| 1 | """executor.py."""
|
| 2 | from __future__ import print_function
|
| 3 |
|
| 4 | from errno import EINTR
|
| 5 |
|
| 6 | from _devbuild.gen.id_kind_asdl import Id
|
| 7 | from _devbuild.gen.option_asdl import builtin_i
|
| 8 | from _devbuild.gen.runtime_asdl import RedirValue, trace
|
| 9 | from _devbuild.gen.syntax_asdl import (
|
| 10 | command,
|
| 11 | command_e,
|
| 12 | CommandSub,
|
| 13 | CompoundWord,
|
| 14 | loc,
|
| 15 | loc_t,
|
| 16 | )
|
| 17 | from _devbuild.gen.value_asdl import value
|
| 18 | from builtin import hay_ysh
|
| 19 | from core import dev
|
| 20 | from core import error
|
| 21 | from core import process
|
| 22 | from core.error import e_die, e_die_status
|
| 23 | from core import pyos
|
| 24 | from core import state
|
| 25 | from core import ui
|
| 26 | from core import vm
|
| 27 | from frontend import consts
|
| 28 | from frontend import lexer
|
| 29 | from mycpp.mylib import log
|
| 30 |
|
| 31 | import posix_ as posix
|
| 32 |
|
| 33 | from typing import cast, Dict, List, Optional, TYPE_CHECKING
|
| 34 | if TYPE_CHECKING:
|
| 35 | from _devbuild.gen.runtime_asdl import (cmd_value, CommandStatus,
|
| 36 | StatusArray)
|
| 37 | from _devbuild.gen.syntax_asdl import command_t
|
| 38 | from builtin import trap_osh
|
| 39 | from core import optview
|
| 40 | from core import state
|
| 41 | from core.vm import _Builtin
|
| 42 |
|
| 43 | _ = log
|
| 44 |
|
| 45 |
|
| 46 | class _ProcessSubFrame(object):
|
| 47 | """To keep track of diff <(cat 1) <(cat 2) > >(tac)"""
|
| 48 |
|
| 49 | def __init__(self):
|
| 50 | # type: () -> None
|
| 51 |
|
| 52 | # These objects appear unconditionally in the main loop, and aren't
|
| 53 | # commonly used, so we manually optimize [] into None.
|
| 54 |
|
| 55 | self._to_wait = [] # type: List[process.Process]
|
| 56 | self._to_close = [] # type: List[int] # file descriptors
|
| 57 | self._locs = [] # type: List[loc_t]
|
| 58 | self._modified = False
|
| 59 |
|
| 60 | def WasModified(self):
|
| 61 | # type: () -> bool
|
| 62 | return self._modified
|
| 63 |
|
| 64 | def Append(self, p, fd, status_loc):
|
| 65 | # type: (process.Process, int, loc_t) -> None
|
| 66 | self._modified = True
|
| 67 |
|
| 68 | self._to_wait.append(p)
|
| 69 | self._to_close.append(fd)
|
| 70 | self._locs.append(status_loc)
|
| 71 |
|
| 72 | def MaybeWaitOnProcessSubs(self, waiter, status_array):
|
| 73 | # type: (process.Waiter, StatusArray) -> None
|
| 74 |
|
| 75 | # Wait in the same order that they were evaluated. That seems fine.
|
| 76 | for fd in self._to_close:
|
| 77 | posix.close(fd)
|
| 78 |
|
| 79 | codes = [] # type: List[int]
|
| 80 | locs = [] # type: List[loc_t]
|
| 81 | for i, p in enumerate(self._to_wait):
|
| 82 | #log('waiting for %s', p)
|
| 83 | st = p.Wait(waiter)
|
| 84 | codes.append(st)
|
| 85 | locs.append(self._locs[i])
|
| 86 |
|
| 87 | status_array.codes = codes
|
| 88 | status_array.locs = locs
|
| 89 |
|
| 90 |
|
| 91 | # Big flgas for RunSimpleCommand
|
| 92 | DO_FORK = 1 << 1
|
| 93 | NO_CALL_PROCS = 1 << 2 # command ls suppresses function lookup
|
| 94 | USE_DEFAULT_PATH = 1 << 3 # for command -p ls changes the path
|
| 95 |
|
| 96 | # Copied from var.c in dash
|
| 97 | DEFAULT_PATH = [
|
| 98 | '/usr/local/sbin', '/usr/local/bin', '/usr/sbin', '/usr/bin', '/sbin',
|
| 99 | '/bin'
|
| 100 | ]
|
| 101 |
|
| 102 |
|
| 103 | class ShellExecutor(vm._Executor):
|
| 104 | """An executor combined with the OSH language evaluators in osh/ to create
|
| 105 | a shell interpreter."""
