From: Lukas_Sandström <lukass@etek.chalmers.se>
Date: Wed, 9 Nov 2005 23:16:13 +0000 (+0100)
Subject: Rename git-pack-intersect to git-pack-redundant
X-Git-Tag: v0.99.9h^2~6
X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=9bc0f32c77b755b8d77d215cc47fafff53cad6f5;p=git.git

Rename git-pack-intersect to git-pack-redundant

This patch renames git-pack-intersect to git-pack-redundant
as suggested by Petr Baudis. The new name reflects what the
program does, rather than how it does it.

Also fix a small argument parsing bug.

Signed-off-by: Lukas Sandström <lukass@etek.chalmers.se>
Signed-off-by: Junio C Hamano <junkio@cox.net>
---

diff --git a/.gitignore b/.gitignore
index 6ff25300..1d1aa576 100644
--- a/.gitignore
+++ b/.gitignore
@@ -60,7 +60,7 @@ git-mktag
 git-name-rev
 git-mv
 git-octopus
-git-pack-intersect
+git-pack-redundant
 git-pack-objects
 git-parse-remote
 git-patch-id
diff --git a/Documentation/git-pack-intersect.txt b/Documentation/git-pack-intersect.txt
deleted file mode 100644
index e5d6fc7d..00000000
--- a/Documentation/git-pack-intersect.txt
+++ /dev/null
@@ -1,47 +0,0 @@
-git-pack-intersect(1)
-=====================
-
-NAME
-----
-git-pack-intersect - Program used to find redundant pack files.
-
-
-SYNOPSIS
---------
-'git-pack-intersect [ -v ] < -a | .pack filename ... >'
-
-DESCRIPTION
------------
-This program computes which packs in your repository
-are redundant. The output is suitable for piping to
-'xargs rm' if you are in the root of the repository.
-
-OPTIONS
--------
-
--v::
-	Verbose. Outputs some statistics to stderr.
-	Has a small performance penalty.
-
--a::
-	All. Processes all the local packs. Any filenames on
-	the commandline are ignored.
-
-Author
-------
-Written by Lukas Sandström <lukass@etek.chalmers.se>
-
-Documentation
---------------
-Documentation by Lukas Sandström <lukass@etek.chalmers.se>
-
-See-Also
---------
-gitlink:git-pack-objects[1]
-gitlink:git-repack[1]
-gitlink:git-prune-packed[1]
-
-GIT
----
-Part of the gitlink:git[7] suite
-
diff --git a/Documentation/git-pack-redundant.txt b/Documentation/git-pack-redundant.txt
new file mode 100644
index 00000000..55c0d48b
--- /dev/null
+++ b/Documentation/git-pack-redundant.txt
@@ -0,0 +1,47 @@
+git-pack-redundant(1)
+=====================
+
+NAME
+----
+git-pack-redundant - Program used to find redundant pack files.
+
+
+SYNOPSIS
+--------
+'git-pack-redundant [ -v ] < -a | .pack filename ... >'
+
+DESCRIPTION
+-----------
+This program computes which packs in your repository
+are redundant. The output is suitable for piping to
+'xargs rm' if you are in the root of the repository.
+
+OPTIONS
+-------
+
+-v::
+	Verbose. Outputs some statistics to stderr.
+	Has a small performance penalty.
+
+-a::
+	All. Processes all the local packs. Any filenames on
+	the commandline are ignored.
+
+Author
+------
+Written by Lukas Sandström <lukass@etek.chalmers.se>
+
+Documentation
+--------------
+Documentation by Lukas Sandström <lukass@etek.chalmers.se>
+
+See-Also
+--------
+gitlink:git-pack-objects[1]
+gitlink:git-repack[1]
+gitlink:git-prune-packed[1]
+
+GIT
+---
+Part of the gitlink:git[7] suite
+
diff --git a/Makefile b/Makefile
index 4c646c9e..b4dca5f2 100644
--- a/Makefile
+++ b/Makefile
@@ -122,7 +122,7 @@ PROGRAMS = \
 	git-unpack-objects$X git-update-index$X git-update-server-info$X \
 	git-upload-pack$X git-verify-pack$X git-write-tree$X \
 	git-update-ref$X git-symbolic-ref$X git-check-ref-format$X \
-	git-name-rev$X git-pack-intersect$X $(SIMPLE_PROGRAMS)
+	git-name-rev$X git-pack-redundant$X $(SIMPLE_PROGRAMS)
 
 # Backward compatibility -- to be removed after 1.0
 PROGRAMS += git-ssh-pull$X git-ssh-push$X
diff --git a/git-repack.sh b/git-repack.sh
index 3f283005..4ce00225 100755
--- a/git-repack.sh
+++ b/git-repack.sh
@@ -45,7 +45,7 @@ if [ -z "$name" ]; then
 	if test "$remove_redandant" = t ; then
 		echo "Removing redundant packs."
