Fix crash in linux.environ plugin when environ file is missing

dissect/target/plugins/os/unix/linux/proc.py

@@ -472,7 +472,11 @@ def _parse_proc_stat_entry(self) -> dict[str, str | int]:
     def _parse_environ(self) -> Iterator[Environ]:
         """Internal function to parse entries in ``/proc/[pid]/environ``."""
         # entries in /proc/<pid>/environ are null-terminated
-        lines = self.get("environ").read_text().split("\x00")
+        environ_path = self.get("environ")
+        if not environ_path.exists():
+            return
+
+        lines = environ_path.read_text().split("\x00")
 
         for line in lines:
             if line == "":

tests/conftest.py

@@ -236,7 +236,7 @@ def fs_linux_proc(fs_linux: VirtualFilesystem) -> VirtualFilesystem:
             "proc/1337",
             VirtualSymlink(fs, "/proc/1337/fd/4", "socket:[1337]"),
             "acquire\x00-p\x00full\x00--proc\x00",
-            "VAR=1",
+            "",
         ),
     )
     stat_files_data = (
@@ -253,7 +253,8 @@ def fs_linux_proc(fs_linux: VirtualFilesystem) -> VirtualFilesystem:
 
         fs.map_file_fh(dir + "/stat", BytesIO(stat_files_data[idx].encode()))
         fs.map_file_fh(dir + "/cmdline", BytesIO(cmdline.encode()))
-        fs.map_file_fh(dir + "/environ", BytesIO(environ.encode()))
+        if environ:
+            fs.map_file_fh(dir + "/environ", BytesIO(environ.encode()))
 
     # symlink acquire process to self
     fs.link("/proc/1337", "/proc/self")

tests/plugins/os/unix/linux/test_environ.py

@@ -10,6 +10,10 @@
 
 
 def test_environ(target_linux_users: Target, fs_linux_proc: VirtualFilesystem) -> None:
+    # Reference the fixture to ensure its setup logic runs (side effects).
+    # Assigned to `_` to suppress "unused variable" linter warnings.
+    _ = fs_linux_proc
+
     target_linux_users.add_plugin(ProcPlugin)
     results = list(target_linux_users.environ())
-    assert len(results) == 4
+    assert len(results) == 3