|
| 106 |
|
| 107 | def __init__(
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| 108 | self,
|
| 109 | mem, # type: state.Mem
|
| 110 | exec_opts, # type: optview.Exec
|
| 111 | mutable_opts, # type: state.MutableOpts
|
| 112 | procs, # type: Dict[str, value.Proc]
|
| 113 | hay_state, # type: hay_ysh.HayState
|
| 114 | builtins, # type: Dict[int, _Builtin]
|
| 115 | search_path, # type: state.SearchPath
|
| 116 | ext_prog, # type: process.ExternalProgram
|
| 117 | waiter, # type: process.Waiter
|
| 118 | tracer, # type: dev.Tracer
|
| 119 | job_control, # type: process.JobControl
|
| 120 | job_list, # type: process.JobList
|
| 121 | fd_state, # type: process.FdState
|
| 122 | trap_state, # type: trap_osh.TrapState
|
| 123 | errfmt # type: ui.ErrorFormatter
|
| 124 | ):
|
| 125 | # type: (...) -> None
|
| 126 | vm._Executor.__init__(self)
|
| 127 | self.mem = mem
|
| 128 | self.exec_opts = exec_opts
|
| 129 | self.mutable_opts = mutable_opts # for IsDisabled(), not mutating
|
| 130 | self.procs = procs
|
| 131 | self.hay_state = hay_state
|
| 132 | self.builtins = builtins
|
| 133 | self.search_path = search_path
|
| 134 | self.ext_prog = ext_prog
|
| 135 | self.waiter = waiter
|
| 136 | self.tracer = tracer
|
| 137 | self.multi_trace = tracer.multi_trace
|
| 138 | self.job_control = job_control
|
| 139 | # sleep 5 & puts a (PID, job#) entry here. And then "jobs" displays it.
|
| 140 | self.job_list = job_list
|
| 141 | self.fd_state = fd_state
|
| 142 | self.trap_state = trap_state
|
| 143 | self.errfmt = errfmt
|
| 144 | self.process_sub_stack = [] # type: List[_ProcessSubFrame]
|
| 145 | self.clean_frame_pool = [] # type: List[_ProcessSubFrame]
|
| 146 |
|
| 147 | # When starting a pipeline in the foreground, we need to pass a handle to it
|
| 148 | # through the evaluation of the last node back to ourselves for execution.
|
| 149 | # We use this handle to make sure any processes forked for the last part of
|
| 150 | # the pipeline are placed into the same process group as the rest of the
|
| 151 | # pipeline. Since there is, by design, only ever one foreground pipeline and
|
| 152 | # any pipelines started within subshells run in their parent's process
|
| 153 | # group, we only need one pointer here, not some collection.
|
| 154 | self.fg_pipeline = None # type: Optional[process.Pipeline]
|
| 155 |
|
| 156 | def CheckCircularDeps(self):
|
| 157 | # type: () -> None
|
| 158 | assert self.cmd_ev is not None
|
| 159 |
|
| 160 | def _MakeProcess(self, node, inherit_errexit=True):
|
| 161 | # type: (command_t, bool) -> process.Process
|
| 162 | """Assume we will run the node in another process.
|
| 163 |
|
| 164 | Return a process.
|
| 165 | """
|
| 166 | UP_node = node
|
| 167 | if node.tag() == command_e.ControlFlow:
|
| 168 | node = cast(command.ControlFlow, UP_node)
|
| 169 | # Pipeline or subshells with control flow are invalid, e.g.:
|
| 170 | # - break | less
|
| 171 | # - continue | less
|
| 172 | # - ( return )
|
| 173 | # NOTE: This could be done at parse time too.
|
| 174 | if node.keyword.id != Id.ControlFlow_Exit:
|
| 175 | e_die(
|
| 176 | 'Invalid control flow %r in pipeline / subshell / background'
|
| 177 | % lexer.TokenVal(node.keyword), node.keyword)
|
| 178 |
|
| 179 | # NOTE: If ErrExit(), we could be verbose about subprogram errors? This
|
| 180 | # only really matters when executing 'exit 42', because the child shell
|
| 181 | # inherits errexit and will be verbose. Other notes:
|
| 182 | #
|
| 183 | # - We might want errors to fit on a single line so they don't get #
|
| 184 | # interleaved.
