Merge branch 'jc/cache-unmerge'

* jc/cache-unmerge:
  rerere forget path: forget recorded resolution
  rerere: refactor rerere logic to make it independent from I/O
  rerere: remove silly 1024-byte line limit
  resolve-undo: teach "update-index --unresolve" to use resolve-undo info
  resolve-undo: "checkout -m path" uses resolve-undo information
  resolve-undo: allow plumbing to clear the information
  resolve-undo: basic tests
  resolve-undo: record resolved conflicts in a new index extension section
  builtin-merge.c: use standard active_cache macros

Conflicts:
	builtin-ls-files.c
	builtin-merge.c
	builtin-rerere.c

Makefile

@@ -497,6 +497,7 @@ LIB_H += reflog-walk.h
 LIB_H += refs.h
 LIB_H += remote.h
 LIB_H += rerere.h
+LIB_H += resolve-undo.h
 LIB_H += revision.h
 LIB_H += run-command.h
 LIB_H += sha1-lookup.h
@@ -592,6 +593,7 @@ LIB_OBJS += refs.o
 LIB_OBJS += remote.o
 LIB_OBJS += replace_object.o
 LIB_OBJS += rerere.o
+LIB_OBJS += resolve-undo.o
 LIB_OBJS += revision.o
 LIB_OBJS += run-command.o
 LIB_OBJS += server-info.o

builtin-checkout.c

@@ -17,6 +17,7 @@
 #include "blob.h"
 #include "xdiff-interface.h"
 #include "ll-merge.h"
+#include "resolve-undo.h"
 
 static const char * const checkout_usage[] = {
 	"git checkout [options] <branch>",
@@ -234,6 +235,10 @@ static int checkout_paths(struct tree *source_tree, const char **pathspec,
 	if (report_path_error(ps_matched, pathspec, 0))
 		return 1;
 
+	/* "checkout -m path" to recreate conflicted state */
+	if (opts->merge)
+		unmerge_cache(pathspec);
+
 	/* Any unmerged paths? */
 	for (pos = 0; pos < active_nr; pos++) {
 		struct cache_entry *ce = active_cache[pos];
@@ -370,6 +375,7 @@ static int merge_working_tree(struct checkout_opts *opts,
 	if (read_cache_preload(NULL) < 0)
 		return error("corrupt index file");
 
+	resolve_undo_clear();
 	if (opts->force) {
 		ret = reset_tree(new->commit->tree, opts, 1);
 		if (ret)

builtin-ls-files.c

@@ -11,13 +11,16 @@
 #include "builtin.h"
 #include "tree.h"
 #include "parse-options.h"
+#include "resolve-undo.h"
+#include "string-list.h"
 
 static int abbrev;
 static int show_deleted;
 static int show_cached;
 static int show_others;
 static int show_stage;
 static int show_unmerged;
+static int show_resolve_undo;
 static int show_modified;
 static int show_killed;
 static int show_valid_bit;
@@ -38,6 +41,7 @@ static const char *tag_other = "";
 static const char *tag_killed = "";
 static const char *tag_modified = "";
 static const char *tag_skip_worktree = "";
+static const char *tag_resolve_undo = "";
 
 static void show_dir_entry(const char *tag, struct dir_entry *ent)
 {
@@ -156,6 +160,38 @@ static void show_ce_entry(const char *tag, struct cache_entry *ce)
 	write_name_quoted(ce->name + offset, stdout, line_terminator);
 }
 
