##// END OF EJS Templates
plan9: initial support for plan 9 from bell labs...
plan9: initial support for plan 9 from bell labs This patch contains support for Plan 9 from Bell Labs. A README is provided in contrib/plan9 which describes the port in greater detail. A new extension is also provided named factotum which permits the factotum(4) authentication agent to provide credentials for HTTP repositories. This extension is also applicable to other POSIX platforms which make use of Plan 9 from User Space (aka plan9ports).

File last commit:

r15033:2ef2d3a5 stable
r16383:f5dd179b default
Show More
mpatch.c
470 lines | 9.6 KiB | text/x-c | CLexer
/*
mpatch.c - efficient binary patching for Mercurial
This implements a patch algorithm that's O(m + nlog n) where m is the
size of the output and n is the number of patches.
Given a list of binary patches, it unpacks each into a hunk list,
then combines the hunk lists with a treewise recursion to form a
single hunk list. This hunk list is then applied to the original
text.
The text (or binary) fragments are copied directly from their source
Python objects into a preallocated output string to avoid the
allocation of intermediate Python objects. Working memory is about 2x
the total number of hunks.
Copyright 2005, 2006 Matt Mackall <mpm@selenic.com>
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 <stdlib.h>
#include <string.h>
#include "util.h"
/* Definitions to get compatibility with python 2.4 and earlier which
does not have Py_ssize_t. See also PEP 353.
Note: msvc (8 or earlier) does not have ssize_t, so we use Py_ssize_t.
*/
#if PY_VERSION_HEX < 0x02050000 && !defined(PY_SSIZE_T_MIN)
typedef int Py_ssize_t;
#define PY_SSIZE_T_MAX INT_MAX
#define PY_SSIZE_T_MIN INT_MIN
#endif
#ifdef _WIN32
#ifdef _MSC_VER
/* msvc 6.0 has problems */
#define inline __inline
typedef unsigned long uint32_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 char mpatch_doc[] = "Efficient binary patching.";
static PyObject *mpatch_Error;
struct frag {
int start, end, len;
const char *data;
};
struct flist {
struct frag *base, *head, *tail;
};
static struct flist *lalloc(int size)
{
struct flist *a = NULL;
if (size < 1)
size = 1;
a = (struct flist *)malloc(sizeof(struct flist));
if (a) {
a->base = (struct frag *)malloc(sizeof(struct frag) * size);
if (a->base) {
a->head = a->tail = a->base;
return a;
}
free(a);
a = NULL;
}
if (!PyErr_Occurred())
PyErr_NoMemory();
return NULL;
}
static void lfree(struct flist *a)
{
if (a) {
free(a->base);
free(a);
}
}
static int lsize(struct flist *a)
{
return a->tail - a->head;
}
/* move hunks in source that are less cut to dest, compensating
for changes in offset. the last hunk may be split if necessary.
*/
static int gather(struct flist *dest, struct flist *src, int cut, int offset)
{
struct frag *d = dest->tail, *s = src->head;
int postend, c, l;
while (s != src->tail) {
if (s->start + offset >= cut)
break; /* we've gone far enough */
postend = offset + s->start + s->len;
if (postend <= cut) {
/* save this hunk */
offset += s->start + s->len - s->end;
*d++ = *s++;
}
else {
/* break up this hunk */
c = cut - offset;
if (s->end < c)
c = s->end;
l = cut - offset - s->start;
if (s->len < l)
l = s->len;
offset += s->start + l - c;
d->start = s->start;
d->end = c;
d->len = l;
d->data = s->data;
d++;
s->start = c;
s->len = s->len - l;
s->data = s->data + l;
break;
}
}
dest->tail = d;
src->head = s;
return offset;
}
/* like gather, but with no output list */
static int discard(struct flist *src, int cut, int offset)
{
struct frag *s = src->head;
int postend, c, l;
while (s != src->tail) {
if (s->start + offset >= cut)
break;
postend = offset + s->start + s->len;
if (postend <= cut) {
offset += s->start + s->len - s->end;
s++;
}
else {
c = cut - offset;
if (s->end < c)
c = s->end;
l = cut - offset - s->start;
if (s->len < l)
l = s->len;
offset += s->start + l - c;
s->start = c;
s->len = s->len - l;
s->data = s->data + l;
break;
}
}
src->head = s;
return offset;
}
/* combine hunk lists a and b, while adjusting b for offset changes in a/
this deletes a and b and returns the resultant list. */
static struct flist *combine(struct flist *a, struct flist *b)
{
struct flist *c = NULL;
struct frag *bh, *ct;
int offset = 0, post;
if (a && b)
c = lalloc((lsize(a) + lsize(b)) * 2);
if (c) {
for (bh = b->head; bh != b->tail; bh++) {
/* save old hunks */
offset = gather(c, a, bh->start, offset);
/* discard replaced hunks */
post = discard(a, bh->end, offset);
/* insert new hunk */
ct = c->tail;
ct->start = bh->start - offset;
ct->end = bh->end - post;
ct->len = bh->len;
ct->data = bh->data;
c->tail++;
offset = post;
}
/* hold on to tail from a */
memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a));