 		sync
-		redundant=$(git-pack-intersect -a)
+		redundant=$(git-pack-redundant -a)
 		if test "$redundant" != "" ; then
 			echo $redundant | xargs rm
 		fi
@@ -63,7 +63,7 @@ exit
 if test "$remove_redandant" = t
 then
 	sync
-	redundant=$(git-pack-intersect -a)
+	redundant=$(git-pack-redundant -a)
 	if test "$redundant" != "" ; then
 		echo $redundant | xargs rm
 	fi
diff --git a/pack-intersect.c b/pack-intersect.c
deleted file mode 100644
index 2267478c..00000000
--- a/pack-intersect.c
+++ /dev/null
@@ -1,577 +0,0 @@
-/*
-*
-* Copyright 2005, Lukas Sandstrom <lukass@etek.chalmers.se>
-*
-* This file is licensed under the GPL v2.
-*
-*/
-
-#include "cache.h"
-
-static const char pack_intersect_usage[] =
-"git-pack-intersect [ -v ]  < -a | <.pack filename> ...>";
-
-int all = 0, verbose = 0;
-
-struct llist_item {
-	struct llist_item *next;
-	char *sha1;
-};
-struct llist {
-	struct llist_item *front;
-	struct llist_item *back;
-	size_t size;
-} *all_objects;
-
-struct pack_list {
-	struct pack_list *next;
-	struct packed_git *pack;
-	struct llist *unique_objects;
-	struct llist *all_objects;
-} *pack_list;
-
-struct pll {
-	struct pll *next;
-	struct pack_list *pl;
-};
-
-inline void llist_free(struct llist *list)
-{
-	while((list->back = list->front)) {
-		list->front = list->front->next;
-		free(list->back);
-	}
-	free(list);
-}
-
-inline void llist_init(struct llist **list)
-{
-	*list = xmalloc(sizeof(struct llist));
-	(*list)->front = (*list)->back = NULL;
-	(*list)->size = 0;
-}
-
-struct llist * llist_copy(struct llist *list)
-{
-	struct llist *ret;
-	struct llist_item *new, *old, *prev;
-	
-	llist_init(&ret);
-
-	if ((ret->size = list->size) == 0)
-		return ret;
-
-	new = ret->front = xmalloc(sizeof(struct llist_item));
-	new->sha1 = list->front->sha1;
-
-	old = list->front->next;
-	while (old) {
-		prev = new;
-		new = xmalloc(sizeof(struct llist_item));
-		prev->next = new;
-		new->sha1 = old->sha1;
-		old = old->next;
-	}
-	new->next = NULL;
-	ret->back = new;
-	
-	return ret;
-}
-
-inline struct llist_item * llist_insert(struct llist *list,
-					struct llist_item *after, char *sha1)
-{
-	struct llist_item *new = xmalloc(sizeof(struct llist_item));
-	new->sha1 = sha1;
-	new->next = NULL;
-
-	if (after != NULL) {
-		new->next = after->next;
-		after->next = new;
-		if (after == list->back)
-			list->back = new;
-	} else {/* insert in front */
-		if (list->size == 0)
-			list->back = new;
-		else
-			new->next = list->front;
-		list->front = new;
-	}
-	list->size++;
-	return new;
-}
-
-inline struct llist_item * llist_insert_back(struct llist *list, char *sha1)
-{
-	return llist_insert(list, list->back, sha1);
-}
-
-inline struct llist_item * llist_insert_sorted_unique(struct llist *list,
-					char *sha1, struct llist_item *hint)
-{
-	struct llist_item *prev = NULL, *l;
-
-	l = (hint == NULL) ? list->front : hint;
-	while (l) {
-		int cmp = memcmp(l->sha1, sha1, 20);
-		if (cmp > 0) { /* we insert before this entry */
-			return llist_insert(list, prev, sha1);
-		}
-		if(!cmp) { /* already exists */
-			return l;
-		}
-		prev = l;
-		l = l->next;
-	}
-	/* insert at the end */
-	return llist_insert_back(list, sha1);
-}
-
-/* computes A\B */
-struct llist * llist_sorted_difference(struct llist_item *A,
-				       struct llist_item *B)
-{
-	struct llist *ret;
-	llist_init(&ret);
-
-	while (A != NULL && B != NULL) {
-		int cmp = memcmp(A->sha1, B->sha1, 20);
-		if (!cmp) {
-			A = A->next;
-			B = B->next;
-			continue;
-		}
-		if(cmp > 0) { /* we'll never find this B */
-			B = B->next;
-			continue;
-		}
-		/* A has the object, B doesn't */
-		llist_insert_back(ret, A->sha1);
-		A = A->next;
-	}
-	while (A != NULL) {
