chiark / gitweb /
systemd-python: fix segfault on double close
[elogind.git] / src / python-systemd / _reader.c
index 207b9e76cb26ba12cdc6681dfb4f69f03112b307..160ab69a3caa5c13f80f9e2bb10de0eeb1dbb8e3 100644 (file)
   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
-#include <systemd/sd-journal.h>
 
 #include <Python.h>
 #include <structmember.h>
 #include <datetime.h>
+#include <stdio.h>
+
+#include <systemd/sd-journal.h>
+
+#include "pyutil.h"
+#include "macro.h"
+#include "util.h"
 
 #if PY_MAJOR_VERSION >=3
 # define unicode_FromStringAndSize PyUnicode_FromStringAndSize
@@ -44,8 +50,8 @@
 typedef struct {
     PyObject_HEAD
     sd_journal *j;
-} Journal;
-static PyTypeObject JournalType;
+} Reader;
+static PyTypeObject ReaderType;
 
 static int set_error(int r, const char* path, const char* invalid_message) {
     if (r >= 0)
@@ -58,35 +64,64 @@ static int set_error(int r, const char* path, const char* invalid_message) {
         errno = -r;
         PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
     }
-    return 1;
+    return -1;
 }
 
-static void Journal_dealloc(Journal* self)
+#if PY_MAJOR_VERSION >= 3
+static PyTypeObject MonotonicType;
+
+PyDoc_STRVAR(MonotonicType__doc__,
+             "A tuple of (timestamp, bootid) for holding monotonic timestamps");
+
+static PyStructSequence_Field MonotonicType_fields[] = {
+    {(char*) "timestamp", (char*) "Time"},
+    {(char*) "bootid", (char*) "Unique identifier of the boot"},
+    {NULL, NULL}
+};
+
+static PyStructSequence_Desc Monotonic_desc = {
+    (char*) "journal.Monotonic",
+    MonotonicType__doc__,
+    MonotonicType_fields,
+    2,
+};
+#endif
+
+static void Reader_dealloc(Reader* self)
 {
     sd_journal_close(self->j);
     Py_TYPE(self)->tp_free((PyObject*)self);
 }
 
-PyDoc_STRVAR(Journal__doc__,
-             "Journal([flags][,path]) -> ...\n\n"
-             "Journal allows filtering and retrieval of Journal entries.\n"
+PyDoc_STRVAR(Reader__doc__,
+             "Reader([flags | path]) -> ...\n\n"
+             "Reader allows filtering and retrieval of Journal entries.\n"
+             "Note: this is a low-level interface, and probably not what you\n"
+             "want, use systemd.journal.Reader instead.\n\n"
              "Argument `flags` sets open flags of the journal, which can be one\n"
              "of, or ORed combination of constants: LOCAL_ONLY (default) opens\n"
              "journal on local machine only; RUNTIME_ONLY opens only\n"
              "volatile journal files; and SYSTEM_ONLY opens only\n"
-             "journal files of system services and the kernel.\n"
+             "journal files of system services and the kernel.\n\n"
              "Argument `path` is the directory of journal files. Note that\n"
-             "currently flags are ignored when `path` is present as they are\n"
-             "not relevant.");
-static int Journal_init(Journal *self, PyObject *args, PyObject *keywds)
+             "`flags` and `path` are exclusive.\n");
+static int Reader_init(Reader *self, PyObject *args, PyObject *keywds)
 {
-    int flags = SD_JOURNAL_LOCAL_ONLY, r;
+    int flags = 0, r;
     char *path = NULL;
 
     static const char* const kwlist[] = {"flags", "path", NULL};
     if (!PyArg_ParseTupleAndKeywords(args, keywds, "|iz", (char**) kwlist,
                                      &flags, &path))
-        return 1;
+        return -1;
+
+    if (!flags)
+        flags = SD_JOURNAL_LOCAL_ONLY;
+    else
+        if (path) {
+            PyErr_SetString(PyExc_ValueError, "cannot use both flags and path");
+            return -1;
+        }
 
     Py_BEGIN_ALLOW_THREADS
     if (path)
@@ -98,19 +133,60 @@ static int Journal_init(Journal *self, PyObject *args, PyObject *keywds)
     return set_error(r, path, "Invalid flags or path");
 }
 
