[systemd-devel] [PATCH] systemd-analyze: filter dot output with a regular expression

[Zbigniew Jędrzejewski-Szmek]

On Sun, Mar 24, 2013 at 01:32:41PM +0100, Łukasz Stelmach wrote:
> Make "systemd-analyze dot" output only lines matching a regular
> expression passed on the command line. Without the regular expression
> print everything.
> ---
> 
> A graph created with the full output of dot is completely incomprehensible
> on a regular system. It thus makes perfect sense IMHO to add filtering
> to systemd-analyze instead of trying to use sed/grep/awk/perl to filter
> the dependencies but preserving the first and last line with the braces.

What regexps could one use?

Zbyszek

> 
> This, of course, is the first attempt so any comments are more than
> welcome.
> 
>  src/analyze/systemd-analyze.c | 35 ++++++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/src/analyze/systemd-analyze.c b/src/analyze/systemd-analyze.c
> index 01bf55e..bddbeda 100644
> --- a/src/analyze/systemd-analyze.c
> +++ b/src/analyze/systemd-analyze.c
> @@ -25,6 +25,9 @@
>  #include <getopt.h>
>  #include <locale.h>
>  #include <sys/utsname.h>
> +#include <sys/types.h>
> +#include <regex.h>
> +#include <string.h>
>  
>  #include "install.h"
>  #include "log.h"
> @@ -578,7 +581,7 @@ static int analyze_time(DBusConnection *bus) {
>          return 0;
>  }
>  
> -static int graph_one_property(const char *name, const char *prop, DBusMessageIter *iter) {
> +static int graph_one_property(const char *name, const char *prop, DBusMessageIter *iter, regex_t* regexp) {
>  
>          static const char * const colors[] = {
>                  "Requires",              "[color=\"black\"]",
> @@ -591,6 +594,7 @@ static int graph_one_property(const char *name, const char *prop, DBusMessageIte
>                  "After",                 "[color=\"green\"]"
>          };
>  
> +        char buf[1024];
>          const char *c = NULL;
>          unsigned i;
>  
> @@ -624,14 +628,16 @@ static int graph_one_property(const char *name, const char *prop, DBusMessageIte
>  
>                          assert(dbus_message_iter_get_arg_type(&sub) == DBUS_TYPE_STRING);
>                          dbus_message_iter_get_basic(&sub, &s);
> -                        printf("\t\"%s\"->\"%s\" %s;\n", name, s, c);
> +                        snprintf(buf, sizeof(buf), "\t\"%s\"->\"%s\" %s;", name, s, c);
> +                        if (regexp == NULL || regexec(regexp, buf, 0, NULL, 0) == 0)
> +                                puts(buf);
>                  }
>          }
>  
>          return 0;
>  }
>  
> -static int graph_one(DBusConnection *bus, const struct unit_info *u) {
> +static int graph_one(DBusConnection *bus, const struct unit_info *u, regex_t* regexp) {
>          _cleanup_dbus_message_unref_ DBusMessage *reply = NULL;
>          const char *interface = "org.freedesktop.systemd1.Unit";
>          int r;
> @@ -675,7 +681,7 @@ static int graph_one(DBusConnection *bus, const struct unit_info *u) {
>                  }
>  
>                  dbus_message_iter_recurse(&sub2, &sub3);
> -                r = graph_one_property(u->id, prop, &sub3);
> +                r = graph_one_property(u->id, prop, &sub3, regexp);
>                  if (r < 0)
>                          return r;
>          }
> @@ -683,10 +689,12 @@ static int graph_one(DBusConnection *bus, const struct unit_info *u) {
>          return 0;
>  }
>  
> -static int dot(DBusConnection *bus) {
> +static int dot(DBusConnection *bus, char* regexp_s) {
>          _cleanup_dbus_message_unref_ DBusMessage *reply = NULL;
>          DBusMessageIter iter, sub;
>          int r;
> +        regex_t regexp;
> +        int use_regexp = 0;
>  
>          r = bus_method_call_with_reply(
>                          bus,
> @@ -707,6 +715,16 @@ static int dot(DBusConnection *bus) {
>                  return -EIO;
>          }
>  
> +        memset(&regexp, 0, sizeof(regexp));
> +        if (regexp_s != NULL) {
> +                r = regcomp(&regexp, regexp_s, REG_NOSUB);
> +                if (r != 0) {
> +                        log_error("Invalid regular expression.");
> +                        return -EINVAL;
> +                }
> +                use_regexp = 1;
> +        }
> +
>          printf("digraph systemd {\n");
>  
>          for (dbus_message_iter_recurse(&iter, &sub);
> @@ -718,13 +736,16 @@ static int dot(DBusConnection *bus) {
>                  if (r < 0)
>                          return -EIO;
>  
> -                r = graph_one(bus, &u);
> +                r = graph_one(bus, &u, use_regexp ? &regexp : NULL);
>                  if (r < 0)
>                          return r;
>          }
>  
>          printf("}\n");
>  
> +        if (use_regexp)
> +                regfree(&regexp);
> +
>          log_info("   Color legend: black     = Requires\n"
>                   "                 dark blue = Requisite\n"
>                   "                 dark grey = Wants\n"
> @@ -844,7 +865,7 @@ int main(int argc, char *argv[]) {
>          else if (streq(argv[optind], "plot"))
>                  r = analyze_plot(bus);
>          else if (streq(argv[optind], "dot"))
> -                r = dot(bus);
> +                r = dot(bus, argv[optind+1]);
>          else
>                  log_error("Unknown operation '%s'.", argv[optind]);
>  
> -- 
> 1.8.1.5
> 
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