-		llist_insert_back(ret, A->sha1);
-		A = A->next;
-	}
-	return ret;
-}
-
-/* returns a pointer to an item in front of sha1 */
-inline struct llist_item * llist_sorted_remove(struct llist *list, char *sha1,
-					       struct llist_item *hint)
-{
-	struct llist_item *prev, *l;
-
-redo_from_start:
-	l = (hint == NULL) ? list->front : hint;
-	prev = NULL;
-	while (l) {
-		int cmp = memcmp(l->sha1, sha1, 20);
-		if (cmp > 0) /* not in list, since sorted */
-			return prev;
-		if(!cmp) { /* found */
-			if (prev == NULL) {
-				if (hint != NULL && hint != list->front) {
-					/* we don't know the previous element */
-					hint = NULL;
-					goto redo_from_start;
-				}
-				list->front = l->next;
-			} else
-				prev->next = l->next;
-			if (l == list->back)
-				list->back = prev;
-			free(l);
-			list->size--;
-			return prev;
-		}
-		prev = l;
-		l = l->next;
-	}
-	return prev;
-}
-
-inline struct pack_list * pack_list_insert(struct pack_list **pl,
-					   struct pack_list *entry)
-{
-	struct pack_list *p = xmalloc(sizeof(struct pack_list));
-	memcpy(p, entry, sizeof(struct pack_list));
-	p->next = *pl;
-	*pl = p;
-	return p;
-}
-
-struct pack_list * pack_list_difference(struct pack_list *A,
-					struct pack_list *B)
-{
-	struct pack_list *ret, *pl;
-
-	if (A == NULL)
-		return NULL;
-
-	pl = B;
-	while (pl != NULL) {
-		if (A->pack == pl->pack)
-			return pack_list_difference(A->next, B);
-		pl = pl->next;
-	}
-	ret = xmalloc(sizeof(struct pack_list));
-	memcpy(ret, A, sizeof(struct pack_list));
-	ret->next = pack_list_difference(A->next, B);
-	return ret;
-}
-
-void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
-{
-	int p1_off, p2_off;
-	void *p1_base, *p2_base;
-	struct llist_item *p1_hint = NULL, *p2_hint = NULL;
-	
-	p1_off = p2_off = 256 * 4 + 4;
-	p1_base = (void *)p1->pack->index_base;
-	p2_base = (void *)p2->pack->index_base;
-
-	while (p1_off <= p1->pack->index_size - 3 * 20 &&
-	       p2_off <= p2->pack->index_size - 3 * 20)
-	{
-		int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
-		/* cmp ~ p1 - p2 */
-		if (cmp == 0) {
-			p1_hint = llist_sorted_remove(p1->unique_objects,
-					p1_base + p1_off, p1_hint);
-			p2_hint = llist_sorted_remove(p2->unique_objects,
-					p1_base + p1_off, p2_hint);
-			p1_off+=24;
-			p2_off+=24;
-			continue;
-		}
-		if (cmp < 0) { /* p1 has the object, p2 doesn't */
-			p1_off+=24;
-		} else { /* p2 has the object, p1 doesn't */
-			p2_off+=24;
-		}
-	}
-}
-
-/* all the permutations have to be free()d at the same time,
- * since they refer to each other
- */
-struct pll * get_all_permutations(struct pack_list *list)
-{
-	struct pll *subset, *pll, *new_pll = NULL; /*silence warning*/
-
-	if (list == NULL)
-		return NULL;
-
-	if (list->next == NULL) {
-		new_pll = xmalloc(sizeof(struct pll));
-		new_pll->next = NULL;
-		new_pll->pl = list;
-		return new_pll;
-	}
-
-	pll = subset = get_all_permutations(list->next);
-	while (pll) {
-		new_pll = xmalloc(sizeof(struct pll));
-		new_pll->next = pll->next;
-		pll->next = new_pll;
-
-		new_pll->pl = xmalloc(sizeof(struct pack_list));
-		memcpy(new_pll->pl, list, sizeof(struct pack_list));
-		new_pll->pl->next = pll->pl;
-
-		pll = new_pll->next;
-	}
-	/* add ourself to the end */
-	new_pll->next = xmalloc(sizeof(struct pll));
-	new_pll->next->pl = xmalloc(sizeof(struct pack_list));
-	new_pll->next->next = NULL;
-	memcpy(new_pll->next->pl, list, sizeof(struct pack_list));
-	new_pll->next->pl->next = NULL;
-
-	return subset;
-}
-
-int is_superset(struct pack_list *pl, struct llist *list)
-{
-	struct llist *diff, *old;
-
-	diff = llist_copy(list);
-
-	while (pl) {
-		old = diff;
-		diff = llist_sorted_difference(diff->front,
-					       pl->all_objects->front);
