Declare the sysctl(3) prototype, check errors and retry grown values

.github/workflows/ci.yml

@@ -0,0 +1,58 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  build:
+    name: Build distribution
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v7
+      - uses: actions/setup-python@v6
+        with:
+          python-version: "3.12"
+      - run: python -m pip install build twine
+      - run: python -m build
+      - run: python -m twine check dist/*
+      - run: python -m pip install dist/*.whl
+      - run: python -c "import freebsd_sysctl; print(freebsd_sysctl.__version__)"
+
+  test-freebsd:
+    name: Test on FreeBSD ${{ matrix.release }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        release: ["14.4", "15.1"]
+    steps:
+      - uses: actions/checkout@v7
+      - name: Enable KVM
+        run: |
+          echo 'KERNEL=="kvm", GROUP="kvm", MODE="0666", OPTIONS+="static_node=kvm"' \
+            | sudo tee /etc/udev/rules.d/99-kvm4all.rules
+          sudo udevadm control --reload-rules
+          sudo udevadm trigger --name-match=kvm
+      - name: Install QEMU
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends \
+            qemu-system-x86 qemu-utils ovmf genisoimage
+      - name: Cache FreeBSD VM image
+        uses: actions/cache@v6
+        with:
+          path: ~/.cache/freebsd_sysctl-vm/*.xz
+          key: freebsd-vm-${{ matrix.release }}-v1
+      - name: Run the test suite in a FreeBSD VM
+        run: tests/vm/run.sh --release "${{ matrix.release }}"
+      - name: Upload VM console log
+        if: failure()
+        uses: actions/upload-artifact@v7
+        with:
+          name: vm-console-${{ matrix.release }}
+          path: /tmp/freebsd_sysctl-vm-*/console.log
+          if-no-files-found: ignore

.gitignore

@@ -7,3 +7,5 @@ build/
 dist/
 *.egg-info/
 .eggs/
+*.qcow2
+*.iso

freebsd_sysctl/__init__.py

@@ -23,6 +23,7 @@
 # POSSIBILITY OF SUCH DAMAGE.
 import typing
 import ctypes
+import errno
 import struct
 import enum
 import freebsd_sysctl.libc
@@ -31,9 +32,7 @@
 
 from freebsd_sysctl.__version__ import __version__
 
-NULL_BYTES = b"\x00"
-CTL_MAXNAME = ctypes.c_uint(24)
-T_OID = (ctypes.c_int * 2)
+CTL_MAXNAME = 24
 BUFSIZ = 1024 # see /include/stdio.h#L209
 
 
@@ -117,206 +116,103 @@ def next(self):
     def children(self) -> typing.Iterator['Sysctl']:
         if self.ctl_type != freebsd_sysctl.types.NODE:
             return
-        current = self.next
-        while self.oid == current.oid[:len(self.oid)]:
-            yield current
-            current = current.next
+        try:
+            current = self.next
+            while self.oid == current.oid[:len(self.oid)]:
+                yield current
+                current = current.next
+        except OSError as err:
+            # the last OID of the sysctl tree has no successor
+            if err.errno != errno.ENOENT:
+                raise
 
     def __query_kind_and_fmt(self) -> None:
         self._kind, self._fmt = self.query_fmt(self.oid)
 
     @staticmethod
     def name2oid(name: str) -> typing.List[int]:
-        p_name = ctypes.c_char_p(name.encode() + NULL_BYTES)
-        oid = T_OID(0, 3)
-        p_oid = ctypes.POINTER(T_OID)(oid)
-
-        length = ctypes.c_int(CTL_MAXNAME.value * ctypes.sizeof(ctypes.c_int))
-        p_length = ctypes.POINTER(ctypes.c_int)(length)
-
-        Res = ctypes.c_int*length.value
-        res = (Res)()
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_oid,
-            2,
-            ctypes.POINTER(Res)(res),
-            p_length,
-            p_name,
-            len(p_name.value)
+        encoded_name = name.encode()
+        res = (ctypes.c_int * CTL_MAXNAME)()
+        oldlen = ctypes.c_size_t(ctypes.sizeof(res))
+
+        freebsd_sysctl.libc.sysctl(
+            [0, 3],
+            res,
+            oldlen,
+            ctypes.c_char_p(encoded_name),
+            len(encoded_name)
         )
 
