hgweb: send proper HTTP response after uncaught exception
This patch fixes a bug where hgweb would send an incomplete HTTP
response.
If an uncaught exception is raised when hgweb is processing a request,
hgweb attempts to send a generic error response and log that exception.
The server defaults to chunked transfer coding. If an uncaught exception
occurred, it was sending the error response string / chunk properly.
However, RFC 7230 Section 4.1 mandates a 0 size last chunk be sent to
indicate end of the entity body. hgweb was failing to send this last
chunk. As a result, properly written HTTP clients would assume more data
was coming and they would likely time out waiting for another chunk to
arrive.
Mercurial's own test harness was paving over the improper HTTP behavior
by not attempting to read the response body if the status code was 500.
This incorrect workaround was added in ba6577a19656 and has been removed
with this patch.
/*
dirs.c - dynamic directory diddling for dirstates
Copyright 2013 Facebook
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 "util.h"
/*
* This is a multiset of directory names, built from the files that
* appear in a dirstate or manifest.
*
* A few implementation notes:
*
* We modify Python integers for refcounting, but those integers are
* never visible to Python code.
*
* We mutate strings in-place, but leave them immutable once they can
* be seen by Python code.
*/
typedef struct {
PyObject_HEAD
PyObject *dict;
} dirsObject;
static inline Py_ssize_t _finddir(PyObject *path, Py_ssize_t pos)
{
const char *s = PyString_AS_STRING(path);
while (pos != -1) {
if (s[pos] == '/')
break;
pos -= 1;
}
return pos;
}
static int _addpath(PyObject *dirs, PyObject *path)
{
const char *cpath = PyString_AS_STRING(path);
Py_ssize_t pos = PyString_GET_SIZE(path);
PyObject *key = NULL;
int ret = -1;
while ((pos = _finddir(path, pos - 1)) != -1) {
PyObject *val;
/* It's likely that every prefix already has an entry
in our dict. Try to avoid allocating and
deallocating a string for each prefix we check. */
if (key != NULL)
((PyStringObject *)key)->ob_shash = -1;
else {
/* Force Python to not reuse a small shared string. */
key = PyString_FromStringAndSize(cpath,
pos < 2 ? 2 : pos);
if (key == NULL)
goto bail;
}
PyString_GET_SIZE(key) = pos;
PyString_AS_STRING(key)[pos] = '\0';
val = PyDict_GetItem(dirs, key);
if (val != NULL) {
PyInt_AS_LONG(val) += 1;
continue;
}
/* Force Python to not reuse a small shared int. */
val = PyInt_FromLong(0x1eadbeef);
if (val == NULL)
goto bail;
PyInt_AS_LONG(val) = 1;
ret = PyDict_SetItem(dirs, key, val);
Py_DECREF(val);
if (ret == -1)
goto bail;
Py_CLEAR(key);
}
ret = 0;
bail:
Py_XDECREF(key);
return ret;
}
static int _delpath(PyObject *dirs, PyObject *path)
{
Py_ssize_t pos = PyString_GET_SIZE(path);
PyObject *key = NULL;
int ret = -1;
while ((pos = _finddir(path, pos - 1)) != -1) {
PyObject *val;
key = PyString_FromStringAndSize(PyString_AS_STRING(path), pos);
if (key == NULL)
goto bail;
val = PyDict_GetItem(dirs, key);
if (val == NULL) {
PyErr_SetString(PyExc_ValueError,
"expected a value, found none");
goto bail;
}
if (--PyInt_AS_LONG(val) <= 0 &&
PyDict_DelItem(dirs, key) == -1)
goto bail;
Py_CLEAR(key);
}
ret = 0;
bail:
Py_XDECREF(key);
return ret;
}
static int dirs_fromdict(PyObject *dirs, PyObject *source, char skipchar)
{
PyObject *key, *value;
Py_ssize_t pos = 0;
while (PyDict_Next(source, &pos, &key, &value)) {
if (!PyString_Check(key)) {
PyErr_SetString(PyExc_TypeError, "expected string key");
return -1;
}
if (skipchar) {
if (!dirstate_tuple_check(value)) {
PyErr_SetString(PyExc_TypeError,
"expected a dirstate tuple");
return -1;
}
if (((dirstateTupleObject *)value)->state == skipchar)
continue;
}
if (_addpath(dirs, key) == -1)
return -1;
}
return 0;
}
static int dirs_fromiter(PyObject *dirs, PyObject *source)
{
PyObject *iter, *item = NULL;
int ret;
iter = PyObject_GetIter(source);
if (iter == NULL)
return -1;
while ((item = PyIter_Next(iter)) != NULL) {
if (!PyString_Check(item)) {
PyErr_SetString(PyExc_TypeError, "expected string");
break;
}
if (_addpath(dirs, item) == -1)
break;
Py_CLEAR(item);
}
ret = PyErr_Occurred() ? -1 : 0;
Py_XDECREF(item);
return ret;
}
/*
* Calculate a refcounted set of directory names for the files in a
* dirstate.