-		llist_free(old);
-		if (diff->size == 0) { /* we're done */
-			llist_free(diff);
-			return 1;
-		}
-		pl = pl->next;
-	}
-	llist_free(diff);
-	return 0;
-}
-
-size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
-{
-	size_t ret = 0;
-	int p1_off, p2_off;
-	void *p1_base, *p2_base;
-
-	p1_off = p2_off = 256 * 4 + 4;
-	p1_base = (void *)p1->index_base;
-	p2_base = (void *)p2->index_base;
-
-	while (p1_off <= p1->index_size - 3 * 20 &&
-	       p2_off <= p2->index_size - 3 * 20)
-	{
-		int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
-		/* cmp ~ p1 - p2 */
-		if (cmp == 0) {
-			ret++;
-			p1_off+=24;
-			p2_off+=24;
-			continue;
-		}
-		if (cmp < 0) { /* p1 has the object, p2 doesn't */
-			p1_off+=24;
-		} else { /* p2 has the object, p1 doesn't */
-			p2_off+=24;
-		}
-	}
-	return ret;
-}
-
-/* another O(n^2) function ... */
-size_t get_pack_redundancy(struct pack_list *pl)
-{
-	struct pack_list *subset;
-	size_t ret = 0;
-	while ((subset = pl->next)) {
-		while(subset) {
-			ret += sizeof_union(pl->pack, subset->pack);
-			subset = subset->next;
-		}
-		pl = pl->next;
-	}
-	return ret;
-}
-
-inline size_t pack_set_bytecount(struct pack_list *pl)
-{
-	size_t ret = 0;
-	while (pl) {
-		ret += pl->pack->pack_size;
-		ret += pl->pack->index_size;
-		pl = pl->next;
-	}
-	return ret;
-}
-
-void minimize(struct pack_list **min)
-{
-	struct pack_list *pl, *unique = NULL,
-		*non_unique = NULL, *min_perm = NULL;
-	struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
-	struct llist *missing, *old;
-	size_t min_perm_size = (size_t)-1, perm_size;
-
-	pl = pack_list;
-	while (pl) {
-		if(pl->unique_objects->size)
-			pack_list_insert(&unique, pl);
-		else
-			pack_list_insert(&non_unique, pl);
-		pl = pl->next;
-	}
-	/* find out which objects are missing from the set of unique packs */
-	missing = llist_copy(all_objects);
-	pl = unique;
-	while (pl) {
-		old = missing;
-		missing = llist_sorted_difference(missing->front,
-						  pl->all_objects->front);
-		llist_free(old);
-		pl = pl->next;
-	}
-
-	if (missing->size == 0) {
-		*min = unique;
-		return;
-	}
-
-	/* find the permutations which contain all missing objects */
-	perm_all = perm = get_all_permutations(non_unique);
-	while (perm) {
-		if (is_superset(perm->pl, missing)) {
-			new_perm = xmalloc(sizeof(struct pll));
-			new_perm->pl = perm->pl;
-			new_perm->next = perm_ok;
-			perm_ok = new_perm;
-		}
-		perm = perm->next;
-	}
-	
-	if (perm_ok == NULL)
-		die("Internal error: No complete sets found!\n");
-
-	/* find the permutation with the smallest size */
-	perm = perm_ok;
-	while (perm) {
-		perm_size = pack_set_bytecount(perm->pl);
-		if (min_perm_size > perm_size) {
-			min_perm_size = perm_size;
-			min_perm = perm->pl;
-		}
-		perm = perm->next;
-	}
-	*min = min_perm;
-	/* add the unique packs to the list */
-	pl = unique;
-	while(pl) {
-		pack_list_insert(min, pl);
-		pl = pl->next;
-	}
-}
-
-void load_all_objects()
-{
-	struct pack_list *pl = pack_list;
-	struct llist_item *hint, *l;
-	int i;
-
-	llist_init(&all_objects);
-
-	while (pl) {
-		i = 0;
-		hint = NULL;
-		l = pl->all_objects->front;
-		while (l) {
-			hint = llist_insert_sorted_unique(all_objects,
-							  l->sha1, hint);
-			l = l->next;
-		}
-		pl = pl->next;
-	}
-}
-
-/* this scales like O(n^2) */
-void cmp_packs()
-{
-	struct pack_list *subset, *curr = pack_list;
-
-	while ((subset = curr)) {
-		while((subset = subset->next))
-			cmp_two_packs(curr, subset);
-		curr = curr->next;
-	}
-}
-
-struct pack_list * add_pack(struct packed_git *p)
-{
-	struct pack_list l;
-	size_t off;
-	void *base;
-
-	l.pack = p;
-	llist_init(&l.all_objects);
-
-	off = 256 * 4 + 4;
-	base = (void *)p->index_base;
