tls: prepare for ECDH_anon ciphers
[oweals/busybox.git] / procps / watch.c
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 source tree.
9  */
10 //config:config WATCH
11 //config:       bool "watch (4.1 kb)"
12 //config:       default y
13 //config:       help
14 //config:       watch is used to execute a program periodically, showing
15 //config:       output to the screen.
16
17 //applet:IF_WATCH(APPLET(watch, BB_DIR_BIN, BB_SUID_DROP))
18
19 //kbuild:lib-$(CONFIG_WATCH) += watch.o
20
21 //usage:#define watch_trivial_usage
22 //usage:       "[-n SEC] [-t] PROG ARGS"
23 //usage:#define watch_full_usage "\n\n"
24 //usage:       "Run PROG periodically\n"
25 //usage:     "\n        -n      Loop period in seconds (default 2)"
26 //usage:     "\n        -t      Don't print header"
27 //usage:
28 //usage:#define watch_example_usage
29 //usage:       "$ watch date\n"
30 //usage:       "Mon Dec 17 10:31:40 GMT 2000\n"
31 //usage:       "Mon Dec 17 10:31:42 GMT 2000\n"
32 //usage:       "Mon Dec 17 10:31:44 GMT 2000"
33
34 /* BB_AUDIT SUSv3 N/A */
35 /* BB_AUDIT GNU defects -- only option -n is supported. */
36
37 #include "libbb.h"
38
39 #define ESC "\033"
40
41 // procps 2.0.18:
42 // watch [-d] [-n seconds]
43 //   [--differences[=cumulative]] [--interval=seconds] command
44 //
45 // procps-3.2.3:
46 // watch [-dt] [-n seconds]
47 //   [--differences[=cumulative]] [--interval=seconds] [--no-title] command
48 //
49 // (procps 3.x and procps 2.x are forks, not newer/older versions of the same)
50
51 int watch_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
52 int watch_main(int argc UNUSED_PARAM, char **argv)
53 {
54         unsigned opt;
55         unsigned period = 2;
56         unsigned width, new_width;
57         char *header;
58         char *cmd;
59
60 #if 0 // maybe ENABLE_DESKTOP?
61         // procps3 compat - "echo TEST | watch cat" doesn't show TEST:
62         close(STDIN_FILENO);
63         xopen("/dev/null", O_RDONLY);
64 #endif
65
66         // "+": stop at first non-option (procps 3.x only); -n NUM
67         // at least one param
68         opt = getopt32(argv, "^+" "dtn:+" "\0" "-1", &period);
69         argv += optind;
70
71         // watch from both procps 2.x and 3.x does concatenation. Example:
72         // watch ls -l "a /tmp" "2>&1" - ls won't see "a /tmp" as one param
73         cmd = *argv;
74         while (*++argv)
75                 cmd = xasprintf("%s %s", cmd, *argv); // leaks cmd
76
77         width = (unsigned)-1; // make sure first time new_width != width
78         header = NULL;
79         while (1) {
80                 /* home; clear to the end of screen */
81                 printf(ESC"[H" ESC"[J");
82                 if (!(opt & 0x2)) { // no -t
83                         const unsigned time_len = sizeof("1234-67-90 23:56:89");
84
85                         // STDERR_FILENO is procps3 compat:
86                         // "watch ls 2>/dev/null" does not detect tty size
87                         new_width = get_terminal_width(STDERR_FILENO);
88                         if (new_width != width) {
89                                 width = new_width;
90                                 free(header);
91                                 header = xasprintf("Every %us: %-*s", period, (int)width, cmd);
92                         }
93                         if (time_len < width) {
94                                 strftime_YYYYMMDDHHMMSS(
95                                         header + width - time_len,
96                                         time_len,
97                                         /*time_t*:*/ NULL
98                                 );
99                         }
100
101                         // compat: empty line between header and cmd output
102                         printf("%s\n\n", header);
103                 }
104                 fflush_all();
105                 // TODO: 'real' watch pipes cmd's output to itself
106                 // and does not allow it to overflow the screen
107                 // (taking into account linewrap!)
108                 system(cmd);
109                 sleep(period);
110         }
111         return 0; // gcc thinks we can reach this :)
112 }