+static int show_one_ru(struct string_list_item *item, void *cbdata)
+{
+	int offset = prefix_offset;
+	const char *path = item->string;
+	struct resolve_undo_info *ui = item->util;
+	int i, len;
+
+	len = strlen(path);
+	if (len < prefix_len)
+		return 0; /* outside of the prefix */
+	if (!match_pathspec(pathspec, path, len, prefix_len, ps_matched))
+		return 0; /* uninterested */
+	for (i = 0; i < 3; i++) {
+		if (!ui->mode[i])
+			continue;
+		printf("%s%06o %s %d\t", tag_resolve_undo, ui->mode[i],
+		       abbrev
+		       ? find_unique_abbrev(ui->sha1[i], abbrev)
+		       : sha1_to_hex(ui->sha1[i]),
+		       i + 1);
+		write_name_quoted(path + offset, stdout, line_terminator);
+	}
+	return 0;
+}
+
+static void show_ru_info(const char *prefix)
+{
+	if (!the_index.resolve_undo)
+		return;
+	for_each_string_list(show_one_ru, the_index.resolve_undo, NULL);
+}
+
 static void show_files(struct dir_struct *dir, const char *prefix)
 {
 	int i;
@@ -458,6 +494,8 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 			DIR_HIDE_EMPTY_DIRECTORIES),
 		OPT_BOOLEAN('u', "unmerged", &show_unmerged,
 			"show unmerged files in the output"),
+		OPT_BOOLEAN(0, "resolve-undo", &show_resolve_undo,
+			    "show resolve-undo information"),
 		{ OPTION_CALLBACK, 'x', "exclude", &dir.exclude_list[EXC_CMDL], "pattern",
 			"skip files matching pattern",
 			0, option_parse_exclude },
@@ -498,6 +536,7 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 		tag_other = "? ";
 		tag_killed = "K ";
 		tag_skip_worktree = "S ";
+		tag_resolve_undo = "U ";
 	}
 	if (show_modified || show_others || show_deleted || (dir.flags & DIR_SHOW_IGNORED) || show_killed)
 		require_work_tree = 1;
@@ -536,7 +575,7 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 
 	/* With no flags, we default to showing the cached files */
 	if (!(show_stage | show_deleted | show_others | show_unmerged |
-	      show_killed | show_modified))
+	      show_killed | show_modified | show_resolve_undo))
 		show_cached = 1;
 
 	if (prefix)
@@ -551,6 +590,8 @@ int cmd_ls_files(int argc, const char **argv, const char *prefix)
 		overlay_tree_on_cache(with_tree, prefix);
 	}
 	show_files(&dir, prefix);
+	if (show_resolve_undo)
+		show_ru_info(prefix);
 
 	if (ps_matched) {
 		int bad;

builtin-merge.c

@@ -24,6 +24,7 @@
 #include "rerere.h"
 #include "help.h"
 #include "merge-recursive.h"
+#include "resolve-undo.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -606,6 +607,7 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		discard_cache();
 		if (read_cache() < 0)
 			die("failed to read the cache");
+		resolve_undo_clear();
 		return ret;
 	}
 }
@@ -620,11 +622,10 @@ static void count_diff_files(struct diff_queue_struct *q,
 
 static int count_unmerged_entries(void)
 {
-	const struct index_state *state = &the_index;
 	int i, ret = 0;
 
-	for (i = 0; i < state->cache_nr; i++)
-		if (ce_stage(state->cache[i]))
+	for (i = 0; i < active_nr; i++)
+		if (ce_stage(active_cache[i]))
 			ret++;
 
 	return ret;
@@ -864,6 +865,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			die("You have not concluded your merge (MERGE_HEAD exists).");
 	}
 
+	resolve_undo_clear();
 	/*
 	 * Check if we are _not_ on a detached HEAD, i.e. if there is a
 	 * current branch.

builtin-read-tree.c

@@ -13,6 +13,7 @@
 #include "dir.h"
 #include "builtin.h"
 #include "parse-options.h"
+#include "resolve-undo.h"
 
 static int nr_trees;
 static struct tree *trees[MAX_UNPACK_TREES];
@@ -124,6 +125,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 			die("You need to resolve your current index first");
 		stage = opts.merge = 1;
 	}
+	resolve_undo_clear();
 
 	for (i = 0; i < argc; i++) {
 		const char *arg = argv[i];

builtin-rerere.c

@@ -120,6 +120,9 @@ int cmd_rerere(int argc, const char **argv, const char *prefix)
 	if (argc < 2)
 		return rerere(flags);
 
+	if (!strcmp(argv[1], "forget"))
+		return rerere_forget(argv + 2);
+
 	fd = setup_rerere(&merge_rr, flags);
 	if (fd < 0)
 		return 0;

builtin-update-index.c

@@ -9,6 +9,7 @@
 #include "tree-walk.h"
 #include "builtin.h"
 #include "refs.h"
+#include "resolve-undo.h"
 
 /*
  * Default to not allowing changes to the list of files. The
@@ -440,7 +441,18 @@ static int unresolve_one(const char *path)
 