|
| 185 | # - We could turn the `exit` builtin into a error.FatalRuntime exception
|
| 186 | # and get this check for "free".
|
| 187 | thunk = process.SubProgramThunk(self.cmd_ev,
|
| 188 | node,
|
| 189 | self.trap_state,
|
| 190 | self.multi_trace,
|
| 191 | inherit_errexit=inherit_errexit)
|
| 192 | p = process.Process(thunk, self.job_control, self.job_list,
|
| 193 | self.tracer)
|
| 194 | return p
|
| 195 |
|
| 196 | def RunBuiltin(self, builtin_id, cmd_val):
|
| 197 | # type: (int, cmd_value.Argv) -> int
|
| 198 | """Run a builtin.
|
| 199 |
|
| 200 | Also called by the 'builtin' builtin.
|
| 201 | """
|
| 202 | self.tracer.OnBuiltin(builtin_id, cmd_val.argv)
|
| 203 |
|
| 204 | builtin_func = self.builtins[builtin_id]
|
| 205 |
|
| 206 | with vm.ctx_FlushStdout():
|
| 207 | # note: could be second word, like 'builtin read'
|
| 208 | with ui.ctx_Location(self.errfmt, cmd_val.arg_locs[0]):
|
| 209 | try:
|
| 210 | status = builtin_func.Run(cmd_val)
|
| 211 | assert isinstance(status, int)
|
| 212 | except error.Usage as e:
|
| 213 | arg0 = cmd_val.argv[0]
|
| 214 | # e.g. 'type' doesn't accept flag '-x'
|
| 215 | self.errfmt.PrefixPrint(e.msg, '%r ' % arg0, e.location)
|
| 216 | status = 2 # consistent error code for usage error
|
| 217 |
|
| 218 | return status
|
| 219 |
|
| 220 | def RunSimpleCommand(self, cmd_val, cmd_st, run_flags):
|
| 221 | # type: (cmd_value.Argv, CommandStatus, int) -> int
|
| 222 | """Run builtins, functions, external commands.
|
| 223 |
|
| 224 | Possible variations:
|
| 225 | - YSH might have different, simpler rules. No special builtins, etc.
|
| 226 | - YSH might have OILS_PATH = :| /bin /usr/bin | or something.
|
| 227 | - Interpreters might want to define all their own builtins.
|
| 228 | """
|
| 229 | argv = cmd_val.argv
|
| 230 | if len(cmd_val.arg_locs):
|
| 231 | arg0_loc = cmd_val.arg_locs[0] # type: loc_t
|
| 232 | else:
|
| 233 | arg0_loc = loc.Missing
|
| 234 |
|
| 235 | # This happens when you write "$@" but have no arguments.
|
| 236 | if len(argv) == 0:
|
| 237 | if self.exec_opts.strict_argv():
|
| 238 | e_die("Command evaluated to an empty argv array", arg0_loc)
|
| 239 | else:
|
| 240 | return 0 # status 0, or skip it?
|
| 241 |
|
| 242 | arg0 = argv[0]
|
| 243 |
|
| 244 | builtin_id = consts.LookupAssignBuiltin(arg0)
|
| 245 | if builtin_id != consts.NO_INDEX:
|
| 246 | # command readonly is disallowed, for technical reasons. Could relax it
|
| 247 | # later.
|
| 248 | self.errfmt.Print_("Can't run assignment builtin recursively",
|
| 249 | arg0_loc)
|
| 250 | return 1
|
| 251 |
|
| 252 | builtin_id = consts.LookupSpecialBuiltin(arg0)
|
| 253 | if builtin_id != consts.NO_INDEX:
|
| 254 | cmd_st.show_code = True # this is a "leaf" for errors
|
| 255 | status = self.RunBuiltin(builtin_id, cmd_val)
|
| 256 | # TODO: Enable this and fix spec test failures.
|
| 257 | # Also update _SPECIAL_BUILTINS in osh/builtin.py.
|
| 258 | #if status != 0:
|
| 259 | # e_die_status(status, 'special builtin failed')
|
| 260 | return status
|
| 261 |
|
| 262 | call_procs = not (run_flags & NO_CALL_PROCS)
|
| 263 | # Builtins like 'true' can be redefined as functions.
