view mercurial/cext/parsers.c @ 47965:f9e6f2bb721d

rhg: Don’t compare ambiguous files one byte at a time

Even though the use of `BufReader` reduces the number of syscalls to read
the file from disk, `.bytes()` yields a separate `Result` for every byte.
Creating those results and dispatching on them is most likely costly.

Instead, this commit opts for simplicity by reading the entire file into memory
and comparing a single pair of byte strings. Note that memory already needs to
contain the entire previous contents of the file, as read from the filelog.
So with an extremely large file this doubles memory use but does not make it
grow by orders of magnitude.

At first I wrote code that still avoids reading the entire file into memory
and compares one buffer at a time with `BufReader`. Find this code below for
posterity. However its correctness is subtle. I ended up preferring the
simplicity of the obviously-correct single comparison.

```rust
let mut reader = BufReader::new(fobj);
let mut expected = &contents_in_p1[..];
loop {
    let buf = reader.fill_buf().when_reading_file(&fs_path)?;
    if buf.is_empty() {
        // Found EOF
        return Ok(expected.is_empty());
    } else if let Some(rest) = expected.drop_prefix(buf) {
        // What we read so far matches the expected content, continue reading
        let buf_len = buf.len();
        reader.consume(buf_len);
        expected = rest
    } else {
        // Found different content
        return Ok(false);
    }
}
```

Differential Revision: https://phab.mercurial-scm.org/D11412

/*
 parsers.c - efficient content parsing

 Copyright 2008 Olivia Mackall <[e-mail]> and others

 This software may be used and distributed according to the terms of
 the GNU General Public License, incorporated herein by reference.
*/

#define PY_SSIZE_T_CLEAN
#include <Python.h>
#include <ctype.h>
#include <stddef.h>
#include <string.h>

#include "bitmanipulation.h"
#include "charencode.h"
#include "util.h"

#ifdef IS_PY3K
/* The mapping of Python types is meant to be temporary to get Python
 * 3 to compile. We should remove this once Python 3 support is fully
 * supported and proper types are used in the extensions themselves. */
#define PyInt_Check PyLong_Check
#define PyInt_FromLong PyLong_FromLong
#define PyInt_FromSsize_t PyLong_FromSsize_t
#define PyInt_AsLong PyLong_AsLong
#endif

static const char *const versionerrortext = "Python minor version mismatch";

static const int dirstate_v1_from_p2 = -2;
static const int dirstate_v1_nonnormal = -1;
static const int ambiguous_time = -1;

static PyObject *dict_new_presized(PyObject *self, PyObject *args)
{
	Py_ssize_t expected_size;

	if (!PyArg_ParseTuple(args, "n:make_presized_dict", &expected_size)) {
		return NULL;
	}

	return _dict_new_presized(expected_size);
}

static PyObject *dirstate_item_new(PyTypeObject *subtype, PyObject *args,
                                   PyObject *kwds)
{
	/* We do all the initialization here and not a tp_init function because
	 * dirstate_item is immutable. */
	dirstateItemObject *t;
	int wc_tracked;
	int p1_tracked;
	int p2_tracked;
	int merged;
	int clean_p1;
	int clean_p2;
	int possibly_dirty;
	PyObject *parentfiledata;
	static char *keywords_name[] = {
	    "wc_tracked",     "p1_tracked",     "p2_tracked",
	    "merged",         "clean_p1",       "clean_p2",
	    "possibly_dirty", "parentfiledata", NULL,
	};
	wc_tracked = 0;
	p1_tracked = 0;
	p2_tracked = 0;
	merged = 0;
	clean_p1 = 0;
	clean_p2 = 0;
	possibly_dirty = 0;
	parentfiledata = Py_None;
	if (!PyArg_ParseTupleAndKeywords(args, kwds, "iiiiiiiO", keywords_name,
	                                 &wc_tracked, &p1_tracked, &p2_tracked,
	                                 &merged, &clean_p1, &clean_p2,
	                                 &possibly_dirty, &parentfiledata

	                                 )) {
		return NULL;
	}
	if (merged && (clean_p1 || clean_p2)) {
		PyErr_SetString(PyExc_RuntimeError,
		                "`merged` argument incompatible with "
		                "`clean_p1`/`clean_p2`");
		return NULL;
	}
	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}

	t->flags = 0;
	if (wc_tracked) {
		t->flags |= dirstate_flag_wc_tracked;
	}
	if (p1_tracked) {
		t->flags |= dirstate_flag_p1_tracked;
	}
	if (p2_tracked) {
		t->flags |= dirstate_flag_p2_tracked;
	}
	if (possibly_dirty) {
		t->flags |= dirstate_flag_possibly_dirty;
	}
	if (merged) {
		t->flags |= dirstate_flag_merged;
	}
	if (clean_p1) {
		t->flags |= dirstate_flag_clean_p1;
	}
	if (clean_p2) {
		t->flags |= dirstate_flag_clean_p2;
	}
	t->mode = 0;
	t->size = dirstate_v1_nonnormal;
	t->mtime = ambiguous_time;
	if (parentfiledata != Py_None) {
		if (!PyTuple_CheckExact(parentfiledata)) {
			PyErr_SetString(
			    PyExc_TypeError,
			    "parentfiledata should be a Tuple or None");
			return NULL;
		}
		t->mode =
		    (int)PyLong_AsLong(PyTuple_GetItem(parentfiledata, 0));
		t->size =
		    (int)PyLong_AsLong(PyTuple_GetItem(parentfiledata, 1));
		t->mtime =
		    (int)PyLong_AsLong(PyTuple_GetItem(parentfiledata, 2));
	}
	return (PyObject *)t;
}

