mpatch: raise MemoryError instead of mpatchError if lalloc() failed

MemoryError is handled differently in dispatch._runcatch().

Since mpatch_errors[] isn't that useful now, I've changed it to a simple
switch statement.

mercurial/mpatch.c

@@ -1,283 +1,280 b''
 /*
  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 <[e-mail]>
 
  This software may be used and distributed according to the terms
  of the GNU General Public License, incorporated herein by reference.
 */
 
 #include <stdlib.h>
 #include <string.h>
 
 #include "bitmanipulation.h"
 #include "compat.h"
 #include "mpatch.h"
 
-char *mpatch_errors[] = {NULL, "invalid patch", "patch cannot be decoded",
-						"no memory"};
-
 static struct mpatch_flist *lalloc(ssize_t size)
 {
 	struct mpatch_flist *a = NULL;
 
 	if (size < 1)
 		size = 1;
 
 	a = (struct mpatch_flist *)malloc(sizeof(struct mpatch_flist));
 	if (a) {
 		a->base = (struct mpatch_frag *)malloc(sizeof(struct mpatch_frag) * size);
 		if (a->base) {
 			a->head = a->tail = a->base;
 			return a;
 		}
 		free(a);
 	}
 	return NULL;
 }
 
 void mpatch_lfree(struct mpatch_flist *a)
 {
 	if (a) {
 		free(a->base);
 		free(a);
 	}
 }
 
 static ssize_t lsize(struct mpatch_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 mpatch_flist *dest, struct mpatch_flist *src, int cut,
 	int offset)
 {
 	struct mpatch_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 mpatch_flist *src, int cut, int offset)
 {
 	struct mpatch_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 mpatch_flist *combine(struct mpatch_flist *a,
 	struct mpatch_flist *b)
 {
 	struct mpatch_flist *c = NULL;
 	struct mpatch_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 mpatch_frag) * lsize(a));
 		c->tail += lsize(a);
 	}
 
 	mpatch_lfree(a);
 	mpatch_lfree(b);
 	return c;
 }
 
 /* decode a binary patch into a hunk list */
 int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res)
 {
 	struct mpatch_flist *l;
 	struct mpatch_frag *lt;
 	int pos = 0;
 
 	/* assume worst case size, we won't have many of these lists */
 	l = lalloc(len / 12 + 1);
 	if (!l)
 		return MPATCH_ERR_NO_MEM;
 
 	lt = l->tail;
 
 	while (pos >= 0 && pos < len) {
 		lt->start = getbe32(bin + pos);
 		lt->end = getbe32(bin + pos + 4);
 		lt->len = getbe32(bin + pos + 8);
 		lt->data = bin + pos + 12;
 		pos += 12 + lt->len;
 		if (lt->start > lt->end || lt->len < 0)
 			break; /* sanity check */
 		lt++;
 	}
 
 	if (pos != len) {
 		mpatch_lfree(l);
 		return MPATCH_ERR_CANNOT_BE_DECODED;
 	}
 
 	l->tail = lt;
 	*res = l;
 	return 0;
 }
 
 /* calculate the size of resultant text */
 ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l)
 {
 	ssize_t outlen = 0, last = 0;
 	struct mpatch_frag *f = l->head;
 
 	while (f != l->tail) {
 		if (f->start < last || f->end > len) {
 			return MPATCH_ERR_INVALID_PATCH;
 		}
 		outlen += f->start - last;
 		last = f->end;
 		outlen += f->len;
 		f++;
 	}
 
 	outlen += len - last;
 	return outlen;
 }
 
 int mpatch_apply(char *buf, const char *orig, ssize_t len,
 	struct mpatch_flist *l)
 {
 	struct mpatch_frag *f = l->head;
 	int last = 0;
 	char *p = buf;
 
 	while (f != l->tail) {
 		if (f->start < last || f->end > len) {
 			return MPATCH_ERR_INVALID_PATCH;
 		}
 		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 0;
 }
 
 /* recursively generate a patch of all bins between start and end */
 struct mpatch_flist *mpatch_fold(void *bins,
 	struct mpatch_flist* (*get_next_item)(void*, ssize_t),
 	ssize_t start, ssize_t end)
 {
 	ssize_t len;
 
 	if (start + 1 == end) {
 		/* trivial case, output a decoded list */
 		return get_next_item(bins, start);
 	}
 
