1/* vi: set sw=4 ts=4: */
2/*
3 * Mini watch implementation for busybox
4 *
5 * Copyright (C) 2001 by Michael Habermann <mhabermann@gmx.de>
6 * Copyrigjt (C) Mar 16, 2003 Manuel Novoa III   (mjn3@codepoet.org)
7 *
8 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
9 */
10
11/* BB_AUDIT SUSv3 N/A */
12/* BB_AUDIT GNU defects -- only option -n is supported. */
13
14#include "libbb.h"
15
16// procps 2.0.18:
17// watch [-d] [-n seconds]
18//   [--differences[=cumulative]] [--interval=seconds] command
19//
20// procps-3.2.3:
21// watch [-dt] [-n seconds]
22//   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
23//
24// (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
25
26int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
27int watch_main(int argc UNUSED_PARAM, char **argv)
28{
29	unsigned opt;
30	unsigned period = 2;
31	unsigned width, new_width;
32	char *header;
33	char *cmd;
34
35#if 0 // maybe ENABLE_DESKTOP?
36	// procps3 compat - "echo TEST | watch cat" doesn't show TEST:
37	close(STDIN_FILENO);
38	xopen("/dev/null", O_RDONLY);
39#endif
40
41	opt_complementary = "-1:n+"; // at least one param; -n NUM
42	// "+": stop at first non-option (procps 3.x only)
43	opt = getopt32(argv, "+dtn:", &period);
44	argv += optind;
45
46	// watch from both procps 2.x and 3.x does concatenation. Example:
47	// watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
48	cmd = *argv;
49	while (*++argv)
50		cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
51
52	width = (unsigned)-1; // make sure first time new_width != width
53	header = NULL;
54	while (1) {
55		/* home; clear to the end of screen */
56		printf("\033[H""\033[J");
57		if (!(opt & 0x2)) { // no -t
58			const unsigned time_len = sizeof("1234-67-90 23:56:89");
59			time_t t;
60
61			// STDERR_FILENO is procps3 compat:
62			// "watch ls 2>/dev/null" does not detect tty size
63			get_terminal_width_height(STDERR_FILENO, &new_width, NULL);
64			if (new_width != width) {
65				width = new_width;
66				free(header);
67				header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
68			}
69			time(&t);
70			if (time_len < width)
71				strftime(header + width - time_len, time_len,
72					"%Y-%m-%d %H:%M:%S", localtime(&t));
73
74			// compat: empty line between header and cmd output
75			printf("%s\n\n", header);
76		}
77		fflush_all();
78		// TODO: 'real' watch pipes cmd's output to itself
79		// and does not allow it to overflow the screen
80		// (taking into account linewrap!)
81		system(cmd);
82		sleep(period);
83	}
84	return 0; // gcc thinks we can reach this :)
85}
86