jw-pkg/src/python/jw/pkg/lib/ExecContext.py

# -*- coding: utf-8 -*-

from __future__ import annotations

import abc, re, sys, errno
from enum import Enum, auto
from typing import NamedTuple, TYPE_CHECKING
from decimal import Decimal, ROUND_FLOOR

if TYPE_CHECKING:
    from typing import Self, Type
    from types import TracebackType

from .log import *
from .base import Input, InputMode, Result, StatResult
from .FileContext import FileContext as Base

_US = "\x1f"  # unlikely to appear in numeric output
_BILLION = Decimal(1_000_000_000)

def _looks_like_option_error(stderr: str) -> bool:
    s = stderr.lower()
    return any(
        needle in s
        for needle in (
            "unrecognized option",
            "illegal option",
            "unknown option",
            "invalid option",
            "option requires an argument",
        )
    )

def _raise_stat_error(path: str, stderr: str, returncode: int) -> None:
    msg = (stderr or "").strip() or f"stat exited with status {returncode}"
    lower = msg.lower()
    if "no such file" in lower:
        raise FileNotFoundError(errno.ENOENT, msg, path)
    if "permission denied" in lower or "operation not permitted" in lower:
        raise PermissionError(errno.EACCES, msg, path)
    raise OSError(errno.EIO, msg, path)

def _parse_epoch(value: str) -> tuple[int, float, int]:
    """
    Convert a decimal epoch timestamp string into:
      (integer seconds for tuple slot, float seconds for attribute, ns for *_ns)
    """
    dec = Decimal(value.strip())
    sec = int(dec.to_integral_value(rounding=ROUND_FLOOR))
    ns = int((dec * _BILLION).to_integral_value(rounding=ROUND_FLOOR))
    return sec, float(dec), ns

def _build_stat_result(fields: list[str], mode_base: int) -> StatResult:
    if len(fields) != 13:
        raise ValueError(
            f"unexpected stat output: expected 13 fields, got {len(fields)}: {fields!r}"
        )

    (
        mode_s,
        ino_s,
        dev_s,
        nlink_s,
        uid_s,
        gid_s,
        size_s,
        atime_s,
        mtime_s,
        ctime_s,
        blksize_s,
        blocks_s,
        rdev_s,
    ) = fields

    st_mode = int(mode_s, mode_base)
    st_ino = int(ino_s)
    st_dev = int(dev_s)
    st_nlink = int(nlink_s)
    st_uid = uid_s
    st_gid = gid_s
    st_size = int(size_s)

    st_atime_i, st_atime_f, st_atime_ns = _parse_epoch(atime_s)
    st_mtime_i, st_mtime_f, st_mtime_ns = _parse_epoch(mtime_s)
    st_ctime_i, st_ctime_f, st_ctime_ns = _parse_epoch(ctime_s)

    st_blksize = int(blksize_s)
    st_blocks = int(blocks_s)
    st_rdev = int(rdev_s)

    return StatResult(
        mode = st_mode,
        owner = st_uid,
        group = st_gid,
        size = st_size,
        atime = st_atime_i,
        mtime = st_mtime_i,
        ctime = st_ctime_i,
    )

class ExecContext(Base):

    class CallContext:

        def __init__(
                self,
                parent: ExecContext,
                title: str|None,
                cmd: list[str],
                cmd_input: Input,
                env: dict[str, str]|None,
                wd: str|None,
                log_prefix: str,
                throw: bool,
                verbose: bool
            ) -> None:
            self.__cmd = cmd
            self.__wd = wd
            self.__log_prefix = log_prefix
            self.__parent = parent
            self.__title = title
            self.__pretty_cmd: str|None = None
            self.__delim = title if title is not None else f'---- {parent.uri}: Running {self.pretty_cmd} -'
            delim_len = 120
            self.__delim += '-' * max(0, delim_len - len(self.__delim))
            self.__env = {'LC_ALL': 'C'} if env is None else env