-	while (off <= p->index_size - 3 * 20) {
-		llist_insert_back(l.all_objects, base + off);
-		off+=24;
-	}
-	/* this list will be pruned in cmp_two_packs later */
-	l.unique_objects = llist_copy(l.all_objects);
-	return pack_list_insert(&pack_list, &l);
-}
-
-struct pack_list * add_pack_file(char *filename)
-{
-	struct packed_git *p = packed_git;
-
-	if (strlen(filename) < 40)
-		die("Bad pack filename: %s\n", filename);
-
-	while (p) {
-		if (strstr(p->pack_name, filename))
-			/* this will silently ignore packs in alt-odb */
-			return add_pack(p);
-		p = p->next;
-	}
-	die("Filename %s not found in packed_git\n", filename);
-}
-
-void load_all()
-{
-	struct packed_git *p = packed_git;
-
-	while (p) {
-		if (p->pack_local) /* ignore alt-odb for now */
-			add_pack(p);
-		p = p->next;
-	}
-}
-
-int main(int argc, char **argv)
-{
-	int i;
-	struct pack_list *min, *red, *pl;
-
-	for (i = 1; i < argc; i++) {
-		const char *arg = argv[i];
-		if(!strcmp(arg, "--"))
-			break;
-		if(!strcmp(arg, "-a")) {
-			all = 1;
-			continue;
-		}
-		if(!strcmp(arg, "-v")) {
-			verbose = 1;
-			continue;
-		}
-		if(*arg == '-')
-			usage(pack_intersect_usage);
-		else
-			break;
-	}
-
-	prepare_packed_git();
-
-	if(all)
-		load_all();
-	else
-		while (*(argv + i) != NULL)
-			add_pack_file(*(argv + i++));
-
-	if (pack_list == NULL)
-		die("Zero packs found!\n");
-
-	cmp_packs();
-
-	load_all_objects();
-
-	minimize(&min);
-	if (verbose) {
-		fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
-		pl = min;
-		while (pl) {
-			fprintf(stderr, "\t%s\n", pl->pack->pack_name);
-			pl = pl->next;
-		}
-		fprintf(stderr, "containing %ld duplicate objects "
-				"with a total size of %ldkb.\n",
-			get_pack_redundancy(min), pack_set_bytecount(min)/1024);
-		fprintf(stderr, "Redundant packs (with indexes):\n");
-	}
-	pl = red = pack_list_difference(pack_list, min);
-	while (pl) {
-		printf("%s\n%s\n",
-		       sha1_pack_index_name(pl->pack->sha1), pl->pack->pack_name);
-		pl = pl->next;
-	}
-
-	return 0;
-}
diff --git a/pack-redundant.c b/pack-redundant.c
new file mode 100644
index 00000000..db3dcde2
--- /dev/null
+++ b/pack-redundant.c
@@ -0,0 +1,579 @@
+/*
+*
+* Copyright 2005, Lukas Sandstrom <lukass@etek.chalmers.se>
+*
+* This file is licensed under the GPL v2.
+*
+*/
+
+#include "cache.h"
+
+static const char pack_redundant_usage[] =
+"git-pack-redundant [ -v ]  < -a | <.pack filename> ...>";
+
+int all = 0, verbose = 0;
+
+struct llist_item {
+	struct llist_item *next;
+	char *sha1;
+};
+struct llist {
+	struct llist_item *front;
+	struct llist_item *back;
+	size_t size;
+} *all_objects;
+
+struct pack_list {
+	struct pack_list *next;
+	struct packed_git *pack;
+	struct llist *unique_objects;
+	struct llist *all_objects;
+} *pack_list;
+
+struct pll {
+	struct pll *next;
+	struct pack_list *pl;
+};
+
+inline void llist_free(struct llist *list)
+{
+	while((list->back = list->front)) {
+		list->front = list->front->next;
+		free(list->back);
+	}
+	free(list);
+}
+
+inline void llist_init(struct llist **list)
+{
+	*list = xmalloc(sizeof(struct llist));
+	(*list)->front = (*list)->back = NULL;
+	(*list)->size = 0;
+}
+
+struct llist * llist_copy(struct llist *list)
+{
+	struct llist *ret;
+	struct llist_item *new, *old, *prev;
+	
+	llist_init(&ret);
+
+	if ((ret->size = list->size) == 0)
+		return ret;
+
+	new = ret->front = xmalloc(sizeof(struct llist_item));
+	new->sha1 = list->front->sha1;
+
+	old = list->front->next;
+	while (old) {
+		prev = new;
+		new = xmalloc(sizeof(struct llist_item));
+		prev->next = new;
+		new->sha1 = old->sha1;
+		old = old->next;
+	}
+	new->next = NULL;
+	ret->back = new;
+	
+	return ret;
+}
+
+inline struct llist_item * llist_insert(struct llist *list,
