view mercurial/cext/charencode.c @ 37058:c5e9c3b47366

wireproto: support for receiving multiple requests

Now that we have request IDs on each frame and a specification
that allows multiple requests to be issued simultaneously,
possibly interleaved, let's teach the server to deal with that.

Instead of tracking the state for *the* active command request,
we instead track the state of each receiving command by its
request ID. The multiple states in our state machine for processing
each command's state has been collapsed into a single state for
"receiving commands."

Tests have been added so our branch coverage covers all meaningful
branches.

However, we did lose some logical coverage. The implementation
of this new feature opens up the door to a server having partial
command requests when end of input is reached. We will probably
want a mechanism to deal with partial requests. For now, I've
tracked that as a known issue in the class docstring. I've
also noted an abuse vector that becomes a little bit easier to
exploit with this feature.

Differential Revision: https://phab.mercurial-scm.org/D2870

/*
 charencode.c - miscellaneous character encoding

 Copyright 2008 Matt 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 <assert.h>

#include "charencode.h"
#include "compat.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_Type PyLong_Type
#define PyInt_AS_LONG PyLong_AS_LONG
#endif

/* clang-format off */
static const char lowertable[128] = {
	'\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
	'\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
	'\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
	'\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
	'\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
	'\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
	'\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
	'\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
	'\x40',
	        '\x61', '\x62', '\x63', '\x64', '\x65', '\x66', '\x67', /* A-G */
	'\x68', '\x69', '\x6a', '\x6b', '\x6c', '\x6d', '\x6e', '\x6f', /* H-O */
	'\x70', '\x71', '\x72', '\x73', '\x74', '\x75', '\x76', '\x77', /* P-W */
	'\x78', '\x79', '\x7a',                                         /* X-Z */
	                        '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
	'\x60', '\x61', '\x62', '\x63', '\x64', '\x65', '\x66', '\x67',
	'\x68', '\x69', '\x6a', '\x6b', '\x6c', '\x6d', '\x6e', '\x6f',
	'\x70', '\x71', '\x72', '\x73', '\x74', '\x75', '\x76', '\x77',
	'\x78', '\x79', '\x7a', '\x7b', '\x7c', '\x7d', '\x7e', '\x7f'
};

static const char uppertable[128] = {
	'\x00', '\x01', '\x02', '\x03', '\x04', '\x05', '\x06', '\x07',
	'\x08', '\x09', '\x0a', '\x0b', '\x0c', '\x0d', '\x0e', '\x0f',
	'\x10', '\x11', '\x12', '\x13', '\x14', '\x15', '\x16', '\x17',
	'\x18', '\x19', '\x1a', '\x1b', '\x1c', '\x1d', '\x1e', '\x1f',
	'\x20', '\x21', '\x22', '\x23', '\x24', '\x25', '\x26', '\x27',
	'\x28', '\x29', '\x2a', '\x2b', '\x2c', '\x2d', '\x2e', '\x2f',
	'\x30', '\x31', '\x32', '\x33', '\x34', '\x35', '\x36', '\x37',
	'\x38', '\x39', '\x3a', '\x3b', '\x3c', '\x3d', '\x3e', '\x3f',
	'\x40', '\x41', '\x42', '\x43', '\x44', '\x45', '\x46', '\x47',
	'\x48', '\x49', '\x4a', '\x4b', '\x4c', '\x4d', '\x4e', '\x4f',
	'\x50', '\x51', '\x52', '\x53', '\x54', '\x55', '\x56', '\x57',
	'\x58', '\x59', '\x5a', '\x5b', '\x5c', '\x5d', '\x5e', '\x5f',
	'\x60',
		'\x41', '\x42', '\x43', '\x44', '\x45', '\x46', '\x47', /* a-g */
	'\x48', '\x49', '\x4a', '\x4b', '\x4c', '\x4d', '\x4e', '\x4f', /* h-o */
	'\x50', '\x51', '\x52', '\x53', '\x54', '\x55', '\x56', '\x57', /* p-w */
	'\x58', '\x59', '\x5a', 					/* x-z */
				'\x7b', '\x7c', '\x7d', '\x7e', '\x7f'
};

/* 1: no escape, 2: \<c>, 6: \u<x> */
static const uint8_t jsonlentable[256] = {
	6, 6, 6, 6, 6, 6, 6, 6, 2, 2, 2, 6, 2, 2, 6, 6, /* b, t, n, f, r */
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
	1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* " */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, /* \\ */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, /* DEL */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
};

static const uint8_t jsonparanoidlentable[128] = {
	6, 6, 6, 6, 6, 6, 6, 6, 2, 2, 2, 6, 2, 2, 6, 6, /* b, t, n, f, r */
	6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,
	1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* " */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, 1, 6, 1, /* <, > */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, /* \\ */
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 6, /* DEL */
};

static const char hexchartable[16] = {
	'0', '1', '2', '3', '4', '5', '6', '7',
	'8', '9', 'a', 'b', 'c', 'd', 'e', 'f',
};
/* clang-format on */

