Created
September 22, 2015 20:10
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opensnoop using eBPF/bcc, Sep-2015 version
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#!/usr/bin/python | |
# | |
# opensnoop Trace open() syscalls. | |
# For Linux, uses BCC, eBPF. Embedded C. | |
# | |
# USAGE: opensnoop [-h] [-t] [-x] [-p PID] | |
# | |
# Copyright (c) 2015 Brendan Gregg. | |
# Licensed under the Apache License, Version 2.0 (the "License") | |
# | |
# 17-Sep-2015 Brendan Gregg Created this. | |
from __future__ import print_function | |
from bcc import BPF | |
import argparse | |
# arguments | |
examples = """examples: | |
./opensnoop # trace all open() syscalls | |
./opensnoop -t # include timestamps | |
./opensnoop -x # only show failed opens | |
./opensnoop -p 181 # only trace PID 181 | |
""" | |
parser = argparse.ArgumentParser( | |
description="Trace open() 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 opens") | |
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 kprobe__sys_open(struct pt_regs *ctx, const char __user *filename) | |
{ | |
u32 pid = bpf_get_current_pid_tgid(); | |
FILTER | |
args_filename.update(&pid, &filename); | |
return 0; | |
}; | |
int kretprobe__sys_open(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("%s %d\\n", *filenamep, ret); | |
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) | |
# 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() | |
(filename, ret_s) = msg.split(" ") | |
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)) |
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