c->tail += lsize(a);
}
lfree(a);
lfree(b);
return c;
}
/* decode a binary patch into a hunk list */
static struct flist *decode(const char *bin, int len)
{
struct flist *l;
struct frag *lt;
const char *data = bin + 12, *end = bin + len;
uint32_t decode[3]; /* for dealing with alignment issues */
/* assume worst case size, we won't have many of these lists */
l = lalloc(len / 12);
if (!l)
return NULL;
lt = l->tail;
while (data <= end) {
memcpy(decode, bin, 12);
lt->start = ntohl(decode[0]);
lt->end = ntohl(decode[1]);
lt->len = ntohl(decode[2]);
if (lt->start > lt->end)
break; /* sanity check */
bin = data + lt->len;
if (bin < data)
break; /* big data + big (bogus) len can wrap around */
lt->data = data;
data = bin + 12;
lt++;
}
if (bin != end) {
if (!PyErr_Occurred())
PyErr_SetString(mpatch_Error, "patch cannot be decoded");
lfree(l);
return NULL;
}
l->tail = lt;
return l;
}
/* calculate the size of resultant text */
static int calcsize(int len, struct flist *l)
{
int outlen = 0, last = 0;
struct frag *f = l->head;
while (f != l->tail) {
if (f->start < last || f->end > len) {
if (!PyErr_Occurred())
PyErr_SetString(mpatch_Error,
"invalid patch");
return -1;
}
outlen += f->start - last;
last = f->end;
outlen += f->len;
f++;
}
outlen += len - last;
return outlen;
}
static int apply(char *buf, const char *orig, int len, struct flist *l)
{
struct frag *f = l->head;
int last = 0;
char *p = buf;
while (f != l->tail) {
if (f->start < last || f->end > len) {
if (!PyErr_Occurred())
PyErr_SetString(mpatch_Error,
"invalid patch");
return 0;
}
memcpy(p, orig + last, f->start - last);
p += f->start - last;
memcpy(p, f->data, f->len);
last = f->end;
p += f->len;
f++;
}
memcpy(p, orig + last, len - last);
return 1;
}
/* recursively generate a patch of all bins between start and end */
static struct flist *fold(PyObject *bins, int start, int end)
{
int len;
Py_ssize_t blen;
const char *buffer;
if (start + 1 == end) {
/* trivial case, output a decoded list */
PyObject *tmp = PyList_GetItem(bins, start);
if (!tmp)
return NULL;
if (PyObject_AsCharBuffer(tmp, &buffer, &blen))
return NULL;
return decode(buffer, blen);
}
/* divide and conquer, memory management is elsewhere */
len = (end - start) / 2;
return combine(fold(bins, start, start + len),
fold(bins, start + len, end));
}
static PyObject *
patches(PyObject *self, PyObject *args)
{
PyObject *text, *bins, *result;
struct flist *patch;
const char *in;
char *out;
int len, outlen;
Py_ssize_t inlen;
if (!PyArg_ParseTuple(args, "OO:mpatch", &text, &bins))
return NULL;
len = PyList_Size(bins);
if (!len) {
/* nothing to do */
Py_INCREF(text);
return text;
}
if (PyObject_AsCharBuffer(text, &in, &inlen))
return NULL;
patch = fold(bins, 0, len);
if (!patch)
return NULL;
outlen = calcsize(inlen, patch);
if (outlen < 0) {
result = NULL;
goto cleanup;
}
result = PyBytes_FromStringAndSize(NULL, outlen);
if (!result) {
result = NULL;
goto cleanup;
}
out = PyBytes_AsString(result);
if (!apply(out, in, inlen, patch)) {
Py_DECREF(result);
result = NULL;
}
cleanup:
lfree(patch);
return result;
}
/* calculate size of a patched file directly */
static PyObject *
patchedsize(PyObject *self, PyObject *args)
{
long orig, start, end, len, outlen = 0, last = 0;
int patchlen;
char *bin, *binend, *data;
uint32_t decode[3]; /* for dealing with alignment issues */
if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen))
return NULL;
binend = bin + patchlen;
data = bin + 12;
while (data <= binend) {
memcpy(decode, bin, 12);
start = ntohl(decode[0]);
end = ntohl(decode[1]);
len = ntohl(decode[2]);
if (start > end)
break; /* sanity check */
bin = data + len;
if (bin < data)
break; /* big data + big (bogus) len can wrap around */
data = bin + 12;
outlen += start - last;
last = end;
outlen += len;
}
if (bin != binend) {
if (!PyErr_Occurred())
PyErr_SetString(mpatch_Error, "patch cannot be decoded");
return NULL;
}
outlen += orig - last;
return Py_BuildValue("l", outlen);
}
static PyMethodDef methods[] = {
{"patches", patches, METH_VARARGS, "apply a series of patches\n"},
{"patchedsize", patchedsize, METH_VARARGS, "calculed patched size\n"},
{NULL, NULL}
};
#ifdef IS_PY3K
static struct PyModuleDef mpatch_module = {
PyModuleDef_HEAD_INIT,
"mpatch",
mpatch_doc,
-1,
methods
};
PyMODINIT_FUNC PyInit_mpatch(void)
{
PyObject *m;
m = PyModule_Create(&mpatch_module);
if (m == NULL)
return NULL;
mpatch_Error = PyErr_NewException("mpatch.mpatchError", NULL, NULL);
Py_INCREF(mpatch_Error);
PyModule_AddObject(m, "mpatchError", mpatch_Error);
return m;
}
#else
PyMODINIT_FUNC
initmpatch(void)
{
Py_InitModule3("mpatch", methods, mpatch_doc);
mpatch_Error = PyErr_NewException("mpatch.mpatchError", NULL, NULL);
}
#endif