static void dirstate_item_dealloc(PyObject *o)
{
	PyObject_Del(o);
}

static inline bool dirstate_item_c_tracked(dirstateItemObject *self)
{
	return (self->flags & dirstate_flag_wc_tracked);
}

static inline bool dirstate_item_c_added(dirstateItemObject *self)
{
	char mask = (dirstate_flag_wc_tracked | dirstate_flag_p1_tracked |
	             dirstate_flag_p2_tracked);
	char target = dirstate_flag_wc_tracked;
	return (self->flags & mask) == target;
}

static inline bool dirstate_item_c_removed(dirstateItemObject *self)
{
	if (self->flags & dirstate_flag_wc_tracked) {
		return false;
	}
	return (self->flags &
	        (dirstate_flag_p1_tracked | dirstate_flag_p2_tracked));
}

static inline bool dirstate_item_c_merged(dirstateItemObject *self)
{
	return ((self->flags & dirstate_flag_wc_tracked) &&
	        (self->flags & dirstate_flag_merged));
}

static inline bool dirstate_item_c_merged_removed(dirstateItemObject *self)
{
	if (!dirstate_item_c_removed(self)) {
		return false;
	}
	return (self->flags & dirstate_flag_merged);
}

static inline bool dirstate_item_c_from_p2(dirstateItemObject *self)
{
	if (!dirstate_item_c_tracked(self)) {
		return false;
	}
	return (self->flags & dirstate_flag_clean_p2);
}

static inline bool dirstate_item_c_from_p2_removed(dirstateItemObject *self)
{
	if (!dirstate_item_c_removed(self)) {
		return false;
	}
	return (self->flags & dirstate_flag_clean_p2);
}

static inline char dirstate_item_c_v1_state(dirstateItemObject *self)
{
	if (self->flags & dirstate_flag_rust_special) {
		return ' ';
	} else if (dirstate_item_c_removed(self)) {
		return 'r';
	} else if (dirstate_item_c_merged(self)) {
		return 'm';
	} else if (dirstate_item_c_added(self)) {
		return 'a';
	} else {
		return 'n';
	}
}

static inline int dirstate_item_c_v1_mode(dirstateItemObject *self)
{
	return self->mode;
}

static inline int dirstate_item_c_v1_size(dirstateItemObject *self)
{
	if (self->flags & dirstate_flag_rust_special) {
		return self->size;
	} else if (dirstate_item_c_merged_removed(self)) {
		return dirstate_v1_nonnormal;
	} else if (dirstate_item_c_from_p2_removed(self)) {
		return dirstate_v1_from_p2;
	} else if (dirstate_item_c_removed(self)) {
		return 0;
	} else if (dirstate_item_c_merged(self)) {
		return dirstate_v1_from_p2;
	} else if (dirstate_item_c_added(self)) {
		return dirstate_v1_nonnormal;
	} else if (dirstate_item_c_from_p2(self)) {
		return dirstate_v1_from_p2;
	} else if (self->flags & dirstate_flag_possibly_dirty) {
		return self->size; /* NON NORMAL ? */
	} else {
		return self->size;
	}
}

static inline int dirstate_item_c_v1_mtime(dirstateItemObject *self)
{
	if (self->flags & dirstate_flag_rust_special) {
		return self->mtime;
	} else if (dirstate_item_c_removed(self)) {
		return 0;
	} else if (self->flags & dirstate_flag_possibly_dirty) {
		return ambiguous_time;
	} else if (dirstate_item_c_merged(self)) {
		return ambiguous_time;
	} else if (dirstate_item_c_added(self)) {
		return ambiguous_time;
	} else if (dirstate_item_c_from_p2(self)) {
		return ambiguous_time;
	} else {
		return self->mtime;
	}
}

static PyObject *dirstate_item_v1_state(dirstateItemObject *self)
{
	char state = dirstate_item_c_v1_state(self);
	return PyBytes_FromStringAndSize(&state, 1);
};

static PyObject *dirstate_item_v1_mode(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_mode(self));
};

static PyObject *dirstate_item_v1_size(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_size(self));
};

static PyObject *dirstate_item_v1_mtime(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_mtime(self));
};

static PyObject *dirstate_item_need_delay(dirstateItemObject *self,
                                          PyObject *value)
{
	long now;
	if (!pylong_to_long(value, &now)) {
		return NULL;
	}
	if (dirstate_item_c_v1_state(self) == 'n' &&
	    dirstate_item_c_v1_mtime(self) == now) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

