1# SPDX-License-Identifier: GPL-2.0
2
3import errno
4import json as _json
5import os
6import random
7import re
8import select
9import socket
10import subprocess
11import time
12
13
14class CmdExitFailure(Exception):
15    def __init__(self, msg, cmd_obj):
16        super().__init__(msg)
17        self.cmd = cmd_obj
18
19
20def fd_read_timeout(fd, timeout):
21    rlist, _, _ = select.select([fd], [], [], timeout)
22    if rlist:
23        return os.read(fd, 1024)
24    else:
25        raise TimeoutError("Timeout waiting for fd read")
26
27
28class cmd:
29    """
30    Execute a command on local or remote host.
31
32    Use bkg() instead to run a command in the background.
33    """
34    def __init__(self, comm, shell=True, fail=True, ns=None, background=False,
35                 host=None, timeout=5, ksft_wait=None):
36        if ns:
37            comm = f'ip netns exec {ns} ' + comm
38
39        self.stdout = None
40        self.stderr = None
41        self.ret = None
42        self.ksft_term_fd = None
43
44        self.comm = comm
45        if host:
46            self.proc = host.cmd(comm)
47        else:
48            # ksft_wait lets us wait for the background process to fully start,
49            # we pass an FD to the child process, and wait for it to write back.
50            # Similarly term_fd tells child it's time to exit.
51            pass_fds = ()
52            env = os.environ.copy()
53            if ksft_wait is not None:
54                rfd, ready_fd = os.pipe()
55                wait_fd, self.ksft_term_fd = os.pipe()
56                pass_fds = (ready_fd, wait_fd, )
57                env["KSFT_READY_FD"] = str(ready_fd)
58                env["KSFT_WAIT_FD"]  = str(wait_fd)
59
60            self.proc = subprocess.Popen(comm, shell=shell, stdout=subprocess.PIPE,
61                                         stderr=subprocess.PIPE, pass_fds=pass_fds,
62                                         env=env)
63            if ksft_wait is not None:
64                os.close(ready_fd)
65                os.close(wait_fd)
66                msg = fd_read_timeout(rfd, ksft_wait)
67                os.close(rfd)
68                if not msg:
69                    raise Exception("Did not receive ready message")
70        if not background:
71            self.process(terminate=False, fail=fail, timeout=timeout)
72
73    def process(self, terminate=True, fail=None, timeout=5):
74        if fail is None:
75            fail = not terminate
76
77        if self.ksft_term_fd:
78            os.write(self.ksft_term_fd, b"1")
79        if terminate:
80            self.proc.terminate()
81        stdout, stderr = self.proc.communicate(timeout)
82        self.stdout = stdout.decode("utf-8")
83        self.stderr = stderr.decode("utf-8")
84        self.proc.stdout.close()
85        self.proc.stderr.close()
86        self.ret = self.proc.returncode
87
88        if self.proc.returncode != 0 and fail:
89            if len(stderr) > 0 and stderr[-1] == "\n":
90                stderr = stderr[:-1]
91            raise CmdExitFailure("Command failed: %s\nSTDOUT: %s\nSTDERR: %s" %
92                                 (self.proc.args, stdout, stderr), self)
93
94
95class bkg(cmd):
96    """
97    Run a command in the background.
98
99    Examples usage:
100
101    Run a command on remote host, and wait for it to finish.
102    This is usually paired with wait_port_listen() to make sure
103    the command has initialized:
104
105        with bkg("socat ...", exit_wait=True, host=cfg.remote) as nc:
106            ...
107
108    Run a command and expect it to let us know that it's ready
109    by writing to a special file descriptor passed via KSFT_READY_FD.
110    Command will be terminated when we exit the context manager:
111
112        with bkg("my_binary", ksft_wait=5):
113    """
114    def __init__(self, comm, shell=True, fail=None, ns=None, host=None,
115                 exit_wait=False, ksft_wait=None):
116        super().__init__(comm, background=True,
117                         shell=shell, fail=fail, ns=ns, host=host,
118                         ksft_wait=ksft_wait)
119        self.terminate = not exit_wait and not ksft_wait
120        self.check_fail = fail
121
122        if shell and self.terminate:
123            print("# Warning: combining shell and terminate is risky!")
124            print("#          SIGTERM may not reach the child on zsh/ksh!")
125
126    def __enter__(self):
127        return self
128
129    def __exit__(self, ex_type, ex_value, ex_tb):
130        return self.process(terminate=self.terminate, fail=self.check_fail)
131
132
133global_defer_queue = []
134
135
136class defer:
137    def __init__(self, func, *args, **kwargs):
138        global global_defer_queue
139
140        if not callable(func):
141            raise Exception("defer created with un-callable object, did you call the function instead of passing its name?")
142
143        self.func = func
144        self.args = args
145        self.kwargs = kwargs
146
147        self._queue =  global_defer_queue
148        self._queue.append(self)
149
150    def __enter__(self):
151        return self
152
153    def __exit__(self, ex_type, ex_value, ex_tb):
154        return self.exec()
155
156    def exec_only(self):
157        self.func(*self.args, **self.kwargs)
158
159    def cancel(self):
160        self._queue.remove(self)
161
162    def exec(self):
163        self.cancel()
164        self.exec_only()
165
166
167def tool(name, args, json=None, ns=None, host=None):
168    cmd_str = name + ' '
169    if json:
170        cmd_str += '--json '
171    cmd_str += args
172    cmd_obj = cmd(cmd_str, ns=ns, host=host)
173    if json:
174        return _json.loads(cmd_obj.stdout)
175    return cmd_obj
176
177
178def ip(args, json=None, ns=None, host=None):
179    if ns:
180        args = f'-netns {ns} ' + args
181    return tool('ip', args, json=json, host=host)
182
183
184def ethtool(args, json=None, ns=None, host=None):
185    return tool('ethtool', args, json=json, ns=ns, host=host)
186
187
188def rand_port(type=socket.SOCK_STREAM):
189    """
190    Get a random unprivileged port.
191    """
192    with socket.socket(socket.AF_INET6, type) as s:
193        s.bind(("", 0))
194        return s.getsockname()[1]
195
196
197def wait_port_listen(port, proto="tcp", ns=None, host=None, sleep=0.005, deadline=5):
198    end = time.monotonic() + deadline
199
200    pattern = f":{port:04X} .* "
201    if proto == "tcp": # for tcp protocol additionally check the socket state
202        pattern += "0A"
203    pattern = re.compile(pattern)
204
205    while True:
206        data = cmd(f'cat /proc/net/{proto}*', ns=ns, host=host, shell=True).stdout
207        for row in data.split("\n"):
208            if pattern.search(row):
209                return
210        if time.monotonic() > end:
211            raise Exception("Waiting for port listen timed out")
212        time.sleep(sleep)
213