view mercurial/parsers.c @ 14093:ce99d887585f

httprepo: long arguments support (issue2126)

Send the command arguments in the HTTP headers. The command is still part
of the URL. If the server does not have the 'httpheader' capability, the
client will send the command arguments in the URL as it did previously.

Web servers typically allow more data to be placed within the headers than
in the URL, so this approach will:
- Avoid HTTP errors due to using a URL that is too large.
- Allow Mercurial to implement a more efficient wire protocol.

An alternate approach is to send the arguments as part of the request body.
This approach has been rejected because it requires the use of POST
requests, so it would break any existing configuration that relies on the
request type for authentication or caching.

Extensibility:
- The header size is provided by the server, which makes it possible to
  introduce an hgrc setting for it.
- The client ignores the capability value after the first comma, which
  allows more information to be included in the future.

/*
 parsers.c - efficient content parsing

 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.
*/

#include <Python.h>
#include <ctype.h>
#include <string.h>

#include "util.h"

static int hexdigit(char c)
{
	if (c >= '0' && c <= '9')
		return c - '0';
	if (c >= 'a' && c <= 'f')
		return c - 'a' + 10;
	if (c >= 'A' && c <= 'F')
		return c - 'A' + 10;

	PyErr_SetString(PyExc_ValueError, "input contains non-hex character");
	return 0;
}

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

	ret = PyBytes_FromStringAndSize(NULL, len / 2);

	if (!ret)
		return NULL;

	d = PyBytes_AsString(ret);

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

	return ret;
}

/*
 * This code assumes that a manifest is stitched together with newline
 * ('\n') characters.
 */
static PyObject *parse_manifest(PyObject *self, PyObject *args)
{
	PyObject *mfdict, *fdict;
	char *str, *cur, *start, *zero;
	int len;

	if (!PyArg_ParseTuple(args, "O!O!s#:parse_manifest",
			      &PyDict_Type, &mfdict,
			      &PyDict_Type, &fdict,
			      &str, &len))
		goto quit;

	for (start = cur = str, zero = NULL; cur < str + len; cur++) {
		PyObject *file = NULL, *node = NULL;
		PyObject *flags = NULL;
		int nlen;

		if (!*cur) {
			zero = cur;
			continue;
		}
		else if (*cur != '\n')
			continue;

		if (!zero) {
			PyErr_SetString(PyExc_ValueError,
					"manifest entry has no separator");
			goto quit;
		}

		file = PyBytes_FromStringAndSize(start, zero - start);

		if (!file)
			goto bail;

		nlen = cur - zero - 1;

		node = unhexlify(zero + 1, nlen > 40 ? 40 : nlen);
		if (!node)
			goto bail;

		if (nlen > 40) {
			flags = PyBytes_FromStringAndSize(zero + 41,
							   nlen - 40);
			if (!flags)
				goto bail;

			if (PyDict_SetItem(fdict, file, flags) == -1)
				goto bail;
		}

		if (PyDict_SetItem(mfdict, file, node) == -1)
			goto bail;

		start = cur + 1;
		zero = NULL;

		Py_XDECREF(flags);
		Py_XDECREF(node);
		Py_XDECREF(file);
		continue;
	bail:
		Py_XDECREF(flags);
		Py_XDECREF(node);
		Py_XDECREF(file);
		goto quit;
	}

	if (len > 0 && *(cur - 1) != '\n') {
		PyErr_SetString(PyExc_ValueError,
				"manifest contains trailing garbage");
		goto quit;
	}

	Py_INCREF(Py_None);
	return Py_None;
quit:
	return NULL;
}

#ifdef _WIN32
#ifdef _MSC_VER
/* msvc 6.0 has problems */
#define inline __inline
typedef unsigned long uint32_t;
typedef unsigned __int64 uint64_t;
#else
#include <stdint.h>
#endif
static uint32_t ntohl(uint32_t x)
{
	return ((x & 0x000000ffUL) << 24) |
	       ((x & 0x0000ff00UL) <<  8) |
	       ((x & 0x00ff0000UL) >>  8) |
	       ((x & 0xff000000UL) >> 24);
}
#else
/* not windows */
#include <sys/types.h>
#if defined __BEOS__ && !defined __HAIKU__
#include <ByteOrder.h>
#else
#include <arpa/inet.h>
#endif
#include <inttypes.h>
#endif

static PyObject *parse_dirstate(PyObject *self, PyObject *args)
{
	PyObject *dmap, *cmap, *parents = NULL, *ret = NULL;
	PyObject *fname = NULL, *cname = NULL, *entry = NULL;
	char *str, *cur, *end, *cpos;
	int state, mode, size, mtime;
	unsigned int flen;
	int len;
	char decode[16]; /* for alignment */

	if (!PyArg_ParseTuple(args, "O!O!s#:parse_dirstate",
			      &PyDict_Type, &dmap,
			      &PyDict_Type, &cmap,
			      &str, &len))
		goto quit;

	/* read parents */
	if (len < 40)
		goto quit;

	parents = Py_BuildValue("s#s#", str, 20, str + 20, 20);
	if (!parents)
		goto quit;

	/* read filenames */
	cur = str + 40;
	end = str + len;

	while (cur < end - 17) {
		/* unpack header */
		state = *cur;
		memcpy(decode, cur + 1, 16);
		mode = ntohl(*(uint32_t *)(decode));
		size = ntohl(*(uint32_t *)(decode + 4));
		mtime = ntohl(*(uint32_t *)(decode + 8));
		flen = ntohl(*(uint32_t *)(decode + 12));
		cur += 17;
		if (cur + flen > end || cur + flen < cur) {
			PyErr_SetString(PyExc_ValueError, "overflow in dirstate");
			goto quit;
		}

		entry = Py_BuildValue("ciii", state, mode, size, mtime);
		if (!entry)
			goto quit;
		PyObject_GC_UnTrack(entry); /* don't waste time with this */