+					struct llist_item *after, char *sha1)
+{
+	struct llist_item *new = xmalloc(sizeof(struct llist_item));
+	new->sha1 = sha1;
+	new->next = NULL;
+
+	if (after != NULL) {
+		new->next = after->next;
+		after->next = new;
+		if (after == list->back)
+			list->back = new;
+	} else {/* insert in front */
+		if (list->size == 0)
+			list->back = new;
+		else
+			new->next = list->front;
+		list->front = new;
+	}
+	list->size++;
+	return new;
+}
+
+inline struct llist_item * llist_insert_back(struct llist *list, char *sha1)
+{
+	return llist_insert(list, list->back, sha1);
+}
+
+inline struct llist_item * llist_insert_sorted_unique(struct llist *list,
+					char *sha1, struct llist_item *hint)
+{
+	struct llist_item *prev = NULL, *l;
+
+	l = (hint == NULL) ? list->front : hint;
+	while (l) {
+		int cmp = memcmp(l->sha1, sha1, 20);
+		if (cmp > 0) { /* we insert before this entry */
+			return llist_insert(list, prev, sha1);
+		}
+		if(!cmp) { /* already exists */
+			return l;
+		}
+		prev = l;
+		l = l->next;
+	}
+	/* insert at the end */
+	return llist_insert_back(list, sha1);
+}
+
+/* computes A\B */
+struct llist * llist_sorted_difference(struct llist_item *A,
+				       struct llist_item *B)
+{
+	struct llist *ret;
+	llist_init(&ret);
+
+	while (A != NULL && B != NULL) {
+		int cmp = memcmp(A->sha1, B->sha1, 20);
+		if (!cmp) {
+			A = A->next;
+			B = B->next;
+			continue;
+		}
+		if(cmp > 0) { /* we'll never find this B */
+			B = B->next;
+			continue;
+		}
+		/* A has the object, B doesn't */
+		llist_insert_back(ret, A->sha1);
+		A = A->next;
+	}
+	while (A != NULL) {
+		llist_insert_back(ret, A->sha1);
+		A = A->next;
+	}
+	return ret;
+}
+
+/* returns a pointer to an item in front of sha1 */
+inline struct llist_item * llist_sorted_remove(struct llist *list, char *sha1,
+					       struct llist_item *hint)
+{
+	struct llist_item *prev, *l;
+
+redo_from_start:
+	l = (hint == NULL) ? list->front : hint;
+	prev = NULL;
+	while (l) {
+		int cmp = memcmp(l->sha1, sha1, 20);
+		if (cmp > 0) /* not in list, since sorted */
+			return prev;
+		if(!cmp) { /* found */
+			if (prev == NULL) {
+				if (hint != NULL && hint != list->front) {
+					/* we don't know the previous element */
+					hint = NULL;
+					goto redo_from_start;
+				}
+				list->front = l->next;
+			} else
+				prev->next = l->next;
+			if (l == list->back)
+				list->back = prev;
+			free(l);
+			list->size--;
+			return prev;
+		}
+		prev = l;
+		l = l->next;
+	}
+	return prev;
+}
+
+inline struct pack_list * pack_list_insert(struct pack_list **pl,
+					   struct pack_list *entry)
+{
+	struct pack_list *p = xmalloc(sizeof(struct pack_list));
+	memcpy(p, entry, sizeof(struct pack_list));
+	p->next = *pl;
+	*pl = p;
+	return p;
+}
+
+struct pack_list * pack_list_difference(struct pack_list *A,
+					struct pack_list *B)
+{
+	struct pack_list *ret, *pl;
+
+	if (A == NULL)
+		return NULL;
+
+	pl = B;
+	while (pl != NULL) {
+		if (A->pack == pl->pack)
+			return pack_list_difference(A->next, B);
+		pl = pl->next;
+	}
+	ret = xmalloc(sizeof(struct pack_list));
+	memcpy(ret, A, sizeof(struct pack_list));
+	ret->next = pack_list_difference(A->next, B);
+	return ret;
+}
+
+void cmp_two_packs(struct pack_list *p1, struct pack_list *p2)
+{
+	int p1_off, p2_off;
+	void *p1_base, *p2_base;
+	struct llist_item *p1_hint = NULL, *p2_hint = NULL;
+	
+	p1_off = p2_off = 256 * 4 + 4;
+	p1_base = (void *)p1->pack->index_base;
+	p2_base = (void *)p2->pack->index_base;
+
+	while (p1_off <= p1->pack->index_size - 3 * 20 &&
+	       p2_off <= p2->pack->index_size - 3 * 20)
+	{
+		int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
+		/* cmp ~ p1 - p2 */
