run-tests: stuff a `python3.exe` into the test bin directory on Windows
Windows doesn't have `python3.exe` as part of the python.org distribution, and
that broke every script with a shebang after c102b704edb5. Windows itself
provides a `python3.exe` app execution alias[1], but it is some sort of reparse
point that MSYS is incapable of handling[2]. When run by MSYS, it simply prints
$ python3 -V
- Cannot open
That in turn caused every `hghave` check, and test that invokes shebang scripts
directly, to fail. Rather than try to patch up every script call to be invoked
with `$PYTHON` (and regress when non Windows developers forget), copying the
executable into the test binary directory with the new name just works. Since
this directory is prepended to the system PATH value, it also overrides the
broken execution alias. (The `_tmpbindir` is used instead of `_bindir` because
the latter causes python3.exe to be copied into the repo next to hg.exe when
`test-run-tests.t` runs. Something runs with this version of the executable and
subsequent runs of `run-tests.py` inside `test-run-tests.t` try to copy over it
while it is in use, and fail. This avoids the failures and the clutter.)
I didn't conditionalize this on py3 because `python3.exe` needs to be present
(for the shebangs) even when running py2 tests. It shouldn't matter to these
simple scripts, and I think the intention is to make the test runner use py3
always, even if testing a py2 build. For now, still supporting py2 is helping
to clean up the mess that is py3 tests.
[1] https://stackoverflow.com/a/57168165
[2] https://stackoverflow.com/questions/59148628/solved-unable-to-run-python-3-7-on-windows-10-permission-denied#comment104524397_59148666
Differential Revision: https://phab.mercurial-scm.org/D9543
/*
bdiff.c - efficient binary diff extension for Mercurial
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.
Based roughly on Python difflib
*/
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "bdiff.h"
#include "bitmanipulation.h"
#include "compat.h"
/* Hash implementation from diffutils */
#define ROL(v, n) ((v) << (n) | (v) >> (sizeof(v) * CHAR_BIT - (n)))
#define HASH(h, c) ((c) + ROL(h, 7))
struct pos {
int pos, len;
};
int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr)
{
unsigned hash;
int i;
const char *p, *b = a;
const char *const plast = a + len - 1;
struct bdiff_line *l;
/* count the lines */
i = 1; /* extra line for sentinel */
for (p = a; p < plast; p++) {
if (*p == '\n') {
i++;
}
}
if (p == plast) {
i++;
}
*lr = l = (struct bdiff_line *)calloc(i, sizeof(struct bdiff_line));
if (!l) {
return -1;
}
/* build the line array and calculate hashes */
hash = 0;
for (p = a; p < plast; p++) {
hash = HASH(hash, *p);
if (*p == '\n') {
l->hash = hash;
hash = 0;
l->len = p - b + 1;
l->l = b;
l->n = INT_MAX;
l++;
b = p + 1;
}
}
if (p == plast) {
hash = HASH(hash, *p);
l->hash = hash;
l->len = p - b + 1;
l->l = b;
l->n = INT_MAX;
l++;
}
/* set up a sentinel */
l->hash = 0;
l->len = 0;
l->l = a + len;
return i - 1;
}
static inline int cmp(struct bdiff_line *a, struct bdiff_line *b)
{
return a->hash != b->hash || a->len != b->len ||
memcmp(a->l, b->l, a->len);
}
static int equatelines(struct bdiff_line *a, int an, struct bdiff_line *b,
int bn)
{
int i, j, buckets = 1, t, scale;
struct pos *h = NULL;
/* build a hash table of the next highest power of 2 */
while (buckets < bn + 1) {
buckets *= 2;
}
/* try to allocate a large hash table to avoid collisions */
for (scale = 4; scale; scale /= 2) {
h = (struct pos *)calloc(buckets, scale * sizeof(struct pos));
if (h) {
break;
}
}
if (!h) {
return 0;
}
buckets = buckets * scale - 1;
/* clear the hash table */
for (i = 0; i <= buckets; i++) {
h[i].pos = -1;
h[i].len = 0;
}
/* add lines to the hash table chains */
for (i = 0; i < bn; i++) {
/* find the equivalence class */
for (j = b[i].hash & buckets; h[j].pos != -1;
j = (j + 1) & buckets) {
if (!cmp(b + i, b + h[j].pos)) {
break;
}
}
/* add to the head of the equivalence class */
b[i].n = h[j].pos;
b[i].e = j;
h[j].pos = i;