/*
 * Turn a hex-encoded string into binary.
 */
PyObject *unhexlify(const char *str, Py_ssize_t len)
{
	PyObject *ret;
	char *d;
	Py_ssize_t i;

	ret = PyBytes_FromStringAndSize(NULL, len / 2);

	if (!ret)
		return NULL;

	d = PyBytes_AsString(ret);

	for (i = 0; i < len;) {
		int hi = hexdigit(str, i++);
		int lo = hexdigit(str, i++);
		*d++ = (hi << 4) | lo;
	}

	return ret;
}

PyObject *isasciistr(PyObject *self, PyObject *args)
{
	const char *buf;
	Py_ssize_t i, len;
	if (!PyArg_ParseTuple(args, PY23("s#:isasciistr", "y#:isasciistr"),
	                      &buf, &len))
		return NULL;
	i = 0;
	/* char array in PyStringObject should be at least 4-byte aligned */
	if (((uintptr_t)buf & 3) == 0) {
		const uint32_t *p = (const uint32_t *)buf;
		for (; i < len / 4; i++) {
			if (p[i] & 0x80808080U)
				Py_RETURN_FALSE;
		}
		i *= 4;
	}
	for (; i < len; i++) {
		if (buf[i] & 0x80)
			Py_RETURN_FALSE;
	}
	Py_RETURN_TRUE;
}

static inline PyObject *
_asciitransform(PyObject *str_obj, const char table[128], PyObject *fallback_fn)
{
	char *str, *newstr;
	Py_ssize_t i, len;
	PyObject *newobj = NULL;
	PyObject *ret = NULL;

	str = PyBytes_AS_STRING(str_obj);
	len = PyBytes_GET_SIZE(str_obj);

	newobj = PyBytes_FromStringAndSize(NULL, len);
	if (!newobj)
		goto quit;

	newstr = PyBytes_AS_STRING(newobj);

	for (i = 0; i < len; i++) {
		char c = str[i];
		if (c & 0x80) {
			if (fallback_fn != NULL) {
				ret = PyObject_CallFunctionObjArgs(
				    fallback_fn, str_obj, NULL);
			} else {
				PyObject *err = PyUnicodeDecodeError_Create(
				    "ascii", str, len, i, (i + 1),
				    "unexpected code byte");
				PyErr_SetObject(PyExc_UnicodeDecodeError, err);
				Py_XDECREF(err);
			}
			goto quit;
		}
		newstr[i] = table[(unsigned char)c];
	}

	ret = newobj;
	Py_INCREF(ret);
quit:
	Py_XDECREF(newobj);
	return ret;
}

PyObject *asciilower(PyObject *self, PyObject *args)
{
	PyObject *str_obj;
	if (!PyArg_ParseTuple(args, "O!:asciilower", &PyBytes_Type, &str_obj))
		return NULL;
	return _asciitransform(str_obj, lowertable, NULL);
}

PyObject *asciiupper(PyObject *self, PyObject *args)
{
	PyObject *str_obj;
	if (!PyArg_ParseTuple(args, "O!:asciiupper", &PyBytes_Type, &str_obj))
		return NULL;
	return _asciitransform(str_obj, uppertable, NULL);
}

PyObject *make_file_foldmap(PyObject *self, PyObject *args)
{
	PyObject *dmap, *spec_obj, *normcase_fallback;
	PyObject *file_foldmap = NULL;
	enum normcase_spec spec;
	PyObject *k, *v;
	dirstateTupleObject *tuple;
	Py_ssize_t pos = 0;
	const char *table;

	if (!PyArg_ParseTuple(args, "O!O!O!:make_file_foldmap", &PyDict_Type,
	                      &dmap, &PyInt_Type, &spec_obj, &PyFunction_Type,
	                      &normcase_fallback))
		goto quit;

	spec = (int)PyInt_AS_LONG(spec_obj);
	switch (spec) {
	case NORMCASE_LOWER:
		table = lowertable;
		break;
	case NORMCASE_UPPER:
		table = uppertable;
		break;
	case NORMCASE_OTHER:
		table = NULL;
		break;
	default:
		PyErr_SetString(PyExc_TypeError, "invalid normcasespec");
		goto quit;
	}

