mercurial/cext/charencode.c

obsolete: explicitly track folds inside the markers

We now record information to be able to recognize "fold" event from
obsolescence markers. To do so, we track the following pieces of information:

a) a fold ID. Unique to that fold (per successor),
b) the number of predecessors,
c) the index of the predecessor in that fold.

We will now be able to create an algorithm able to find "predecessorssets".

We now store this data in the generic "metadata" field of the markers.
Updating the format to have a more compact storage for this would be useful.

This way of tracking a fold through multiple markers could be applied to split
too. This would have two advantages:

1) We get a simpler format, since number of successors is limited to [0-1].
2) We can better deal with situations where only some of the split successors
   are pushed to a remote repository.

We should look into the relevance of such a change before updating the on-disk
format.

note: unlike splits, folds do not have to deal with cases where only some of
the markers have been synchronized. As they all share the same successor
changesets, they are all relevant to the same nodes.

/*
 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;
}