|
| 264 | if call_procs:
|
| 265 | # TODO: Look shell functions in self.sh_funcs, but procs are
|
| 266 | # value.Proc in the var namespace.
|
| 267 | # Pitfall: What happens if there are two of the same name? I guess
|
| 268 | # that's why you have = and 'type' inspect them
|
| 269 |
|
| 270 | proc_node = self.procs.get(arg0)
|
| 271 | if proc_node is not None:
|
| 272 | if self.exec_opts.strict_errexit():
|
| 273 | disabled_tok = self.mutable_opts.ErrExitDisabledToken()
|
| 274 | if disabled_tok:
|
| 275 | self.errfmt.Print_(
|
| 276 | 'errexit was disabled for this construct',
|
| 277 | disabled_tok)
|
| 278 | self.errfmt.StderrLine('')
|
| 279 | e_die(
|
| 280 | "Can't run a proc while errexit is disabled. "
|
| 281 | "Use 'try' or wrap it in a process with $0 myproc",
|
| 282 | arg0_loc)
|
| 283 |
|
| 284 | with dev.ctx_Tracer(self.tracer, 'proc', argv):
|
| 285 | # NOTE: Functions could call 'exit 42' directly, etc.
|
| 286 | status = self.cmd_ev.RunProc(proc_node, cmd_val)
|
| 287 | return status
|
| 288 |
|
| 289 | # Notes:
|
| 290 | # - procs shadow hay names
|
| 291 | # - hay names shadow normal builtins? Should we limit to CAPS or no?
|
| 292 | if self.hay_state.Resolve(arg0):
|
| 293 | return self.RunBuiltin(builtin_i.haynode, cmd_val)
|
| 294 |
|
| 295 | builtin_id = consts.LookupNormalBuiltin(arg0)
|
| 296 |
|
| 297 | if self.exec_opts._running_hay():
|
| 298 | # Hay: limit the builtins that can be run
|
| 299 | # - declare 'use dialect'
|
| 300 | # - echo and write for debugging
|
| 301 | # - no JSON?
|
| 302 | if builtin_id in (builtin_i.haynode, builtin_i.use, builtin_i.echo,
|
| 303 | builtin_i.write):
|
| 304 | cmd_st.show_code = True # this is a "leaf" for errors
|
| 305 | return self.RunBuiltin(builtin_id, cmd_val)
|
| 306 |
|
| 307 | self.errfmt.Print_('Unknown command %r while running hay' % arg0,
|
| 308 | arg0_loc)
|
| 309 | return 127
|
| 310 |
|
| 311 | if builtin_id != consts.NO_INDEX:
|
| 312 | cmd_st.show_code = True # this is a "leaf" for errors
|
| 313 | return self.RunBuiltin(builtin_id, cmd_val)
|
| 314 |
|
| 315 | environ = self.mem.GetExported() # Include temporary variables
|
| 316 |
|
| 317 | if cmd_val.typed_args:
|
| 318 | e_die(
|
| 319 | '%r appears to be external. External commands don\'t accept typed args (OILS-ERR-200)'
|
| 320 | % arg0, cmd_val.typed_args.left)
|
| 321 |
|
| 322 | # Resolve argv[0] BEFORE forking.