		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;
		}
		cur += flen;
		Py_DECREF(fname);
		Py_DECREF(entry);
		fname = cname = entry = NULL;
	}

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

const char nullid[20];
const int nullrev = -1;

/* RevlogNG format (all in big endian, data may be inlined):
 *    6 bytes: offset
 *    2 bytes: flags
 *    4 bytes: compressed length
 *    4 bytes: uncompressed length
 *    4 bytes: base revision
 *    4 bytes: link revision
 *    4 bytes: parent 1 revision
 *    4 bytes: parent 2 revision
 *   32 bytes: nodeid (only 20 bytes used)
 */
static int _parse_index_ng(const char *data, int size, int inlined,
			   PyObject *index)
{
	PyObject *entry;
	int n = 0, err;
	uint64_t offset_flags;
	int comp_len, uncomp_len, base_rev, link_rev, parent_1, parent_2;
	const char *c_node_id;
	const char *end = data + size;
	char decode[64]; /* to enforce alignment with inline data */

	while (data < end) {
		unsigned int step;

		memcpy(decode, data, 64);
		offset_flags = ntohl(*((uint32_t *) (decode + 4)));
		if (n == 0) /* mask out version number for the first entry */
			offset_flags &= 0xFFFF;
		else {
			uint32_t offset_high =  ntohl(*((uint32_t *)decode));
			offset_flags |= ((uint64_t)offset_high) << 32;
		}

		comp_len = ntohl(*((uint32_t *)(decode + 8)));
		uncomp_len = ntohl(*((uint32_t *)(decode + 12)));
		base_rev = ntohl(*((uint32_t *)(decode + 16)));
		link_rev = ntohl(*((uint32_t *)(decode + 20)));
		parent_1 = ntohl(*((uint32_t *)(decode + 24)));
		parent_2 = ntohl(*((uint32_t *)(decode + 28)));
		c_node_id = decode + 32;

		entry = Py_BuildValue("Liiiiiis#", offset_flags, comp_len,
			      uncomp_len, base_rev, link_rev,
			      parent_1, parent_2, c_node_id, 20);

		if (!entry)
			return 0;

		PyObject_GC_UnTrack(entry); /* don't waste time with this */

		if (inlined) {
			err = PyList_Append(index, entry);
			Py_DECREF(entry);
			if (err)
				return 0;
		} else
			PyList_SET_ITEM(index, n, entry); /* steals reference */

		n++;
		step = 64 + (inlined ? comp_len : 0);
		if (data + step > end || data + step < data)
			break;
		data += step;
	}
	if (data != end) {
		if (!PyErr_Occurred())
			PyErr_SetString(PyExc_ValueError, "corrupt index file");
		return 0;
	}

	/* create the magic nullid entry in the index at [-1] */
	entry = Py_BuildValue("Liiiiiis#", (uint64_t)0, 0, 0, -1, -1, -1, -1, nullid, 20);

	if (!entry)
		return 0;

	PyObject_GC_UnTrack(entry); /* don't waste time with this */

	if (inlined) {
		err = PyList_Append(index, entry);
		Py_DECREF(entry);
		if (err)
			return 0;
	} else
		PyList_SET_ITEM(index, n, entry); /* steals reference */

	return 1;
}

/* This function parses a index file and returns a Python tuple of the
 * following format: (index, cache)
 *
 * index: a list of tuples containing the RevlogNG records
 * cache: if data is inlined, a tuple (index_file_content, 0) else None
 */
static PyObject *parse_index2(PyObject *self, PyObject *args)
{
	const char *data;
	int size, inlined;
	PyObject *rval = NULL, *index = NULL, *cache = NULL;
	PyObject *data_obj = NULL, *inlined_obj;

	if (!PyArg_ParseTuple(args, "s#O", &data, &size, &inlined_obj))
		return NULL;
	inlined = inlined_obj && PyObject_IsTrue(inlined_obj);

	/* If no data is inlined, we know the size of the index list in
	 * advance: size divided by the size of one revlog record (64 bytes)
	 * plus one for nullid */
	index = inlined ? PyList_New(0) : PyList_New(size / 64 + 1);
	if (!index)
		goto quit;

	/* set up the cache return value */
	if (inlined) {
		/* Note that the reference to data_obj is only borrowed */
		data_obj = PyTuple_GET_ITEM(args, 0);
		cache = Py_BuildValue("iO", 0, data_obj);
		if (!cache)
			goto quit;
	} else {
		cache = Py_None;
		Py_INCREF(Py_None);
	}

	/* actually populate the index with data */
	if (!_parse_index_ng(data, size, inlined, index))
		goto quit;

	rval = Py_BuildValue("NN", index, cache);
	if (!rval)
		goto quit;
	return rval;

quit:
	Py_XDECREF(index);
	Py_XDECREF(cache);
	Py_XDECREF(rval);
	return NULL;
}


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

static PyMethodDef methods[] = {
	{"parse_manifest", parse_manifest, METH_VARARGS, "parse a manifest\n"},
	{"parse_dirstate", parse_dirstate, METH_VARARGS, "parse a dirstate\n"},
	{"parse_index2", parse_index2, METH_VARARGS, "parse a revlog index\n"},
	{NULL, NULL}
};

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

PyMODINIT_FUNC PyInit_parsers(void)
{
	return PyModule_Create(&parsers_module);
}
#else
PyMODINIT_FUNC initparsers(void)
{
	Py_InitModule3("parsers", methods, parsers_doc);
}
#endif