From: Adriaan Schmidt <adriaan.schmidt@siemens.com>
Date: Tue, 27 Feb 2024 12:37:17 +0000 (+0100)
Subject: feat: add cgroup_get_threads()
X-Git-Tag: v3.2.0~124
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84ff288c1b95a2060558011d0878037adcbf7660;p=thirdparty%2Flibcgroup.git

feat: add cgroup_get_threads()

In the same way `cgroup_get_procs()` reads the cgroup.procs
file of a cgroup, the new function reads cgroup.threads, which
is useful to interact with threaded cgroups.

Signed-off-by: Adriaan Schmidt <adriaan.schmidt@siemens.com>
Reviewed-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
---

diff --git a/include/libcgroup/groups.h b/include/libcgroup/groups.h
index a79e8244..4fd3169f 100644
--- a/include/libcgroup/groups.h
+++ b/include/libcgroup/groups.h
@@ -588,6 +588,17 @@ char *cgroup_get_value_name(struct cgroup_controller *controller, int index);
  */
 int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size);
 
+/**
+ * Get the list of threads 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_threads(char *name, char *controller, pid_t **pids, int *size);
+
 /**
  * Change permission of files and directories of given group
  * @param cgroup The cgroup which permissions should be changed
diff --git a/src/api.c b/src/api.c
index 645e9a62..526bda8a 100644
--- a/src/api.c
+++ b/src/api.c
@@ -6140,20 +6140,16 @@ static int pid_compare(const void *a, const void *b)
  *
  * Caller must free up pids.
  */
-int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
+static int read_pids(char *path, pid_t **pids, int *size)
 {
-	char cgroup_path[FILENAME_MAX];
-	int tot_procs = 16;
+	int tot_pids = 16;
 	pid_t *tmp_list;
-	FILE *procs;
+	FILE *pid_file;
 	int n = 0;
 	int err;
 
-	cg_build_path(name, cgroup_path, controller);
-	strncat(cgroup_path, "/cgroup.procs", FILENAME_MAX-strlen(cgroup_path));
-
-	procs = fopen(cgroup_path, "r");
-	if (!procs) {
+	pid_file = fopen(path, "r");
+	if (!pid_file) {
 		last_errno = errno;
 		*pids = NULL;
 		*size = 0;
@@ -6164,31 +6160,31 @@ int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
 	}
 
 	/* Keep doubling the memory allocated if needed */
-	tmp_list = malloc(sizeof(pid_t) * tot_procs);
+	tmp_list = malloc(sizeof(pid_t) * tot_pids);
 	if (!tmp_list) {
 		last_errno = errno;
-		fclose(procs);
+		fclose(pid_file);
 		return ECGOTHER;
 	}
 
-	while (!feof(procs)) {
-		while (!feof(procs) && n < tot_procs) {
+	while (!feof(pid_file)) {
+		while (!feof(pid_file) && n < tot_pids) {
 			pid_t pid;
 
-			err = fscanf(procs, "%u", &pid);
+			err = fscanf(pid_file, "%u", &pid);
 			if (err == EOF)
 				break;
 			tmp_list[n] = pid;
 			n++;
 		}
-		if (!feof(procs)) {
+		if (!feof(pid_file)) {
 			pid_t *orig_list = tmp_list;
 
-			tot_procs *= 2;
-			tmp_list = realloc(tmp_list, sizeof(pid_t) * tot_procs);
+			tot_pids *= 2;
+			tmp_list = realloc(tmp_list, sizeof(pid_t) * tot_pids);
 			if (!tmp_list) {
 				last_errno = errno;
-				fclose(procs);
+				fclose(pid_file);
 				free(orig_list);
 				*pids = NULL;
 				*size = 0;
@@ -6196,7 +6192,7 @@ int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
 			}
 		}
 	}
-	fclose(procs);
+	fclose(pid_file);
 
 	*size = n;
 	qsort(tmp_list, n, sizeof(pid_t), &pid_compare);
@@ -6205,6 +6201,26 @@ int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
 	return 0;
 }
 
+int cgroup_get_procs(char *name, char *controller, pid_t **pids, int *size)
+{
+	char cgroup_path[FILENAME_MAX];
+
+	cg_build_path(name, cgroup_path, controller);
+	strncat(cgroup_path, "/cgroup.procs", FILENAME_MAX-strlen(cgroup_path));
+
+	return read_pids(cgroup_path, pids, size);
+}
+
+int cgroup_get_threads(char *name, char *controller, pid_t **pids, int *size)
+{
+	char cgroup_path[FILENAME_MAX];
+
+	cg_build_path(name, cgroup_path, controller);
+	strncat(cgroup_path, "/cgroup.threads", FILENAME_MAX-strlen(cgroup_path));
+
+	return read_pids(cgroup_path, pids, size);
+}
+
 int cgroup_dictionary_create(struct cgroup_dictionary **dict,
 			     int flags)
 {
diff --git a/src/libcgroup.map b/src/libcgroup.map
index 31780656..5e504719 100644
--- a/src/libcgroup.map
+++ b/src/libcgroup.map
@@ -164,3 +164,7 @@ CGROUP_3.0 {
 	cgroup_is_systemd_enabled;
 	cgroup_attach_thread_tid;
 } CGROUP_2.0;
+
+CGROUP_3.2 {
+	cgroup_get_threads;
+} CGROUP_3.0;