+		if (cmp == 0) {
+			p1_hint = llist_sorted_remove(p1->unique_objects,
+					p1_base + p1_off, p1_hint);
+			p2_hint = llist_sorted_remove(p2->unique_objects,
+					p1_base + p1_off, p2_hint);
+			p1_off+=24;
+			p2_off+=24;
+			continue;
+		}
+		if (cmp < 0) { /* p1 has the object, p2 doesn't */
+			p1_off+=24;
+		} else { /* p2 has the object, p1 doesn't */
+			p2_off+=24;
+		}
+	}
+}
+
+/* all the permutations have to be free()d at the same time,
+ * since they refer to each other
+ */
+struct pll * get_all_permutations(struct pack_list *list)
+{
+	struct pll *subset, *pll, *new_pll = NULL; /*silence warning*/
+
+	if (list == NULL)
+		return NULL;
+
+	if (list->next == NULL) {
+		new_pll = xmalloc(sizeof(struct pll));
+		new_pll->next = NULL;
+		new_pll->pl = list;
+		return new_pll;
+	}
+
+	pll = subset = get_all_permutations(list->next);
+	while (pll) {
+		new_pll = xmalloc(sizeof(struct pll));
+		new_pll->next = pll->next;
+		pll->next = new_pll;
+
+		new_pll->pl = xmalloc(sizeof(struct pack_list));
+		memcpy(new_pll->pl, list, sizeof(struct pack_list));
+		new_pll->pl->next = pll->pl;
+
+		pll = new_pll->next;
+	}
+	/* add ourself to the end */
+	new_pll->next = xmalloc(sizeof(struct pll));
+	new_pll->next->pl = xmalloc(sizeof(struct pack_list));
+	new_pll->next->next = NULL;
+	memcpy(new_pll->next->pl, list, sizeof(struct pack_list));
+	new_pll->next->pl->next = NULL;
+
+	return subset;
+}
+
+int is_superset(struct pack_list *pl, struct llist *list)
+{
+	struct llist *diff, *old;
+
+	diff = llist_copy(list);
+
+	while (pl) {
+		old = diff;
+		diff = llist_sorted_difference(diff->front,
+					       pl->all_objects->front);
+		llist_free(old);
+		if (diff->size == 0) { /* we're done */
+			llist_free(diff);
+			return 1;
+		}
+		pl = pl->next;
+	}
+	llist_free(diff);
+	return 0;
+}
+
+size_t sizeof_union(struct packed_git *p1, struct packed_git *p2)
+{
+	size_t ret = 0;
+	int p1_off, p2_off;
+	void *p1_base, *p2_base;
+
+	p1_off = p2_off = 256 * 4 + 4;
+	p1_base = (void *)p1->index_base;
+	p2_base = (void *)p2->index_base;
+
+	while (p1_off <= p1->index_size - 3 * 20 &&
+	       p2_off <= p2->index_size - 3 * 20)
+	{
+		int cmp = memcmp(p1_base + p1_off, p2_base + p2_off, 20);
+		/* cmp ~ p1 - p2 */
+		if (cmp == 0) {
+			ret++;
+			p1_off+=24;
+			p2_off+=24;
+			continue;
+		}
+		if (cmp < 0) { /* p1 has the object, p2 doesn't */
+			p1_off+=24;
+		} else { /* p2 has the object, p1 doesn't */
+			p2_off+=24;
+		}
+	}
+	return ret;
+}
+
+/* another O(n^2) function ... */
+size_t get_pack_redundancy(struct pack_list *pl)
+{
+	struct pack_list *subset;
+	size_t ret = 0;
+	while ((subset = pl->next)) {
+		while(subset) {
+			ret += sizeof_union(pl->pack, subset->pack);
+			subset = subset->next;
+		}
+		pl = pl->next;
+	}
+	return ret;
+}
+
+inline size_t pack_set_bytecount(struct pack_list *pl)
+{
+	size_t ret = 0;
+	while (pl) {
+		ret += pl->pack->pack_size;
+		ret += pl->pack->index_size;
+		pl = pl->next;
+	}
+	return ret;
+}
+
+void minimize(struct pack_list **min)
+{
+	struct pack_list *pl, *unique = NULL,
+		*non_unique = NULL, *min_perm = NULL;
+	struct pll *perm, *perm_all, *perm_ok = NULL, *new_perm;
+	struct llist *missing, *old;
+	size_t min_perm_size = (size_t)-1, perm_size;
+
+	pl = pack_list;
+	while (pl) {
+		if(pl->unique_objects->size)
+			pack_list_insert(&unique, pl);
+		else
+			pack_list_insert(&non_unique, pl);
+		pl = pl->next;
+	}
+	/* find out which objects are missing from the set of unique packs */
+	missing = llist_copy(all_objects);
+	pl = unique;
+	while (pl) {
+		old = missing;
+		missing = llist_sorted_difference(missing->front,
+						  pl->all_objects->front);
+		llist_free(old);
+		pl = pl->next;
+	}
+