-        oid_length = int(length.value / ctypes.sizeof(ctypes.c_int))
+        oid_length = int(oldlen.value / ctypes.sizeof(ctypes.c_int))
         return res[:oid_length]
 
     @staticmethod
     def oid2name(oid: typing.List[int]) -> str:
-        qoid_len = (2 + len(oid))
-        qoid_type = ctypes.c_int * qoid_len
-        qoid = (qoid_type)(*([0, 1] + oid))
-        p_qoid = ctypes.POINTER(qoid_type)(qoid)
-
         buf = ctypes.create_string_buffer(BUFSIZ)
-        buf_void = ctypes.cast(buf, ctypes.c_void_p)
-
-        buf_length = ctypes.sizeof(buf)
-        p_buf_length = ctypes.POINTER(ctypes.c_int)(ctypes.c_int(buf_length))
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_qoid,
-            qoid_len,
-            buf_void,
-            p_buf_length,
-            0,
-            0
-        )
+        oldlen = ctypes.c_size_t(ctypes.sizeof(buf))
+        freebsd_sysctl.libc.sysctl([0, 1] + oid, buf, oldlen)
         return buf.value.decode()
 
     @staticmethod
     def query_fmt(oid: typing.List[int]) -> typing.Tuple[int, str]:
+        buf = ctypes.create_string_buffer(BUFSIZ)
+        oldlen = ctypes.c_size_t(ctypes.sizeof(buf))
+        freebsd_sysctl.libc.sysctl([0, 4] + oid, buf, oldlen)
 
-        qoid_len = (2 + len(oid))
-        qoid_type = ctypes.c_int * qoid_len
-        qoid = (qoid_type)(*([0, 4] + oid))
-        p_qoid = ctypes.POINTER(qoid_type)(qoid)
-
-        buf_type = ctypes.c_char * BUFSIZ
-        buf = buf_type()
-        p_buf = ctypes.POINTER(buf_type)(buf)
-        buf_void = ctypes.cast(p_buf, ctypes.c_void_p)
-
-        buf_length = ctypes.sizeof(buf)
-        p_buf_length = ctypes.POINTER(ctypes.c_int)(ctypes.c_int(buf_length))
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_qoid,
-            qoid_len,
-            buf_void,
-            p_buf_length,
-            0,
-            0
-        )
-
-        if len(buf) < 4:
+        if oldlen.value < 4:
             raise Exception("response buffer too small")
-        result = buf[:buf_length]
+        result = buf.raw[:oldlen.value]
         kind, = struct.unpack("I", result[:4])
-        null_pos = result.find(b'\x00',4) # buf is large and string is small
+        null_pos = result.find(b"\x00", 4)
         fmt = result[4:null_pos].decode()
         return (kind, fmt)
 
     @staticmethod
     def query_size(
         oid: typing.List[int],
         ctl_type: freebsd_sysctl.types.CtlType
-    ) -> bytes:
-
-        oid_type = ctypes.c_int * len(oid)
-        _oid = (oid_type)(*oid)
-        p_oid = ctypes.POINTER(oid_type)(_oid)
-
-        length = ctypes.c_int()
-        p_length = ctypes.POINTER(ctypes.c_int)(length)
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_oid,
-            len(oid),
-            None,
-            p_length,
-            0
-        )
-
-        return max(length.value, ctl_type.min_size)
+    ) -> int:
+        oldlen = ctypes.c_size_t()
+        freebsd_sysctl.libc.sysctl(oid, None, oldlen)
+        return max(oldlen.value, ctl_type.min_size)
 