/* This will never change since it's bound to V1
 */
static inline dirstateItemObject *
dirstate_item_from_v1_data(char state, int mode, int size, int mtime)
{
	dirstateItemObject *t =
	    PyObject_New(dirstateItemObject, &dirstateItemType);
	if (!t) {
		return NULL;
	}

	if (state == 'm') {
		t->flags =
		    (dirstate_flag_wc_tracked | dirstate_flag_p1_tracked |
		     dirstate_flag_p2_tracked | dirstate_flag_merged);
		t->mode = 0;
		t->size = dirstate_v1_from_p2;
		t->mtime = ambiguous_time;
	} else if (state == 'a') {
		t->flags = dirstate_flag_wc_tracked;
		t->mode = 0;
		t->size = dirstate_v1_nonnormal;
		t->mtime = ambiguous_time;
	} else if (state == 'r') {
		t->mode = 0;
		t->size = 0;
		t->mtime = 0;
		if (size == dirstate_v1_nonnormal) {
			t->flags =
			    (dirstate_flag_p1_tracked |
			     dirstate_flag_p2_tracked | dirstate_flag_merged);
		} else if (size == dirstate_v1_from_p2) {
			t->flags =
			    (dirstate_flag_p2_tracked | dirstate_flag_clean_p2);
		} else {
			t->flags = dirstate_flag_p1_tracked;
		}
	} else if (state == 'n') {
		if (size == dirstate_v1_from_p2) {
			t->flags =
			    (dirstate_flag_wc_tracked |
			     dirstate_flag_p2_tracked | dirstate_flag_clean_p2);
			t->mode = 0;
			t->size = dirstate_v1_from_p2;
			t->mtime = ambiguous_time;
		} else if (size == dirstate_v1_nonnormal) {
			t->flags = (dirstate_flag_wc_tracked |
			            dirstate_flag_p1_tracked |
			            dirstate_flag_possibly_dirty);
			t->mode = 0;
			t->size = dirstate_v1_nonnormal;
			t->mtime = ambiguous_time;
		} else if (mtime == ambiguous_time) {
			t->flags = (dirstate_flag_wc_tracked |
			            dirstate_flag_p1_tracked |
			            dirstate_flag_possibly_dirty);
			t->mode = mode;
			t->size = size;
			t->mtime = 0;
		} else {
			t->flags = (dirstate_flag_wc_tracked |
			            dirstate_flag_p1_tracked);
			t->mode = mode;
			t->size = size;
			t->mtime = mtime;
		}
	} else if (state == ' ') {
		/* XXX Rust is using this special case, it should be clean up
		 * later. */
		t->flags = dirstate_flag_rust_special;
		t->mode = mode;
		t->size = size;
		t->mtime = mtime;
	} else {
		PyErr_Format(PyExc_RuntimeError,
		             "unknown state: `%c` (%d, %d, %d)", state, mode,
		             size, mtime, NULL);
		return NULL;
	}

	return t;
}

/* This will never change since it's bound to V1, unlike `dirstate_item_new` */
static PyObject *dirstate_item_from_v1_meth(PyTypeObject *subtype,
                                            PyObject *args)
{
	/* We do all the initialization here and not a tp_init function because
	 * dirstate_item is immutable. */
	char state;
	int size, mode, mtime;
	if (!PyArg_ParseTuple(args, "ciii", &state, &mode, &size, &mtime)) {
		return NULL;
	}
	return (PyObject *)dirstate_item_from_v1_data(state, mode, size, mtime);
};

/* constructor to help legacy API to build a new "added" item

Should eventually be removed */
static PyObject *dirstate_item_new_added(PyTypeObject *subtype)
{
	dirstateItemObject *t;
	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}
	t->flags = dirstate_flag_wc_tracked;
	t->mode = 0;
	t->size = dirstate_v1_nonnormal;
	t->mtime = ambiguous_time;
	return (PyObject *)t;
};

/* constructor to help legacy API to build a new "merged" item

Should eventually be removed */
static PyObject *dirstate_item_new_merged(PyTypeObject *subtype)
{
	dirstateItemObject *t;
	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}
	t->flags = (dirstate_flag_wc_tracked | dirstate_flag_p1_tracked |
	            dirstate_flag_p2_tracked | dirstate_flag_merged);
	t->mode = 0;
	t->size = dirstate_v1_from_p2;
	t->mtime = ambiguous_time;
	return (PyObject *)t;
};

/* constructor to help legacy API to build a new "from_p2" item

Should eventually be removed */
static PyObject *dirstate_item_new_from_p2(PyTypeObject *subtype)
{
	/* We do all the initialization here and not a tp_init function because
	 * dirstate_item is immutable. */
	dirstateItemObject *t;
	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}
	t->flags = (dirstate_flag_wc_tracked | dirstate_flag_p2_tracked |
	            dirstate_flag_clean_p2);
	t->mode = 0;
	t->size = dirstate_v1_from_p2;
	t->mtime = ambiguous_time;
	return (PyObject *)t;
};

/* constructor to help legacy API to build a new "possibly" item

Should eventually be removed */
static PyObject *dirstate_item_new_possibly_dirty(PyTypeObject *subtype)
{
	/* We do all the initialization here and not a tp_init function because
	 * dirstate_item is immutable. */
	dirstateItemObject *t;
	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}
	t->flags = (dirstate_flag_wc_tracked | dirstate_flag_p1_tracked |
	            dirstate_flag_possibly_dirty);
	t->mode = 0;
	t->size = dirstate_v1_nonnormal;
	t->mtime = ambiguous_time;
	return (PyObject *)t;
};

/* constructor to help legacy API to build a new "normal" item

Should eventually be removed */
static PyObject *dirstate_item_new_normal(PyTypeObject *subtype, PyObject *args)
{
	/* We do all the initialization here and not a tp_init function because
	 * dirstate_item is immutable. */
	dirstateItemObject *t;
	int size, mode, mtime;
	if (!PyArg_ParseTuple(args, "iii", &mode, &size, &mtime)) {
		return NULL;
	}

	t = (dirstateItemObject *)subtype->tp_alloc(subtype, 1);
	if (!t) {
		return NULL;
	}
	t->flags = (dirstate_flag_wc_tracked | dirstate_flag_p1_tracked);
	t->mode = mode;
	t->size = size;
	t->mtime = mtime;
	return (PyObject *)t;
};

