cgget tool

Add a tool to query for parameter values. The syntax is very similar to cgset,
including IMHO ugly group specification without list of controllers.

Usage:
cgget [-nv] -r <param. name> [-r <param. name>] [...] <path to group> [...]

 -n - no headers
 -v - print values only (no parameter names)

Example:

$ cgget -r cpuset.cpus / /second
/:
cpuset.cpus=0-1

/second:
cpuset.cpus=1

$ cgget -nv -r cpuset.cpus / /second
0-1
1

Signed-off-by: Jan Safranek <jsafrane@redhat.com>

diff --git a/src/tools/Makefile.am b/src/tools/Makefile.am
index ccfeeaead40a1d42e770964d34368dc77b4e0e66..f7550375f6d7a9c557f555d4f8f0a10e8a79651a 100644 (file)
--- a/src/tools/Makefile.am
+++ b/src/tools/Makefile.am
@@ -3,7 +3,7 @@ LDADD = $(top_builddir)/src/.libs/libcgroup.la
 
 if WITH_TOOLS
 
-bin_PROGRAMS = cgexec cgclassify cgcreate cgset cgdelete lssubsys lscgroup
+bin_PROGRAMS = cgexec cgclassify cgcreate cgset cgget cgdelete lssubsys lscgroup
 
 sbin_PROGRAMS = cgconfigparser cgclear
 
@@ -15,6 +15,8 @@ cgcreate_SOURCES = cgcreate.c tools-common.c tools-common.h
 
 cgset_SOURCES = cgset.c tools-common.c tools-common.h
 
+cgget_SOURCES = cgget.c tools-common.c tools-common.h
+
 cgconfigparser_SOURCES = cgconfig.c
 
 cgclear_SOURCES = cgclear.c

diff --git a/src/tools/cgget.c b/src/tools/cgget.c
new file mode 100644 (file)
index 0000000..13b7764
--- /dev/null
+++ b/src/tools/cgget.c
@@ -0,0 +1,194 @@
+#include <libcgroup.h>
+#include <libcgroup-internal.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <getopt.h>
+
+#include "tools-common.h"
+
+#define MODE_SHOW_HEADERS      1
+#define MODE_SHOW_NAMES                2
+
+void usage(int status, char *program_name)
+{
+       if (status != 0)
+               fprintf(stderr, "Wrong input parameters,"
+                       " try %s -h' for more information.\n",
+                       program_name);
+       else {
+               printf("Usage: %s [-nv] -r <name> [-r <name>] ... <path> ...\n",
+                       program_name);
+       }
+}
+
+int display_values(char **names, int count, const char* group_name,
+               const char *program_name, int mode)
+{
+       int i;
+       struct cgroup_controller *group_controller = NULL;
+       struct cgroup *group = NULL;
+       int ret = 0;
+       char *controller = NULL, *parameter = NULL;
+       char *value = NULL;
+
+       if (mode & MODE_SHOW_HEADERS)
+               printf("%s:\n", group_name);
+
+       group = cgroup_new_cgroup(group_name);
+       if (group == NULL) {
+               fprintf(stderr, "%s: cannot create group '%s'\n", program_name,
+                               group_name);
+               return -1;
+       }
+       ret = cgroup_get_cgroup(group);
+       if (ret != 0) {
+               fprintf(stderr, "%s: cannot read group '%s': %s\n",
+                               program_name, group_name, cgroup_strerror(ret));
+               goto err;
+       }
+
+       for (i = 0; i < count; i++) {
+               /* Parse the controller out of 'controller.parameter'. */
+               free(controller);
+               controller = strdup(names[i]);
+               if (controller == NULL) {
+                       fprintf(stderr, "%s: out of memory\n", program_name);
+                       ret = -1;
+                       goto err;
+               }
+               parameter = strchr(controller, '.');
+               if (parameter == NULL) {
+                       fprintf(stderr, "%s: error parsing parameter name\n" \
+                                       " '%s'", program_name, names[i]);
+                       ret = -1;
+                       goto err;
+               }
+               *parameter = '\0';
+               parameter++;
+
+               /* Find appropriate controller. */
+               group_controller = cgroup_get_controller(group, controller);
+               if (group_controller == NULL) {
+                       fprintf(stderr, "%s: cannot find controller " \
+                                       "'%s' in group '%s'\n", program_name,
+                                       controller, group_name);
+                       ret = -1;
+                       goto err;
+               }
+
+               /*
+                * Finally read the parameter value.
+                */
+               ret = cgroup_get_value_string(group_controller, names[i],
+                               &value);
+               if (ret != 0) {
+                       fprintf(stderr, "%s: cannot read parameter '%s.%s' "\
+                                       "from group '%s': %s\n", program_name,
+                                       controller, parameter, group_name,
+                                       cgroup_strerror(ret));
+                       goto err;
+               }
+               if (mode & MODE_SHOW_NAMES)
+                       printf("%s.%s=", controller, parameter);
+               printf("%s\n", value);
+               free(value);
+       }
+err:
+       if (controller)
+               free(controller);
+       if (group)
+               cgroup_free(&group);
+       return ret;
+}
+
+int main(int argc, char *argv[])
+{
+       int ret = 0;
+       int c, i;
+
+       char **names = NULL;
+       int n_number = 0;
+       int n_max = 0;
+       int mode = MODE_SHOW_NAMES | MODE_SHOW_HEADERS;
+
+       /* No parameter on input? */
+       if (argc < 2) {
+               usage(1, argv[0]);
+               return 1;
+       }
+
+       /* Parse arguments. */
+       while ((c = getopt(argc, argv, "r:hnv")) != -1) {
+               switch (c) {
+               case 'h':
+                       usage(0, argv[0]);
+                       ret = 0;
+                       goto err;
+                       break;
+
+               case 'n':
+                       /* Do not show headers. */
+                       mode = mode & (INT_MAX ^ MODE_SHOW_HEADERS);
+                       break;
+
+               case 'v':
+                       /* Do not show parameter names. */
+                       mode = mode & (INT_MAX ^ MODE_SHOW_NAMES);
+                       break;
+
+               case 'r':
+                       /* Add name to buffer. */
+                       if (n_number >= n_max) {
+                               n_max += CG_NV_MAX;
+                               names = (char **) realloc(names,
+                                       n_max * sizeof(char *));
+                               if (!names) {
+                                       fprintf(stderr, "%s: "
+                                               "not enough memory\n", argv[0]);
+                                       ret = -1;
+                                       goto err;
+                               }
+                       }
+
+                       names[n_number] = optarg;
+                       n_number++;
+                       break;
+               default:
+                       usage(1, argv[0]);
+                       ret = 1;
+                       goto err;
+                       break;
+               }
+       }
+
+       if (!argv[optind]) {
+               fprintf(stderr, "%s: no cgroup specified\n", argv[0]);
+               ret = -1;
+               goto err;
+       }
+
+       /* Initialize libcgroup. */
+       ret = cgroup_init();
+       if (ret) {
+               fprintf(stderr, "%s: libcgroup initialization failed: %s\n",
+                       argv[0], cgroup_strerror(ret));
+               goto err;
+       }
+
+       /* Parse control groups and print them .*/
+       for (i = optind; i < argc; i++) {
+               ret = display_values(names, n_number, argv[i], argv[0], mode);
+               if (ret)
+                       goto err;
+               /* Separate each group with empty line. */
+               if (mode & MODE_SHOW_HEADERS && i != argc-1)
+                       printf("\n");
+       }
+
+err:
+       free(names);
+       return ret;
+}