| 1 | #!/usr/bin/env python2
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| 2 | """Builtin_trap.py."""
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| 3 | from __future__ import print_function
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| 4 |
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| 5 | from signal import SIG_DFL, SIGINT, SIGKILL, SIGSTOP, SIGWINCH
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| 6 |
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| 7 | from _devbuild.gen import arg_types
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| 8 | from _devbuild.gen.runtime_asdl import cmd_value
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| 9 | from _devbuild.gen.syntax_asdl import loc, source
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| 10 | from core import alloc
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| 11 | from core import dev
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| 12 | from core import error
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| 13 | from core import main_loop
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| 14 | from mycpp.mylib import log
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| 15 | from core import pyos
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| 16 | from core import vm
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| 17 | from frontend import flag_util
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| 18 | from frontend import signal_def
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| 19 | from frontend import reader
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| 20 | from mycpp import mylib
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| 21 | from mycpp.mylib import iteritems, print_stderr
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| 22 |
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| 23 | from typing import Dict, List, Optional, TYPE_CHECKING
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| 24 | if TYPE_CHECKING:
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| 25 | from _devbuild.gen.syntax_asdl import command_t
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| 26 | from display import ui
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| 27 | from frontend.parse_lib import ParseContext
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| 28 |
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| 29 | _ = log
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| 30 |
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| 31 |
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| 32 | class TrapState(object):
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| 33 | """Traps are shell callbacks that the user wants to run on certain events.
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| 34 |
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| 35 | There are 2 catogires:
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| 36 | 1. Signals like SIGUSR1
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| 37 | 2. Hooks like EXIT
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| 38 |
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| 39 | Signal handlers execute in the main loop, and within blocking syscalls.
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| 40 |
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| 41 | EXIT, DEBUG, ERR, RETURN execute in specific places in the interpreter.
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| 42 | """
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| 43 |
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| 44 | def __init__(self, signal_safe):
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| 45 | # type: (pyos.SignalSafe) -> None
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| 46 | self.signal_safe = signal_safe
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| 47 | self.hooks = {} # type: Dict[str, command_t]
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| 48 | self.traps = {} # type: Dict[int, command_t]
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| 49 |
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| 50 | def ClearForSubProgram(self, inherit_errtrace):
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| 51 | # type: (bool) -> None
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| 52 | """SubProgramThunk uses this because traps aren't inherited."""
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| 53 |
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| 54 | # bash clears hooks like DEBUG in subshells.
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| 55 | # The ERR can be preserved if set -o errtrace
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| 56 | hook_err = self.hooks.get('ERR')
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| 57 | self.hooks.clear()
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| 58 | if hook_err is not None and inherit_errtrace:
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| 59 | self.hooks['ERR'] = hook_err
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| 60 |
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| 61 | self.traps.clear()
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| 62 |
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| 63 | def GetHook(self, hook_name):
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| 64 | # type: (str) -> command_t
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| 65 | """ e.g. EXIT hook. """
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| 66 | return self.hooks.get(hook_name, None)
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| 67 |
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| 68 | def AddUserHook(self, hook_name, handler):
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| 69 | # type: (str, command_t) -> None
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| 70 | self.hooks[hook_name] = handler
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| 71 |
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| 72 | def RemoveUserHook(self, hook_name):
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| 73 | # type: (str) -> None
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| 74 | mylib.dict_erase(self.hooks, hook_name)
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| 75 |
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| 76 | def AddUserTrap(self, sig_num, handler):
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| 77 | # type: (int, command_t) -> None
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| 78 | """E.g.
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| 79 |
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| 80 | SIGUSR1.
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| 81 | """
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| 82 | self.traps[sig_num] = handler
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| 83 |
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| 84 | if sig_num == SIGWINCH:
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| 85 | self.signal_safe.SetSigWinchCode(SIGWINCH)
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| 86 | else:
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| 87 | pyos.RegisterSignalInterest(sig_num)
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| 88 |
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| 89 | def RemoveUserTrap(self, sig_num):
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| 90 | # type: (int) -> None
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| 91 |
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| 92 | mylib.dict_erase(self.traps, sig_num)
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| 93 |
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| 94 | if sig_num == SIGINT:
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| 95 | # Don't disturb the runtime signal handlers:
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| 96 | # 1. from CPython
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| 97 | # 2. pyos::InitSignalSafe() calls RegisterSignalInterest(SIGINT)
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| 98 | pass
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| 99 | elif sig_num == SIGWINCH:
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| 100 | self.signal_safe.SetSigWinchCode(pyos.UNTRAPPED_SIGWINCH)
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| 101 | else:
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| 102 | pyos.Sigaction(sig_num, SIG_DFL)
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| 103 |
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| 104 | def GetPendingTraps(self):
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| 105 | # type: () -> Optional[List[command_t]]
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| 106 | """Transfer ownership of the current queue of pending trap handlers to
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| 107 | the caller."""
