| 1 | """
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| 2 | pyos.py -- Wrappers for the operating system.
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| 3 |
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| 4 | Like py{error,util}.py, it won't be translated to C++.
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| 5 | """
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| 6 | from __future__ import print_function
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| 7 |
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| 8 | import pwd
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| 9 | import resource
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| 10 | import signal
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| 11 | import select
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| 12 | import sys
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| 13 | import termios # for read -n
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| 14 | import time
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| 15 |
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| 16 | from mycpp import mops
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| 17 | from mycpp.mylib import log
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| 18 |
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| 19 | import posix_ as posix
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| 20 | from posix_ import WUNTRACED
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| 21 |
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| 22 | from typing import Optional, Tuple, List, Dict, cast, Any, TYPE_CHECKING
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| 23 | if TYPE_CHECKING:
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| 24 | from core import error
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| 25 |
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| 26 | _ = log
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| 27 |
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| 28 | EOF_SENTINEL = 256 # bigger than any byte
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| 29 | NEWLINE_CH = 10 # ord('\n')
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| 30 |
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| 31 |
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| 32 | def FlushStdout():
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| 33 | # type: () -> Optional[error.IOError_OSError]
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| 34 | """Flush CPython buffers.
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| 35 |
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| 36 | Return error because we call this in a C++ destructor, and those can't
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| 37 | throw exceptions.
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| 38 | """
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| 39 | err = None # type: Optional[error.IOError_OSError]
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| 40 | try:
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| 41 | sys.stdout.flush()
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| 42 | except (IOError, OSError) as e:
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| 43 | err = e
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| 44 | return err
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| 45 |
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| 46 |
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| 47 | def WaitPid(waitpid_options):
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| 48 | # type: (int) -> Tuple[int, int]
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| 49 | """
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| 50 | Return value:
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| 51 | pid is 0 if WNOHANG passed, and nothing has changed state
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| 52 | status: value that can be parsed with WIFEXITED() etc.
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| 53 | """
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| 54 | try:
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| 55 | # Notes:
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| 56 | # - The arg -1 makes it like wait(), which waits for any process.
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| 57 | # - WUNTRACED is necessary to get stopped jobs. What about WCONTINUED?
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| 58 | # - We don't retry on EINTR, because the 'wait' builtin should be
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| 59 | # interruptible.
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| 60 | # - waitpid_options can be WNOHANG
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| 61 | pid, status = posix.waitpid(-1, WUNTRACED | waitpid_options)
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| 62 | except OSError as e:
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| 63 | return -1, e.errno
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| 64 |
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| 65 | return pid, status
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| 66 |
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| 67 |
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| 68 | class ReadError(Exception):
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| 69 | """Wraps errno returned by read().
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| 70 |
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| 71 | Used by 'read' and 'mapfile' builtins.
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| 72 | """
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| 73 |
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| 74 | def __init__(self, err_num):
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| 75 | # type: (int) -> None
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| 76 | self.err_num = err_num
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| 77 |
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| 78 |
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| 79 | def Read(fd, n, chunks):
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| 80 | # type: (int, int, List[str]) -> Tuple[int, int]
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| 81 | """C-style wrapper around Python's posix.read() that uses return values
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| 82 | instead of exceptions for errors. We will implement this directly in C++
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| 83 | and not use exceptions at all.
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| 84 |
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| 85 | It reads n bytes from the given file descriptor and appends it to chunks.
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| 86 |
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| 87 | Returns:
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| 88 | (-1, errno) on failure
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| 89 | (number of bytes read, 0) on success. Where 0 bytes read indicates EOF.
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| 90 | """
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| 91 | try:
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| 92 | chunk = posix.read(fd, n)
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| 93 | except OSError as e:
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| 94 | return -1, e.errno
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| 95 | else:
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| 96 | length = len(chunk)
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| 97 | if length:
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| 98 | chunks.append(chunk)
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| 99 | return length, 0
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| 100 |
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| 101 |
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| 102 | def ReadByte(fd):
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| 103 | # type: (int) -> Tuple[int, int]
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| 104 | """Another low level interface with a return value interface. Used by
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| 105 | _ReadUntilDelim() and _ReadLineSlowly().