|
| 323 | if run_flags & USE_DEFAULT_PATH:
|
| 324 | argv0_path = state.LookupExecutable(arg0, DEFAULT_PATH)
|
| 325 | else:
|
| 326 | argv0_path = self.search_path.CachedLookup(arg0)
|
| 327 | if argv0_path is None:
|
| 328 | self.errfmt.Print_('%r not found (OILS-ERR-100)' % arg0, arg0_loc)
|
| 329 | return 127
|
| 330 |
|
| 331 | # Normal case: ls /
|
| 332 | if run_flags & DO_FORK:
|
| 333 | thunk = process.ExternalThunk(self.ext_prog, argv0_path, cmd_val,
|
| 334 | environ)
|
| 335 | p = process.Process(thunk, self.job_control, self.job_list,
|
| 336 | self.tracer)
|
| 337 |
|
| 338 | if self.job_control.Enabled():
|
| 339 | if self.fg_pipeline is not None:
|
| 340 | pgid = self.fg_pipeline.ProcessGroupId()
|
| 341 | # If job control is enabled, this should be true
|
| 342 | assert pgid != process.INVALID_PGID
|
| 343 |
|
| 344 | change = process.SetPgid(pgid, self.tracer)
|
| 345 | self.fg_pipeline = None # clear to avoid confusion in subshells
|
| 346 | else:
|
| 347 | change = process.SetPgid(process.OWN_LEADER, self.tracer)
|
| 348 | p.AddStateChange(change)
|
| 349 |
|
| 350 | status = p.RunProcess(self.waiter, trace.External(cmd_val.argv))
|
| 351 |
|
| 352 | # this is close to a "leaf" for errors
|
| 353 | # problem: permission denied EACCESS prints duplicate messages
|
| 354 | # TODO: add message command 'ls' failed
|
| 355 | cmd_st.show_code = True
|
| 356 |
|
| 357 | return status
|
| 358 |
|
| 359 | self.tracer.OnExec(cmd_val.argv)
|
| 360 |
|
| 361 | # Already forked for pipeline: ls / | wc -l
|
| 362 | self.ext_prog.Exec(argv0_path, cmd_val, environ) # NEVER RETURNS
|
| 363 |
|
| 364 | raise AssertionError('for -Wreturn-type in C++')
|
| 365 |
|
| 366 | def RunBackgroundJob(self, node):
|
| 367 | # type: (command_t) -> int
|
| 368 | """For & etc."""
|
| 369 | # Special case for pipeline. There is some evidence here:
|
| 370 | # https://www.gnu.org/software/libc/manual/html_node/Launching-Jobs.html#Launching-Jobs
|
| 371 | #
|
| 372 | # "You can either make all the processes in the process group be children
|
| 373 | # of the shell process, or you can make one process in group be the
|
| 374 | # ancestor of all the other processes in that group. The sample shell
|
| 375 | # program presented in this chapter uses the first approach because it
|
| 376 | # makes bookkeeping somewhat simpler."
|
| 377 | UP_node = node
|
| 378 |
|
| 379 | if UP_node.tag() == command_e.Pipeline:
|
| 380 | node = cast(command.Pipeline, UP_node)
|
| 381 | pi = process.Pipeline(self.exec_opts.sigpipe_status_ok(),
|
| 382 | self.job_control, self.job_list, self.tracer)
|
| 383 | for child in node.children:
|
| 384 | p = self._MakeProcess(child)
|
| 385 | p.Init_ParentPipeline(pi)
|
| 386 | pi.Add(p)
|
| 387 |
|
| 388 | pi.StartPipeline(self.waiter)
|
| 389 | pi.SetBackground()
|
| 390 | last_pid = pi.LastPid()
|
| 391 | self.mem.last_bg_pid = last_pid # for $!
|
| 392 |
|
| 393 | self.job_list.AddJob(pi) # show in 'jobs' list
|
| 394 |
|
| 395 | else:
|
| 396 | # Problem: to get the 'set -b' behavior of immediate notifications, we
|
| 397 | # have to register SIGCHLD. But then that introduces race conditions.
|
| 398 | # If we haven't called Register yet, then we won't know who to notify.
|
| 399 |
|
| 400 | p = self._MakeProcess(node)
|
| 401 | if self.job_control.Enabled():
|
| 402 | p.AddStateChange(
|
| 403 | process.SetPgid(process.OWN_LEADER, self.tracer))
|
| 404 |
|
| 405 | p.SetBackground()
|
| 406 | pid = p.StartProcess(trace.Fork)
|
| 407 | self.mem.last_bg_pid = pid # for $!
|
| 408 | self.job_list.AddJob(p) # show in 'jobs' list
|
| 409 | return 0
|
| 410 |
|
| 411 | def RunPipeline(self, node, status_out):
|
| 412 | # type: (command.Pipeline, CommandStatus) -> None
|
| 413 |
|
| 414 | pi = process.Pipeline(self.exec_opts.sigpipe_status_ok(),
|
| 415 | self.job_control, self.job_list, self.tracer)
|
| 416 |
|
| 417 | # initialized with CommandStatus.CreateNull()
|
| 418 | pipe_locs = [] # type: List[loc_t]
|
| 419 |
|
| 420 | # First n-1 processes (which is empty when n == 1)
|
| 421 | n = len(node.children)
|
| 422 | for i in xrange(n - 1):
|
| 423 | child = node.children[i]
|
| 424 |
|
| 425 | # TODO: determine these locations at parse time?