/* This means the next status call will have to actually check its content
   to make sure it is correct. */
static PyObject *dirstate_item_set_possibly_dirty(dirstateItemObject *self)
{
	if (self->flags |= dirstate_flag_possibly_dirty) {
		Py_RETURN_NONE;
	}
}

static PyObject *dirstate_item_set_untracked(dirstateItemObject *self)
{
	self->flags &= ~dirstate_flag_wc_tracked;
	self->mode = 0;
	self->mtime = 0;
	self->size = 0;
	Py_RETURN_NONE;
}

static PyMethodDef dirstate_item_methods[] = {
    {"v1_state", (PyCFunction)dirstate_item_v1_state, METH_NOARGS,
     "return a \"state\" suitable for v1 serialization"},
    {"v1_mode", (PyCFunction)dirstate_item_v1_mode, METH_NOARGS,
     "return a \"mode\" suitable for v1 serialization"},
    {"v1_size", (PyCFunction)dirstate_item_v1_size, METH_NOARGS,
     "return a \"size\" suitable for v1 serialization"},
    {"v1_mtime", (PyCFunction)dirstate_item_v1_mtime, METH_NOARGS,
     "return a \"mtime\" suitable for v1 serialization"},
    {"need_delay", (PyCFunction)dirstate_item_need_delay, METH_O,
     "True if the stored mtime would be ambiguous with the current time"},
    {"from_v1_data", (PyCFunction)dirstate_item_from_v1_meth,
     METH_VARARGS | METH_CLASS, "build a new DirstateItem object from V1 data"},
    {"new_added", (PyCFunction)dirstate_item_new_added,
     METH_NOARGS | METH_CLASS,
     "constructor to help legacy API to build a new \"added\" item"},
    {"new_merged", (PyCFunction)dirstate_item_new_merged,
     METH_NOARGS | METH_CLASS,
     "constructor to help legacy API to build a new \"merged\" item"},
    {"new_from_p2", (PyCFunction)dirstate_item_new_from_p2,
     METH_NOARGS | METH_CLASS,
     "constructor to help legacy API to build a new \"from_p2\" item"},
    {"new_possibly_dirty", (PyCFunction)dirstate_item_new_possibly_dirty,
     METH_NOARGS | METH_CLASS,
     "constructor to help legacy API to build a new \"possibly_dirty\" item"},
    {"new_normal", (PyCFunction)dirstate_item_new_normal,
     METH_VARARGS | METH_CLASS,
     "constructor to help legacy API to build a new \"normal\" item"},
    {"set_possibly_dirty", (PyCFunction)dirstate_item_set_possibly_dirty,
     METH_NOARGS, "mark a file as \"possibly dirty\""},
    {"set_untracked", (PyCFunction)dirstate_item_set_untracked, METH_NOARGS,
     "mark a file as \"untracked\""},
    {NULL} /* Sentinel */
};

static PyObject *dirstate_item_get_mode(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_mode(self));
};

static PyObject *dirstate_item_get_size(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_size(self));
};

static PyObject *dirstate_item_get_mtime(dirstateItemObject *self)
{
	return PyInt_FromLong(dirstate_item_c_v1_mtime(self));
};

static PyObject *dirstate_item_get_state(dirstateItemObject *self)
{
	char state = dirstate_item_c_v1_state(self);
	return PyBytes_FromStringAndSize(&state, 1);
};

static PyObject *dirstate_item_get_tracked(dirstateItemObject *self)
{
	if (dirstate_item_c_tracked(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_added(dirstateItemObject *self)
{
	if (dirstate_item_c_added(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_merged(dirstateItemObject *self)
{
	if (dirstate_item_c_merged(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_merged_removed(dirstateItemObject *self)
{
	if (dirstate_item_c_merged_removed(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_from_p2(dirstateItemObject *self)
{
	if (dirstate_item_c_from_p2(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_from_p2_removed(dirstateItemObject *self)
{
	if (dirstate_item_c_from_p2_removed(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dirstate_item_get_removed(dirstateItemObject *self)
{
	if (dirstate_item_c_removed(self)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyObject *dm_nonnormal(dirstateItemObject *self)
{
	if ((dirstate_item_c_v1_state(self) != 'n') ||
	    (dirstate_item_c_v1_mtime(self) == ambiguous_time)) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};
static PyObject *dm_otherparent(dirstateItemObject *self)
{
	if (dirstate_item_c_v1_mtime(self) == dirstate_v1_from_p2) {
		Py_RETURN_TRUE;
	} else {
		Py_RETURN_FALSE;
	}
};

static PyGetSetDef dirstate_item_getset[] = {
    {"mode", (getter)dirstate_item_get_mode, NULL, "mode", NULL},
    {"size", (getter)dirstate_item_get_size, NULL, "size", NULL},
    {"mtime", (getter)dirstate_item_get_mtime, NULL, "mtime", NULL},
    {"state", (getter)dirstate_item_get_state, NULL, "state", NULL},
    {"tracked", (getter)dirstate_item_get_tracked, NULL, "tracked", NULL},
    {"added", (getter)dirstate_item_get_added, NULL, "added", NULL},
    {"merged_removed", (getter)dirstate_item_get_merged_removed, NULL,
     "merged_removed", NULL},
    {"merged", (getter)dirstate_item_get_merged, NULL, "merged", NULL},
    {"from_p2_removed", (getter)dirstate_item_get_from_p2_removed, NULL,
     "from_p2_removed", NULL},
    {"from_p2", (getter)dirstate_item_get_from_p2, NULL, "from_p2", NULL},
    {"removed", (getter)dirstate_item_get_removed, NULL, "removed", NULL},
    {"dm_nonnormal", (getter)dm_nonnormal, NULL, "dm_nonnormal", NULL},
    {"dm_otherparent", (getter)dm_otherparent, NULL, "dm_otherparent", NULL},
    {NULL} /* Sentinel */
};

