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/*
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mpatch.c - efficient binary patching for Mercurial
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This implements a patch algorithm that's O(m + nlog n) where m is the
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size of the output and n is the number of patches.
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Given a list of binary patches, it unpacks each into a hunk list,
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then combines the hunk lists with a treewise recursion to form a
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single hunk list. This hunk list is then applied to the original
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text.
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The text (or binary) fragments are copied directly from their source
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Python objects into a preallocated output string to avoid the
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allocation of intermediate Python objects. Working memory is about 2x
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the total number of hunks.
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Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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This software may be used and distributed according to the terms
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of the GNU General Public License, incorporated herein by reference.
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*/
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#define PY_SSIZE_T_CLEAN
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#include <Python.h>
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#include <stdlib.h>
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#include <string.h>
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#include "bitmanipulation.h"
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#include "compat.h"
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#include "mpatch.h"
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#include "util.h"
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static char mpatch_doc[] = "Efficient binary patching.";
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static PyObject *mpatch_Error;
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static void setpyerr(int r)
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{
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switch (r) {
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case MPATCH_ERR_NO_MEM:
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PyErr_NoMemory();
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break;
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case MPATCH_ERR_CANNOT_BE_DECODED:
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PyErr_SetString(mpatch_Error, "patch cannot be decoded");
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break;
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case MPATCH_ERR_INVALID_PATCH:
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PyErr_SetString(mpatch_Error, "invalid patch");
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break;
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}
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}
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struct mpatch_flist *cpygetitem(void *bins, ssize_t pos)
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{
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const char *buffer;
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struct mpatch_flist *res;
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ssize_t blen;
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int r;
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PyObject *tmp = PyList_GetItem((PyObject*)bins, pos);
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if (!tmp)
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return NULL;
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if (PyObject_AsCharBuffer(tmp, &buffer, (Py_ssize_t*)&blen))
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return NULL;
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if ((r = mpatch_decode(buffer, blen, &res)) < 0) {
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if (!PyErr_Occurred())
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setpyerr(r);
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return NULL;
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}
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return res;
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}
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static PyObject *
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patches(PyObject *self, PyObject *args)
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{
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PyObject *text, *bins, *result;
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struct mpatch_flist *patch;
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const char *in;
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int r = 0;
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char *out;
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Py_ssize_t len, outlen, inlen;
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if (!PyArg_ParseTuple(args, "OO:mpatch", &text, &bins))
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return NULL;
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len = PyList_Size(bins);
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if (!len) {
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/* nothing to do */
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Py_INCREF(text);
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return text;
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}
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if (PyObject_AsCharBuffer(text, &in, &inlen))
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return NULL;
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patch = mpatch_fold(bins, cpygetitem, 0, len);
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if (!patch) { /* error already set or memory error */
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if (!PyErr_Occurred())
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PyErr_NoMemory();
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return NULL;
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}
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outlen = mpatch_calcsize(inlen, patch);
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if (outlen < 0) {
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r = (int)outlen;
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result = NULL;
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goto cleanup;
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}
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result = PyBytes_FromStringAndSize(NULL, outlen);
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if (!result) {
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result = NULL;
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goto cleanup;
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}
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out = PyBytes_AsString(result);
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if ((r = mpatch_apply(out, in, inlen, patch)) < 0) {
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Py_DECREF(result);
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result = NULL;
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}
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cleanup:
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mpatch_lfree(patch);
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if (!result && !PyErr_Occurred())
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setpyerr(r);
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return result;
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}
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/* calculate size of a patched file directly */
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static PyObject *
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patchedsize(PyObject *self, PyObject *args)
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{
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long orig, start, end, len, outlen = 0, last = 0, pos = 0;
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Py_ssize_t patchlen;
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char *bin;
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if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen))
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return NULL;
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while (pos >= 0 && pos < patchlen) {
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start = getbe32(bin + pos);
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end = getbe32(bin + pos + 4);
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len = getbe32(bin + pos + 8);
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if (start > end)
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break; /* sanity check */
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pos += 12 + len;
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outlen += start - last;
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last = end;
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outlen += len;
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}
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if (pos != patchlen) {
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if (!PyErr_Occurred())
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PyErr_SetString(mpatch_Error, "patch cannot be decoded");
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return NULL;
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}
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outlen += orig - last;
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return Py_BuildValue("l", outlen);
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}
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static PyMethodDef methods[] = {
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{"patches", patches, METH_VARARGS, "apply a series of patches\n"},
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{"patchedsize", patchedsize, METH_VARARGS, "calculed patched size\n"},
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{NULL, NULL}
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};
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static const int version = 1;
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#ifdef IS_PY3K
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static struct PyModuleDef mpatch_module = {
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PyModuleDef_HEAD_INIT,
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"mpatch",
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mpatch_doc,
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-1,
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methods
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};
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PyMODINIT_FUNC PyInit_mpatch(void)
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{
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PyObject *m;
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m = PyModule_Create(&mpatch_module);
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if (m == NULL)
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return NULL;
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mpatch_Error = PyErr_NewException("mercurial.cext.mpatch.mpatchError",
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NULL, NULL);
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Py_INCREF(mpatch_Error);
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PyModule_AddObject(m, "mpatchError", mpatch_Error);
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PyModule_AddIntConstant(m, "version", version);
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return m;
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}
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#else
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PyMODINIT_FUNC
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initmpatch(void)
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{
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PyObject *m;
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m = Py_InitModule3("mpatch", methods, mpatch_doc);
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mpatch_Error = PyErr_NewException("mercurial.cext.mpatch.mpatchError",
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NULL, NULL);
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PyModule_AddIntConstant(m, "version", version);
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}
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#endif
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