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| 108 | signals = self.signal_safe.TakePendingSignals()
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| 109 |
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| 110 | # Optimization for the common case: do not allocate a list. This function
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| 111 | # is called in the interpreter loop.
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| 112 | if len(signals) == 0:
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| 113 | self.signal_safe.ReuseEmptyList(signals)
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| 114 | return None
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| 115 |
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| 116 | run_list = [] # type: List[command_t]
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| 117 | for sig_num in signals:
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| 118 | node = self.traps.get(sig_num, None)
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| 119 | if node is not None:
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| 120 | run_list.append(node)
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| 121 |
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| 122 | # Optimization to avoid allocation in the main loop.
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| 123 | del signals[:]
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| 124 | self.signal_safe.ReuseEmptyList(signals)
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| 125 |
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| 126 | return run_list
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| 127 |
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| 128 | def ThisProcessHasTraps(self):
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| 129 | # type: () -> bool
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| 130 | """
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| 131 | nolastfork optimizations should be disabled when the process has code
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| 132 | to run after fork!
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| 133 | """
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| 134 | if 0:
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| 135 | log('traps %d', len(self.traps))
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| 136 | log('hooks %d', len(self.hooks))
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| 137 | return len(self.traps) != 0 or len(self.hooks) != 0
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| 138 |
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| 139 |
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| 140 | def _GetSignalNumber(sig_spec):
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| 141 | # type: (str) -> int
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| 142 |
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| 143 | # POSIX lists the numbers that are required.
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| 144 | # http://pubs.opengroup.org/onlinepubs/9699919799/
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| 145 | #
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| 146 | # Added 13 for SIGPIPE because autoconf's 'configure' uses it!
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| 147 | if sig_spec.strip() in ('1', '2', '3', '6', '9', '13', '14', '15'):
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| 148 | return int(sig_spec)
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| 149 |
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| 150 | # INT is an alias for SIGINT
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| 151 | if sig_spec.startswith('SIG'):
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| 152 | sig_spec = sig_spec[3:]
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| 153 | return signal_def.GetNumber(sig_spec)
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| 154 |
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| 155 |
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| 156 | _HOOK_NAMES = ['EXIT', 'ERR', 'RETURN', 'DEBUG']
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| 157 |
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| 158 | # bash's default -p looks like this:
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| 159 | # trap -- '' SIGTSTP
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| 160 | # trap -- '' SIGTTIN
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| 161 | # trap -- '' SIGTTOU
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| 162 | #
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| 163 | # CPython registers different default handlers. The C++ rewrite should make
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| 164 | # OVM match sh/bash more closely.
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| 165 |
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| 166 | # Example of trap:
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| 167 | # trap -- 'echo "hi there" | wc ' SIGINT
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| 168 | #
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| 169 | # Then hit Ctrl-C.
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| 170 |
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| 171 |
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| 172 | class Trap(vm._Builtin):
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| 173 |
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| 174 | def __init__(self, trap_state, parse_ctx, tracer, errfmt):
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| 175 | # type: (TrapState, ParseContext, dev.Tracer, ui.ErrorFormatter) -> None
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| 176 | self.trap_state = trap_state
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| 177 | self.parse_ctx = parse_ctx
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| 178 | self.arena = parse_ctx.arena
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| 179 | self.tracer = tracer
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| 180 | self.errfmt = errfmt
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| 181 |
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| 182 | def _ParseTrapCode(self, code_str):
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| 183 | # type: (str) -> command_t
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| 184 | """
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| 185 | Returns:
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| 186 | A node, or None if the code is invalid.
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| 187 | """
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| 188 | line_reader = reader.StringLineReader(code_str, self.arena)
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| 189 | c_parser = self.parse_ctx.MakeOshParser(line_reader)
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| 190 |
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| 191 | # TODO: the SPID should be passed through argv.