PyTypeObject dirstateItemType = {
    PyVarObject_HEAD_INIT(NULL, 0)     /* header */
    "dirstate_tuple",                  /* tp_name */
    sizeof(dirstateItemObject),        /* tp_basicsize */
    0,                                 /* tp_itemsize */
    (destructor)dirstate_item_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,                /* tp_flags */
    "dirstate tuple",                  /* tp_doc */
    0,                                 /* tp_traverse */
    0,                                 /* tp_clear */
    0,                                 /* tp_richcompare */
    0,                                 /* tp_weaklistoffset */
    0,                                 /* tp_iter */
    0,                                 /* tp_iternext */
    dirstate_item_methods,             /* tp_methods */
    0,                                 /* tp_members */
    dirstate_item_getset,              /* tp_getset */
    0,                                 /* tp_base */
    0,                                 /* tp_dict */
    0,                                 /* tp_descr_get */
    0,                                 /* tp_descr_set */
    0,                                 /* tp_dictoffset */
    0,                                 /* tp_init */
    0,                                 /* tp_alloc */
    dirstate_item_new,                 /* tp_new */
};

static PyObject *parse_dirstate(PyObject *self, PyObject *args)
{
	PyObject *dmap, *cmap, *parents = NULL, *ret = NULL;
	PyObject *fname = NULL, *cname = NULL, *entry = NULL;
	char state, *cur, *str, *cpos;
	int mode, size, mtime;
	unsigned int flen, pos = 40;
	Py_ssize_t len = 40;
	Py_ssize_t readlen;

	if (!PyArg_ParseTuple(
	        args, PY23("O!O!s#:parse_dirstate", "O!O!y#:parse_dirstate"),
	        &PyDict_Type, &dmap, &PyDict_Type, &cmap, &str, &readlen)) {
		goto quit;
	}

	len = readlen;

	/* read parents */
	if (len < 40) {
		PyErr_SetString(PyExc_ValueError,
		                "too little data for parents");
		goto quit;
	}

	parents = Py_BuildValue(PY23("s#s#", "y#y#"), str, (Py_ssize_t)20,
	                        str + 20, (Py_ssize_t)20);
	if (!parents) {
		goto quit;
	}

	/* read filenames */
	while (pos >= 40 && pos < len) {
		if (pos + 17 > len) {
			PyErr_SetString(PyExc_ValueError,
			                "overflow in dirstate");
			goto quit;
		}
		cur = str + pos;
		/* unpack header */
		state = *cur;
		mode = getbe32(cur + 1);
		size = getbe32(cur + 5);
		mtime = getbe32(cur + 9);
		flen = getbe32(cur + 13);
		pos += 17;
		cur += 17;
		if (flen > len - pos) {
			PyErr_SetString(PyExc_ValueError,
			                "overflow in dirstate");
			goto quit;
		}

		entry = (PyObject *)dirstate_item_from_v1_data(state, mode,
		                                               size, mtime);
		cpos = memchr(cur, 0, flen);
		if (cpos) {
			fname = PyBytes_FromStringAndSize(cur, cpos - cur);
			cname = PyBytes_FromStringAndSize(
			    cpos + 1, flen - (cpos - cur) - 1);
			if (!fname || !cname ||
			    PyDict_SetItem(cmap, fname, cname) == -1 ||
			    PyDict_SetItem(dmap, fname, entry) == -1) {
				goto quit;
			}
			Py_DECREF(cname);
		} else {
			fname = PyBytes_FromStringAndSize(cur, flen);
			if (!fname ||
			    PyDict_SetItem(dmap, fname, entry) == -1) {
				goto quit;
			}
		}
		Py_DECREF(fname);
		Py_DECREF(entry);
		fname = cname = entry = NULL;
		pos += flen;
	}

	ret = parents;
	Py_INCREF(ret);
quit:
	Py_XDECREF(fname);
	Py_XDECREF(cname);
	Py_XDECREF(entry);
	Py_XDECREF(parents);
	return ret;
}