-PyDoc_STRVAR(Journal_get_next__doc__,
+PyDoc_STRVAR(Reader_fileno__doc__,
+             "fileno() -> int\n\n"
+             "Get a file descriptor to poll for changes in the journal.\n"
+             "This method invokes sd_journal_get_fd().\n"
+             "See man:sd_journal_get_fd(3).");
+static PyObject* Reader_fileno(Reader *self, PyObject *args)
+{
+    int r;
+    r = sd_journal_get_fd(self->j);
+    set_error(r, NULL, NULL);
+    if (r < 0)
+        return NULL;
+    return long_FromLong(r);
+}
+
+PyDoc_STRVAR(Reader_reliable_fd__doc__,
+             "reliable_fd() -> bool\n\n"
+             "Returns True iff the journal can be polled reliably.\n"
+             "This method invokes sd_journal_reliable_fd().\n"
+             "See man:sd_journal_reliable_fd(3).");
+static PyObject* Reader_reliable_fd(Reader *self, PyObject *args)
+{
+    int r;
+    r = sd_journal_reliable_fd(self->j);
+    set_error(r, NULL, NULL);
+    if (r < 0)
+        return NULL;
+    return PyBool_FromLong(r);
+}
+
+PyDoc_STRVAR(Reader_close__doc__,
+             "close() -> None\n\n"
+             "Free resources allocated by this Reader object.\n"
+             "This method invokes sd_journal_close().\n"
+             "See man:sd_journal_close(3).");
+static PyObject* Reader_close(Reader *self, PyObject *args)
+{
+    sd_journal_close(self->j);
+    self->j = NULL;
+    Py_RETURN_NONE;
+}
+
+PyDoc_STRVAR(Reader_get_next__doc__,
              "get_next([skip]) -> dict\n\n"
              "Return dictionary of the next log entry. Optional skip value will\n"
              "return the `skip`\\-th log entry.");
-static PyObject* Journal_get_next(Journal *self, PyObject *args)
+static PyObject* Reader_get_next(Reader *self, PyObject *args)
 {
     PyObject *dict;
     const void *msg;
     size_t msg_len;
-    const char *delim_ptr;
-    PyObject *key, *value, *cur_value, *tmp_list;
+    int64_t skip = 1LL;
+    int r;
 
-    int64_t skip = 1LL, r = -EINVAL;
     if (!PyArg_ParseTuple(args, "|L", &skip))
         return NULL;
 
@@ -128,6 +204,8 @@ static PyObject* Journal_get_next(Journal *self, PyObject *args)
         r = sd_journal_next_skip(self->j, skip);
     else if (skip < -1LL)
         r = sd_journal_previous_skip(self->j, -skip);
+    else
+        assert_not_reached("should not be here");
     Py_END_ALLOW_THREADS
 
     set_error(r, NULL, NULL);
@@ -137,77 +215,150 @@ static PyObject* Journal_get_next(Journal *self, PyObject *args)
         return PyDict_New();
 
     dict = PyDict_New();
+    if (!dict)
+            return NULL;
 
     SD_JOURNAL_FOREACH_DATA(self->j, msg, msg_len) {
+        PyObject _cleanup_Py_DECREF_ *key = NULL, *value = NULL;
+        const char *delim_ptr;
+
         delim_ptr = memchr(msg, '=', msg_len);
+        if (!delim_ptr) {
+            PyErr_SetString(PyExc_OSError,
+                            "journal gave us a field without '='");
+            goto error;
+        }
+
         key = unicode_FromStringAndSize(msg, delim_ptr - (const char*) msg);
-        value = PyBytes_FromStringAndSize(delim_ptr + 1, (const char*) msg + msg_len - (delim_ptr + 1) );
+        if (!key)
+            goto error;
+
+        value = PyBytes_FromStringAndSize(
+                delim_ptr + 1,
+                (const char*) msg + msg_len - (delim_ptr + 1) );
+        if (!value)
+            goto error;
+
         if (PyDict_Contains(dict, key)) {
-            cur_value = PyDict_GetItem(dict, key);
+            PyObject *cur_value = PyDict_GetItem(dict, key);
+
             if (PyList_CheckExact(cur_value)) {
-                PyList_Append(cur_value, value);
-            }else{
-                tmp_list = PyList_New(0);
-                PyList_Append(tmp_list, cur_value);
-                PyList_Append(tmp_list, value);
-                PyDict_SetItem(dict, key, tmp_list);
-                Py_DECREF(tmp_list);
+                r = PyList_Append(cur_value, value);
+                if (r < 0)
+                    goto error;
+            } else {
+                PyObject _cleanup_Py_DECREF_ *tmp_list = PyList_New(0);
+                if (!tmp_list)
+                    goto error;
+
+                r = PyList_Append(tmp_list, cur_value);
+                if (r < 0)
+                    goto error;
+
+                r = PyList_Append(tmp_list, value);
+                if (r < 0)
+                    goto error;
+
+                r = PyDict_SetItem(dict, key, tmp_list);
+                if (r < 0)
+                    goto error;
             }
-        }else{
-            PyDict_SetItem(dict, key, value);
+        } else {
+            r = PyDict_SetItem(dict, key, value);
+            if (r < 0)
+                goto error;
         }
-        Py_DECREF(key);
-        Py_DECREF(value);
     }
 