h[j].len++; /* keep track of popularity */
}
/* compute popularity threshold */
t = (bn >= 31000) ? bn / 1000 : 1000000 / (bn + 1);
/* match items in a to their equivalence class in b */
for (i = 0; i < an; i++) {
/* find the equivalence class */
for (j = a[i].hash & buckets; h[j].pos != -1;
j = (j + 1) & buckets) {
if (!cmp(a + i, b + h[j].pos)) {
break;
}
}
a[i].e = j; /* use equivalence class for quick compare */
if (h[j].len <= t) {
a[i].n = h[j].pos; /* point to head of match list */
} else {
a[i].n = -1; /* too popular */
}
}
/* discard hash tables */
free(h);
return 1;
}
static int longest_match(struct bdiff_line *a, struct bdiff_line *b,
struct pos *pos, int a1, int a2, int b1, int b2,
int *omi, int *omj)
{
int mi = a1, mj = b1, mk = 0, i, j, k, half, bhalf;
/* window our search on large regions to better bound
worst-case performance. by choosing a window at the end, we
reduce skipping overhead on the b chains. */
if (a2 - a1 > 30000) {
a1 = a2 - 30000;
}
half = (a1 + a2 - 1) / 2;
bhalf = (b1 + b2 - 1) / 2;
for (i = a1; i < a2; i++) {
/* skip all lines in b after the current block */
for (j = a[i].n; j >= b2; j = b[j].n) {
;
}
/* loop through all lines match a[i] in b */
for (; j >= b1; j = b[j].n) {
/* does this extend an earlier match? */
for (k = 1; j - k >= b1 && i - k >= a1; k++) {
/* reached an earlier match? */
if (pos[j - k].pos == i - k) {
k += pos[j - k].len;
break;
}
/* previous line mismatch? */
if (a[i - k].e != b[j - k].e) {
break;
}
}
pos[j].pos = i;
pos[j].len = k;
/* best match so far? we prefer matches closer
to the middle to balance recursion */
if (k > mk) {
/* a longer match */
mi = i;
mj = j;
mk = k;
} else if (k == mk) {
if (i > mi && i <= half && j > b1) {
/* same match but closer to half */
mi = i;
mj = j;
} else if (i == mi && (mj > bhalf || i == a1)) {
/* same i but best earlier j */
mj = j;
}
}
}
}
if (mk) {
mi = mi - mk + 1;
mj = mj - mk + 1;
}
/* expand match to include subsequent popular lines */
while (mi + mk < a2 && mj + mk < b2 && a[mi + mk].e == b[mj + mk].e) {
mk++;
}
*omi = mi;
*omj = mj;
return mk;
}
static struct bdiff_hunk *recurse(struct bdiff_line *a, struct bdiff_line *b,
struct pos *pos, int a1, int a2, int b1,
int b2, struct bdiff_hunk *l)
{
int i, j, k;
while (1) {
/* find the longest match in this chunk */
k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j);
if (!k) {
return l;
}
/* and recurse on the remaining chunks on either side */
l = recurse(a, b, pos, a1, i, b1, j, l);
if (!l) {
return NULL;
}
l->next =
(struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk));
if (!l->next) {
return NULL;
}
l = l->next;
l->a1 = i;
l->a2 = i + k;
l->b1 = j;
l->b2 = j + k;
l->next = NULL;
/* tail-recursion didn't happen, so do equivalent iteration */
a1 = i + k;
b1 = j + k;
}
}
int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,
struct bdiff_hunk *base)
{
struct bdiff_hunk *curr;
struct pos *pos;
int t, count = 0;
/* allocate and fill arrays */
t = equatelines(a, an, b, bn);
pos = (struct pos *)calloc(bn ? bn : 1, sizeof(struct pos));
if (pos && t) {
/* generate the matching block list */
curr = recurse(a, b, pos, 0, an, 0, bn, base);
if (!curr) {
return -1;
}
/* sentinel end hunk */
curr->next =
(struct bdiff_hunk *)malloc(sizeof(struct bdiff_hunk));
if (!curr->next) {
return -1;
}
curr = curr->next;
curr->a1 = curr->a2 = an;
curr->b1 = curr->b2 = bn;
curr->next = NULL;
}
free(pos);
/* normalize the hunk list, try to push each hunk towards the end */
for (curr = base->next; curr; curr = curr->next) {
struct bdiff_hunk *next = curr->next;
if (!next) {
break;
}
if (curr->a2 == next->a1 || curr->b2 == next->b1) {
while (curr->a2 < an && curr->b2 < bn &&
next->a1 < next->a2 && next->b1 < next->b2 &&
!cmp(a + curr->a2, b + curr->b2)) {
curr->a2++;
next->a1++;
curr->b2++;
next->b1++;
}
}
}
for (curr = base->next; curr; curr = curr->next) {
count++;
}
return count;
}
/* deallocate list of hunks; l may be NULL */
void bdiff_freehunks(struct bdiff_hunk *l)
{
struct bdiff_hunk *n;
for (; l; l = n) {
n = l->next;
free(l);
}
}