/*
 * Build a set of non-normal and other parent entries from the dirstate dmap
 */
static PyObject *nonnormalotherparententries(PyObject *self, PyObject *args)
{
	PyObject *dmap, *fname, *v;
	PyObject *nonnset = NULL, *otherpset = NULL, *result = NULL;
	Py_ssize_t pos;

	if (!PyArg_ParseTuple(args, "O!:nonnormalentries", &PyDict_Type,
	                      &dmap)) {
		goto bail;
	}

	nonnset = PySet_New(NULL);
	if (nonnset == NULL) {
		goto bail;
	}

	otherpset = PySet_New(NULL);
	if (otherpset == NULL) {
		goto bail;
	}

	pos = 0;
	while (PyDict_Next(dmap, &pos, &fname, &v)) {
		dirstateItemObject *t;
		if (!dirstate_tuple_check(v)) {
			PyErr_SetString(PyExc_TypeError,
			                "expected a dirstate tuple");
			goto bail;
		}
		t = (dirstateItemObject *)v;

		if (dirstate_item_c_from_p2(t)) {
			if (PySet_Add(otherpset, fname) == -1) {
				goto bail;
			}
		}
		if (!(t->flags & dirstate_flag_wc_tracked) ||
		    !(t->flags &
		      (dirstate_flag_p1_tracked | dirstate_flag_p2_tracked)) ||
		    (t->flags &
		     (dirstate_flag_possibly_dirty | dirstate_flag_merged))) {
			if (PySet_Add(nonnset, fname) == -1) {
				goto bail;
			}
		}
	}

	result = Py_BuildValue("(OO)", nonnset, otherpset);
	if (result == NULL) {
		goto bail;
	}
	Py_DECREF(nonnset);
	Py_DECREF(otherpset);
	return result;
bail:
	Py_XDECREF(nonnset);
	Py_XDECREF(otherpset);
	Py_XDECREF(result);
	return NULL;
}

/*
 * Efficiently pack a dirstate object into its on-disk format.
 */
static PyObject *pack_dirstate(PyObject *self, PyObject *args)
{
	PyObject *packobj = NULL;
	PyObject *map, *copymap, *pl, *mtime_unset = NULL;
	Py_ssize_t nbytes, pos, l;
	PyObject *k, *v = NULL, *pn;
	char *p, *s;
	int now;

	if (!PyArg_ParseTuple(args, "O!O!O!i:pack_dirstate", &PyDict_Type, &map,
	                      &PyDict_Type, &copymap, &PyTuple_Type, &pl,
	                      &now)) {
		return NULL;
	}

	if (PyTuple_Size(pl) != 2) {
		PyErr_SetString(PyExc_TypeError, "expected 2-element tuple");
		return NULL;
	}

	/* Figure out how much we need to allocate. */
	for (nbytes = 40, pos = 0; PyDict_Next(map, &pos, &k, &v);) {
		PyObject *c;
		if (!PyBytes_Check(k)) {
			PyErr_SetString(PyExc_TypeError, "expected string key");
			goto bail;
		}
		nbytes += PyBytes_GET_SIZE(k) + 17;
		c = PyDict_GetItem(copymap, k);
		if (c) {
			if (!PyBytes_Check(c)) {
				PyErr_SetString(PyExc_TypeError,
				                "expected string key");
				goto bail;
			}
			nbytes += PyBytes_GET_SIZE(c) + 1;
		}
	}

	packobj = PyBytes_FromStringAndSize(NULL, nbytes);
	if (packobj == NULL) {
		goto bail;
	}

	p = PyBytes_AS_STRING(packobj);

	pn = PyTuple_GET_ITEM(pl, 0);
	if (PyBytes_AsStringAndSize(pn, &s, &l) == -1 || l != 20) {
		PyErr_SetString(PyExc_TypeError, "expected a 20-byte hash");
		goto bail;
	}
	memcpy(p, s, l);
	p += 20;
	pn = PyTuple_GET_ITEM(pl, 1);
	if (PyBytes_AsStringAndSize(pn, &s, &l) == -1 || l != 20) {
		PyErr_SetString(PyExc_TypeError, "expected a 20-byte hash");
		goto bail;
	}
	memcpy(p, s, l);
	p += 20;

	for (pos = 0; PyDict_Next(map, &pos, &k, &v);) {
		dirstateItemObject *tuple;
		char state;
		int mode, size, mtime;
		Py_ssize_t len, l;
		PyObject *o;
		char *t;

		if (!dirstate_tuple_check(v)) {
			PyErr_SetString(PyExc_TypeError,
			                "expected a dirstate tuple");
			goto bail;
		}
		tuple = (dirstateItemObject *)v;

		state = dirstate_item_c_v1_state(tuple);
		mode = dirstate_item_c_v1_mode(tuple);
		size = dirstate_item_c_v1_size(tuple);
		mtime = dirstate_item_c_v1_mtime(tuple);
		if (state == 'n' && mtime == now) {
			/* See pure/parsers.py:pack_dirstate for why we do
			 * this. */
			mtime = -1;
			mtime_unset = (PyObject *)dirstate_item_from_v1_data(
			    state, mode, size, mtime);
			if (!mtime_unset) {
				goto bail;
			}
			if (PyDict_SetItem(map, k, mtime_unset) == -1) {
				goto bail;
			}
			Py_DECREF(mtime_unset);
			mtime_unset = NULL;
		}
		*p++ = state;
		putbe32((uint32_t)mode, p);
		putbe32((uint32_t)size, p + 4);
		putbe32((uint32_t)mtime, p + 8);
		t = p + 12;
		p += 16;
		len = PyBytes_GET_SIZE(k);
		memcpy(p, PyBytes_AS_STRING(k), len);
		p += len;
		o = PyDict_GetItem(copymap, k);
		if (o) {
			*p++ = '\0';
			l = PyBytes_GET_SIZE(o);
			memcpy(p, PyBytes_AS_STRING(o), l);
			p += l;
			len += l + 1;
		}
		putbe32((uint32_t)len, t);
	}

	pos = p - PyBytes_AS_STRING(packobj);
	if (pos != nbytes) {
		PyErr_Format(PyExc_SystemError, "bad dirstate size: %ld != %ld",
		             (long)pos, (long)nbytes);
		goto bail;
	}

	return packobj;
bail:
	Py_XDECREF(mtime_unset);
	Py_XDECREF(packobj);
	Py_XDECREF(v);
	return NULL;
}