     {
+        PyObject _cleanup_Py_DECREF_ *key = NULL, *value = NULL;
         uint64_t realtime;
-        if (sd_journal_get_realtime_usec(self->j, &realtime) == 0) {
-            char realtime_str[20];
-            sprintf(realtime_str, "%llu", (long long unsigned) realtime);
-            key = unicode_FromString("__REALTIME_TIMESTAMP");
-            value = PyBytes_FromString(realtime_str);
-            PyDict_SetItem(dict, key, value);
-            Py_DECREF(key);
-            Py_DECREF(value);
-        }
+
+        r = sd_journal_get_realtime_usec(self->j, &realtime);
+        if (set_error(r, NULL, NULL))
+            goto error;
+
+        key = unicode_FromString("__REALTIME_TIMESTAMP");
+        if (!key)
+            goto error;
+
+        assert_cc(sizeof(unsigned long long) == sizeof(realtime));
+        value = PyLong_FromUnsignedLongLong(realtime);
+        if (!value)
+            goto error;
+
+        if (PyDict_SetItem(dict, key, value))
+            goto error;
     }
 
     {
-        sd_id128_t sd_id;
+        PyObject _cleanup_Py_DECREF_
+            *key = NULL, *timestamp = NULL, *bytes = NULL, *value = NULL;
+        sd_id128_t id;
         uint64_t monotonic;
-        if (sd_journal_get_monotonic_usec(self->j, &monotonic, &sd_id) == 0) {
-            char monotonic_str[20];
-            sprintf(monotonic_str, "%llu", (long long unsigned) monotonic);
-            key = unicode_FromString("__MONOTONIC_TIMESTAMP");
-            value = PyBytes_FromString(monotonic_str);
-
-            PyDict_SetItem(dict, key, value);
-            Py_DECREF(key);
-            Py_DECREF(value);
-        }
+
+        r = sd_journal_get_monotonic_usec(self->j, &monotonic, &id);
+        if (set_error(r, NULL, NULL))
+            goto error;
+
+        assert_cc(sizeof(unsigned long long) == sizeof(monotonic));
+        key = unicode_FromString("__MONOTONIC_TIMESTAMP");
+        timestamp = PyLong_FromUnsignedLongLong(monotonic);
+        bytes = PyBytes_FromStringAndSize((const char*) &id.bytes, sizeof(id.bytes));
+#if PY_MAJOR_VERSION >= 3
+        value = PyStructSequence_New(&MonotonicType);
+#else
+        value = PyTuple_New(2);
+#endif
+        if (!key || !timestamp || !bytes || !value)
+            goto error;
+
+        Py_INCREF(timestamp);
+        Py_INCREF(bytes);
+
+#if PY_MAJOR_VERSION >= 3
+        PyStructSequence_SET_ITEM(value, 0, timestamp);
+        PyStructSequence_SET_ITEM(value, 1, bytes);
+#else
+        PyTuple_SET_ITEM(value, 0, timestamp);
+        PyTuple_SET_ITEM(value, 1, bytes);
+#endif
+
+        if (PyDict_SetItem(dict, key, value))
+            goto error;
     }
 
     {
-        char *cursor;
-        if (sd_journal_get_cursor(self->j, &cursor) > 0) { //Should return 0...
-            key = unicode_FromString("__CURSOR");
-            value = PyBytes_FromString(cursor);
-            PyDict_SetItem(dict, key, value);
-            free(cursor);
-            Py_DECREF(key);
-            Py_DECREF(value);
-        }
+        PyObject _cleanup_Py_DECREF_ *key = NULL, *value = NULL;
+        char _cleanup_free_ *cursor = NULL;
+
+        r = sd_journal_get_cursor(self->j, &cursor);
+        if (set_error(r, NULL, NULL))
+            goto error;
+
+        key = unicode_FromString("__CURSOR");
+        if (!key)
+            goto error;
+
+        value = PyBytes_FromString(cursor);
+        if (!value)
+            goto error;
+
+        if (PyDict_SetItem(dict, key, value))
+            goto error;
     }
 
     return dict;
+error:
+    Py_DECREF(dict);
+    return NULL;
 }
 
-PyDoc_STRVAR(Journal_get_previous__doc__,
+PyDoc_STRVAR(Reader_get_previous__doc__,
              "get_previous([skip]) -> dict\n\n"
              "Return dictionary of the previous log entry. Optional skip value\n"
              "will return the -`skip`\\-th log entry. Equivalent to get_next(-skip).");
-static PyObject* Journal_get_previous(Journal *self, PyObject *args)
+static PyObject* Reader_get_previous(Reader *self, PyObject *args)
 {
     int64_t skip = 1LL;
     if (!PyArg_ParseTuple(args, "|L", &skip))
@@ -217,13 +368,13 @@ static PyObject* Journal_get_previous(Journal *self, PyObject *args)
                                (char*) "L", -skip);
 }
 
