Merge branch 'cc/reset-more'

* cc/reset-more:
  t7111: check that reset options work as described in the tables
  Documentation: reset: add some missing tables
  Fix bit assignment for CE_CONFLICTED
  "reset --merge": fix unmerged case
  reset: use "unpack_trees()" directly instead of "git read-tree"
  reset: add a few tests for "git reset --merge"
  Documentation: reset: add some tables to describe the different options
  reset: improve mixed reset error message when in a bare repo

7 files changed, 435 insertions, 20 deletions

diff --git a/Documentation/git-reset.txt b/Documentation/git-reset.txt
index 9df6de2e7d..c7aa444317 100644
--- a/Documentation/git-reset.txt
+++ b/Documentation/git-reset.txt
@@ -68,6 +68,95 @@ linkgit:git-add[1]).
 <commit>::
 	Commit to make the current HEAD. If not given defaults to HEAD.
 
+DISCUSSION
+----------
+
+The tables below show what happens when running:
+
+----------
+git reset --option target
+----------
+
+to reset the HEAD to another commit (`target`) with the different
+reset options depending on the state of the files.
+
+In these tables, A, B, C and D are some different states of a
+file. For example, the first line of the first table means that if a
+file is in state A in the working tree, in state B in the index, in
+state C in HEAD and in state D in the target, then "git reset --soft
+target" will put the file in state A in the working tree, in state B
+in the index and in state D in HEAD.
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       A       B     C    D     --soft   A       B     D
+				--mixed  A       D     D
+				--hard   D       D     D
+				--merge (disallowed)
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       A       B     C    C     --soft   A       B     C
+				--mixed  A       C     C
+				--hard   C       C     C
+				--merge (disallowed)
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       B       B     C    D     --soft   B       B     D
+				--mixed  B       D     D
+				--hard   D       D     D
+				--merge  D       D     D
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       B       B     C    C     --soft   B       B     C
+				--mixed  B       C     C
+				--hard   C       C     C
+				--merge  C       C     C
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       B       C     C    D     --soft   B       C     D
+				--mixed  B       D     D
+				--hard   D       D     D
+				--merge (disallowed)
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       B       C     C    C     --soft   B       C     C
+				--mixed  B       C     C
+				--hard   C       C     C
+				--merge  B       C     C
+
+"reset --merge" is meant to be used when resetting out of a conflicted
+merge. Any mergy operation guarantees that the work tree file that is
+involved in the merge does not have local change wrt the index before
+it starts, and that it writes the result out to the work tree. So if
+we see some difference between the index and the target and also
+between the index and the work tree, then it means that we are not
+resetting out from a state that a mergy operation left after failing
+with a conflict. That is why we disallow --merge option in this case.
+
+The following tables show what happens when there are unmerged
+entries:
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       X       U     A    B     --soft  (disallowed)
+				--mixed  X       B     B
+				--hard   B       B     B
+				--merge  B       B     B
+
+      working index HEAD target         working index HEAD
+      ----------------------------------------------------
+       X       U     A    A     --soft  (disallowed)
+				--mixed  X       A     A
+				--hard   A       A     A
+				--merge  A       A     A
+
+X means any state and U means an unmerged index.
+
 Examples
 --------
 
diff --git a/builtin-reset.c b/builtin-reset.c
index 5b647422d6..0f5022eed2 100644
--- a/builtin-reset.c
+++ b/builtin-reset.c
@@ -18,6 +18,8 @@
 #include "tree.h"
 #include "branch.h"
 #include "parse-options.h"
+#include "unpack-trees.h"
+#include "cache-tree.h"
 
 static const char * const git_reset_usage[] = {
 	"git reset [--mixed | --soft | --hard | --merge] [-q] [<commit>]",
@@ -54,27 +56,44 @@ static inline int is_merge(void)
 
 static int reset_index_file(const unsigned char *sha1, int reset_type, int quiet)
 {
-	int i = 0;
-	const char *args[6];
+	int nr = 1;
+	int newfd;
+	struct tree_desc desc[2];
+	struct unpack_trees_options opts;
+	struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 
-	args[i++] = "read-tree";
+	memset(&opts, 0, sizeof(opts));
+	opts.head_idx = 1;
+	opts.src_index = &the_index;
+	opts.dst_index = &the_index;
+	opts.fn = oneway_merge;
+	opts.merge = 1;
 	if (!quiet)
-		args[i++] = "-v";
+		opts.verbose_update = 1;
 	switch (reset_type) {
 	case MERGE:
-		args[i++] = "-u";
-		args[i++] = "-m";
+		opts.update = 1;
 		break;
 	case HARD:
-		args[i++] = "-u";
+		opts.update = 1;
 		/* fallthrough */
 	default:
-		args[i++] = "--reset";
+		opts.reset = 1;
 	}
-	args[i++] = sha1_to_hex(sha1);
-	args[i] = NULL;
 