 	/* divide and conquer, memory management is elsewhere */
 	len = (end - start) / 2;
 	return combine(mpatch_fold(bins, get_next_item, start, start + len),
 		       mpatch_fold(bins, get_next_item, start + len, end));
 }

mercurial/mpatch.h

@@ -1,28 +1,26 b''
 #ifndef _HG_MPATCH_H_
 #define _HG_MPATCH_H_
 
-extern char *mpatch_errors[];
-
 #define MPATCH_ERR_NO_MEM -3
 #define MPATCH_ERR_CANNOT_BE_DECODED -2
 #define MPATCH_ERR_INVALID_PATCH -1
 
 struct mpatch_frag {
 	int start, end, len;
 	const char *data;
 };
 
 struct mpatch_flist {
 	struct mpatch_frag *base, *head, *tail;
 };
 
 int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist** res);
 ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l);
 void mpatch_lfree(struct mpatch_flist *a);
 int mpatch_apply(char *buf, const char *orig, ssize_t len,
 	struct mpatch_flist *l);
 struct mpatch_flist *mpatch_fold(void *bins,
 	struct mpatch_flist* (*get_next_item)(void*, ssize_t),
 	ssize_t start, ssize_t end);
 
 #endif

mercurial/mpatch_module.c

@@ -1,180 +1,195 b''
 /*
  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 <[e-mail]>
 
  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 <stdlib.h>
 #include <string.h>
 
 #include "util.h"
 #include "bitmanipulation.h"
 #include "compat.h"
 #include "mpatch.h"
 
 static char mpatch_doc[] = "Efficient binary patching.";
 static PyObject *mpatch_Error;
 
+static void setpyerr(int r)
+{
+	switch (r) {
+	case MPATCH_ERR_NO_MEM:
+		PyErr_NoMemory();
+		break;
+	case MPATCH_ERR_CANNOT_BE_DECODED:
+		PyErr_SetString(mpatch_Error, "patch cannot be decoded");
+		break;
+	case MPATCH_ERR_INVALID_PATCH:
+		PyErr_SetString(mpatch_Error, "invalid patch");
+		break;
+	}
+}
+
 struct mpatch_flist *cpygetitem(void *bins, ssize_t pos)
 {
 	const char *buffer;
 	struct mpatch_flist *res;
 	ssize_t blen;
 	int r;
 
 	PyObject *tmp = PyList_GetItem((PyObject*)bins, pos);
 	if (!tmp)
 		return NULL;
 	if (PyObject_AsCharBuffer(tmp, &buffer, (Py_ssize_t*)&blen))
 		return NULL;
 	if ((r = mpatch_decode(buffer, blen, &res)) < 0) {
 		if (!PyErr_Occurred())
-			PyErr_SetString(mpatch_Error, mpatch_errors[-r]);
+			setpyerr(r);
 		return NULL;
 	}
 	return res;
 }
 
 static PyObject *
 patches(PyObject *self, PyObject *args)
 {
 	PyObject *text, *bins, *result;
 	struct mpatch_flist *patch;
 	const char *in;
 	int r = 0;
 	char *out;
 	Py_ssize_t len, outlen, 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 = mpatch_fold(bins, cpygetitem, 0, len);
 	if (!patch) { /* error already set or memory error */
 		if (!PyErr_Occurred())
 			PyErr_NoMemory();
 		return NULL;
 	}
 
 	outlen = mpatch_calcsize(inlen, patch);
 	if (outlen < 0) {
 		r = (int)outlen;
 		result = NULL;
 		goto cleanup;
 	}
 	result = PyBytes_FromStringAndSize(NULL, outlen);
 	if (!result) {
 		result = NULL;
 		goto cleanup;
 	}
 	out = PyBytes_AsString(result);
 	if ((r = mpatch_apply(out, in, inlen, patch)) < 0) {
 		Py_DECREF(result);
 		result = NULL;
 	}
 cleanup:
 	mpatch_lfree(patch);
 	if (!result && !PyErr_Occurred())
-		PyErr_SetString(mpatch_Error, mpatch_errors[-r]);
+		setpyerr(r);
 	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, pos = 0;
 	Py_ssize_t patchlen;
 	char *bin;
 
 	if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen))
 		return NULL;
 
 	while (pos >= 0 && pos < patchlen) {
 		start = getbe32(bin + pos);
 		end = getbe32(bin + pos + 4);
 		len = getbe32(bin + pos + 8);
 		if (start > end)
 			break; /* sanity check */
 		pos += 12 + len;
 		outlen += start - last;
 		last = end;
 		outlen += len;
 	}
 
 	if (pos != patchlen) {
 		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("mercurial.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("mercurial.mpatch.mpatchError",
 					  NULL, NULL);
 }
 #endif