From: Ivana Hutarova Varekova <varekova@redhat.com>
Date: Thu, 2 Sep 2010 10:17:14 +0000 (+0200)
Subject: new iterator api for reading variables
X-Git-Tag: v0.37.1~43
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e388d1c10187f9c30ff1f22314647bb9a42b0601;p=thirdparty%2Flibcgroup.git

new iterator api for reading variables

This patch adds three iterators api function
cgroup_read_vars_begin
cgroup_read_vars_next
cgroup_read_vars_end

 They read the values of the given variable for the specified
 controller and control group. The string with the maximal
 length max is returned line is returned per
 cgroup_read_stats_begin() and cgroup_read_stats_next() call.

(there already are _stat_ versions of function which can read only stat
variables)

Signed-off-by: Ivana Hutarova Varekova <varekova@redhat.com>
Signed-off-by: Jan Safranek <jsafrane@redhat.com>
---

diff --git a/include/libcgroup/iterators.h b/include/libcgroup/iterators.h
index f572beca..ed4e6de2 100644
--- a/include/libcgroup/iterators.h
+++ b/include/libcgroup/iterators.h
@@ -173,6 +173,44 @@ int cgroup_walk_tree_end(void **handle);
  */
 int cgroup_walk_tree_set_flags(void **handle, int flags);
 
+/**
+ * Read the value of the given variable for the specified
+ * controller and control group.
+ * The value is read up to newline character or at most max-1 characters,
+ * whichever comes first (i.e. similar to fgets()).
+ * @param controller Name of the controller for which stats are requested.
+ * @param path Path to control group, relative to hierarchy root.
+ * @param name is variable name.
+ * @param handle Handle to be used during iteration.
+ * @param buffer Buffer to read the value into.
+ * The buffer is always zero-terminated.
+ * @param max Maximal lenght of the buffer
+ * @return #ECGEOF when the stats file is empty.
+ */
+
+int cgroup_read_value_begin(const char *controller, const char *path,
+	char *name, void **handle, char *buffer, int max);
+
+/**
+  * Read the next string from the given variable handle
+  * which is generated by cgroup_read_stats_begin() function.
+  * the value is read up to newline character or at most max-1 characters,
+  * whichever comes first (i.e. similar to fgets()) per
+  * cgroup_read_stats_next() call
+  * @param handle Handle to be used during iteration.
+  * @param data returned the string.
+  * @param buffer Buffer to read the value into.
+  * The buffer is always zero-terminated.
+  * @param max Maximal lenght of the buffer
+  * @return #ECGEOF when the iterator finishes getting the list of stats.
+  */
+int cgroup_read_value_next(void **handle, char *buffer, int max);
+
+/**
+ * Release the iterator.
+ */
+int cgroup_read_value_end(void **handle);
+
 /**
  * @}
  *
diff --git a/src/api.c b/src/api.c
index b9a906f1..1e6e3c3c 100644
--- a/src/api.c
+++ b/src/api.c
@@ -2830,6 +2830,81 @@ out_free:
 	return ret;
 }
 
+
+int cgroup_read_value_end(void **handle)
+{
+	FILE *fp;
+
+	if (!cgroup_initialized)
+		return ECGROUPNOTINITIALIZED;
+
+	if (!handle)
+		return ECGINVAL;
+
+	fp = (FILE *)*handle;
+	fclose(fp);
+
+	return 0;
+}
+
+int cgroup_read_value_next(void **handle, char *buffer, int max)
+{
+	int ret = 0;
+	char *ret_c;
+	FILE *fp;
+
+	if (!cgroup_initialized)
+		return ECGROUPNOTINITIALIZED;
+
+	if (!buffer || !handle)
+		return ECGINVAL;
+
+	fp = (FILE *)*handle;
+	ret_c = fgets(buffer, max, fp);
+	if (ret_c == NULL)
+		ret = ECGEOF;
+
+	return ret;
+}
+
+int cgroup_read_value_begin(const char *controller, const char *path,
+	char *name, void **handle, char *buffer, int max)
+{
+	int ret = 0;
+	char *ret_c = NULL;
+	char stat_file[FILENAME_MAX];
+	char stat_path[FILENAME_MAX];
+	FILE *fp;
+
+	if (!cgroup_initialized)
+		return ECGROUPNOTINITIALIZED;
+
+	if (!buffer || !handle)
+		return ECGINVAL;
+
+	if (!cg_build_path(path, stat_path, controller))
+		return ECGOTHER;
+
+	snprintf(stat_file, sizeof(stat_file), "%s/%s", stat_path,
+		name);
+	fp = fopen(stat_file, "re");
+	if (!fp) {
+		cgroup_dbg("fopen failed\n");
+		last_errno = errno;
+		*handle = NULL;
+		return ECGOTHER;
+	}
+
+	ret_c = fgets(buffer, max, fp);
+	if (ret_c == NULL)
+		ret = ECGEOF;
+
+	*handle = fp;
+	return 0;
+}
+
+
+
 int cgroup_read_stats_end(void **handle)
 {
 	FILE *fp;
diff --git a/src/libcgroup.map b/src/libcgroup.map
index 130fc768..60970cac 100644
--- a/src/libcgroup.map
+++ b/src/libcgroup.map
@@ -91,4 +91,7 @@ CGROUP_0.36 {
 
 CGROUP_0.37 {
 	cgroup_get_procs;
+	cgroup_read_value_begin;
+	cgroup_read_value_next;
+	cgroup_read_value_end;
 } CGROUP_0.36;