|
| 426 | pipe_locs.append(loc.Command(child))
|
| 427 |
|
| 428 | p = self._MakeProcess(child)
|
| 429 | p.Init_ParentPipeline(pi)
|
| 430 | pi.Add(p)
|
| 431 |
|
| 432 | last_child = node.children[n - 1]
|
| 433 | # Last piece of code is in THIS PROCESS. 'echo foo | read line; echo $line'
|
| 434 | pi.AddLast((self.cmd_ev, last_child))
|
| 435 | pipe_locs.append(loc.Command(last_child))
|
| 436 |
|
| 437 | with dev.ctx_Tracer(self.tracer, 'pipeline', None):
|
| 438 | pi.StartPipeline(self.waiter)
|
| 439 | self.fg_pipeline = pi
|
| 440 | status_out.pipe_status = pi.RunLastPart(self.waiter, self.fd_state)
|
| 441 | self.fg_pipeline = None # clear in case we didn't end up forking
|
| 442 |
|
| 443 | status_out.pipe_locs = pipe_locs
|
| 444 |
|
| 445 | def RunSubshell(self, node):
|
| 446 | # type: (command_t) -> int
|
| 447 | p = self._MakeProcess(node)
|
| 448 | if self.job_control.Enabled():
|
| 449 | p.AddStateChange(process.SetPgid(process.OWN_LEADER, self.tracer))
|
| 450 |
|
| 451 | return p.RunProcess(self.waiter, trace.ForkWait)
|
| 452 |
|
| 453 | def RunCommandSub(self, cs_part):
|
| 454 | # type: (CommandSub) -> str
|
| 455 |
|
| 456 | if not self.exec_opts._allow_command_sub():
|
| 457 | # _allow_command_sub is used in two places. Only one of them turns off _allow_process_sub
|
| 458 | if not self.exec_opts._allow_process_sub():
|
| 459 | why = "status wouldn't be checked (strict_errexit)"
|
| 460 | else:
|
| 461 | why = 'eval_unsafe_arith is off'
|
| 462 |
|
| 463 | e_die("Command subs not allowed here because %s" % why,
|
| 464 | loc.WordPart(cs_part))
|
| 465 |
|
| 466 | node = cs_part.child
|
| 467 |
|
| 468 | # Hack for weird $(<file) construct
|
| 469 | if node.tag() == command_e.Simple:
|
| 470 | simple = cast(command.Simple, node)
|
| 471 | # Detect '< file'
|
| 472 | if (len(simple.words) == 0 and len(simple.redirects) == 1 and
|
| 473 | simple.redirects[0].op.id == Id.Redir_Less):
|
| 474 | # change it to __cat < file
|
| 475 | # TODO: change to 'internal cat' (issue 1013)
|
| 476 | tok = lexer.DummyToken(Id.Lit_Chars, '__cat')
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| 477 | cat_word = CompoundWord([tok])
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| 478 | # MUTATE the command.Simple node. This will only be done the first
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| 479 | # time in the parent process.
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| 480 | simple.words.append(cat_word)
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| 481 |
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| 482 | p = self._MakeProcess(node,
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| 483 | inherit_errexit=self.exec_opts.inherit_errexit())
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| 484 | # Shell quirk: Command subs remain part of the shell's process group, so we
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| 485 | # don't use p.AddStateChange(process.SetPgid(...))
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| 486 |
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| 487 | r, w = posix.pipe()
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| 488 | p.AddStateChange(process.StdoutToPipe(r, w))
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| 489 |
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| 490 | p.StartProcess(trace.CommandSub)
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| 491 | #log('Command sub started %d', pid)
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| 492 |
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| 493 | chunks = [] # type: List[str]
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| 494 | posix.close(w) # not going to write
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| 495 | while True:
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| 496 | n, err_num = pyos.Read(r, 4096, chunks)
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| 497 |
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| 498 | if n < 0:
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| 499 | if err_num == EINTR:
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| 500 | pass # retry
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| 501 | else:
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| 502 | # Like the top level IOError handler
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| 503 | e_die_status(
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| 504 | 2,
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| 505 | 'osh I/O error (read): %s' % posix.strerror(err_num))
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| 506 |
|
| 507 | elif n == 0: # EOF
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| 508 | break
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| 509 | posix.close(r)
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| 510 |
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| 511 | status = p.Wait(self.waiter)
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| 512 |
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| 513 | # OSH has the concept of aborting in the middle of a WORD. We're not
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| 514 | # waiting until the command is over!