*/
static int dirs_init(dirsObject *self, PyObject *args)
{
PyObject *dirs = NULL, *source = NULL;
char skipchar = 0;
int ret = -1;
self->dict = NULL;
if (!PyArg_ParseTuple(args, "|Oc:__init__", &source, &skipchar))
return -1;
dirs = PyDict_New();
if (dirs == NULL)
return -1;
if (source == NULL)
ret = 0;
else if (PyDict_Check(source))
ret = dirs_fromdict(dirs, source, skipchar);
else if (skipchar)
PyErr_SetString(PyExc_ValueError,
"skip character is only supported "
"with a dict source");
else
ret = dirs_fromiter(dirs, source);
if (ret == -1)
Py_XDECREF(dirs);
else
self->dict = dirs;
return ret;
}
PyObject *dirs_addpath(dirsObject *self, PyObject *args)
{
PyObject *path;
if (!PyArg_ParseTuple(args, "O!:addpath", &PyString_Type, &path))
return NULL;
if (_addpath(self->dict, path) == -1)
return NULL;
Py_RETURN_NONE;
}
static PyObject *dirs_delpath(dirsObject *self, PyObject *args)
{
PyObject *path;
if (!PyArg_ParseTuple(args, "O!:delpath", &PyString_Type, &path))
return NULL;
if (_delpath(self->dict, path) == -1)
return NULL;
Py_RETURN_NONE;
}
static int dirs_contains(dirsObject *self, PyObject *value)
{
return PyString_Check(value) ? PyDict_Contains(self->dict, value) : 0;
}
static void dirs_dealloc(dirsObject *self)
{
Py_XDECREF(self->dict);
PyObject_Del(self);
}
static PyObject *dirs_iter(dirsObject *self)
{
return PyObject_GetIter(self->dict);
}
static PySequenceMethods dirs_sequence_methods;
static PyMethodDef dirs_methods[] = {
{"addpath", (PyCFunction)dirs_addpath, METH_VARARGS, "add a path"},
{"delpath", (PyCFunction)dirs_delpath, METH_VARARGS, "remove a path"},
{NULL} /* Sentinel */
};
static PyTypeObject dirsType = { PyObject_HEAD_INIT(NULL) };
void dirs_module_init(PyObject *mod)
{
dirs_sequence_methods.sq_contains = (objobjproc)dirs_contains;
dirsType.tp_name = "parsers.dirs";
dirsType.tp_new = PyType_GenericNew;
dirsType.tp_basicsize = sizeof(dirsObject);
dirsType.tp_dealloc = (destructor)dirs_dealloc;
dirsType.tp_as_sequence = &dirs_sequence_methods;
dirsType.tp_flags = Py_TPFLAGS_DEFAULT;
dirsType.tp_doc = "dirs";
dirsType.tp_iter = (getiterfunc)dirs_iter;
dirsType.tp_methods = dirs_methods;
dirsType.tp_init = (initproc)dirs_init;
if (PyType_Ready(&dirsType) < 0)
return;
Py_INCREF(&dirsType);
PyModule_AddObject(mod, "dirs", (PyObject *)&dirsType);
}