-PyDoc_STRVAR(Journal_add_match__doc__,
+PyDoc_STRVAR(Reader_add_match__doc__,
              "add_match(match) -> None\n\n"
              "Add a match to filter journal log entries. All matches of different\n"
              "fields are combined with logical AND, and matches of the same field\n"
              "are automatically combined with logical OR.\n"
              "Match is a string of the form \"FIELD=value\".");
-static PyObject* Journal_add_match(Journal *self, PyObject *args, PyObject *keywds)
+static PyObject* Reader_add_match(Reader *self, PyObject *args, PyObject *keywds)
 {
     char *match;
     int match_len, r;
@@ -238,10 +389,10 @@ static PyObject* Journal_add_match(Journal *self, PyObject *args, PyObject *keyw
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_add_disjunction__doc__,
+PyDoc_STRVAR(Reader_add_disjunction__doc__,
              "add_disjunction() -> None\n\n"
              "Inserts a logical OR between matches added before and afterwards.");
-static PyObject* Journal_add_disjunction(Journal *self, PyObject *args)
+static PyObject* Reader_add_disjunction(Reader *self, PyObject *args)
 {
     int r;
     r = sd_journal_add_disjunction(self->j);
@@ -251,78 +402,52 @@ static PyObject* Journal_add_disjunction(Journal *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_flush_matches__doc__,
+PyDoc_STRVAR(Reader_flush_matches__doc__,
              "flush_matches() -> None\n\n"
              "Clear all current match filters.");
-static PyObject* Journal_flush_matches(Journal *self, PyObject *args)
+static PyObject* Reader_flush_matches(Reader *self, PyObject *args)
 {
     sd_journal_flush_matches(self->j);
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_seek__doc__,
-             "seek(offset[, whence]) -> None\n\n"
-             "Jump `offset` entries in the journal. Argument\n"
-             "`whence` defines what the offset is relative to:\n"
-             "os.SEEK_SET (default) from first match in journal;\n"
-             "os.SEEK_CUR from current position in journal;\n"
-             "and os.SEEK_END is from last match in journal.");
-static PyObject* Journal_seek(Journal *self, PyObject *args, PyObject *keywds)
+PyDoc_STRVAR(Reader_seek_head__doc__,
+             "seek_head() -> None\n\n"
+             "Jump to the beginning of the journal.\n"
+             "This method invokes sd_journal_seek_head().\n"
+             "See man:sd_journal_seek_head(3).");
+static PyObject* Reader_seek_head(Reader *self, PyObject *args)
 {
-    int64_t offset;
-    int whence = SEEK_SET;
-    PyObject *result = NULL;
-
-    static const char* const kwlist[] = {"offset", "whence", NULL};
-    if (!PyArg_ParseTupleAndKeywords(args, keywds, "L|i", (char**) kwlist,
-                                     &offset, &whence))
+    int r;
+    Py_BEGIN_ALLOW_THREADS
+    r = sd_journal_seek_head(self->j);
+    Py_END_ALLOW_THREADS
+    if (set_error(r, NULL, NULL))
         return NULL;
+    Py_RETURN_NONE;
+}
 
