undef/git-commit-vandalism
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Make repack less likely to corrupt repository

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Some platforms refuse to rename a file that is open.  When repacking an
already packed repository without adding any new object, the resulting
pack will contain the same set of objects as an existing pack, and on such
platforms, a newly created packfile cannot replace the existing one.

The logic detected this issue but did not try hard enough to recover from
it.  Especially because the files that needs renaming come in pairs, there
potentially are different failure modes that one can be renamed but the
others cannot.  Asking manual recovery to end users were error prone.

This patch tries to make it more robust by first making sure all the
existing files that need to be renamed have been renamed before
continuing, and attempts to roll back if some failed to rename.

This is based on an initial patch by Robin Rosenberg.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Junio C Hamano 2009-02-10 12:16:31 -08:00
parent 784f8affe4
commit 3e6b1d0abc
1 changed files with 67 additions and 20 deletions
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87
git-repack.sh
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@ -88,32 +88,79 @@ if [ -z "$names" ]; then
echo Nothing new to pack.
fi
fi
for name in $names ; do
# Ok we have prepared all new packfiles.
mkdir -p "$PACKDIR" || exit
# First see if there are packs of the same name and if so
# if we can move them out of the way (this can happen if we
# repacked immediately after packing fully.
rollback=
failed=
for name in $names
do
for sfx in pack idx
do
file=pack-$name.$sfx
test -f "$PACKDIR/$file" || continue
rm -f "$PACKDIR/old-$file" &&
mv "$PACKDIR/$file" "$PACKDIR/old-$file" || {
failed=t
break
}
rollback="$rollback $file"
done
test -z "$failed" || break
done
# If renaming failed for any of them, roll the ones we have
# already renamed back to their original names.
if test -n "$failed"
then
rollback_failure=
for file in $rollback
do
mv "$PACKDIR/old-$file" "$PACKDIR/$file" ||
rollback_failure="$rollback_failure $file"
done
if test -n "$rollback_failure"
then
echo >&2 "WARNING: Some packs in use have been renamed by"
echo >&2 "WARNING: prefixing old- to their name, in order to"
echo >&2 "WARNING: replace them with the new version of the"
echo >&2 "WARNING: file. But the operation failed, and"
echo >&2 "WARNING: attempt to rename them back to their"
echo >&2 "WARNING: original names also failed."
echo >&2 "WARNING: Please rename them in $PACKDIR manually:"
for file in $rollback_failure
do
echo >&2 "WARNING: old-$file -> $file"
done
fi
exit 1
fi
# Now the ones with the same name are out of the way...
fullbases=
for name in $names
do
fullbases="$fullbases pack-$name"
chmod a-w "$PACKTMP-$name.pack"
chmod a-w "$PACKTMP-$name.idx"
mkdir -p "$PACKDIR" || exit
for sfx in pack idx
do
if test -f "$PACKDIR/pack-$name.$sfx"
then
mv -f "$PACKDIR/pack-$name.$sfx" \
"$PACKDIR/old-pack-$name.$sfx"
fi
done &&
mv -f "$PACKTMP-$name.pack" "$PACKDIR/pack-$name.pack" &&
mv -f "$PACKTMP-$name.idx" "$PACKDIR/pack-$name.idx" &&
test -f "$PACKDIR/pack-$name.pack" &&
test -f "$PACKDIR/pack-$name.idx" || {
echo >&2 "Couldn't replace the existing pack with updated one."
echo >&2 "The original set of packs have been saved as"
echo >&2 "old-pack-$name.{pack,idx} in $PACKDIR."
exit 1
}
rm -f "$PACKDIR/old-pack-$name.pack" "$PACKDIR/old-pack-$name.idx"
mv -f "$PACKTMP-$name.idx" "$PACKDIR/pack-$name.idx" ||
exit
done
# Remove the "old-" files
for name in $names
do
rm -f "$PACKDIR/old-pack-$name.idx"
rm -f "$PACKDIR/old-pack-$name.pack"
done
# End of pack replacement.
if test "$remove_redundant" = t
then
# We know $existing are all redundant.