+	if (missing->size == 0) {
+		*min = unique;
+		return;
+	}
+
+	/* find the permutations which contain all missing objects */
+	perm_all = perm = get_all_permutations(non_unique);
+	while (perm) {
+		if (is_superset(perm->pl, missing)) {
+			new_perm = xmalloc(sizeof(struct pll));
+			new_perm->pl = perm->pl;
+			new_perm->next = perm_ok;
+			perm_ok = new_perm;
+		}
+		perm = perm->next;
+	}
+	
+	if (perm_ok == NULL)
+		die("Internal error: No complete sets found!\n");
+
+	/* find the permutation with the smallest size */
+	perm = perm_ok;
+	while (perm) {
+		perm_size = pack_set_bytecount(perm->pl);
+		if (min_perm_size > perm_size) {
+			min_perm_size = perm_size;
+			min_perm = perm->pl;
+		}
+		perm = perm->next;
+	}
+	*min = min_perm;
+	/* add the unique packs to the list */
+	pl = unique;
+	while(pl) {
+		pack_list_insert(min, pl);
+		pl = pl->next;
+	}
+}
+
+void load_all_objects()
+{
+	struct pack_list *pl = pack_list;
+	struct llist_item *hint, *l;
+	int i;
+
+	llist_init(&all_objects);
+
+	while (pl) {
+		i = 0;
+		hint = NULL;
+		l = pl->all_objects->front;
+		while (l) {
+			hint = llist_insert_sorted_unique(all_objects,
+							  l->sha1, hint);
+			l = l->next;
+		}
+		pl = pl->next;
+	}
+}
+
+/* this scales like O(n^2) */
+void cmp_packs()
+{
+	struct pack_list *subset, *curr = pack_list;
+
+	while ((subset = curr)) {
+		while((subset = subset->next))
+			cmp_two_packs(curr, subset);
+		curr = curr->next;
+	}
+}
+
+struct pack_list * add_pack(struct packed_git *p)
+{
+	struct pack_list l;
+	size_t off;
+	void *base;
+
+	l.pack = p;
+	llist_init(&l.all_objects);
+
+	off = 256 * 4 + 4;
+	base = (void *)p->index_base;
+	while (off <= p->index_size - 3 * 20) {
+		llist_insert_back(l.all_objects, base + off);
+		off+=24;
+	}
+	/* this list will be pruned in cmp_two_packs later */
+	l.unique_objects = llist_copy(l.all_objects);
+	return pack_list_insert(&pack_list, &l);
+}
+
+struct pack_list * add_pack_file(char *filename)
+{
+	struct packed_git *p = packed_git;
+
+	if (strlen(filename) < 40)
+		die("Bad pack filename: %s\n", filename);
+
+	while (p) {
+		if (strstr(p->pack_name, filename))
+			/* this will silently ignore packs in alt-odb */
+			return add_pack(p);
+		p = p->next;
+	}
+	die("Filename %s not found in packed_git\n", filename);
+}
+
+void load_all()
+{
+	struct packed_git *p = packed_git;
+
+	while (p) {
+		if (p->pack_local) /* ignore alt-odb for now */
+			add_pack(p);
+		p = p->next;
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int i;
+	struct pack_list *min, *red, *pl;
+
+	for (i = 1; i < argc; i++) {
+		const char *arg = argv[i];
+		if(!strcmp(arg, "--")) {
+			i++;
+			break;
+		}
+		if(!strcmp(arg, "-a")) {
+			all = 1;
+			continue;
+		}
+		if(!strcmp(arg, "-v")) {
+			verbose = 1;
+			continue;
+		}
+		if(*arg == '-')
+			usage(pack_redundant_usage);
+		else
+			break;
+	}
+
+	prepare_packed_git();
+
+	if(all)
+		load_all();
+	else
+		while (*(argv + i) != NULL)
+			add_pack_file(*(argv + i++));
+
+	if (pack_list == NULL)
+		die("Zero packs found!\n");
+
+	cmp_packs();
+
+	load_all_objects();
+
+	minimize(&min);
+	if (verbose) {
+		fprintf(stderr, "The smallest (bytewise) set of packs is:\n");
+		pl = min;
+		while (pl) {
+			fprintf(stderr, "\t%s\n", pl->pack->pack_name);
+			pl = pl->next;
+		}
+		fprintf(stderr, "containing %ld duplicate objects "
+				"with a total size of %ldkb.\n",
+			get_pack_redundancy(min), pack_set_bytecount(min)/1024);
+		fprintf(stderr, "Redundant packs (with indexes):\n");
+	}
+	pl = red = pack_list_difference(pack_list, min);
+	while (pl) {
+		printf("%s\n%s\n",
+		       sha1_pack_index_name(pl->pack->sha1), pl->pack->pack_name);
+		pl = pl->next;
+	}
+
+	return 0;
+}