            # -- At the end of this dance, interactive needs to be either True
            # or False
            interactive: bool|None = None
            if not isinstance(cmd_input, InputMode):
                interactive = False
                self.__cmd_input = (
                    cmd_input if isinstance(cmd_input, bytes) else
                    cmd_input.encode(sys.stdout.encoding or "utf-8")
                )
            else:
                match cmd_input:
                    case InputMode.Interactive:
                        interactive = True
                    case InputMode.NonInteractive:
                        interactive = False
                    case InputMode.OptInteractive:
                        interactive = parent.interactive
                    case InputMode.Auto:
                        interactive = sys.stdin.isatty()
                if interactive is None:
                    interactive = parent.interactive
                if interactive is None:
                    interactive = sys.stdin.isatty()
                self.__cmd_input = None
            assert interactive in [ True, False ]
            self.__interactive = interactive

            self.__cmd_input = cmd_input if not isinstance(cmd_input, InputMode) else None
            self.__throw = throw
            self.__verbose = verbose if verbose is not None else parent.verbose_default

        def __enter__(self) -> CallContext:
            self.log_delim(start=True)
            return self

        def __exit__(
            self,
            exc_type: Type[BaseException]|None,
            exc_value: BaseException|None,
            traceback: TracebackType|None
        ) -> bool:
            self.log_delim(start=False)

        @property
        def log_prefix(self) -> str:
            return self.__log_prefix

        @property
        def interactive(self) -> bool:
            return self.__interactive

        @property
        def verbose(self) -> bool:
            return self.__verbose

        @property
        def cmd_input(self) -> bytes|None:
            return self.__cmd_input

        @property
        def env(self) -> dict[str, str]:
            return self.__env

        @property
        def throw(self) -> bool:
            return self.__throw

        @property
        def wd(self) -> str|None:
            return self.__wd

        @property
        def cmd(self) -> list[str]:
            return self.__cmd

        @property
        def pretty_cmd(self) -> str:
            if self.__pretty_cmd is None:
                from .util import pretty_cmd
                self.__pretty_cmd = pretty_cmd(self.__cmd, self.__wd)
            return self.__pretty_cmd

        def log(prio: int, *args, **kwargs) -> None:
            log(prio, self.__log_prefix, *args, **kwargs)

        def log_delim(self, start: bool) -> None:
            if not self.__verbose:
                return None
            if self.__interactive: # Don't log footer in interative mode
                if start:
                    log(NOTICE, self.__delim)
                return
            delim = ',' + self.__delim + ' >' if start else '`' + self.__delim + ' <'
            log(NOTICE, delim)

        def check_exit_code(self, result: Result) -> None:
            if result.status == 0:
                return
            if (self.__throw or self.__verbose):
                msg = f'Command exited with status {result.status}: {self.pretty_cmd}'
                if result.stderr:
                    msg += ': ' + result.decode().stderr.strip()
                if self.__throw:
                    raise RuntimeError(msg)

        def exception(self, result: Result, e: Exception) -> Result:
            log(ERR, self.__log_prefix, f'Failed to run {self.pretty_cmd}')
            if self.__throw:
                raise e
            return result

    def __init__(self, uri: str, interactive: bool|None=None, verbose_default=False):
        super().__init__(uri=uri, interactive=interactive, verbose_default=verbose_default)

    @abc.abstractmethod
    async def _run(self, *args, **kwargs) -> Result:
        pass

    async def run(
        self,
        cmd: list[str],
        wd: str|None = None,
        throw: bool = True,
        verbose: bool|None = None,
        cmd_input: Input = InputMode.OptInteractive,
        env: dict[str, str]|None = None,
        title: str=None
    ) -> Result:
        """
        Run a command asynchronously and return its output

        Args:
            cmd:     Command and arguments
            wd:      Optional working directory
            throw:   Raise an exception on non-zero exit status if True
            verbose: Emit log output while the command runs
            cmd_input:
                - "InputMode.OptInteractive"  -> Let --interactive govern how to handle interactivity (default)
                - "InputMode.Interactive"     -> Inherit terminal stdin
                - "InputMode.Auto"            -> Inherit terminal stdin if it is a TTY
                - "InputMode.NonInteractive"  -> stdin from /dev/null
                - None                        -> Alias for InputMode.NonInteractive
                - otherwise                   -> Feed cmd_input to stdin
            env:     The environment the command should be run in

        Returns:
            A Result instance
              In PTY mode stderr is always None because PTY merges stdout/stderr.
        """

        # Note that in the calls to the wrapped method, cmd_input == None can
        # be returned by CallContext and is very much allowed
        assert cmd_input is not None

        ret = Result(None, None, 1)
        with self.CallContext(self, title=title, cmd=cmd, cmd_input=cmd_input, env=env, wd=wd,
                              log_prefix='|', throw=throw, verbose=verbose) as cc:
            try:
                ret = await self._run(
                    cmd=cc.cmd,
                    wd=wd,
                    verbose=cc.verbose,
                    cmd_input=cc.cmd_input,
                    env=cc.env,
                    interactive=cc.interactive,
                    log_prefix=cc.log_prefix
                )
            except Exception as e:
                return cc.exception(ret, e)
            cc.check_exit_code(ret)
        return ret

    @abc.abstractmethod
    async def _sudo(self, *args, **kwargs) -> Result:
        pass

    async def sudo(
        self,
        cmd: list[str],
        mod_env: dict[str, str]|None=None,
        opts: list[str]|None=None,
        wd: str|None = None,
        throw: bool = True,
        verbose: bool|None = None,
        cmd_input: Input = InputMode.OptInteractive,
        env: dict[str, str]|None = None,
        title: str=None,
    ) -> Result:

        # Note that in the calls to the wrapped method, cmd_input == None can
        # be returned by CallContext and is very much allowed
        assert cmd_input is not None

        ret = Result(None, None, 1)
        if opts is None:
            opts = {}
        with self.CallContext(self, title=title, cmd=cmd, cmd_input=cmd_input, env=env, wd=wd,
                              log_prefix='|', throw=throw, verbose=verbose) as cc:
            try:
                ret = await self._sudo(
                    cmd=cc.cmd,
                    mod_env=mod_env,
                    opts=opts,
                    wd=wd,
                    verbose=cc.verbose,
                    cmd_input=cc.cmd_input,
                    env=cc.env,
                    interactive=cc.interactive,
                    log_prefix=cc.log_prefix,
                )
            except Exception as e:
                return cc.exception(ret, e)
            cc.check_exit_code(ret)
        return ret

    async def _get(
        self,
        path: str,
        wd: str|None,
        throw: bool,
        verbose: bool|None,
        title: str
    ) -> Result:
        ret = Result(None, None, 1)
        if wd is not None:
            path = wd + '/' + path
        with self.CallContext(self, title=title, cmd=['cat', path],
                              cmd_input=InputMode.NonInteractive, wd=None, env=None,
                              log_prefix='|', throw=throw, verbose=verbose) as cc:
            try:
                ret = await self._run(
                    cmd=cc.cmd,
                    wd=wd,
                    verbose=cc.verbose,
                    cmd_input=cc.cmd_input,
                    env=cc.env,
                    interactive=cc.interactive,
                    log_prefix=cc.log_prefix
                )
            except Exception as e:
                return cc.exception(ret, e)
            if ret.status != 0 and ret.stderr.decode().find('No such file') != -1:
                raise FileNotFoundError(ret.stderr)
            cc.check_exit_code(ret)
        return ret

    async def _put(
        self,
        path: str,
        content: bytes,
        wd: str|None,
        throw: bool,
        verbose: bool|None,
        title: str,
        owner: str|None,
        group: str|None,
        mode: str|None,
        atomic: bool,
    ) -> Result:

        from .util import pretty_cmd

        async def __run(cmd: list[str], cmd_input: Input=InputMode.NonInteractive, **kwargs) -> Result:
            return await self.run(cmd, cmd_input=cmd_input, **kwargs)

