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statsnoop.py
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statsnoop.py
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#!/usr/bin/python
# @lint-avoid-python-3-compatibility-imports
#
# statsnoop Trace stat() syscalls.
# For Linux, uses BCC, eBPF. Embedded C.
#
# USAGE: statsnoop [-h] [-t] [-x] [-p PID]
#
# Copyright 2016 Netflix, Inc.
# Licensed under the Apache License, Version 2.0 (the "License")
#
# 08-Feb-2016 Brendan Gregg Created this.
from __future__ import print_function
from bcc import BPF
import argparse
# arguments
examples = """examples:
./statsnoop # trace all stat() syscalls
./statsnoop -t # include timestamps
./statsnoop -x # only show failed stats
./statsnoop -p 181 # only trace PID 181
"""
parser = argparse.ArgumentParser(
description="Trace stat() syscalls",
formatter_class=argparse.RawDescriptionHelpFormatter,
epilog=examples)
parser.add_argument("-t", "--timestamp", action="store_true",
help="include timestamp on output")
parser.add_argument("-x", "--failed", action="store_true",
help="only show failed stats")
parser.add_argument("-p", "--pid",
help="trace this PID only")
args = parser.parse_args()
debug = 0
# define BPF program
bpf_text = """
#include <uapi/linux/ptrace.h>
BPF_HASH(args_filename, u32, const char *);
int trace_entry(struct pt_regs *ctx, const char __user *filename)
{
u32 pid = bpf_get_current_pid_tgid();
FILTER
args_filename.update(&pid, &filename);
return 0;
};
int trace_return(struct pt_regs *ctx)
{
const char **filenamep;
int ret = ctx->ax;
u32 pid = bpf_get_current_pid_tgid();
filenamep = args_filename.lookup(&pid);
if (filenamep == 0) {
// missed entry
return 0;
}
bpf_trace_printk("%d %s\\n", ret, *filenamep);
args_filename.delete(&pid);
return 0;
}
"""
if args.pid:
bpf_text = bpf_text.replace('FILTER',
'if (pid != %s) { return 0; }' % args.pid)
else:
bpf_text = bpf_text.replace('FILTER', '')
if debug:
print(bpf_text)
# initialize BPF
b = BPF(text=bpf_text)
b.attach_kprobe(event="sys_stat", fn_name="trace_entry")
b.attach_kprobe(event="sys_statfs", fn_name="trace_entry")
b.attach_kprobe(event="sys_newstat", fn_name="trace_entry")
b.attach_kretprobe(event="sys_stat", fn_name="trace_return")
b.attach_kretprobe(event="sys_statfs", fn_name="trace_return")
b.attach_kretprobe(event="sys_newstat", fn_name="trace_return")
# header
if args.timestamp:
print("%-14s" % ("TIME(s)"), end="")
print("%-6s %-16s %4s %3s %s" % ("PID", "COMM", "FD", "ERR", "PATH"))
start_ts = 0
# format output
while 1:
(task, pid, cpu, flags, ts, msg) = b.trace_fields()
(ret_s, filename) = msg.split(" ", 1)
ret = int(ret_s)
if (args.failed and (ret >= 0)):
continue
# split return value into FD and errno columns
if ret >= 0:
fd_s = ret
err = 0
else:
fd_s = "-1"
err = - ret
# print columns
if args.timestamp:
if start_ts == 0:
start_ts = ts
print("%-14.9f" % (ts - start_ts), end="")
print("%-6d %-16s %4s %3s %s" % (pid, task, fd_s, err, filename))