diff options
| -rw-r--r-- | python/vyos/util.py | 138 |
1 files changed, 105 insertions, 33 deletions
diff --git a/python/vyos/util.py b/python/vyos/util.py index 291ce64ea..9ca229136 100644 --- a/python/vyos/util.py +++ b/python/vyos/util.py @@ -16,67 +16,137 @@ import os import re import sys -from subprocess import Popen, PIPE, STDOUT, DEVNULL +from subprocess import Popen +from subprocess import PIPE +from subprocess import STDOUT +from subprocess import DEVNULL + def debug(flag): - # this is to force all new flags to be registered here so that - # they can be documented: - # - developer: the code will drop into PBD on un-handled exception - # - ifconfig: prints command and sysfs access on stdout for interface + """ + Check is a debug flag was set by the user. + a flag can be set by touching the file /tmp/vyos.flag.debug + with flag being the flag name, the current flags are: + - developer: the code will drop into PBD on un-handled exception + - ifconfig: prints command and sysfs access on stdout for interface + The function returns an empty string if the flag was not set, + """ + + # this is to force all new flags to be registered here to be documented: if flag not in ['developer', 'ifconfig']: return '' return flag if os.path.isfile(f'/tmp/vyos.{flag}.debug') else '' -def debug_msg(message, section=''): - if debug(section): - print(f'DEBUG/{section:<6} {message}') +def debug_msg(message, flag=''): + """ + print a debug message line on stdout if debugging is enabled for the flag + """ + + if debug(flag): + print(f'DEBUG/{flag:<6} {message}') + +# There is many (too many) ways to run command with python +# os.system, subprocess.Popen, subproces.{run,call,check_output} +# which all have slighty different behaviour -def popen(command, section='', shell=None, input=None, timeout=None, env=None, - universal_newlines=None, stdout=PIPE, stderr=STDOUT, decode=None): - """ popen does not raise, returns the output and error code of command """ + +def popen(command, flag='', shell=None, input=None, timeout=None, env=None, + stdout=PIPE, stderr=None, decode=None): + """ + popen is a wrapper helper aound subprocess.Popen + with it default setting it will return a tuple (out, err) + out: the output of the program run + err: the error code returned by the program + + it can be affected by the following flags: + shell: do not try to auto-detect if a shell is required + for example if a pipe (|) or redirection (>, >>) is used + input: data to sent to the child process via STDIN + the data should be bytes but string will be converted + timeout: time after which the command will be considered to have failed + env: mapping that defines the environment variables for the new process + stdout: define how the output of the program should be handled + - PIPE (default), sends stdout to the output + - DEVNULL, discard the output + stderr: define how the output of the program should be handled + - None (default), send/merge the data to/with stderr + - PIPE, popen will append it to output + - STDOUT, send the data to be merged with stdout + - DEVNULL, discard the output + decode: specify the expected text encoding (utf-8, ascii, ...) + + usage: + to get both stdout, and stderr: popen('command', stdout=PIPE, stderr=STDOUT) + to discard stdout and get stderr: popen('command', stdout=DEVNUL, stderr=PIPE) + """ + debug_msg(f"cmd '{command}'", flag) use_shell = shell + stdin = None if shell is None: - use_shell = True if ' ' in command else False + use_shell = False + if ' ' in command: + use_shell = True + if env: + use_shell = True + if input: + stdin = PIPE + input = input.encode() if type(input) is str else input p = Popen( command, - stdout=stdout, stderr=stderr, + stdin=stdin, stdout=stdout, stderr=stderr, env=env, shell=use_shell, - universal_newlines=universal_newlines, ) - tmp = p.communicate(input, timeout)[0].strip() - debug_msg(f"cmd '{command}'", section) - decoded = tmp.decode(decode) if decode else tmp.decode() + tmp = p.communicate(input, timeout) + out1 = b'' + out2 = b'' + if stdout == PIPE: + out1 = tmp[0] + if stderr == PIPE: + out2 += tmp[1] + decoded1 = out1.decode(decode) if decode else out1.decode() + decoded2 = out2.decode(decode) if decode else out2.decode() + decoded1 = decoded1.replace('\r\n', '\n').strip() + decoded2 = decoded2.replace('\r\n', '\n').strip() + nl = '\n' if decoded1 and decoded2 else '' + decoded = decoded1 + nl + decoded2 if decoded: - debug_msg(f"returned:\n{decoded}", section) + debug_msg(f"returned:\n{decoded}", flag) return decoded, p.returncode -def run(command, section='', shell=None, input=None, timeout=None, env=None, - universal_newlines=None, stdout=PIPE, stderr=STDOUT, decode=None): - """ does not raise exception on error, returns error code """ +def run(command, flag='', shell=None, input=None, timeout=None, env=None, + stdout=DEVNULL, stderr=None, decode=None): + """ + A wrapper around vyos.util.popen, which discard the stdout and + will return the error code of a command + """ _, code = popen( - command, section, + command, flag, stdout=stdout, stderr=stderr, input=input, timeout=timeout, env=env, shell=shell, - universal_newlines=universal_newlines, decode=decode, ) return code -def cmd(command, section='', shell=None, input=None, timeout=None, env=None, - universal_newlines=None, stdout=PIPE, stderr=STDOUT, decode=None, +def cmd(command, flag='', shell=None, input=None, timeout=None, env=None, + stdout=PIPE, stderr=None, decode=None, raising=None, message=''): - """ does raise exception, returns output of command """ + """ + A wrapper around vyos.util.popen, which returns the stdout and + will raise the error code of a command + + raising: specify which call should be used when raising (default is OSError) + the class should only require a string as parameter + """ decoded, code = popen( - command, section, + command, flag, stdout=stdout, stderr=stderr, input=input, timeout=timeout, env=env, shell=shell, - universal_newlines=universal_newlines, decode=decode, ) if code != 0: @@ -92,15 +162,17 @@ def cmd(command, section='', shell=None, input=None, timeout=None, env=None, return decoded -def call(command, section='', shell=None, input=None, timeout=None, env=None, - universal_newlines=None, stdout=PIPE, stderr=STDOUT, decode=None): - """ does not raise exception on error, returns error code, print output """ +def call(command, flag='', shell=None, input=None, timeout=None, env=None, + stdout=PIPE, stderr=None, decode=None): + """ + A wrapper around vyos.util.popen, which print the stdout and + will return the error code of a command + """ out, code = popen( - command, section, + command, flag, stdout=stdout, stderr=stderr, input=input, timeout=timeout, env=env, shell=shell, - universal_newlines=universal_newlines, decode=decode, ) print(out) |