Re: [PATCH] dmesg colorized output

Karel Zak
2012-10-10T09:19:28Z

On Wed, Oct 10, 2012 at 09:44:05AM +0200, Ondrej Oprala wrote:
> new file mode 100644
> index 0000000..90b62a7
> --- /dev/null
> +++ b/include/colors.h
> @@ -0,0 +1,19 @@

Please, see another files in include/.

#ifndef UTIL_LINUX_COLOR_H
#define UTIL_LINUX_COLOR_H

> +/*
> + * Copyright (C) 2012 Ondrej Oprala <ooprala@redhat.com>
> + *
> + * This file may be distributed under the terms of the
> + * GNU Lesser General Public License.
> + */
> +
> +#include <stdio.h>
> +#include <unistd.h>
> +#define CLR_RST "\033[0m"

#define UL_COLOR_RESET

to keep it readable. It would be also nice to have macros for
individual colors (UL_COLOR_{RED,YELLOW,BLUE,...} and extra modes like
bold.

(It's also possible to set background colors, but I guess that
foreground colors are enough for our utils.)

> --- /dev/null
> +++ b/lib/colors.c
> @@ -0,0 +1,20 @@
> +/*
> + * Copyright (C) 2012 Ondrej Oprala <ooprala@redhat.com>
> + *
> + * This file may be distributed under the terms of the
> + * GNU Lesser General Public License.
> + */
> +
> +#include "colors.h"
> +
> +void set_clr(const char *clr_scheme, FILE *out)

color_enable()

Is it necessary to care about "out"? Maybe we can assume that the
output is stdout.

> +{
> + if (isatty(fileno(out)))
> + fprintf(out, clr_scheme);
> +}

if I good remember than isatty() is internally implemented by any
ioctl(). It would be probably better to have something like:

int colors_init();

where we check all necessary terminal features and initialize a
global variable, so in color_enable/disable() we will check the
variable only.

> +void rst_clr(FILE *out)

color_disable()

Maybe for the functions names we should also use ul_ prefix to avoid
collisions (for example ncurses library also uses pretty generic names
for color functions).

> +{
> + if (isatty(fileno(out)))
> + fprintf(out, CLR_RST);
> +}

Please, use fputs() rather than fprintf().

> diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c
> index 4c85f9f..fc384d7 100644
> --- a/sys-utils/dmesg.c
> +++ b/sys-utils/dmesg.c
> @@ -23,6 +23,7 @@
> #include <fcntl.h>
>
> #include "c.h"
> +#include "colors.h"
> #include "nls.h"
> #include "strutils.h"
> #include "xalloc.h"
> @@ -33,6 +34,11 @@
> #include "optutils.h"
> #include "mangle.h"
>
> +#define K_PANIC 1
> +#define K_ERR 3

really no, already defined by LOG_* macros in
<sys/syslog.h>, see also level_names[] array in dmesg.c.

> +#define CLR_PANIC "\033[31m" //Red
> +#define CLR_ERR "\033[1;31m" //Bright Red

#define DMESG_COLOR_ALERT UL_COLOR_RED
#define DMESG_COLOR_ERR UL_COLOR_BRIGHT_RED

> /* Close the log. Currently a NOP. */
> #define SYSLOG_ACTION_CLOSE 0
> /* Open the log. Currently a NOP. */
> @@ -147,7 +153,8 @@ struct dmesg_control {
> notime:1, /* don't print timestamp */
> delta:1, /* show time deltas */
> reltime:1, /* show human readable relative times */
> - ctime:1; /* show human readable time */
> + ctime:1, /* show human readable time */
> + color:1; /* colorize error and panic messages */
> };
>
> struct dmesg_record {
> @@ -193,6 +200,7 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
> " -f, --facility restrict output to defined facilities\n"
> " -h, --help display this help and exit\n"
> " -k, --kernel display kernel messages\n"
> + " -L, --color colorize error and panic messages\n"
> " -l, --level restrict output to defined levels\n"
> " -n, --console-level <level> set level of messages printed to console\n"
> " -r, --raw print the raw message buffer\n"
> @@ -839,8 +847,16 @@ static void print_record(struct dmesg_control *ctl,
> printf("[%5d.%06d] ", (int) rec->tv.tv_sec, (int) rec->tv.tv_usec);
>
> mesg:
> + //Change the output color for panic and error messages
> + if (ctl->color)
> + set_clr(rec->level == K_PANIC ? CLR_PANIC :
> + rec->level == K_ERR ? CLR_ERR : CLR_RST, stdout);

keep it elegant:

if (ctl->color)
set_level_color(rec->level);

:-)

> safe_fwrite(rec->mesg, rec->mesg_size, stdout);
>
> + if (ctl->color)
> + rst_clr(stdout);
> +
> if (*(rec->mesg + rec->mesg_size - 1) != '\n')
> putchar('\n');
> }
> @@ -1046,6 +1062,7 @@ int main(int argc, char *argv[])
> static const struct option longopts[] = {
> { "buffer-size", required_argument, NULL, 's' },
> { "clear", no_argument, NULL, 'C' },
> + { "color", no_argument, NULL, 'L' },
> { "console-level", required_argument, NULL, 'n' },
> { "console-off", no_argument, NULL, 'D' },
> { "console-on", no_argument, NULL, 'E' },
> @@ -1080,7 +1097,7 @@ int main(int argc, char *argv[])
> textdomain(PACKAGE);
> atexit(close_stdout);
>
> - while ((c = getopt_long(argc, argv, "CcDdEeF:f:hkl:n:rSs:TtuVwx",
> + while ((c = getopt_long(argc, argv, "CcDdEeF:f:hkLl:n:rSs:TtuVwx",
> longopts, NULL)) != -1) {
>
> err_exclusive_options(c, longopts, excl, excl_st);
> @@ -1123,6 +1140,9 @@ int main(int argc, char *argv[])
> ctl.fltr_fac = 1;
> setbit(ctl.facilities, FAC_BASE(LOG_KERN));
> break;
> + case 'L':
> + ctl.color = 1;
> + break;
> case 'l':
> ctl.fltr_lev= 1;
> if (string_to_bitarray(optarg,
> @@ -1180,9 +1200,9 @@ int main(int argc, char *argv[])
> usage(stderr);
>
> if (ctl.raw && (ctl.fltr_lev || ctl.fltr_fac || ctl.delta ||
> - ctl.notime || ctl.ctime || ctl.decode))
> + ctl.notime || ctl.ctime || ctl.decode || ctl.color))
> errx(EXIT_FAILURE, _("--raw can't be used together with level, "
> - "facility, decode, delta, ctime or notime options"));
> + "facility, decode, delta, ctime, notime or color options"));

if (ctl.color && ul_color_init() != 0)
ctl.color = 0;

Thanks!

Karel

--
Karel Zak <kzak@redhat.com>