-    switch(whence) {
-    case SEEK_SET: {
-        int r;
-        Py_BEGIN_ALLOW_THREADS
-        r = sd_journal_seek_head(self->j);
-        Py_END_ALLOW_THREADS
-        if (set_error(r, NULL, NULL))
-            return NULL;
-
-        if (offset > 0LL)
-            result = PyObject_CallMethod((PyObject *)self, (char*) "get_next",
-                                         (char*) "L", offset);
-        break;
-    }
-    case SEEK_CUR:
-        result = PyObject_CallMethod((PyObject *)self, (char*) "get_next",
-                                     (char*) "L", offset);
-        break;
-    case SEEK_END: {
-        int r;
-        Py_BEGIN_ALLOW_THREADS
-        r = sd_journal_seek_tail(self->j);
-        Py_END_ALLOW_THREADS
-        if (set_error(r, NULL, NULL))
-            return NULL;
-
-        result = PyObject_CallMethod((PyObject *)self, (char*) "get_next",
-                                     (char*) "L", offset < 0LL ? offset : -1LL);
-        break;
-    }
-    default:
-        PyErr_SetString(PyExc_ValueError, "Invalid value for whence");
-    }
-
-    Py_XDECREF(result);
-    if (PyErr_Occurred())
+PyDoc_STRVAR(Reader_seek_tail__doc__,
+             "seek_tail() -> None\n\n"
+             "Jump to the end of the journal.\n"
+             "This method invokes sd_journal_seek_tail().\n"
+             "See man:sd_journal_seek_tail(3).");
+static PyObject* Reader_seek_tail(Reader *self, PyObject *args)
+{
+    int r;
+    Py_BEGIN_ALLOW_THREADS
+    r = sd_journal_seek_tail(self->j);
+    Py_END_ALLOW_THREADS
+    if (set_error(r, NULL, NULL))
         return NULL;
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_seek_realtime__doc__,
+PyDoc_STRVAR(Reader_seek_realtime__doc__,
              "seek_realtime(realtime) -> None\n\n"
              "Seek to nearest matching journal entry to `realtime`. Argument\n"
              "`realtime` can must be an integer unix timestamp.");
-static PyObject* Journal_seek_realtime(Journal *self, PyObject *args)
+static PyObject* Reader_seek_realtime(Reader *self, PyObject *args)
 {
     double timedouble;
     uint64_t timestamp;
@@ -345,18 +470,18 @@ static PyObject* Journal_seek_realtime(Journal *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_seek_monotonic__doc__,
+PyDoc_STRVAR(Reader_seek_monotonic__doc__,
              "seek_monotonic(monotonic[, bootid]) -> None\n\n"
              "Seek to nearest matching journal entry to `monotonic`. Argument\n"
              "`monotonic` is an timestamp from boot in seconds.\n"
              "Argument `bootid` is a string representing which boot the\n"
              "monotonic time is reference to. Defaults to current bootid.");
-static PyObject* Journal_seek_monotonic(Journal *self, PyObject *args)
+static PyObject* Reader_seek_monotonic(Reader *self, PyObject *args)
 {
     double timedouble;
     char *bootid = NULL;
     uint64_t timestamp;
-    sd_id128_t sd_id;
+    sd_id128_t id;
     int r;
 
     if (!PyArg_ParseTuple(args, "d|z", &timedouble, &bootid))
@@ -370,26 +495,26 @@ static PyObject* Journal_seek_monotonic(Journal *self, PyObject *args)
     }
 
     if (bootid) {
-        r = sd_id128_from_string(bootid, &sd_id);
+        r = sd_id128_from_string(bootid, &id);
         if (set_error(r, NULL, "Invalid bootid"))
             return NULL;
     } else {
         Py_BEGIN_ALLOW_THREADS
-        r = sd_id128_get_boot(&sd_id);
+        r = sd_id128_get_boot(&id);
         Py_END_ALLOW_THREADS
         if (set_error(r, NULL, NULL))
             return NULL;
     }
 
     Py_BEGIN_ALLOW_THREADS
-    r = sd_journal_seek_monotonic_usec(self->j, sd_id, timestamp);
+    r = sd_journal_seek_monotonic_usec(self->j, id, timestamp);
     Py_END_ALLOW_THREADS
     if (set_error(r, NULL, NULL))
         return NULL;
     Py_RETURN_NONE;
 }
 
-PyDoc_STRVAR(Journal_wait__doc__,
+PyDoc_STRVAR(Reader_wait__doc__,
              "wait([timeout]) -> state change (integer)\n\n"
              "Wait for a change in the journal. Argument `timeout` specifies\n"
              "the maximum number of seconds to wait before returning\n"
@@ -398,7 +523,7 @@ PyDoc_STRVAR(Journal_wait__doc__,
              "Will return constants: NOP if no change; APPEND if new\n"
              "entries have been added to the end of the journal; and\n"
              "INVALIDATE if journal files have been added or removed.");
-static PyObject* Journal_wait(Journal *self, PyObject *args, PyObject *keywds)
+static PyObject* Reader_wait(Reader *self, PyObject *args, PyObject *keywds)
 {
     int r;
     int64_t timeout = 0LL;
@@ -407,18 +532,19 @@ static PyObject* Journal_wait(Journal *self, PyObject *args, PyObject *keywds)
         return NULL;
 
     Py_BEGIN_ALLOW_THREADS
-    r = sd_journal_wait(self->j, timeout ==0 ? (uint64_t) -1 : timeout * 1E6);
+    r = sd_journal_wait(self->j,
+                        timeout == 0 ? (uint64_t) -1 : timeout * 1E6);
     Py_END_ALLOW_THREADS
-    if (set_error(r, NULL, NULL))
+    if (set_error(r, NULL, NULL) < 0)
         return NULL;
 
     return long_FromLong(r);
 }
 
-PyDoc_STRVAR(Journal_seek_cursor__doc__,
+PyDoc_STRVAR(Reader_seek_cursor__doc__,
              "seek_cursor(cursor) -> None\n\n"
              "Seek to journal entry by given unique reference `cursor`.");
-static PyObject* Journal_seek_cursor(Journal *self, PyObject *args)
+static PyObject* Reader_seek_cursor(Reader *self, PyObject *args)
 {
     const char *cursor;
     int r;
@@ -434,13 +560,13 @@ static PyObject* Journal_seek_cursor(Journal *self, PyObject *args)
     Py_RETURN_NONE;
 }
 