#define BUMPED_FIX 1
#define USING_SHA_256 2
#define FM1_HEADER_SIZE (4 + 8 + 2 + 2 + 1 + 1 + 1)

static PyObject *readshas(const char *source, unsigned char num,
                          Py_ssize_t hashwidth)
{
	int i;
	PyObject *list = PyTuple_New(num);
	if (list == NULL) {
		return NULL;
	}
	for (i = 0; i < num; i++) {
		PyObject *hash = PyBytes_FromStringAndSize(source, hashwidth);
		if (hash == NULL) {
			Py_DECREF(list);
			return NULL;
		}
		PyTuple_SET_ITEM(list, i, hash);
		source += hashwidth;
	}
	return list;
}

static PyObject *fm1readmarker(const char *databegin, const char *dataend,
                               uint32_t *msize)
{
	const char *data = databegin;
	const char *meta;

	double mtime;
	int16_t tz;
	uint16_t flags;
	unsigned char nsuccs, nparents, nmetadata;
	Py_ssize_t hashwidth = 20;

	PyObject *prec = NULL, *parents = NULL, *succs = NULL;
	PyObject *metadata = NULL, *ret = NULL;
	int i;

	if (data + FM1_HEADER_SIZE > dataend) {
		goto overflow;
	}

	*msize = getbe32(data);
	data += 4;
	mtime = getbefloat64(data);
	data += 8;
	tz = getbeint16(data);
	data += 2;
	flags = getbeuint16(data);
	data += 2;

	if (flags & USING_SHA_256) {
		hashwidth = 32;
	}

	nsuccs = (unsigned char)(*data++);
	nparents = (unsigned char)(*data++);
	nmetadata = (unsigned char)(*data++);

	if (databegin + *msize > dataend) {
		goto overflow;
	}
	dataend = databegin + *msize; /* narrow down to marker size */

	if (data + hashwidth > dataend) {
		goto overflow;
	}
	prec = PyBytes_FromStringAndSize(data, hashwidth);
	data += hashwidth;
	if (prec == NULL) {
		goto bail;
	}

	if (data + nsuccs * hashwidth > dataend) {
		goto overflow;
	}
	succs = readshas(data, nsuccs, hashwidth);
	if (succs == NULL) {
		goto bail;
	}
	data += nsuccs * hashwidth;

	if (nparents == 1 || nparents == 2) {
		if (data + nparents * hashwidth > dataend) {
			goto overflow;
		}
		parents = readshas(data, nparents, hashwidth);
		if (parents == NULL) {
			goto bail;
		}
		data += nparents * hashwidth;
	} else {
		parents = Py_None;
		Py_INCREF(parents);
	}

	if (data + 2 * nmetadata > dataend) {
		goto overflow;
	}
	meta = data + (2 * nmetadata);
	metadata = PyTuple_New(nmetadata);
	if (metadata == NULL) {
		goto bail;
	}
	for (i = 0; i < nmetadata; i++) {
		PyObject *tmp, *left = NULL, *right = NULL;
		Py_ssize_t leftsize = (unsigned char)(*data++);
		Py_ssize_t rightsize = (unsigned char)(*data++);
		if (meta + leftsize + rightsize > dataend) {
			goto overflow;
		}
		left = PyBytes_FromStringAndSize(meta, leftsize);
		meta += leftsize;
		right = PyBytes_FromStringAndSize(meta, rightsize);
		meta += rightsize;
		tmp = PyTuple_New(2);
		if (!left || !right || !tmp) {
			Py_XDECREF(left);
			Py_XDECREF(right);
			Py_XDECREF(tmp);
			goto bail;
		}
		PyTuple_SET_ITEM(tmp, 0, left);
		PyTuple_SET_ITEM(tmp, 1, right);
		PyTuple_SET_ITEM(metadata, i, tmp);
	}
	ret = Py_BuildValue("(OOHO(di)O)", prec, succs, flags, metadata, mtime,
	                    (int)tz * 60, parents);
	goto bail; /* return successfully */

overflow:
	PyErr_SetString(PyExc_ValueError, "overflow in obsstore");
bail:
	Py_XDECREF(prec);
	Py_XDECREF(succs);
	Py_XDECREF(metadata);
	Py_XDECREF(parents);
	return ret;
}

static PyObject *fm1readmarkers(PyObject *self, PyObject *args)
{
	const char *data, *dataend;
	Py_ssize_t datalen, offset, stop;
	PyObject *markers = NULL;

	if (!PyArg_ParseTuple(args, PY23("s#nn", "y#nn"), &data, &datalen,
	                      &offset, &stop)) {
		return NULL;
	}
	if (offset < 0) {
		PyErr_SetString(PyExc_ValueError,
		                "invalid negative offset in fm1readmarkers");
		return NULL;
	}
	if (stop > datalen) {
		PyErr_SetString(
		    PyExc_ValueError,
		    "stop longer than data length in fm1readmarkers");
		return NULL;
	}
	dataend = data + datalen;
	data += offset;
	markers = PyList_New(0);
	if (!markers) {
		return NULL;
	}
	while (offset < stop) {
		uint32_t msize;
		int error;
		PyObject *record = fm1readmarker(data, dataend, &msize);
		if (!record) {
			goto bail;
		}
		error = PyList_Append(markers, record);
		Py_DECREF(record);
		if (error) {
			goto bail;
		}
		data += msize;
		offset += msize;
	}
	return markers;
bail:
	Py_DECREF(markers);
	return NULL;
}

static char parsers_doc[] = "Efficient content parsing.";

