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>

2 files changed, 197 insertions, 1 deletions

diff --git a/src/tools/Makefile.am b/src/tools/Makefile.am
index ccfeeae..f755037 100644
--- 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
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;
+}