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| 515 | if self.exec_opts.command_sub_errexit():
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| 516 | if status != 0:
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| 517 | msg = 'Command Sub exited with status %d' % status
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| 518 | raise error.ErrExit(status, msg, loc.WordPart(cs_part))
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| 519 |
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| 520 | else:
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| 521 | # Set a flag so we check errexit at the same time as bash. Example:
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| 522 | #
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| 523 | # a=$(false)
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| 524 | # echo foo # no matter what comes here, the flag is reset
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| 525 | #
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| 526 | # Set ONLY until this command node has finished executing.
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| 527 |
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| 528 | # HACK: move this
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| 529 | self.cmd_ev.check_command_sub_status = True
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| 530 | self.mem.SetLastStatus(status)
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| 531 |
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| 532 | # Runtime errors test case: # $("echo foo > $@")
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| 533 | # Why rstrip()?
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| 534 | # https://unix.stackexchange.com/questions/17747/why-does-shell-command-substitution-gobble-up-a-trailing-newline-char
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| 535 | return ''.join(chunks).rstrip('\n')
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| 536 |
|
| 537 | def RunProcessSub(self, cs_part):
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| 538 | # type: (CommandSub) -> str
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| 539 | """Process sub creates a forks a process connected to a pipe.
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| 540 |
|
| 541 | The pipe is typically passed to another process via a /dev/fd/$FD path.
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| 542 |
|
| 543 | Life cycle of a process substitution:
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| 544 |
|
| 545 | 1. Start with this code
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| 546 |
|
| 547 | diff <(seq 3) <(seq 4)
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| 548 |
|
| 549 | 2. To evaluate the command line, we evaluate every word. The
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| 550 | NormalWordEvaluator this method, RunProcessSub(), which does 3 things:
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| 551 |
|
| 552 | a. Create a pipe(), getting r and w
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| 553 | b. Starts the seq process, which inherits r and w
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| 554 | It has a StdoutToPipe() redirect, which means that it dup2(w, 1)
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| 555 | and close(r)
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| 556 | c. Close the w FD, because neither the shell or 'diff' will write to it.
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| 557 | However we must retain 'r', because 'diff' hasn't opened /dev/fd yet!
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| 558 | d. We evaluate <(seq 3) to /dev/fd/$r, so "diff" can read from it
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| 559 |
|
| 560 | 3. Now we're done evaluating every word, so we know the command line of
|
| 561 | diff, which looks like
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| 562 |
|
| 563 | diff /dev/fd/64 /dev/fd/65
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| 564 |
|
| 565 | Those are the FDs for the read ends of the pipes we created.
|
| 566 |
|
| 567 | 4. diff inherits a copy of the read end of bot pipes. But it actually
|
| 568 | calls open() both files passed as argv. (I think this is fine.)
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| 569 |
|
| 570 | 5. wait() for the diff process.
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| 571 |
|
| 572 | 6. The shell closes both the read ends of both pipes. Neither us or
|
| 573 | 'diffd' will read again.
|
| 574 |
|
| 575 | 7. The shell waits for both 'seq' processes.
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| 576 |
|
| 577 | Related:
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| 578 | shopt -s process_sub_fail
|
| 579 | _process_sub_status
|
| 580 | """
|
| 581 | cs_loc = loc.WordPart(cs_part)
|
| 582 |
|
| 583 | if not self.exec_opts._allow_process_sub():
|
| 584 | e_die(
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| 585 | "Process subs not allowed here because status wouldn't be checked (strict_errexit)",
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| 586 | cs_loc)
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| 587 |
|
| 588 | p = self._MakeProcess(cs_part.child)
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| 589 |
|
| 590 | r, w = posix.pipe()
|
| 591 | #log('pipe = %d, %d', r, w)
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| 592 |
|
| 593 | op_id = cs_part.left_token.id
|
| 594 | if op_id == Id.Left_ProcSubIn:
|
| 595 | # Example: cat < <(head foo.txt)
|
| 596 | #
|
| 597 | # The head process should write its stdout to a pipe.
|
| 598 | redir = process.StdoutToPipe(r,
|
| 599 | w) # type: process.ChildStateChange
|
| 600 |
|
| 601 | elif op_id == Id.Left_ProcSubOut:
|
| 602 | # Example: head foo.txt > >(tac)
|
| 603 | #
|
| 604 | # The tac process should read its stdin from a pipe.