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| 192 | src = source.ArgvWord('trap', loc.Missing)
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| 193 | with alloc.ctx_SourceCode(self.arena, src):
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| 194 | try:
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| 195 | node = main_loop.ParseWholeFile(c_parser)
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| 196 | except error.Parse as e:
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| 197 | self.errfmt.PrettyPrintError(e)
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| 198 | return None
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| 199 |
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| 200 | return node
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| 201 |
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| 202 | def Run(self, cmd_val):
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| 203 | # type: (cmd_value.Argv) -> int
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| 204 | attrs, arg_r = flag_util.ParseCmdVal('trap', cmd_val)
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| 205 | arg = arg_types.trap(attrs.attrs)
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| 206 |
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| 207 | if arg.p: # Print registered handlers
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| 208 | # The unit tests rely on this being one line.
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| 209 | # bash prints a line that can be re-parsed.
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| 210 | for name, _ in iteritems(self.trap_state.hooks):
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| 211 | print('%s TrapState' % (name, ))
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| 212 |
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| 213 | for sig_num, _ in iteritems(self.trap_state.traps):
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| 214 | print('%d TrapState' % (sig_num, ))
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| 215 |
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| 216 | return 0
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| 217 |
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| 218 | if arg.l: # List valid signals and hooks
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| 219 | for hook_name in _HOOK_NAMES:
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| 220 | print(' %s' % hook_name)
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| 221 |
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| 222 | signal_def.PrintSignals()
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| 223 |
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| 224 | return 0
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| 225 |
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| 226 | code_str = arg_r.ReadRequired('requires a code string')
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| 227 | sig_spec, sig_loc = arg_r.ReadRequired2(
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| 228 | 'requires a signal or hook name')
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| 229 |
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| 230 | # sig_key is NORMALIZED sig_spec: a signal number string or string hook
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| 231 | # name.
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| 232 | sig_key = None # type: Optional[str]
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| 233 | sig_num = signal_def.NO_SIGNAL
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| 234 |
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| 235 | if sig_spec in _HOOK_NAMES:
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| 236 | sig_key = sig_spec
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| 237 | elif sig_spec == '0': # Special case
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| 238 | sig_key = 'EXIT'
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| 239 | else:
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| 240 | sig_num = _GetSignalNumber(sig_spec)
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| 241 | if sig_num != signal_def.NO_SIGNAL:
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| 242 | sig_key = str(sig_num)
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| 243 |
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| 244 | if sig_key is None:
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| 245 | self.errfmt.Print_("Invalid signal or hook %r" % sig_spec,
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| 246 | blame_loc=cmd_val.arg_locs[2])
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| 247 | return 1
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| 248 |
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| 249 | # NOTE: sig_spec isn't validated when removing handlers.
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| 250 | if code_str == '-':
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| 251 | if sig_key in _HOOK_NAMES:
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| 252 | self.trap_state.RemoveUserHook(sig_key)
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| 253 | return 0
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| 254 |
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| 255 | if sig_num != signal_def.NO_SIGNAL:
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| 256 | self.trap_state.RemoveUserTrap(sig_num)
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| 257 | return 0
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| 258 |
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| 259 | raise AssertionError('Signal or trap')
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| 260 |
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| 261 | # Try parsing the code first.
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| 262 |
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| 263 | # TODO: If simple_trap is on (for oil:upgrade), then it must be a function
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| 264 | # name? And then you wrap it in 'try'?
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| 265 |
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| 266 | node = self._ParseTrapCode(code_str)
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| 267 | if node is None:
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| 268 | return 1 # ParseTrapCode() prints an error for us.
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| 269 |
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| 270 | # Register a hook.
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| 271 | if sig_key in _HOOK_NAMES:
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| 272 | if sig_key == 'RETURN':
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| 273 | print_stderr("osh warning: The %r hook isn't implemented" %
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| 274 | sig_spec)
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| 275 | self.trap_state.AddUserHook(sig_key, node)
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| 276 | return 0
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| 277 |
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| 278 | # Register a signal.
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| 279 | if sig_num != signal_def.NO_SIGNAL:
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| 280 | # For signal handlers, the traps dictionary is used only for debugging.
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| 281 | if sig_num in (SIGKILL, SIGSTOP):
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| 282 | self.errfmt.Print_("Signal %r can't be handled" % sig_spec,
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| 283 | blame_loc=sig_loc)
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| 284 | # Other shells return 0, but this seems like an obvious error
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| 285 | return 1
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| 286 | self.trap_state.AddUserTrap(sig_num, node)
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| 287 | return 0
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| 288 |
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| 289 | raise AssertionError('Signal or trap')
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