-static PyObject* Journal_iter(PyObject *self)
+static PyObject* Reader_iter(PyObject *self)
 {
     Py_INCREF(self);
     return self;
 }
 
-static PyObject* Journal_iternext(PyObject *self)
+static PyObject* Reader_iternext(PyObject *self)
 {
     PyObject *dict;
     Py_ssize_t dict_size;
@@ -451,18 +577,18 @@ static PyObject* Journal_iternext(PyObject *self)
     dict_size = PyDict_Size(dict);
     if ((int64_t) dict_size > 0LL) {
         return dict;
-    }else{
+    } else {
         Py_DECREF(dict);
         PyErr_SetNone(PyExc_StopIteration);
         return NULL;
     }
 }
 
-PyDoc_STRVAR(Journal_query_unique__doc__,
+PyDoc_STRVAR(Reader_query_unique__doc__,
              "query_unique(field) -> a set of values\n\n"
              "Return a set of unique values appearing in journal for the\n"
              "given `field`. Note this does not respect any journal matches.");
-static PyObject* Journal_query_unique(Journal *self, PyObject *args)
+static PyObject* Reader_query_unique(Reader *self, PyObject *args)
 {
     char *query;
     int r;
@@ -486,7 +612,9 @@ static PyObject* Journal_query_unique(Journal *self, PyObject *args)
         const char *delim_ptr;
 
         delim_ptr = memchr(uniq, '=', uniq_len);
-        value = PyBytes_FromStringAndSize(delim_ptr + 1, (const char*) uniq + uniq_len - (delim_ptr + 1));
+        value = PyBytes_FromStringAndSize(
+            delim_ptr + 1,
+            (const char*) uniq + uniq_len - (delim_ptr + 1));
         PySet_Add(value_set, value);
         Py_DECREF(value);
     }
@@ -495,11 +623,11 @@ static PyObject* Journal_query_unique(Journal *self, PyObject *args)
 }
 
 PyDoc_STRVAR(data_threshold__doc__,
-             "Threshold for field size truncation.\n\n"
+             "Threshold for field size truncation in bytes.\n\n"
              "Fields longer than this will be truncated to the threshold size.\n"
              "Defaults to 64Kb.");
 
-static PyObject* Journal_get_data_threshold(Journal *self, void *closure)
+static PyObject* Reader_get_data_threshold(Reader *self, void *closure)
 {
     size_t cvalue;
     int r;
@@ -511,11 +639,11 @@ static PyObject* Journal_get_data_threshold(Journal *self, void *closure)
     return long_FromSize_t(cvalue);
 }
 
-static int Journal_set_data_threshold(Journal *self, PyObject *value, void *closure)
+static int Reader_set_data_threshold(Reader *self, PyObject *value, void *closure)
 {
     int r;
     if (value == NULL) {
-        PyErr_SetString(PyExc_TypeError, "Cannot delete data threshold");
+        PyErr_SetString(PyExc_AttributeError, "Cannot delete data threshold");
         return -1;
     }
     if (!long_Check(value)){
@@ -526,80 +654,73 @@ static int Journal_set_data_threshold(Journal *self, PyObject *value, void *clos
     return set_error(r, NULL, NULL);
 }
 
-static PyGetSetDef Journal_getseters[] = {
+static PyGetSetDef Reader_getseters[] = {
     {(char*) "data_threshold",
-     (getter)Journal_get_data_threshold,
-     (setter)Journal_set_data_threshold,
+     (getter) Reader_get_data_threshold,
+     (setter) Reader_set_data_threshold,
      (char*) data_threshold__doc__,
      NULL},
     {NULL}
 };
 