 	/* See if there is such entry in the index. */
 	pos = cache_name_pos(path, namelen);
-	if (pos < 0) {
+	if (0 <= pos) {
+		/* already merged */
+		pos = unmerge_cache_entry_at(pos);
+		if (pos < active_nr) {
+			struct cache_entry *ce = active_cache[pos];
+			if (ce_stage(ce) &&
+			    ce_namelen(ce) == namelen &&
+			    !memcmp(ce->name, path, namelen))
+				return 0;
+		}
+		/* no resolve-undo information; fall back */
+	} else {
 		/* If there isn't, either it is unmerged, or
 		 * resolved as "removed" by mistake.  We do not
 		 * want to do anything in the former case.
@@ -719,6 +731,10 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 				verbose = 1;
 				continue;
 			}
+			if (!strcmp(path, "--clear-resolve-undo")) {
+				resolve_undo_clear();
+				continue;
+			}
 			if (!strcmp(path, "-h") || !strcmp(path, "--help"))
 				usage(update_index_usage);
 			die("unknown option %s", path);

cache.h

@@ -288,6 +288,7 @@ static inline int ce_to_dtype(const struct cache_entry *ce)
 struct index_state {
 	struct cache_entry **cache;
 	unsigned int cache_nr, cache_alloc, cache_changed;
+	struct string_list *resolve_undo;
 	struct cache_tree *cache_tree;
 	struct cache_time timestamp;
 	void *alloc;
@@ -342,6 +343,9 @@ static inline void remove_name_hash(struct cache_entry *ce)
 #define ce_modified(ce, st, options) ie_modified(&the_index, (ce), (st), (options))
 #define cache_name_exists(name, namelen, igncase) index_name_exists(&the_index, (name), (namelen), (igncase))
 #define cache_name_is_other(name, namelen) index_name_is_other(&the_index, (name), (namelen))
+#define resolve_undo_clear() resolve_undo_clear_index(&the_index)
+#define unmerge_cache_entry_at(at) unmerge_index_entry_at(&the_index, at)
+#define unmerge_cache(pathspec) unmerge_index(&the_index, pathspec)
 #endif
 
 enum object_type {

read-cache.c

@@ -14,6 +14,7 @@
 #include "diffcore.h"
 #include "revision.h"
 #include "blob.h"
+#include "resolve-undo.h"
 
 static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int really);
 
@@ -28,6 +29,7 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
 
 #define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
 #define CACHE_EXT_TREE 0x54524545	/* "TREE" */
+#define CACHE_EXT_RESOLVE_UNDO 0x52455543 /* "REUN" */
 
 struct index_state the_index;
 
@@ -456,6 +458,7 @@ int remove_index_entry_at(struct index_state *istate, int pos)
 {
 	struct cache_entry *ce = istate->cache[pos];
 
+	record_resolve_undo(istate, ce);
 	remove_name_hash(ce);
 	istate->cache_changed = 1;
 	istate->cache_nr--;
@@ -1183,6 +1186,9 @@ static int read_index_extension(struct index_state *istate,
 	case CACHE_EXT_TREE:
 		istate->cache_tree = cache_tree_read(data, sz);
 		break;
+	case CACHE_EXT_RESOLVE_UNDO:
+		istate->resolve_undo = resolve_undo_read(data, sz);
+		break;
 	default:
 		if (*ext < 'A' || 'Z' < *ext)
 			return error("index uses %.4s extension, which we do not understand",
@@ -1362,6 +1368,7 @@ int is_index_unborn(struct index_state *istate)
 
 int discard_index(struct index_state *istate)
 {
+	resolve_undo_clear_index(istate);
 	istate->cache_nr = 0;
 	istate->cache_changed = 0;
 	istate->timestamp.sec = 0;
@@ -1587,6 +1594,17 @@ int write_index(struct index_state *istate, int newfd)
 		if (err)
 			return -1;
 	}
+	if (istate->resolve_undo) {
+		struct strbuf sb = STRBUF_INIT;
+
+		resolve_undo_write(&sb, istate->resolve_undo);
+		err = write_index_ext_header(&c, newfd, CACHE_EXT_RESOLVE_UNDO,
+					     sb.len) < 0
+			|| ce_write(&c, newfd, sb.buf, sb.len) < 0;
+		strbuf_release(&sb);
+		if (err)
+			return -1;
+	}
 
 	if (ce_flush(&c, newfd) || fstat(newfd, &st))
 		return -1;