From: Dhaval Giani <dhaval.giani@gmail.com>
Date: Tue, 27 Jul 2010 11:51:36 +0000 (+0200)
Subject: libcgroup: Get the list of procs
X-Git-Tag: v0.37.1~59
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1e943cf1af573fbe748d9f290f341511b8482de2;p=thirdparty%2Flibcgroup.git

libcgroup: Get the list of procs

This patch adds a new API to get a list of procs. This is
guaranteed to be sorted.

TODO:
1. Ensure only unique values make it through

[balbir@linux.vnet.ibm.com: Add a missing EOF check]
Signed-off-by: Dhaval Giani <dhaval.giani@gmail.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
---

diff --git a/include/libcgroup/error.h b/include/libcgroup/error.h
index 9f914793..908845ee 100644
--- a/include/libcgroup/error.h
+++ b/include/libcgroup/error.h
@@ -71,6 +71,7 @@ enum {
 	ECGNAMESPACEPATHS,
 	ECGNAMESPACECONTROLLER,
 	ECGMOUNTNAMESPACE,
+	ECGROUPUNSUPP,
 };
 
 /**
diff --git a/include/libcgroup/groups.h b/include/libcgroup/groups.h
index 3cdb832f..d212ec02 100644
--- a/include/libcgroup/groups.h
+++ b/include/libcgroup/groups.h
@@ -507,6 +507,16 @@ int cgroup_get_value_name_count(struct cgroup_controller *controller);
  */
 char *cgroup_get_value_name(struct cgroup_controller *controller, int index);
 
+/**
+ * Get the list of process in a cgroup. This list is guaranteed to
+ * be sorted. It is not necessary that it is unique.
+ * @param name The name of the cgroup
+ * @param controller The name of the controller
+ * @param pids The list of pids. Should be uninitialized when passed
+ * to the API. Should be freed by the caller using free.
+ * @param size The size of the pids array returned by the API.
+ */
+int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size);
 
 /**
  * @}
diff --git a/src/api.c b/src/api.c
index 33c64ccb..195e0e6a 100644
--- a/src/api.c
+++ b/src/api.c
@@ -116,6 +116,7 @@ const char const *cgroup_strerror_codes[] = {
 	"Have multiple paths for the same namespace",
 	"Controller in namespace does not exist",
 	"Cannot have mount and namespace keyword in the same configuration file",
+	"This kernel does not support this feature",
 };
 
 static int cg_chown_file(FTS *fts, FTSENT *ent, uid_t owner, gid_t group)
@@ -3445,3 +3446,85 @@ int cgroup_get_all_controller_begin(void **handle, struct controller_data *info)
 
 	return cgroup_get_all_controller_next(handle, info);
 }
+
+static int pid_compare(const void *a, const void *b)
+{
+	const pid_t *pid1, *pid2;
+
+	pid1 = (pid_t *) a;
+	pid2 = (pid_t *) b;
+
+	return (*pid1 - *pid2);
+}
+
+/*
+ *pids needs to be completely uninitialized so that we can set it up
+ *
+ * Caller must free up pids.
+ */
+int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
+{
+	char cgroup_path[FILENAME_MAX];
+	FILE *procs;
+	pid_t *tmp_list;
+	int tot_procs = 16;
+	int n = 0;
+	int err;
+
+	cg_build_path(name, cgroup_path, controller);
+	strncat(cgroup_path, "/cgroup.procs", FILENAME_MAX-strlen(cgroup_path));
+
+	/*
+	 * This kernel does have support for cgroup.procs
+	 */
+	if (access(cgroup_path, F_OK))
+		return ECGROUPUNSUPP;
+
+	/*
+	 * Read all the procs and then sort them up.
+	 */
+
+	tmp_list = *pids;
+
+	/*
+	 * Keep doubling the memory allocated if needed
+	 */
+	tmp_list= malloc(sizeof(pid_t) * tot_procs);
+	if (!tmp_list) {
+		last_errno = errno;
+		return ECGOTHER;
+	}
+
+	procs = fopen(cgroup_path, "r");
+	if (!procs) {
+		last_errno = errno;
+		return ECGOTHER;
+	}
+
+	while (!feof(procs)) {
+		while (!feof(procs) && n < tot_procs) {
+			pid_t pid;
+			err = fscanf(procs, "%u", &pid);
+			if (err == EOF)
+				break;
+			tmp_list[n] = pid;
+			n++;
+		}
+		if (!feof(procs)) {
+			tot_procs *= 2;
+			tmp_list = realloc(tmp_list, sizeof(pid_t) * tot_procs);
+			if (!tmp_list) {
+				last_errno = errno;
+				return ECGOTHER;
+			}
+		}
+	}
+
+	*size = n;
+
+	qsort(tmp_list, n, sizeof(pid_t), &pid_compare);
+
+	*pids = tmp_list;
+
+	return 0;
+}
diff --git a/src/libcgroup.map b/src/libcgroup.map
index 06c5e072..130fc768 100644
--- a/src/libcgroup.map
+++ b/src/libcgroup.map
@@ -85,3 +85,10 @@ global:
 	cgroup_get_value_name_count;
 	cgroup_get_value_name;
 } CGROUP_0.34;
+
+CGROUP_0.36 {
+} CGROUP_0.35;
+
+CGROUP_0.37 {
+	cgroup_get_procs;
+} CGROUP_0.36;