fix: properly handle root requirement for apt build-dep in build drivers

Author: mikonse

.github/workflows/ci.yml

@@ -123,6 +123,6 @@ jobs:
       - name: Install the project
         run: uv sync --locked --all-extras --dev
       - name: Install required apt 
-        run: apt-get install -y devscripts
+        run: sudo apt-get install -y devscripts
       - name: Run Debmagic build on ourself
         run: uv run debmagic build --driver=none

src/debmagic/_build_driver/build.py

@@ -18,7 +18,7 @@ def _create_driver(build_driver: BuildDriverType, config: BuildConfig) -> BuildD
 def build(build_driver: BuildDriverType, config: BuildConfig):
     driver = _create_driver(build_driver, config)
     try:
-        driver.run_command(["apt-get", "-y", "build-dep", "."], cwd=config.source_dir)
+        driver.run_command(["apt-get", "-y", "build-dep", "."], cwd=config.source_dir, requires_root=True)
         driver.run_command(["debuild", "-nc", "-uc", "-b"], cwd=config.source_dir)
 
         # TODO: copy packages to output directory

src/debmagic/_build_driver/common.py

@@ -27,7 +27,7 @@ def create(cls, config: BuildConfig) -> "BuildDriver":
         pass
 
     @abc.abstractmethod
-    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None):
+    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None, requires_root: bool = False):
         pass
 
     @abc.abstractmethod

src/debmagic/_build_driver/driver_docker.py

@@ -97,7 +97,9 @@ def create(cls, config: BuildConfig):
         instance = cls(config=config, workdir=workdir, container_name=docker_container_name)
         return instance
 
-    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None):
+    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None, requires_root: bool = False):
+        del requires_root  # we assume to always be root in the container
+
         if cwd:
             cwd = self._translate_source_path(cwd)
 

src/debmagic/_build_driver/driver_lxd.py

@@ -9,8 +9,14 @@ class BuildDriverLxd(BuildDriver):
     def create(cls, config: BuildConfig):
         return cls()
 
-    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None):
+    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None, requires_root: bool = False):
+        raise NotImplementedError()
+
+    def copy_file(self, source_dir: Path, glob: str, dest_dir: Path):
         raise NotImplementedError()
 
     def cleanup(self):
-        pass
+        raise NotImplementedError()
+
+    def drop_into_shell(self):
+        raise NotImplementedError()

src/debmagic/_build_driver/driver_none.py

@@ -1,3 +1,4 @@
+import os
 import shutil
 from pathlib import Path
 from typing import Sequence
@@ -14,7 +15,9 @@ def __init__(self, config: BuildConfig) -> None:
     def create(cls, config: BuildConfig):
         return cls(config=config)
 
-    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None):
+    def run_command(self, args: Sequence[str | Path], cwd: Path | None = None, requires_root: bool = False):
+        if requires_root and not os.getuid() == 0:
+            args = ["sudo", *args]
         run_cmd(args=args, dry_run=self._config.dry_run, cwd=cwd)
 
     def copy_file(self, source_dir: Path, glob: str, dest_dir: Path):

src/debmagic/_utils.py

@@ -6,7 +6,7 @@
 import subprocess
 import sys
 from pathlib import Path
-from typing import Sequence
+from typing import Callable, Sequence
 
 
 class Namespace:
@@ -88,22 +88,31 @@ def run_cmd_in_foreground(args: Sequence[str | Path], **kwargs):
     old_pgrp = os.tcgetpgrp(sys.stdin.fileno())
     old_attr = termios.tcgetattr(sys.stdin.fileno())
 
-    # generally, the child process should stop itself
-    # before exec so the parent can set its new pgid.
-    # (setting pgid has to be done before the child execs).
-    # however, Python 'guarantee' that `preexec_fn`
-    # is run before `Popen` returns.
-    # this is because `Popen` waits for the closure of
-    # the error relay pipe '`errpipe_write`',
-    # which happens at child's exec.
-    # this is also the reason the child can't stop itself
-    # in Python's `Popen`, since the `Popen` call would never
-    # terminate then.
-    # `os.kill(os.getpid(), signal.SIGSTOP)`
+    user_preexec_fn: Callable | None = kwargs.pop("preexec_fn", None)
+
+    def new_pgid():
+        if user_preexec_fn:
+            user_preexec_fn()
+
+        # set a new process group id
+        os.setpgid(os.getpid(), os.getpid())
+
+        # generally, the child process should stop itself
+        # before exec so the parent can set its new pgid.
+        # (setting pgid has to be done before the child execs).
+        # however, Python 'guarantee' that `preexec_fn`
+        # is run before `Popen` returns.
+        # this is because `Popen` waits for the closure of
+        # the error relay pipe '`errpipe_write`',
+        # which happens at child's exec.
+        # this is also the reason the child can't stop itself
+        # in Python's `Popen`, since the `Popen` call would never
+        # terminate then.
+        # `os.kill(os.getpid(), signal.SIGSTOP)`
 
     try:
         # fork the child
-        child = subprocess.Popen(args, process_group=os.getpid(), **kwargs)
+        child = subprocess.Popen(args, preexec_fn=new_pgid, **kwargs)  # noqa: PLW1509
 
         # we can't set the process group id from the parent since the child
         # will already have exec'd. and we can't SIGSTOP it before exec,