-static PyMethodDef Journal_methods[] = {
-    {"get_next", (PyCFunction)Journal_get_next, METH_VARARGS,
-    Journal_get_next__doc__},
-    {"get_previous", (PyCFunction)Journal_get_previous, METH_VARARGS,
-    Journal_get_previous__doc__},
-    {"add_match", (PyCFunction)Journal_add_match, METH_VARARGS|METH_KEYWORDS,
-    Journal_add_match__doc__},
-    {"add_disjunction", (PyCFunction)Journal_add_disjunction, METH_NOARGS,
-    Journal_add_disjunction__doc__},
-    {"flush_matches", (PyCFunction)Journal_flush_matches, METH_NOARGS,
-    Journal_flush_matches__doc__},
-    {"seek", (PyCFunction)Journal_seek, METH_VARARGS | METH_KEYWORDS,
-    Journal_seek__doc__},
-    {"seek_realtime", (PyCFunction)Journal_seek_realtime, METH_VARARGS,
-    Journal_seek_realtime__doc__},
-    {"seek_monotonic", (PyCFunction)Journal_seek_monotonic, METH_VARARGS,
-    Journal_seek_monotonic__doc__},
-    {"wait", (PyCFunction)Journal_wait, METH_VARARGS,
-    Journal_wait__doc__},
-    {"seek_cursor", (PyCFunction)Journal_seek_cursor, METH_VARARGS,
-    Journal_seek_cursor__doc__},
-    {"query_unique", (PyCFunction)Journal_query_unique, METH_VARARGS,
-    Journal_query_unique__doc__},
+static PyMethodDef Reader_methods[] = {
+    {"fileno",          (PyCFunction) Reader_fileno, METH_NOARGS, Reader_fileno__doc__},
+    {"reliable_fd",     (PyCFunction) Reader_reliable_fd, METH_NOARGS, Reader_reliable_fd__doc__},
+    {"close",           (PyCFunction) Reader_close, METH_NOARGS, Reader_close__doc__},
+    {"get_next",        (PyCFunction) Reader_get_next, METH_VARARGS, Reader_get_next__doc__},
+    {"get_previous",    (PyCFunction) Reader_get_previous, METH_VARARGS, Reader_get_previous__doc__},
+    {"add_match",       (PyCFunction) Reader_add_match, METH_VARARGS|METH_KEYWORDS, Reader_add_match__doc__},
+    {"add_disjunction", (PyCFunction) Reader_add_disjunction, METH_NOARGS, Reader_add_disjunction__doc__},
+    {"flush_matches",   (PyCFunction) Reader_flush_matches, METH_NOARGS, Reader_flush_matches__doc__},
+    {"seek_head",       (PyCFunction) Reader_seek_head, METH_NOARGS, Reader_seek_head__doc__},
+    {"seek_tail",       (PyCFunction) Reader_seek_tail, METH_NOARGS, Reader_seek_tail__doc__},
+    {"seek_realtime",   (PyCFunction) Reader_seek_realtime, METH_VARARGS, Reader_seek_realtime__doc__},
+    {"seek_monotonic",  (PyCFunction) Reader_seek_monotonic, METH_VARARGS, Reader_seek_monotonic__doc__},
+    {"wait",            (PyCFunction) Reader_wait, METH_VARARGS, Reader_wait__doc__},
+    {"seek_cursor",     (PyCFunction) Reader_seek_cursor, METH_VARARGS, Reader_seek_cursor__doc__},
+    {"query_unique",    (PyCFunction) Reader_query_unique, METH_VARARGS, Reader_query_unique__doc__},
     {NULL}  /* Sentinel */
 };
 
-static PyTypeObject JournalType = {
+static PyTypeObject ReaderType = {
     PyVarObject_HEAD_INIT(NULL, 0)
-    "_reader._Journal",               /*tp_name*/
-    sizeof(Journal),                  /*tp_basicsize*/
-    0,                                /*tp_itemsize*/
-    (destructor)Journal_dealloc,      /*tp_dealloc*/
-    0,                                /*tp_print*/
-    0,                                /*tp_getattr*/
-    0,                                /*tp_setattr*/
-    0,                                /*tp_compare*/
-    0,                                /*tp_repr*/
-    0,                                /*tp_as_number*/
-    0,                                /*tp_as_sequence*/
-    0,                                /*tp_as_mapping*/
-    0,                                /*tp_hash */
-    0,                                /*tp_call*/
-    0,                                /*tp_str*/
-    0,                                /*tp_getattro*/
-    0,                                /*tp_setattro*/
-    0,                                /*tp_as_buffer*/
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,/*tp_flags*/
-    Journal__doc__,                   /* tp_doc */
-    0,                                /* tp_traverse */
-    0,                                /* tp_clear */
-    0,                                /* tp_richcompare */
-    0,                                /* tp_weaklistoffset */
-    Journal_iter,                     /* tp_iter */
-    Journal_iternext,                 /* tp_iternext */
-    Journal_methods,                  /* tp_methods */
-    0,                                /* tp_members */
-    Journal_getseters,                /* tp_getset */
-    0,                                /* tp_base */
-    0,                                /* tp_dict */
-    0,                                /* tp_descr_get */
-    0,                                /* tp_descr_set */
-    0,                                /* tp_dictoffset */
-    (initproc)Journal_init,           /* tp_init */
-    0,                                /* tp_alloc */
-    PyType_GenericNew,                /* tp_new */
+    "_reader._Reader",                        /*tp_name*/
+    sizeof(Reader),                           /*tp_basicsize*/
+    0,                                        /*tp_itemsize*/
+    (destructor)Reader_dealloc,               /*tp_dealloc*/
+    0,                                        /*tp_print*/
+    0,                                        /*tp_getattr*/
+    0,                                        /*tp_setattr*/
+    0,                                        /*tp_compare*/
+    0,                                        /*tp_repr*/
+    0,                                        /*tp_as_number*/
+    0,                                        /*tp_as_sequence*/
+    0,                                        /*tp_as_mapping*/
+    0,                                        /*tp_hash */
+    0,                                        /*tp_call*/
+    0,                                        /*tp_str*/
+    0,                                        /*tp_getattro*/
+    0,                                        /*tp_setattro*/
+    0,                                        /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    Reader__doc__,                            /* tp_doc */
+    0,                                        /* tp_traverse */
+    0,                                        /* tp_clear */
+    0,                                        /* tp_richcompare */
+    0,                                        /* tp_weaklistoffset */
+    Reader_iter,                              /* tp_iter */
+    Reader_iternext,                          /* tp_iternext */
+    Reader_methods,                           /* tp_methods */
+    0,                                        /* tp_members */
+    Reader_getseters,                         /* tp_getset */
+    0,                                        /* tp_base */
+    0,                                        /* tp_dict */
+    0,                                        /* tp_descr_get */
+    0,                                        /* tp_descr_set */
+    0,                                        /* tp_dictoffset */
+    (initproc) Reader_init,                   /* tp_init */
+    0,                                        /* tp_alloc */
+    PyType_GenericNew,                        /* tp_new */
 };
 