     @staticmethod
     def query_value(
         oid: typing.List[int],
         size: int,
         ctl_type: freebsd_sysctl.types.CtlType
     ) -> bytes:
-
-        # ToDo: check if value is readable
-
-        oid_type = ctypes.c_int * len(oid)
-        _oid = (oid_type)(*oid)
-        p_oid = ctypes.POINTER(oid_type)(_oid)
-
-        buf_type = ctypes.c_char * size
-        buf = buf_type()
-        p_buf = ctypes.POINTER(buf_type)(buf)
-        p_buf_void = ctypes.cast(p_buf, ctypes.c_void_p)
-
-        buf_length = ctypes.sizeof(buf)
-        p_buf_length = ctypes.POINTER(ctypes.c_int)(ctypes.c_int(buf_length))
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_oid,
-            ctypes.c_uint32(len(oid)),
-            p_buf_void,
-            p_buf_length,
-            None,
-            0
-        )
-
-        return ctl_type(buf, size)
+        # the value can grow between the size query and the read
+        attempts = 4
+        while True:
+            buf = ctypes.create_string_buffer(size)
+            oldlen = ctypes.c_size_t(size)
+            try:
+                freebsd_sysctl.libc.sysctl(oid, buf, oldlen)
+            except OSError as err:
+                attempts -= 1
+                if (err.errno != errno.ENOMEM) or (attempts == 0):
+                    raise
+                size *= 2
+                continue
+            return ctl_type(buf, size)
 
     @staticmethod
     def query_description(
         oid: typing.List[int]
     ) -> str:
-
-        qoid_len = (2 + len(oid))
-        qoid_type = ctypes.c_int * qoid_len
-        qoid = (qoid_type)(*([0, 5] + oid))
-        p_qoid = ctypes.POINTER(qoid_type)(qoid)
-
-        buf_type = ctypes.c_char * BUFSIZ
-        buf = buf_type()
-        p_buf = ctypes.POINTER(buf_type)(buf)
-        buf_void = ctypes.cast(p_buf, ctypes.c_void_p)
-
-        buf_length = ctypes.sizeof(buf)
-        p_buf_length = ctypes.POINTER(ctypes.c_int)(ctypes.c_int(buf_length))
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_qoid,
-            qoid_len,
-            buf_void,
-            p_buf_length,
-            0,
-            0
-        )
-
+        buf = ctypes.create_string_buffer(BUFSIZ)
+        oldlen = ctypes.c_size_t(ctypes.sizeof(buf))
+        freebsd_sysctl.libc.sysctl([0, 5] + oid, buf, oldlen)
         return buf.value.decode()
 
     @staticmethod
     def query_next(oid: typing.List[int]) -> bytes:
+        buf = (ctypes.c_int * CTL_MAXNAME)()
+        oldlen = ctypes.c_size_t(ctypes.sizeof(buf))
+        freebsd_sysctl.libc.sysctl([0, 2] + oid, buf, oldlen)
 
-        qoid_len = (2 + len(oid))
-        qoid_type = ctypes.c_int * qoid_len
-        qoid = (qoid_type)(*([0, 2] + oid))
-        p_qoid = ctypes.POINTER(qoid_type)(qoid)
-
-        buf_type = ctypes.c_int * CTL_MAXNAME.value
-        buf = buf_type()
-        p_buf = ctypes.POINTER(buf_type)(buf)
-        buf_void = ctypes.cast(p_buf, ctypes.c_void_p)
-
-        buf_length = ctypes.sizeof(buf)
-        p_buf_length = ctypes.POINTER(ctypes.c_int)(ctypes.c_int(buf_length))
-
-        freebsd_sysctl.libc.dll.sysctl(
-            p_qoid,
-            qoid_len,
-            buf_void,
-            p_buf_length,
-            0,
-            0
-        )
-
-        oid_length = int(
-            p_buf_length.contents.value / ctypes.sizeof(ctypes.c_int)
-        )
+        oid_length = int(oldlen.value / ctypes.sizeof(ctypes.c_int))
         return buf[0:oid_length]
 
     @property