avoid executing external tools by using Python's built-in os module to interact with the filesystem directly

frigate/util.py

@@ -9,6 +9,7 @@ import signal
 import traceback
 import urllib.parse
 import yaml
+import os
 
 from abc import ABC, abstractmethod
 from collections import Counter
@@ -740,92 +741,71 @@ def escape_special_characters(path: str) -> str:
 
 
 def get_cgroups_version() -> str:
-    """Determine what version of cgroups is enabled"""
+    """Determine what version of cgroups is enabled."""
 
-    stat_command = ["stat", "-fc", "%T", "/sys/fs/cgroup"]
+    cgroup_path = "/sys/fs/cgroup"
     
-    p = sp.run(
-        stat_command,
-        encoding="ascii",
-        capture_output=True,
-    )
+    try:
+        stat_info = os.stat(cgroup_path)
+        value = os.statvfs(cgroup_path).f_type
         
-    if p.returncode == 0:
-        value: str = p.stdout.strip().lower()
-
-        if value == "cgroup2fs":
+        if value == os.fsencode('cgroup2fs'):
             return "cgroup2"
-        elif value == "tmpfs":
+        elif value == os.fsencode('tmpfs'):
             return "cgroup"
         else:
-            logger.debug(
-                f"Could not determine cgroups version: unhandled filesystem {value}"
-            )
-    else:
-        logger.debug(f"Could not determine cgroups version:  {p.stderr}")
+            logger.debug(f"Could not determine cgroups version: unhandled filesystem {value}")
+    except Exception as e:
+        logger.debug(f"Could not determine cgroups version: {e}")
 
     return "unknown"
 
-
 def get_docker_memlimit_bytes() -> int:
-    """Get mem limit in bytes set in docker if present. Returns -1 if no limit detected"""
+    """Get mem limit in bytes set in docker if present. Returns -1 if no limit detected."""
 
     # check running a supported cgroups version
     if get_cgroups_version() == "cgroup2":
-        memlimit_command = ["cat", "/sys/fs/cgroup/memory.max"]
+        memlimit_path = "/sys/fs/cgroup/memory.max"
 
-        p = sp.run(
-            memlimit_command,
-            encoding="ascii",
-            capture_output=True,
-        )
-
-        if p.returncode == 0:
-            value: str = p.stdout.strip()
+        try:
+            with open(memlimit_path, 'r') as f:
+                value = f.read().strip()
 
             if value.isnumeric():
                 return int(value)
             elif value.lower() == "max":
                 return -1
-        else:
-            logger.debug(f"Unable to get docker memlimit: {p.stderr}")
+        except Exception as e:
+            logger.debug(f"Unable to get docker memlimit: {e}")
 
     return -1
 
-
 def get_cpu_stats() -> dict[str, dict]:
-    """Get cpu usages for each process id"""
+    """Get cpu usages for each process id."""
     usages = {}
-    # -n=2 runs to ensure extraneous values are not included
-    top_command = ["top", "-b", "-n", "2"]
-
     docker_memlimit = get_docker_memlimit_bytes() / 1024
 
-    p = sp.run(
-        top_command,
-        encoding="ascii",
-        capture_output=True,
-    )
-
-    if p.returncode != 0:
-        logger.error(p.stderr)
-        return usages
-    else:
-        lines = p.stdout.split("\n")
-
-        for line in lines:
-            stats = list(filter(lambda a: a != "", line.strip().split(" ")))
+    for pid in os.listdir('/proc'):
+        if pid.isdigit():
             try:
-                if docker_memlimit > 0:
-                    mem_res = int(stats[5])
-                    mem_pct = str(
-                        round((float(mem_res) / float(docker_memlimit)) * 100, 1)
-                    )
-                else:
-                    mem_pct = stats[9]
+                with open(f'/proc/{pid}/stat', 'r') as f:
+                    stat_info = f.read().split()
 
-                usages[stats[0]] = {
-                    "cpu": stats[8],
+                with open('/proc/meminfo', 'r') as f:
+                    mem_info = f.readlines()
+                    total_mem = int(mem_info[0].split()[1])
+
+                mem_res = int(stat_info[23]) / 1024
+                if docker_memlimit > 0:
+                    mem_pct = round((float(mem_res) / float(docker_memlimit)) * 100, 1)
+                else:
+                    mem_pct = round((float(mem_res) / float(total_mem)) * 100, 1)
+
+                cpu_total_time = sum(int(x) for x in stat_info[13:17])
+                cpu_usage = round(cpu_total_time / os.sysconf("SC_CLK_TCK"), 1)
+
+                usages[pid] = {
+                    "cpu": cpu_usage,
                     "mem": mem_pct,
                 }
             except: