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import dataclasses
import os.path
import re
import shutil
from typing import Optional, IO, TYPE_CHECKING
if TYPE_CHECKING:
from debputy.plugin.api import VirtualPath
_SHEBANG_RE = re.compile(
rb"""
^[#][!]\s*
(/\S+/([a-zA-Z][^/\s]*))
""",
re.VERBOSE | re.ASCII,
)
_WORD = re.compile(rb"\s+(\S+)")
_STRIP_VERSION = re.compile(r"(-?\d+(?:[.]\d.+)?)$")
_KNOWN_INTERPRETERS = {
os.path.basename(c): c
for c in ["/bin/sh", "/bin/bash", "/bin/dash", "/usr/bin/perl", "/usr/bin/python"]
}
class Interpreter:
@property
def original_command(self) -> str:
"""The original command (without arguments) from the #! line
This returns the command as it was written (without flags/arguments) in the file.
Note as a special-case, if the original command is `env` then the first argument is included
as well, because it is assumed to be the real command.
>>> # Note: Normally, you would use `VirtualPath.interpreter()` instead for extracting the interpreter
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3 -b")
>>> python3.original_command
'/usr/bin/python3'
>>> env_sh = extract_shebang_interpreter(b"#! /usr/bin/env sh")
>>> env_sh.original_command
'/usr/bin/env sh'
:return: The original command in the #!-line
"""
raise NotImplementedError
@property
def command_full_basename(self) -> str:
"""The full basename of the command (with version)
Note that for #!-lines that uses `env`, this will return the argument for `env` rather than
`env`.
>>> # Note: Normally, you would use `VirtualPath.interpreter()` instead for extracting the interpreter
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3 -b")
>>> python3.command_full_basename
'python3'
>>> env_sh = extract_shebang_interpreter(b"#! /usr/bin/env sh")
>>> env_sh.command_full_basename
'sh'
:return: The full basename of the command.
"""
raise NotImplementedError
@property
def command_stem(self) -> str:
"""The basename of the command **without** version
Note that for #!-lines that uses `env`, this will return the argument for `env` rather than
`env`.
>>> # Note: Normally, you would use `VirtualPath.interpreter()` instead for extracting the interpreter
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3 -b")
>>> python3.command_stem
'python'
>>> env_sh = extract_shebang_interpreter(b"#! /usr/bin/env sh")
>>> env_sh.command_stem
'sh'
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3.12-dbg -b")
>>> python3.command_stem
'python'
:return: The basename of the command **without** version.
"""
raise NotImplementedError
@property
def interpreter_version(self) -> str:
"""The version part of the basename
Note that for #!-lines that uses `env`, this will return the argument for `env` rather than
`env`.
>>> # Note: Normally, you would use `VirtualPath.interpreter()` instead for extracting the interpreter
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3 -b")
>>> python3.interpreter_version
'3'
>>> env_sh = extract_shebang_interpreter(b"#! /usr/bin/env sh")
>>> env_sh.interpreter_version
''
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3.12-dbg -b")
>>> python3.interpreter_version
'3.12-dbg'
:return: The version part of the command or the empty string if the command is versionless.
"""
raise NotImplementedError
@property
def fixup_needed(self) -> bool:
"""Whether the interpreter uses a non-canonical location
>>> # Note: Normally, you would use `VirtualPath.interpreter()` instead for extracting the interpreter
>>> python3 = extract_shebang_interpreter(b"#! /usr/bin/python3 -b")
>>> python3.fixup_needed
False
>>> env_sh = extract_shebang_interpreter(b"#! /usr/bin/env sh")
>>> env_sh.fixup_needed
True
>>> ub_sh = extract_shebang_interpreter(b"#! /usr/bin/sh")
>>> ub_sh.fixup_needed
True
>>> sh = extract_shebang_interpreter(b"#! /bin/sh")
>>> sh.fixup_needed
False
:return: True if this interpreter is uses a non-canonical version.
"""
return False
@dataclasses.dataclass(slots=True, frozen=True)
class DetectedInterpreter(Interpreter):
original_command: str
command_full_basename: str
command_stem: str
interpreter_version: str
correct_command: Optional[str] = None
corrected_shebang_line: Optional[str] = None
@property
def fixup_needed(self) -> bool:
return self.corrected_shebang_line is not None
def replace_shebang_line(self, path: "VirtualPath") -> None:
new_shebang_line = self.corrected_shebang_line
assert new_shebang_line.startswith("#!")
if not new_shebang_line.endswith("\n"):
new_shebang_line += "\n"
parent_dir = path.parent_dir
assert parent_dir is not None
with path.open(byte_io=True) as rfd:
original_first_line = rfd.readline()
if not original_first_line.startswith(b"#!"):
raise ValueError(
f'The provided path "{path.path}" does not start with a shebang line!?'
)
mtime = path.mtime
with path.replace_fs_path_content() as new_fs_path, open(
new_fs_path, "wb"
) as wfd:
wfd.write(new_shebang_line.encode("utf-8"))
shutil.copyfileobj(rfd, wfd)
# Ensure the mtime is not updated (we do not count interpreter correction as a "change")
path.mtime = mtime
def extract_shebang_interpreter_from_file(
fd: IO[bytes],
) -> Optional[DetectedInterpreter]:
first_line = fd.readline(4096)
if b"\n" not in first_line:
# If there is no newline, then it is probably not a shebang line
return None
return extract_shebang_interpreter(first_line)
def extract_shebang_interpreter(first_line: bytes) -> Optional[DetectedInterpreter]:
m = _SHEBANG_RE.search(first_line)
if not m:
return None
raw_command = m.group(1).strip().decode("utf-8")
command_full_basename = m.group(2).strip().decode("utf-8")
endpos = m.end()
if command_full_basename == "env":
wm = _WORD.search(first_line, pos=m.end())
if wm is not None:
command_full_basename = wm.group(1).decode("utf-8")
raw_command += " " + command_full_basename
endpos = wm.end()
command_stem = command_full_basename
vm = _STRIP_VERSION.search(command_full_basename)
if vm:
version = vm.group(1)
command_stem = command_full_basename[: -len(version)]
else:
version = ""
correct_command = _KNOWN_INTERPRETERS.get(command_stem)
if correct_command is not None and version != "":
correct_command += version
if correct_command is not None and correct_command != raw_command:
trailing = first_line[endpos + 1 :].strip().decode("utf-8")
corrected_shebang_line = "#! " + correct_command
if trailing:
corrected_shebang_line += " " + trailing
else:
corrected_shebang_line = None
return DetectedInterpreter(
raw_command,
command_full_basename,
command_stem,
version,
correct_command,
corrected_shebang_line,
)
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