PyObject *encodedir(PyObject *self, PyObject *args);
PyObject *pathencode(PyObject *self, PyObject *args);
PyObject *lowerencode(PyObject *self, PyObject *args);
PyObject *parse_index2(PyObject *self, PyObject *args, PyObject *kwargs);

static PyMethodDef methods[] = {
    {"pack_dirstate", pack_dirstate, METH_VARARGS, "pack a dirstate\n"},
    {"nonnormalotherparententries", nonnormalotherparententries, METH_VARARGS,
     "create a set containing non-normal and other parent entries of given "
     "dirstate\n"},
    {"parse_dirstate", parse_dirstate, METH_VARARGS, "parse a dirstate\n"},
    {"parse_index2", (PyCFunction)parse_index2, METH_VARARGS | METH_KEYWORDS,
     "parse a revlog index\n"},
    {"isasciistr", isasciistr, METH_VARARGS, "check if an ASCII string\n"},
    {"asciilower", asciilower, METH_VARARGS, "lowercase an ASCII string\n"},
    {"asciiupper", asciiupper, METH_VARARGS, "uppercase an ASCII string\n"},
    {"dict_new_presized", dict_new_presized, METH_VARARGS,
     "construct a dict with an expected size\n"},
    {"make_file_foldmap", make_file_foldmap, METH_VARARGS,
     "make file foldmap\n"},
    {"jsonescapeu8fast", jsonescapeu8fast, METH_VARARGS,
     "escape a UTF-8 byte string to JSON (fast path)\n"},
    {"encodedir", encodedir, METH_VARARGS, "encodedir a path\n"},
    {"pathencode", pathencode, METH_VARARGS, "fncache-encode a path\n"},
    {"lowerencode", lowerencode, METH_VARARGS, "lower-encode a path\n"},
    {"fm1readmarkers", fm1readmarkers, METH_VARARGS,
     "parse v1 obsolete markers\n"},
    {NULL, NULL}};

void dirs_module_init(PyObject *mod);
void manifest_module_init(PyObject *mod);
void revlog_module_init(PyObject *mod);

static const int version = 20;

static void module_init(PyObject *mod)
{
	PyObject *capsule = NULL;
	PyModule_AddIntConstant(mod, "version", version);

	/* This module constant has two purposes.  First, it lets us unit test
	 * the ImportError raised without hard-coding any error text.  This
	 * means we can change the text in the future without breaking tests,
	 * even across changesets without a recompile.  Second, its presence
	 * can be used to determine whether the version-checking logic is
	 * present, which also helps in testing across changesets without a
	 * recompile.  Note that this means the pure-Python version of parsers
	 * should not have this module constant. */
	PyModule_AddStringConstant(mod, "versionerrortext", versionerrortext);

	dirs_module_init(mod);
	manifest_module_init(mod);
	revlog_module_init(mod);

	capsule = PyCapsule_New(
	    dirstate_item_from_v1_data,
	    "mercurial.cext.parsers.make_dirstate_item_CAPI", NULL);
	if (capsule != NULL)
		PyModule_AddObject(mod, "make_dirstate_item_CAPI", capsule);

	if (PyType_Ready(&dirstateItemType) < 0) {
		return;
	}
	Py_INCREF(&dirstateItemType);
	PyModule_AddObject(mod, "DirstateItem", (PyObject *)&dirstateItemType);
}

static int check_python_version(void)
{
	PyObject *sys = PyImport_ImportModule("sys"), *ver;
	long hexversion;
	if (!sys) {
		return -1;
	}
	ver = PyObject_GetAttrString(sys, "hexversion");
	Py_DECREF(sys);
	if (!ver) {
		return -1;
	}
	hexversion = PyInt_AsLong(ver);
	Py_DECREF(ver);
	/* sys.hexversion is a 32-bit number by default, so the -1 case
	 * should only occur in unusual circumstances (e.g. if sys.hexversion
	 * is manually set to an invalid value). */
	if ((hexversion == -1) || (hexversion >> 16 != PY_VERSION_HEX >> 16)) {
		PyErr_Format(PyExc_ImportError,
		             "%s: The Mercurial extension "
		             "modules were compiled with Python " PY_VERSION
		             ", but "
		             "Mercurial is currently using Python with "
		             "sys.hexversion=%ld: "
		             "Python %s\n at: %s",
		             versionerrortext, hexversion, Py_GetVersion(),
		             Py_GetProgramFullPath());
		return -1;
	}
	return 0;
}

#ifdef IS_PY3K
static struct PyModuleDef parsers_module = {PyModuleDef_HEAD_INIT, "parsers",
                                            parsers_doc, -1, methods};

PyMODINIT_FUNC PyInit_parsers(void)
{
	PyObject *mod;

	if (check_python_version() == -1)
		return NULL;
	mod = PyModule_Create(&parsers_module);
	module_init(mod);
	return mod;
}
#else
PyMODINIT_FUNC initparsers(void)
{
	PyObject *mod;

	if (check_python_version() == -1) {
		return;
	}
	mod = Py_InitModule3("parsers", methods, parsers_doc);
	module_init(mod);
}
#endif