repack: rewrite the shell script in C

The motivation of this patch is to get closer to a goal of being
able to have a core subset of git functionality built in to git.
That would mean

 * people on Windows could get a copy of at least the core parts
   of Git without having to install a Unix-style shell

 * people using git in on servers with chrooted environments
   do not need to worry about standard tools lacking for shell
   scripts.

This patch is meant to be mostly a literal translation of the
git-repack script; the intent is that later patches would start using
more library facilities, but this patch is meant to be as close to a
no-op as possible so it doesn't do that kind of thing.

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 194 insertions, 0 deletions

diff --git a/contrib/examples/git-repack.sh b/contrib/examples/git-repack.sh
new file mode 100755
index 0000000000..757933174e
--- /dev/null
+++ b/contrib/examples/git-repack.sh
@@ -0,0 +1,194 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Linus Torvalds
+#
+
+OPTIONS_KEEPDASHDASH=
+OPTIONS_SPEC="\
+git repack [options]
+--
+a               pack everything in a single pack
+A               same as -a, and turn unreachable objects loose
+d               remove redundant packs, and run git-prune-packed
+f               pass --no-reuse-delta to git-pack-objects
+F               pass --no-reuse-object to git-pack-objects
+n               do not run git-update-server-info
+q,quiet         be quiet
+l               pass --local to git-pack-objects
+unpack-unreachable=  with -A, do not loosen objects older than this
+ Packing constraints
+window=         size of the window used for delta compression
+window-memory=  same as the above, but limit memory size instead of entries count
+depth=          limits the maximum delta depth
+max-pack-size=  maximum size of each packfile
+"
+SUBDIRECTORY_OK='Yes'
+. git-sh-setup
+
+no_update_info= all_into_one= remove_redundant= unpack_unreachable=
+local= no_reuse= extra=
+while test $# != 0
+do
+	case "$1" in
+	-n)	no_update_info=t ;;
+	-a)	all_into_one=t ;;
+	-A)	all_into_one=t
+		unpack_unreachable=--unpack-unreachable ;;
+	--unpack-unreachable)
+		unpack_unreachable="--unpack-unreachable=$2"; shift ;;
+	-d)	remove_redundant=t ;;
+	-q)	GIT_QUIET=t ;;
+	-f)	no_reuse=--no-reuse-delta ;;
+	-F)	no_reuse=--no-reuse-object ;;
+	-l)	local=--local ;;
+	--max-pack-size|--window|--window-memory|--depth)
+		extra="$extra $1=$2"; shift ;;
+	--) shift; break;;
+	*)	usage ;;
+	esac
+	shift
+done
+
+case "`git config --bool repack.usedeltabaseoffset || echo true`" in
+true)
+	extra="$extra --delta-base-offset" ;;
+esac
+
+PACKDIR="$GIT_OBJECT_DIRECTORY/pack"
+PACKTMP="$PACKDIR/.tmp-$$-pack"
+rm -f "$PACKTMP"-*
+trap 'rm -f "$PACKTMP"-*' 0 1 2 3 15
+
+# There will be more repacking strategies to come...
+case ",$all_into_one," in
+,,)
+	args='--unpacked --incremental'
+	;;
+,t,)
+	args= existing=
+	if [ -d "$PACKDIR" ]; then
+		for e in `cd "$PACKDIR" && find . -type f -name '*.pack' \
+			| sed -e 's/^\.\///' -e 's/\.pack$//'`
+		do
+			if [ -e "$PACKDIR/$e.keep" ]; then
+				: keep
+			else
+				existing="$existing $e"
+			fi
+		done
+		if test -n "$existing" -a -n "$unpack_unreachable" -a \
+			-n "$remove_redundant"
+		then
+			# This may have arbitrary user arguments, so we
+			# have to protect it against whitespace splitting
+			# when it gets run as "pack-objects $args" later.
+			# Fortunately, we know it's an approxidate, so we
+			# can just use dots instead.
+			args="$args $(echo "$unpack_unreachable" | tr ' ' .)"
+		fi
+	fi
+	;;
+esac
+
+mkdir -p "$PACKDIR" || exit
+
+args="$args $local ${GIT_QUIET:+-q} $no_reuse$extra"
+names=$(git pack-objects --keep-true-parents --honor-pack-keep --non-empty --all --reflog $args </dev/null "$PACKTMP") ||
+	exit 1
+if [ -z "$names" ]; then
+	say Nothing new to pack.
+fi
+
+# Ok we have prepared all new packfiles.
+
+# 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-$name.idx"
+	mv -f "$PACKTMP-$name.pack" "$PACKDIR/pack-$name.pack" &&
+	mv -f "$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 $existing are all redundant.
+	if [ -n "$existing" ]
+	then
+		( cd "$PACKDIR" &&
+		  for e in $existing
+		  do
+			case " $fullbases " in
+			*" $e "*) ;;
+			*)	rm -f "$e.pack" "$e.idx" "$e.keep" ;;
+			esac
+		  done
+		)
+	fi
+	git prune-packed ${GIT_QUIET:+-q}
+fi
+
+case "$no_update_info" in
+t) : ;;
+*) git update-server-info ;;
+esac