	/* Add some more entries to deal with additions outside this
	   function. */
	file_foldmap = _dict_new_presized((PyDict_Size(dmap) / 10) * 11);
	if (file_foldmap == NULL)
		goto quit;

	while (PyDict_Next(dmap, &pos, &k, &v)) {
		if (!dirstate_tuple_check(v)) {
			PyErr_SetString(PyExc_TypeError,
			                "expected a dirstate tuple");
			goto quit;
		}

		tuple = (dirstateTupleObject *)v;
		if (tuple->state != 'r') {
			PyObject *normed;
			if (table != NULL) {
				normed = _asciitransform(k, table,
				                         normcase_fallback);
			} else {
				normed = PyObject_CallFunctionObjArgs(
				    normcase_fallback, k, NULL);
			}

			if (normed == NULL)
				goto quit;
			if (PyDict_SetItem(file_foldmap, normed, k) == -1) {
				Py_DECREF(normed);
				goto quit;
			}
			Py_DECREF(normed);
		}
	}
	return file_foldmap;
quit:
	Py_XDECREF(file_foldmap);
	return NULL;
}

/* calculate length of JSON-escaped string; returns -1 if unsupported */
static Py_ssize_t jsonescapelen(const char *buf, Py_ssize_t len, bool paranoid)
{
	Py_ssize_t i, esclen = 0;

	if (paranoid) {
		/* don't want to process multi-byte escapes in C */
		for (i = 0; i < len; i++) {
			char c = buf[i];
			if (c & 0x80) {
				PyErr_SetString(PyExc_ValueError,
				                "cannot process non-ascii str");
				return -1;
			}
			esclen += jsonparanoidlentable[(unsigned char)c];
			if (esclen < 0) {
				PyErr_SetString(PyExc_MemoryError,
				                "overflow in jsonescapelen");
				return -1;
			}
		}
	} else {
		for (i = 0; i < len; i++) {
			char c = buf[i];
			esclen += jsonlentable[(unsigned char)c];
			if (esclen < 0) {
				PyErr_SetString(PyExc_MemoryError,
				                "overflow in jsonescapelen");
				return -1;
			}
		}
	}

	return esclen;
}

/* map '\<c>' escape character */
static char jsonescapechar2(char c)
{
	switch (c) {
	case '\b':
		return 'b';
	case '\t':
		return 't';
	case '\n':
		return 'n';
	case '\f':
		return 'f';
	case '\r':
		return 'r';
	case '"':
		return '"';
	case '\\':
		return '\\';
	}
	return '\0'; /* should not happen */
}

/* convert 'origbuf' to JSON-escaped form 'escbuf'; 'origbuf' should only
   include characters mappable by json(paranoid)lentable */
static void encodejsonescape(char *escbuf, Py_ssize_t esclen,
                             const char *origbuf, Py_ssize_t origlen,
                             bool paranoid)
{
	const uint8_t *lentable =
	    (paranoid) ? jsonparanoidlentable : jsonlentable;
	Py_ssize_t i, j;

	for (i = 0, j = 0; i < origlen; i++) {
		char c = origbuf[i];
		uint8_t l = lentable[(unsigned char)c];
		assert(j + l <= esclen);
		switch (l) {
		case 1:
			escbuf[j] = c;
			break;
		case 2:
			escbuf[j] = '\\';
			escbuf[j + 1] = jsonescapechar2(c);
			break;
		case 6:
			memcpy(escbuf + j, "\\u00", 4);
			escbuf[j + 4] = hexchartable[(unsigned char)c >> 4];
			escbuf[j + 5] = hexchartable[(unsigned char)c & 0xf];
			break;
		}
		j += l;
	}
}

PyObject *jsonescapeu8fast(PyObject *self, PyObject *args)
{
	PyObject *origstr, *escstr;
	const char *origbuf;
	Py_ssize_t origlen, esclen;
	int paranoid;
	if (!PyArg_ParseTuple(args, "O!i:jsonescapeu8fast", &PyBytes_Type,
	                      &origstr, &paranoid))
		return NULL;

	origbuf = PyBytes_AS_STRING(origstr);
	origlen = PyBytes_GET_SIZE(origstr);
	esclen = jsonescapelen(origbuf, origlen, paranoid);
	if (esclen < 0)
		return NULL; /* unsupported char found or overflow */
	if (origlen == esclen) {
		Py_INCREF(origstr);
		return origstr;
	}

	escstr = PyBytes_FromStringAndSize(NULL, esclen);
	if (!escstr)
		return NULL;
	encodejsonescape(PyBytes_AS_STRING(escstr), esclen, origbuf, origlen,
	                 paranoid);

	return escstr;
}