 #define SUMMARY \
@@ -615,6 +736,10 @@ static PyModuleDef _reader_module = {
 };
 #endif
 
+#if PY_MAJOR_VERSION >= 3
+static bool initialized = false;
+#endif
+
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wmissing-prototypes"
 
@@ -629,7 +754,7 @@ init_reader(void)
 
     PyDateTime_IMPORT;
 
-    if (PyType_Ready(&JournalType) < 0)
+    if (PyType_Ready(&ReaderType) < 0)
 #if PY_MAJOR_VERSION >= 3
         return NULL;
 #else
@@ -640,20 +765,36 @@ init_reader(void)
     m = PyModule_Create(&_reader_module);
     if (m == NULL)
         return NULL;
+
+    if (!initialized) {
+        PyStructSequence_InitType(&MonotonicType, &Monotonic_desc);
+        initialized = true;
+    }
 #else
     m = Py_InitModule3("_reader", NULL, SUMMARY);
     if (m == NULL)
         return;
 #endif
 
-    Py_INCREF(&JournalType);
-    PyModule_AddObject(m, "_Journal", (PyObject *)&JournalType);
-    PyModule_AddIntConstant(m, "NOP", SD_JOURNAL_NOP);
-    PyModule_AddIntConstant(m, "APPEND", SD_JOURNAL_APPEND);
-    PyModule_AddIntConstant(m, "INVALIDATE", SD_JOURNAL_INVALIDATE);
-    PyModule_AddIntConstant(m, "LOCAL_ONLY", SD_JOURNAL_LOCAL_ONLY);
-    PyModule_AddIntConstant(m, "RUNTIME_ONLY", SD_JOURNAL_RUNTIME_ONLY);
-    PyModule_AddIntConstant(m, "SYSTEM_ONLY", SD_JOURNAL_SYSTEM_ONLY);
+    Py_INCREF(&ReaderType);
+#if PY_MAJOR_VERSION >= 3
+    Py_INCREF(&MonotonicType);
+#endif
+    if (PyModule_AddObject(m, "_Reader", (PyObject *) &ReaderType) ||
+#if PY_MAJOR_VERSION >= 3
+        PyModule_AddObject(m, "Monotonic", (PyObject*) &MonotonicType) ||
+#endif
+        PyModule_AddIntConstant(m, "NOP", SD_JOURNAL_NOP) ||
+        PyModule_AddIntConstant(m, "APPEND", SD_JOURNAL_APPEND) ||
+        PyModule_AddIntConstant(m, "INVALIDATE", SD_JOURNAL_INVALIDATE) ||
+        PyModule_AddIntConstant(m, "LOCAL_ONLY", SD_JOURNAL_LOCAL_ONLY) ||
+        PyModule_AddIntConstant(m, "RUNTIME_ONLY", SD_JOURNAL_RUNTIME_ONLY) ||
+        PyModule_AddIntConstant(m, "SYSTEM_ONLY", SD_JOURNAL_SYSTEM_ONLY)) {
+#if PY_MAJOR_VERSION >= 3
+        Py_DECREF(m);
+        return NULL;
+#endif
+    }
 
 #if PY_MAJOR_VERSION >= 3
     return m;