Re: [PATCH] dmesg colorized output

Davidlohr Bueso
2012-10-10T09:26:09Z

On Wed, 2012-10-10 at 11:19 +0200, Karel Zak wrote:
> On Wed, Oct 10, 2012 at 09:44:05AM +0200, Ondrej Oprala wrote:
> > new file mode 100644

Hehe I actually started doing this last night.

I'm wondering if we actually need a new lib file for colors. I mean
AFAICT, dmesg is the only place we want to use it and I don't see that
changing any time soon - Unix hackers don't like colors, we live oh so
boring lives :)

> > 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

how about using /* ... */

>
> #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
>