        ret = Result(None, None, 1)
        try:
            if wd is not None:
                path = wd + '/' + path
            cmds: list[dict[str, str|list[str]|bool]] = []
            out = (await __run(['mktemp', path + '.XXXXXX'])).stdout.decode().strip() if atomic else path
            cmds.append({'cmd': ['tee', out], 'cmd_input': content})
            if owner is not None and group is not None:
                cmds.append({'cmd': ['chown', f'{owner}:{group}', out]})
            elif owner is not None:
                cmds.append({'cmd': ['chown', owner, out]})
            elif group is not None:
                cmds.append({'cmd': ['chgrp', group, out]})
            if mode is not None:
                cmds.append({'cmd': ['chmod', mode, out]})
            if atomic:
                cmds.append({'cmd': ['mv', out, path]})
            for cmd in cmds:
                log(DEBUG, f'{self.log_name}: Running {pretty_cmd(cmd['cmd'], wd)}')
                ret = await __run(**cmd)
            return ret
        except:
            if throw:
                raise
            return cc.exception(ret, e)
        return ret

    async def _unlink(self, path: str) -> None:
        cmd = ['rm', '-f', path]
        await self.run(cmd, cmd_input=InputMode.NonInteractive)

    async def _erase(self, path: str) -> None:
        cmd = ['rm', '-rf', path]
        await self.run(cmd, cmd_input=InputMode.NonInteractive)

    async def _rename(self, src: str, dst: str) -> None:
        cmd = ['mv', src, dst]
        await self.run(cmd, cmd_input=InputMode.NonInteractive)

    async def _mktemp(self, tmpl: str, directory: bool) -> str:
        cmd = ['mktemp']
        if directory:
            cmd.append('-d')
        cmd.append(tmpl)
        result = await self.run(cmd, cmd_input=InputMode.NonInteractive)
        return result.stdout.strip().decode()

    async def _stat(self, path: str, follow_symlinks: bool) -> StatResult:

        async def __stat(opts: list[str]) -> str:
            env = {
                'LC_ALL': 'C'
            }
            cmd = ['stat']
            if follow_symlinks:
                cmd.append('-L')
            cmd.extend(opts)
            cmd.append(path)
            return (await self.run(cmd, env=env, throw=False,
                        cmd_input=InputMode.NonInteractive)).decode()

        # GNU coreutils stat
        gnu_format = _US.join([
            "%f",     # st_mode in hex
            "%i",     # st_ino
            "%d",     # st_dev
            "%h",     # st_nlink
            "%U",     # st_uid
            "%G",     # st_gid
            "%s",     # st_size
            "%.9X",   # st_atime
            "%.9Y",   # st_mtime
            "%.9Z",   # st_ctime
            "%o",     # st_blksize hint
            "%b",     # st_blocks
            "%r",     # st_rdev
        ])

        result = await __stat(['--printf', gnu_format])
        if result.status == 0:
            return _build_stat_result(result.stdout.split(_US), mode_base=16)

        if not _looks_like_option_error(result.stderr.decode()):
            # log(DEBUG, f'GNU stat attempt failed on "{path}" ({str(e)})')
            _raise_stat_error(path, result.stderr, result.status)

        # BSD / macOS / OpenBSD / NetBSD stat
        bsd_format = _US.join([
            "%p",      # st_mode in octal
            "%i",      # st_ino
            "%d",      # st_dev
            "%l",      # st_nlink
            "%U",      # st_uid
            "%G",      # st_gid
            "%z",      # st_size
            "%.9Fa",   # st_atime
            "%.9Fm",   # st_mtime
            "%.9Fc",   # st_ctime
            "%k",      # st_blksize
            "%b",      # st_blocks
            "%r",      # st_rdev
        ])

        result = await __stat(['-n', '-f', bst_format])
        if proc.returncode == 0:
            return _build_stat_result(proc.stdout.rstrip('\n').split(_US), mode_base=8)
        _raise_stat_error(path, result.stderr, result.status)

    async def _chown(self, path: str, owner: str|None, group: str|None) -> None:
        assert owner is not None or group is not None
        if group is None:
            ownership = owner
        elif owner is None:
            ownership = ':' + group
        else:
            ownership = owner + ':' + group
        await self.run(['chown', ownership, path], cmd_input=InputMode.NonInteractive)

    async def _chmod(self, path: str, mode: int) -> None:
        await self.run(['chmod', oct(mode), path], cmd_input=InputMode.NonInteractive)