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| 106 |
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| 107 | Returns:
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| 108 | failure: (-1, errno) on failure
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| 109 | success: (ch integer value or EOF_SENTINEL, 0)
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| 110 | """
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| 111 | try:
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| 112 | b = posix.read(fd, 1)
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| 113 | except OSError as e:
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| 114 | return -1, e.errno
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| 115 | else:
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| 116 | if len(b):
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| 117 | return ord(b), 0
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| 118 | else:
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| 119 | return EOF_SENTINEL, 0
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| 120 |
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| 121 |
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| 122 | def Environ():
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| 123 | # type: () -> Dict[str, str]
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| 124 | return posix.environ
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| 125 |
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| 126 |
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| 127 | def Chdir(dest_dir):
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| 128 | # type: (str) -> int
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| 129 | """Returns 0 for success and nonzero errno for error."""
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| 130 | try:
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| 131 | posix.chdir(dest_dir)
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| 132 | except OSError as e:
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| 133 | return e.errno
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| 134 | return 0
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| 135 |
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| 136 |
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| 137 | def GetMyHomeDir():
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| 138 | # type: () -> Optional[str]
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| 139 | """Get the user's home directory from the /etc/pyos.
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| 140 |
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| 141 | Used by $HOME initialization in osh/state.py. Tilde expansion and
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| 142 | readline initialization use mem.GetValue('HOME').
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| 143 | """
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| 144 | uid = posix.getuid()
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| 145 | try:
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| 146 | e = pwd.getpwuid(uid)
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| 147 | except KeyError:
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| 148 | return None
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| 149 |
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| 150 | return e.pw_dir
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| 151 |
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| 152 |
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| 153 | def GetHomeDir(user_name):
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| 154 | # type: (str) -> Optional[str]
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| 155 | """For ~otheruser/src.
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| 156 |
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| 157 | TODO: Should this be cached?
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| 158 | """
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| 159 | # http://linux.die.net/man/3/getpwnam
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| 160 | try:
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| 161 | e = pwd.getpwnam(user_name)
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| 162 | except KeyError:
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| 163 | return None
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| 164 |
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| 165 | return e.pw_dir
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| 166 |
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| 167 |
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| 168 | class PasswdEntry(object):
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| 169 |
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| 170 | def __init__(self, pw_name, uid, gid):
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| 171 | # type: (str, int, int) -> None
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| 172 | self.pw_name = pw_name
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| 173 | self.pw_uid = uid
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| 174 | self.pw_gid = gid
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| 175 |
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| 176 |
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| 177 | def GetAllUsers():
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| 178 | # type: () -> List[PasswdEntry]
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| 179 | users = [
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| 180 | PasswdEntry(u.pw_name, u.pw_uid, u.pw_gid) for u in pwd.getpwall()
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| 181 | ]
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| 182 | return users
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| 183 |
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| 184 |
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| 185 | def GetUserName(uid):
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| 186 | # type: (int) -> str
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| 187 | try:
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| 188 | e = pwd.getpwuid(uid)
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| 189 | except KeyError:
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| 190 | return "<ERROR: Couldn't determine user name for uid %d>" % uid
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| 191 | else:
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| 192 | return e.pw_name
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| 193 |
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| 194 |
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| 195 | def GetRLimit(res):
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| 196 | # type: (int) -> Tuple[mops.BigInt, mops.BigInt]
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| 197 | """
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| 198 | Raises IOError
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| 199 | """
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| 200 | soft, hard = resource.getrlimit(res)
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| 201 | return (mops.IntWiden(soft), mops.IntWiden(hard))
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| 202 |
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| 203 |
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| 204 | def SetRLimit(res, soft, hard):
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| 205 | # type: (int, mops.BigInt, mops.BigInt) -> None
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| 206 | """
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| 207 | Raises IOError
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| 208 | """
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| 209 | resource.setrlimit(res, (soft.i, hard.i))
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| 210 |
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| 211 |
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| 212 | def Time():
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| 213 | # type: () -> Tuple[float, float, float]
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| 214 | t = time.time() # calls gettimeofday() under the hood
