annotate mercurial/cext/diffhelpers.c @ 36809:3c15b84ab66c

hgweb: teach WSGI parser about query strings

Currently, req.form uses cgi.parse() to populate form data. Depending
on the request, form data can come from POST multipart/form-data,
application/x-www-form-urlencoded, or the URL query string.

Putting all these things into one data structure makes it difficult
to reason about how exactly parameters got to the request. It can
lead to wonkiness such as pulling parameters from both the URL and
POST data.

This commit teaches our WSGI request parser about argument data
in query strings. We populate fields containing the query string
data and only the query string data so it can't be confused with
POST data.

Differential Revision: https://phab.mercurial-scm.org/D2737

/*
 * diffhelpers.c - helper routines for mpatch
 *
 * Copyright 2007 Chris Mason <[e-mail]>
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License v2, incorporated herein by reference.
 */

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

#include "util.h"

static char diffhelpers_doc[] = "Efficient diff parsing";
static PyObject *diffhelpers_Error;

/* fixup the last lines of a and b when the patch has no newline at eof */
static void _fix_newline(PyObject *hunk, PyObject *a, PyObject *b)
{
	Py_ssize_t hunksz = PyList_Size(hunk);
	PyObject *s = PyList_GET_ITEM(hunk, hunksz - 1);
	char *l = PyBytes_AsString(s);
	Py_ssize_t alen = PyList_Size(a);
	Py_ssize_t blen = PyList_Size(b);
	char c = l[0];
	PyObject *hline;
	Py_ssize_t sz = PyBytes_GET_SIZE(s);

	if (sz > 1 && l[sz - 2] == '\r')
		/* tolerate CRLF in last line */
		sz -= 1;

	hline = PyBytes_FromStringAndSize(l, sz - 1);
	if (!hline) {
		return;
	}

	if (c == ' ' || c == '+') {
		PyObject *rline = PyBytes_FromStringAndSize(l + 1, sz - 2);
		PyList_SetItem(b, blen - 1, rline);
	}
	if (c == ' ' || c == '-') {
		Py_INCREF(hline);
		PyList_SetItem(a, alen - 1, hline);
	}
	PyList_SetItem(hunk, hunksz - 1, hline);
}

/* python callable form of _fix_newline */
static PyObject *fix_newline(PyObject *self, PyObject *args)
{
	PyObject *hunk, *a, *b;
	if (!PyArg_ParseTuple(args, "OOO", &hunk, &a, &b))
		return NULL;
	_fix_newline(hunk, a, b);
	return Py_BuildValue("l", 0);
}

#if (PY_VERSION_HEX < 0x02050000)
static const char *addlines_format = "OOiiOO";
#else
static const char *addlines_format = "OOnnOO";
#endif

/*
 * read lines from fp into the hunk.  The hunk is parsed into two arrays
 * a and b.  a gets the old state of the text, b gets the new state
 * The control char from the hunk is saved when inserting into a, but not b
 * (for performance while deleting files)
 */
static PyObject *addlines(PyObject *self, PyObject *args)
{

	PyObject *fp, *hunk, *a, *b, *x;
	Py_ssize_t i;
	Py_ssize_t lena, lenb;
	Py_ssize_t num;
	Py_ssize_t todoa, todob;
	char *s, c;
	PyObject *l;
	if (!PyArg_ParseTuple(args, addlines_format, &fp, &hunk, &lena, &lenb,
	                      &a, &b))
		return NULL;

	while (1) {
		todoa = lena - PyList_Size(a);
		todob = lenb - PyList_Size(b);
		num = todoa > todob ? todoa : todob;
		if (num == 0)
			break;
		for (i = 0; i < num; i++) {
			x = PyFile_GetLine(fp, 0);
			s = PyBytes_AsString(x);
			c = *s;
			if (strcmp(s, "\\ No newline at end of file\n") == 0) {
				_fix_newline(hunk, a, b);
				continue;
			}
			if (c == '\n') {
				/* Some patches may be missing the control char
				 * on empty lines. Supply a leading space. */
				Py_DECREF(x);
				x = PyBytes_FromString(" \n");
			}
			PyList_Append(hunk, x);
			if (c == '+') {
				l = PyBytes_FromString(s + 1);
				PyList_Append(b, l);
				Py_DECREF(l);
			} else if (c == '-') {
				PyList_Append(a, x);
			} else {
				l = PyBytes_FromString(s + 1);
				PyList_Append(b, l);
				Py_DECREF(l);
				PyList_Append(a, x);
			}
			Py_DECREF(x);
		}
	}
	return Py_BuildValue("l", 0);
}

/*
 * compare the lines in a with the lines in b.  a is assumed to have
 * a control char at the start of each line, this char is ignored in the
 * compare
 */
static PyObject *testhunk(PyObject *self, PyObject *args)
{

	PyObject *a, *b;
	long bstart;
	Py_ssize_t alen, blen;
	Py_ssize_t i;
	char *sa, *sb;

	if (!PyArg_ParseTuple(args, "OOl", &a, &b, &bstart))
		return NULL;
	alen = PyList_Size(a);
	blen = PyList_Size(b);
	if (alen > blen - bstart || bstart < 0) {
		return Py_BuildValue("l", -1);
	}
	for (i = 0; i < alen; i++) {
		sa = PyBytes_AsString(PyList_GET_ITEM(a, i));
		sb = PyBytes_AsString(PyList_GET_ITEM(b, i + bstart));
		if (strcmp(sa + 1, sb) != 0)
			return Py_BuildValue("l", -1);
	}
	return Py_BuildValue("l", 0);
}

static PyMethodDef methods[] = {
    {"addlines", addlines, METH_VARARGS, "add lines to a hunk\n"},
    {"fix_newline", fix_newline, METH_VARARGS, "fixup newline counters\n"},
    {"testhunk", testhunk, METH_VARARGS, "test lines in a hunk\n"},
    {NULL, NULL}};

static const int version = 1;

#ifdef IS_PY3K
static struct PyModuleDef diffhelpers_module = {
    PyModuleDef_HEAD_INIT, "diffhelpers", diffhelpers_doc, -1, methods,
};

PyMODINIT_FUNC PyInit_diffhelpers(void)
{
	PyObject *m;

	m = PyModule_Create(&diffhelpers_module);
	if (m == NULL)
		return NULL;

	diffhelpers_Error =
	    PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL);
	Py_INCREF(diffhelpers_Error);
	PyModule_AddObject(m, "diffhelpersError", diffhelpers_Error);
	PyModule_AddIntConstant(m, "version", version);

	return m;
}
#else
PyMODINIT_FUNC initdiffhelpers(void)
{
	PyObject *m;
	m = Py_InitModule3("diffhelpers", methods, diffhelpers_doc);
	diffhelpers_Error =
	    PyErr_NewException("diffhelpers.diffhelpersError", NULL, NULL);
	PyModule_AddIntConstant(m, "version", version);
}
#endif