width - tsl - hlen;
								int using_columns = wcommand_columns;
								int using_characters = wcommand_characters;
								while (using_columns > avail_columns - 4) {
									using_characters--;
									using_columns
									    =
									    wcswidth
									    (wcommand,
									     using_characters);
								}
								mvaddnwstr(0,
									   hlen,
									   wcommand,
									   using_characters);
								mvaddstr(0,
									 width -
									 tsl -
									 4,
									 "... ");
							} else {
								mvaddwstr(0,
									  hlen,
									  wcommand);
							}
#else
							mvaddnstr(0, hlen,
								  command,
								  width - tsl -
								  hlen);
#endif	/* WITH_WATCH8BIT */
						}
					}
				}
				mvaddstr(0, width - tsl + 1, ts);
			}

			free(header);
		}

		/* allocate pipes */
		if (pipe(pipefd) < 0)
			err(7, "pipe");

		/* flush stdout and stderr, since we're about to do fd stuff */
		fflush(stdout);
		fflush(stderr);

		/* fork to prepare to run command */
		child = fork();

		if (child < 0) {	/* fork error */
			err(2, "fork");
		} else if (child == 0) {	/* in child */
			close(pipefd[0]);	/* child doesn't need read side of pipe */
			close(1);		/* prepare to replace stdout with pipe */
			if (dup2(pipefd[1], 1) < 0) {	/* replace stdout with write side of pipe */
				err(3, "dup2");
			}
			dup2(1, 2);	/* stderr should default to stdout */

			if (option_exec) {	/* pass command to exec instead of system */
				if (execvp(command_argv[0], command_argv) == -1) {
					err(4, "exec");
				}
			} else {
				status = system(command);	/* watch manpage promises sh quoting */

				/* propagate command exit status as child exit status */
				if (!WIFEXITED(status)) {	/* child exits nonzero if command does */
					exit(EXIT_FAILURE);
				} else {
					exit(WEXITSTATUS(status));
				}
			}

		}

		/* otherwise, we're in parent */
		close(pipefd[1]);	/* close write side of pipe */
		if ((p = fdopen(pipefd[0], "r")) == NULL)
			err(5, "fdopen");

		for (y = show_title; y < height; y++) {
			int eolseen = 0, tabpending = 0;
#ifdef WITH_WATCH8BIT
			wint_t carry = WEOF;
#endif	/* WITH_WATCH8BIT */
			for (x = 0; x < width; x++) {
#ifdef WITH_WATCH8BIT
				wint_t c = ' ';
#else
				int c = ' ';
#endif	/* WITH_WATCH8BIT */
				int attr = 0;

				if (!eolseen) {
					/* if there is a tab pending, just
					 * spit spaces until the next stop
					 * instead of reading characters */
					if (!tabpending)
#ifdef WITH_WATCH8BIT
						do {
							if (carry == WEOF) {
								c = my_getwc(p);
							} else {
								c = carry;
								carry = WEOF;
							}
						} while (c != WEOF
							 && !isprint(c)
							 && c < 12
							 && wcwidth(c) == 0
							 && c != L'\n'
							 && c != L'\t'
							 && (c != L'\033'
							     || option_color !=
							     1));
#else
						do
							c = getc(p);
						while (c != EOF && !isprint(c)
						       && c != '\n'
						       && c != '\t'
						       && (c != L'\033'
							   || option_color !=
							   1));
#endif	/* WITH_WATCH8BIT */
					if (c == L'\033' && option_color == 1) {
						x--;
						process_ansi(p);
						continue;
					}
					if (c == L'\n')
						if (!oldeolseen && x == 0) {
							x = -1;
							continue;
						} else
							eolseen = 1;
					else if (c == L'\t')
						tabpending = 1;
#ifdef WITH_WATCH8BIT
					if (x == width - 1 && wcwidth(c) == 2) {
						y++;
						x = -1;		/* process this double-width */
						carry = c;	/* character on the next line */
						continue;	/* because it won't fit here */
					}
					if (c == WEOF || c == L'\n'
					    || c == L'\t')
						c = L' ';
#else
					if (c == EOF || c == '\n' || c == '\t')
						c = ' ';
#endif	/* WITH_WATCH8BIT */
					if (tabpending && (((x + 1) % 8) == 0))
						tabpending = 0;
				}
				move(y, x);
				if (option_differences) {
#ifdef WITH_WATCH8BIT
					cchar_t oldc;
					in_wch(&oldc);
					attr = !first_screen
					    && ((wchar_t) c != oldc.chars[0]
						||
						(option_differences_cumulative
						 && (oldc.
						     attr & A_ATTRIBUTES)));
#else
					chtype oldch = inch();
					unsigned char oldc = oldch & A_CHARTEXT;
					attr = !first_screen
					    && ((unsigned char)c != oldc
						||
						(option_differences_cumulative
						 && (oldch & A_ATTRIBUTES)));
#endif	/* WITH_WATCH8BIT */
				}
				if (attr)
					standout();
#ifdef WITH_WATCH8BIT
				addnwstr((wchar_t *) & c, 1);
#else
				addch(c);
#endif	/* WITH_WATCH8BIT */
				if (attr)
					standend();
#ifdef WITH_WATCH8BIT
				if (wcwidth(c) == 0) {
					x--;
				}
				if (wcwidth(c) == 2) {
					x++;
				}
#endif	/* WITH_WATCH8BIT */
			}
			oldeolseen = eolseen;
		}

		fclose(p);

		/* harvest child process and get status, propagated from command */
		if (waitpid(child, &status, 0) < 0)
			err(8, "waitpid");

		/* if child process exited in error, beep if option_beep is set */
		if ((!WIFEXITED(status) || WEXITSTATUS(status))) {
			if (option_beep)
				beep();
			if (option_errexit)
				exit(8);
		}

		first_screen = 0;
		refresh();
		if (precise_timekeeping) {
			watch_usec_t cur_time = get_time_usec();
			next_loop += USECS_PER_SEC * interval;
			if (cur_time < next_loop)
				usleep(next_loop - cur_time);
		} else
			usleep(interval * 1000000);
	}

	endwin();

	return EXIT_SUCCESS;
}