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| 215 | u = resource.getrusage(resource.RUSAGE_SELF)
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| 216 | return t, u.ru_utime, u.ru_stime
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| 217 |
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| 218 |
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| 219 | def PrintTimes():
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| 220 | # type: () -> None
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| 221 | utime, stime, cutime, cstime, elapsed = posix.times()
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| 222 | print("%dm%.3fs %dm%.3fs" %
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| 223 | (utime / 60, utime % 60, stime / 60, stime % 60))
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| 224 | print("%dm%.3fs %dm%.3fs" %
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| 225 | (cutime / 60, cutime % 60, cstime / 60, cstime % 60))
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| 226 |
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| 227 |
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| 228 | # So builtin_misc.py doesn't depend on termios, which makes C++ translation
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| 229 | # easier
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| 230 | TERM_ICANON = termios.ICANON
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| 231 | TERM_ECHO = termios.ECHO
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| 232 |
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| 233 |
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| 234 | def PushTermAttrs(fd, mask):
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| 235 | # type: (int, int) -> Tuple[int, Any]
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| 236 | """Returns opaque type (void* in C++) to be reused in the PopTermAttrs()"""
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| 237 | # https://docs.python.org/2/library/termios.html
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| 238 | term_attrs = termios.tcgetattr(fd)
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| 239 |
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| 240 | # Flip the bits in one field, e.g. ICANON to disable canonical (buffered)
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| 241 | # mode.
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| 242 | orig_local_modes = cast(int, term_attrs[3])
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| 243 | term_attrs[3] = orig_local_modes & mask
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| 244 |
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| 245 | termios.tcsetattr(fd, termios.TCSANOW, term_attrs)
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| 246 | return orig_local_modes, term_attrs
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| 247 |
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| 248 |
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| 249 | def PopTermAttrs(fd, orig_local_modes, term_attrs):
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| 250 | # type: (int, int, Any) -> None
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| 251 |
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| 252 | term_attrs[3] = orig_local_modes
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| 253 | try:
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| 254 | termios.tcsetattr(fd, termios.TCSANOW, term_attrs)
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| 255 | except termios.error as e:
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| 256 | # Superficial fix for issue #1001. I'm not sure why we get errno.EIO,
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| 257 | # but we can't really handle it here. In C++ I guess we ignore the
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| 258 | # error.
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| 259 | pass
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| 260 |
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| 261 |
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| 262 | def OsType():
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| 263 | # type: () -> str
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| 264 | """Compute $OSTYPE variable."""
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| 265 | return posix.uname()[0].lower()
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| 266 |
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| 267 |
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| 268 | def InputAvailable(fd):
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| 269 | # type: (int) -> bool
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| 270 | # similar to lib/sh/input_avail.c in bash
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| 271 | # read, write, except
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| 272 | r, w, exc = select.select([fd], [], [fd], 0)
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| 273 | return len(r) != 0
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| 274 |
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| 275 |
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| 276 | UNTRAPPED_SIGWINCH = -1
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| 277 |
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| 278 |
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| 279 | class SignalSafe(object):
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| 280 | """State that is shared between the main thread and signal handlers.
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| 281 |
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| 282 | See C++ implementation in cpp/core.h
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| 283 | """
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| 284 |
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| 285 | def __init__(self):
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| 286 | # type: () -> None
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| 287 | self.pending_signals = [] # type: List[int]
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| 288 | self.last_sig_num = 0 # type: int
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| 289 | self.received_sigint = False
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| 290 | self.received_sigwinch = False
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| 291 | self.sigwinch_code = UNTRAPPED_SIGWINCH
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| 292 |
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| 293 | def UpdateFromSignalHandler(self, sig_num, unused_frame):
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| 294 | # type: (int, Any) -> None
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| 295 | """Receive the given signal, and update shared state.
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| 296 |
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| 297 | This method is registered as a Python signal handler.
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| 298 | """
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| 299 | self.pending_signals.append(sig_num)
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| 300 |
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| 301 | if sig_num == signal.SIGINT:
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| 302 | self.received_sigint = True
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| 303 |
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| 304 | if sig_num == signal.SIGWINCH:
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| 305 | self.received_sigwinch = True
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| 306 | sig_num = self.sigwinch_code # mutate param
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| 307 |
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| 308 | self.last_sig_num = sig_num
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| 309 |
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| 310 | def LastSignal(self):
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| 311 | # type: () -> int
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| 312 | """Return the number of the last signal that fired."""
