procutils: introduce parse_meminfo()

apport/procutils.py

@@ -0,0 +1,29 @@
+# Copyright (C) 2026 Canonical Ltd.
+# Author: Benjamin Drung <bdrung@ubuntu.com>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 2 of the License, or (at your
+# option) any later version.  See http://www.gnu.org/copyleft/gpl.html for
+# the full text of the license.
+
+"""Functions to operate on files in /proc."""
+
+from collections.abc import Iterable
+
+
+def parse_meminfo(keys: Iterable[str]) -> dict[str, int]:
+    """Parse /proc/meminfo and return a dictionary for the requested keys."""
+    remaining_keys = set(keys)
+    meminfo = {}
+    with open("/proc/meminfo", "r", encoding="utf-8") as meminfo_file:
+        for line in meminfo_file:
+            key, remaining = line.split(":", maxsplit=1)
+            if key not in remaining_keys:
+                continue
+            value = remaining.strip().split(maxsplit=1)[0]
+            meminfo[key] = int(value)
+            remaining_keys.remove(key)
+            if not remaining_keys:
+                return meminfo
+    raise KeyError(f"{' '.join(sorted(remaining_keys))} not found in /proc/meminfo")

data/apport

@@ -43,6 +43,7 @@ from collections.abc import Callable
 
 import apport.fileutils
 import apport.report
+from apport.procutils import parse_meminfo
 from apport.user_group import UserGroupID
 from problem_report import CompressedFile
 
@@ -338,20 +339,11 @@ def write_user_coredump(
     os.close(core_file)
 
 
-def usable_ram():
+def usable_ram() -> int:
     """Return how many bytes of RAM is currently available that can be
     allocated without causing major thrashing."""
-
-    # abuse our excellent RFC822 parser to parse /proc/meminfo
-    r = apport.report.Report()
-    with open("/proc/meminfo", "rb") as f:
-        r.load(f)
-
-    memfree = int(r["MemFree"].split()[0])
-    cached = int(r["Cached"].split()[0])
-    writeback = int(r["Writeback"].split()[0])
-
-    return (memfree + cached - writeback) * 1024
+    meminfo = parse_meminfo({"Cached", "MemFree", "Writeback"})
+    return (meminfo["MemFree"] + meminfo["Cached"] - meminfo["Writeback"]) * 1024
 
 
 def _run_with_output_limit_and_timeout(

tests/system/test_apport_valgrind.py

@@ -15,14 +15,11 @@
 import tempfile
 import unittest
 
+from apport.procutils import parse_meminfo
 from tests.helper import get_gnu_coreutils_cmd, skip_if_command_is_missing
 from tests.paths import local_test_environment
 
-with open("/proc/meminfo", encoding="utf-8") as f:
-    for line in f.readlines():
-        if line.startswith("MemTotal"):
-            MEM_TOTAL_MiB = int(line.split()[1]) // 1024
-            break
+MEM_TOTAL_MiB = parse_meminfo({"MemTotal"})["MemTotal"]
 
 
 @skip_if_command_is_missing("valgrind")

tests/system/test_signal_crashes.py

@@ -17,6 +17,7 @@
 
 import apport.fileutils
 import apport.report
+from apport.procutils import parse_meminfo
 from tests.helper import (
     get_gnu_coreutils_cmd,
     get_init_system,
@@ -159,12 +160,8 @@ def test_limit_size(self) -> None:
         assert self.apport_path is not None
         # determine how much data we have to pump into apport in order to make
         # sure that it will refuse the core dump
-        r = apport.report.Report()
-        with open("/proc/meminfo", "rb") as f:
-            r.load(f)
-        totalmb = int(r["MemFree"].split()[0]) + int(r["Cached"].split()[0])
-        totalmb = int(totalmb / 1024)
-        del r
+        meminfo = parse_meminfo({"Cached", "MemFree"})
+        totalmb = (meminfo["MemFree"] + meminfo["Cached"]) // 1024
 
         test_proc = self.create_test_process()
         try:

tests/unit/test_procutils.py

@@ -0,0 +1,45 @@
+# Copyright (C) 2026 Canonical Ltd.
+# Author: Benjamin Drung <bdrung@ubuntu.com>
+#
+# This program is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 2 of the License, or (at your
+# option) any later version.  See http://www.gnu.org/copyleft/gpl.html for
+# the full text of the license.
+
+"""Unit tests for the apport.procutils module."""
+
+from unittest.mock import mock_open, patch
+
+import pytest
+
+from apport.procutils import parse_meminfo
+
+
+def test_parse_meminfo() -> None:
+    """Test parse_meminfo() reading all values successfully."""
+    open_mock = mock_open(
+        read_data=(
+            "MemTotal:       128887668 kB\n"
+            "MemFree:        81203612 kB\n"
+            "HugePages_Total:       0\n"
+            "DirectMap1G:    127926272 kB\n"
+        )
+    )
+    with patch("builtins.open", open_mock):
+        meminfo = parse_meminfo({"MemTotal", "MemFree", "HugePages_Total"})
+    assert meminfo["MemTotal"] == 128887668
+    assert meminfo["MemFree"] == 81203612
+    assert meminfo["HugePages_Total"] == 0
+    assert len(meminfo) == 3
+
+
+def test_parse_meminfo_missing_key() -> None:
+    """Test parse_meminfo() failing to read the requested keys."""
+    open_mock = mock_open(
+        read_data=("MemTotal:       128887668 kB\nMemFree:        81203612 kB\n")
+    )
+    with patch("builtins.open", open_mock):
+        with pytest.raises(KeyError) as exc_info:
+            parse_meminfo({"MemTotal", "MemAvailable"})
+    exc_info.match("MemAvailable not found in /proc/meminfo")