cgutil: new functions to query a cgroup from pid and get memory use

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/cgutil.c

@@ -108,6 +108,25 @@ char *pid_comm(int pid, char *buf, size_t len)
 	return chomp(buf);
 }
 
+char *pid_cgroup(int pid, char *buf, size_t len)
+{
+	char *ptr;
+	FILE *fp;
+
+	fp = fopenf("r", "/proc/%d/cgroup", pid);
+	if (!fp)
+		return NULL;
+
+	fgets(buf, len, fp);
+	fclose(fp);
+
+	ptr = strchr(buf, '/');
+	if (!ptr)
+		return NULL;
+
+	return chomp(ptr);
+}
+
 static uint64_t cgroup_uint64(char *path, char *file)
 {
 	uint64_t val = 0;
@@ -159,6 +178,16 @@ static uint64_t cgroup_memuse(struct cg *cg)
 	return cg->cg_vmsize = cgroup_uint64(cg->cg_path, "memory.current");
 }
 
+uint64_t cgroup_memory(char *group)
+{
+	char path[256];
+
+	paste(path, sizeof(path), FINIT_CGPATH, group);
+	printf("DBG: %s (%s)\n", path, group);
+
+	return cgroup_uint64(path, "memory.current");
+}
+
 static float cgroup_cpuload(struct cg *cg)
 {
 	char fn[256];

src/cgutil.h

@@ -24,10 +24,14 @@
 #ifndef FINIT_CGUTIL_H_
 #define FINIT_CGUTIL_H_
 
+#include <stdint.h>
 #include <stdlib.h>
 
 char *pid_cmdline (int pid, char *buf, size_t len);
 char *pid_comm    (int pid, char *buf, size_t len);
+char *pid_cgroup  (int pid, char *buf, size_t len);
+
+uint64_t cgroup_memory(char *group);
 
 int   cgroup_tree  (char *path, char *pfx, int top);