lazymanifest: avoid reading uninitialized memory
I got errors running tests with clang UBSAN [1] enabled. One of them is:
```
--- test-dirstate.t
+++ test-dirstate.t.err
@@ -85,9 +85,115 @@
$ echo "[extensions]" >> .hg/hgrc
$ echo "dirstateex=../dirstateexception.py" >> .hg/hgrc
$ hg up 0
- abort: simulated error while recording dirstateupdates
- [255]
+ mercurial/cext/manifest.c:781:13: runtime error: load of value 190, which is not a valid value for type 'bool'
+ #0 0x
7f668a8cf748 in lazymanifest_diff mercurial/cext/manifest.c:781
+ #1 0x
7f6692fc1dc4 in call_function Python-2.7.11/Python/ceval.c:4350
+ .......
+ SUMMARY: UndefinedBehaviorSanitizer: invalid-bool-load mercurial/cext/manifest.c:781:13 in
+ [1]
$ hg log -r . -T '{rev}\n'
1
$ hg status
- ? a
```
While the code is not technically wrong, but switching the condition would
make clang UBSAN happy. So let's do it.
The uninitialized memory could come from, for example, `lazymanifest_copy`
allocates `self->maxlines` items but only writes the first `self->lines`
items.
[1]: https://clang.llvm.org/docs/UndefinedBehaviorSanitizer.html
Test Plan:
Run `test-dirstate.t` with UBSAN and it no longer reports the issue.
Differential Revision: https://phab.mercurial-scm.org/D1948
#!/bin/sh
#
# This is an example of using HGEDITOR to create of diff to review the
# changes while committing.
# If you want to pass your favourite editor some other parameters
# only for Mercurial, modify this:
case "${EDITOR}" in
"")
EDITOR="vi"
;;
emacs)
EDITOR="$EDITOR -nw"
;;
gvim|vim)
EDITOR="$EDITOR -f -o"
;;
esac
HGTMP=""
cleanup_exit() {
rm -rf "$HGTMP"
}
# Remove temporary files even if we get interrupted
trap "cleanup_exit" 0 # normal exit
trap "exit 255" HUP INT QUIT ABRT TERM
HGTMP=$(mktemp -d ${TMPDIR-/tmp}/hgeditor.XXXXXX)
[ x$HGTMP != x -a -d $HGTMP ] || {
echo "Could not create temporary directory! Exiting." 1>&2
exit 1
}
(
grep '^HG: changed' "$1" | cut -b 13- | while read changed; do
"$HG" diff "$changed" >> "$HGTMP/diff"
done
)
cat "$1" > "$HGTMP/msg"
MD5=$(which md5sum 2>/dev/null) || \
MD5=$(which md5 2>/dev/null)
[ -x "${MD5}" ] && CHECKSUM=`${MD5} "$HGTMP/msg"`
if [ -s "$HGTMP/diff" ]; then
$EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $?
else
$EDITOR "$HGTMP/msg" || exit $?
fi
[ -x "${MD5}" ] && (echo "$CHECKSUM" | ${MD5} -c >/dev/null 2>&1 && exit 13)
mv "$HGTMP/msg" "$1"
exit $?