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| 313 | return self.last_sig_num
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| 314 |
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| 315 | def PollSigInt(self):
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| 316 | # type: () -> bool
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| 317 | """Has SIGINT received since the last time PollSigInt() was called?"""
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| 318 | result = self.received_sigint
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| 319 | self.received_sigint = False
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| 320 | return result
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| 321 |
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| 322 | def SetSigWinchCode(self, code):
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| 323 | # type: (int) -> None
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| 324 | """Depending on whether or not SIGWINCH is trapped by a user, it is
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| 325 | expected to report a different code to `wait`.
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| 326 |
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| 327 | SetSigwinchCode() lets us set which code is reported.
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| 328 | """
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| 329 | self.sigwinch_code = code
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| 330 |
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| 331 | def PollSigWinch(self):
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| 332 | # type: () -> bool
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| 333 | """Has SIGWINCH been received since the last time PollSigWinch() was
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| 334 | called?"""
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| 335 | result = self.received_sigwinch
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| 336 | self.received_sigwinch = False
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| 337 | return result
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| 338 |
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| 339 | def TakePendingSignals(self):
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| 340 | # type: () -> List[int]
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| 341 | # A note on signal-safety here. The main loop might be calling this function
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| 342 | # at the same time a signal is firing and appending to
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| 343 | # `self.pending_signals`. We can forgoe using a lock here
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| 344 | # (which would be problematic for the signal handler) because mutual
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| 345 | # exclusivity should be maintained by the atomic nature of pointer
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| 346 | # assignment (i.e. word-sized writes) on most modern platforms.
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| 347 | # The replacement run list is allocated before the swap, so it can be
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| 348 | # interuppted at any point without consequence.
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| 349 | # This means the signal handler always has exclusive access to
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| 350 | # `self.pending_signals`. In the worst case the signal handler might write to
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| 351 | # `new_queue` and the corresponding trap handler won't get executed
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| 352 | # until the main loop calls this function again.
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| 353 | # NOTE: It's important to distinguish between signal-safety an
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| 354 | # thread-safety here. Signals run in the same process context as the main
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| 355 | # loop, while concurrent threads do not and would have to worry about
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| 356 | # cache-coherence and instruction reordering.
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| 357 | new_queue = [] # type: List[int]
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| 358 | ret = self.pending_signals
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| 359 | self.pending_signals = new_queue
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| 360 | return ret
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| 361 |
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| 362 | def ReuseEmptyList(self, empty_list):
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| 363 | # type: (List[int]) -> None
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| 364 | """This optimization only happens in C++."""
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| 365 | pass
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| 366 |
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| 367 |
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| 368 | gSignalSafe = None # type: SignalSafe
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| 369 |
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| 370 |
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| 371 | def InitSignalSafe():
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| 372 | # type: () -> SignalSafe
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| 373 | """Set global instance so the signal handler can access it."""
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| 374 | global gSignalSafe
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| 375 | gSignalSafe = SignalSafe()
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| 376 | return gSignalSafe
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| 377 |
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| 378 |
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| 379 | def Sigaction(sig_num, handler):
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| 380 | # type: (int, Any) -> None
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| 381 | """Register a signal handler."""
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| 382 | signal.signal(sig_num, handler)
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| 383 |
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| 384 |
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| 385 | def RegisterSignalInterest(sig_num):
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| 386 | # type: (int) -> None
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| 387 | """Have the kernel notify the main loop about the given signal."""
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| 388 | assert gSignalSafe is not None
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| 389 | signal.signal(sig_num, gSignalSafe.UpdateFromSignalHandler)
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| 390 |
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| 391 |
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| 392 | def MakeDirCacheKey(path):
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| 393 | # type: (str) -> Tuple[str, int]
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| 394 | """Returns a pair (path with last modified time) that can be used to cache
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| 395 | directory accesses."""
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| 396 | st = posix.stat(path)
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| 397 | return (path, int(st.st_mtime))
|