|
| 605 |
|
| 606 | # Note: this example sometimes requires you to hit "enter" in bash and
|
| 607 | # zsh. WHy?
|
| 608 | redir = process.StdinFromPipe(r, w)
|
| 609 |
|
| 610 | else:
|
| 611 | raise AssertionError()
|
| 612 |
|
| 613 | p.AddStateChange(redir)
|
| 614 |
|
| 615 | if self.job_control.Enabled():
|
| 616 | p.AddStateChange(process.SetPgid(process.OWN_LEADER, self.tracer))
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| 617 |
|
| 618 | # Fork, letting the child inherit the pipe file descriptors.
|
| 619 | p.StartProcess(trace.ProcessSub)
|
| 620 |
|
| 621 | ps_frame = self.process_sub_stack[-1]
|
| 622 |
|
| 623 | # Note: bash never waits() on the process, but zsh does. The calling
|
| 624 | # program needs to read() before we can wait, e.g.
|
| 625 | # diff <(sort left.txt) <(sort right.txt)
|
| 626 |
|
| 627 | # After forking, close the end of the pipe we're not using.
|
| 628 | if op_id == Id.Left_ProcSubIn:
|
| 629 | posix.close(w) # cat < <(head foo.txt)
|
| 630 | ps_frame.Append(p, r, cs_loc) # close later
|
| 631 | elif op_id == Id.Left_ProcSubOut:
|
| 632 | posix.close(r)
|
| 633 | #log('Left_ProcSubOut closed %d', r)
|
| 634 | ps_frame.Append(p, w, cs_loc) # close later
|
| 635 | else:
|
| 636 | raise AssertionError()
|
| 637 |
|
| 638 | # Is /dev Linux-specific?
|
| 639 | if op_id == Id.Left_ProcSubIn:
|
| 640 | return '/dev/fd/%d' % r
|
| 641 |
|
| 642 | elif op_id == Id.Left_ProcSubOut:
|
| 643 | return '/dev/fd/%d' % w
|
| 644 |
|
| 645 | else:
|
| 646 | raise AssertionError()
|
| 647 |
|
| 648 | def PushRedirects(self, redirects, err_out):
|
| 649 | # type: (List[RedirValue], List[error.IOError_OSError]) -> None
|
| 650 | if len(redirects) == 0: # Optimized to avoid allocs
|
| 651 | return
|
| 652 | self.fd_state.Push(redirects, err_out)
|
| 653 |
|
| 654 | def PopRedirects(self, num_redirects, err_out):
|
| 655 | # type: (int, List[error.IOError_OSError]) -> None
|
| 656 | if num_redirects == 0: # Optimized to avoid allocs
|
| 657 | return
|
| 658 | self.fd_state.Pop(err_out)
|
| 659 |
|
| 660 | def PushProcessSub(self):
|
| 661 | # type: () -> None
|
| 662 | if len(self.clean_frame_pool):
|
| 663 | # Optimized to avoid allocs
|
| 664 | new_frame = self.clean_frame_pool.pop()
|
| 665 | else:
|
| 666 | new_frame = _ProcessSubFrame()
|
| 667 | self.process_sub_stack.append(new_frame)
|
| 668 |
|
| 669 | def PopProcessSub(self, compound_st):
|
| 670 | # type: (StatusArray) -> None
|
| 671 | """This method is called by a context manager, which means we always
|
| 672 | wait() on the way out, which I think is the right thing.
|
| 673 |
|
| 674 | We don't always set _process_sub_status, e.g. if some fatal
|
| 675 | error occurs first, but we always wait.
|
| 676 | """
|
| 677 | frame = self.process_sub_stack.pop()
|
| 678 | if frame.WasModified():
|
| 679 | frame.MaybeWaitOnProcessSubs(self.waiter, compound_st)
|
| 680 | else:
|
| 681 | # Optimized to avoid allocs
|
| 682 | self.clean_frame_pool.append(frame)
|
| 683 |
|
| 684 | # Note: the 3 lists in _ProcessSubFrame are hot in our profiles. It would
|
| 685 | # be nice to somehow "destroy" them here, rather than letting them become
|
| 686 | # garbage that needs to be traced.
|
| 687 |
|
| 688 | # The CommandEvaluator could have a ProcessSubStack, which supports Push(),
|
| 689 | # Pop(), and Top() of VALUES rather than GC objects?
|
| 690 |
|
| 691 |
|
| 692 | # vim: sw=4
|