-	return run_command_v_opt(args, RUN_GIT_CMD);
+	newfd = hold_locked_index(lock, 1);
+
+	read_cache_unmerged();
+
+	if (!fill_tree_descriptor(desc + nr - 1, sha1))
+		return error("Failed to find tree of %s.", sha1_to_hex(sha1));
+	if (unpack_trees(nr, desc, &opts))
+		return -1;
+	if (write_cache(newfd, active_cache, active_nr) ||
+	    commit_locked_index(lock))
+		return error("Could not write new index file.");
+
+	return 0;
 }
 
 static void print_new_head_line(struct commit *commit)
@@ -288,6 +307,10 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (reset_type == HARD || reset_type == MERGE)
 		setup_work_tree();
 
+	if (reset_type == MIXED && is_bare_repository())
+		die("%s reset is not allowed in a bare repository",
+		    reset_type_names[reset_type]);
+
 	/* Soft reset does not touch the index file nor the working tree
 	 * at all, but requires them in a good order.  Other resets reset
 	 * the index file to the tree object we are switching to. */
diff --git a/cache.h b/cache.h
index 46606477b6..3e52c4efb1 100644
--- a/cache.h
+++ b/cache.h
@@ -177,6 +177,7 @@ struct cache_entry {
 
 #define CE_HASHED    (0x100000)
 #define CE_UNHASHED  (0x200000)
+#define CE_CONFLICTED (0x800000)
 
 /* Only remove in work directory, not index */
 #define CE_WT_REMOVE (0x400000)
diff --git a/read-cache.c b/read-cache.c
index a0adb272fd..d214abab16 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1617,9 +1617,8 @@ int read_index_unmerged(struct index_state *istate)
 		len = strlen(ce->name);
 		size = cache_entry_size(len);
 		new_ce = xcalloc(1, size);
-		hashcpy(new_ce->sha1, ce->sha1);
 		memcpy(new_ce->name, ce->name, len);
-		new_ce->ce_flags = create_ce_flags(len, 0);
+		new_ce->ce_flags = create_ce_flags(len, 0) | CE_CONFLICTED;
 		new_ce->ce_mode = ce->ce_mode;
 		if (add_index_entry(istate, new_ce, 0))
 			return error("%s: cannot drop to stage #0",
diff --git a/t/t7110-reset-merge.sh b/t/t7110-reset-merge.sh
new file mode 100755
index 0000000000..8704d00196
--- /dev/null
+++ b/t/t7110-reset-merge.sh
@@ -0,0 +1,183 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Christian Couder
+#
+
+test_description='Tests for "git reset --merge"'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+    for i in 1 2 3; do echo line $i; done >file1 &&
+    cat file1 >file2 &&
+    git add file1 file2 &&
+    test_tick &&
+    git commit -m "Initial commit" &&
+    git tag initial &&
+    echo line 4 >>file1 &&
+    cat file1 >file2 &&
+    test_tick &&
+    git commit -m "add line 4 to file1" file1 &&
+    git tag second
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     C       C     C    D     --merge  D       D     D
+# file2:     C       D     D    D     --merge  C       D     D
+test_expect_success 'reset --merge is ok with changes in file it does not touch' '
+    git reset --merge HEAD^ &&
+    ! grep 4 file1 &&
+    grep 4 file2 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse initial)" &&
+    test -z "$(git diff --cached)"
+'
+
+test_expect_success 'reset --merge is ok when switching back' '
+    git reset --merge second &&
+    grep 4 file1 &&
+    grep 4 file2 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse second)" &&
+    test -z "$(git diff --cached)"
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     B       B     C    D     --merge  D       D     D
+# file2:     C       D     D    D     --merge  C       D     D
+test_expect_success 'reset --merge discards changes added to index (1)' '
+    git reset --hard second &&
+    cat file1 >file2 &&
+    echo "line 5" >> file1 &&
+    git add file1 &&
+    git reset --merge HEAD^ &&
+    ! grep 4 file1 &&
+    ! grep 5 file1 &&
+    grep 4 file2 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse initial)" &&
+    test -z "$(git diff --cached)"
+'
+
+test_expect_success 'reset --merge is ok again when switching back (1)' '
+    git reset --hard initial &&
+    echo "line 5" >> file2 &&
+    git add file2 &&
+    git reset --merge second &&
+    ! grep 4 file2 &&
+    ! grep 5 file1 &&
+    grep 4 file1 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse second)" &&
+    test -z "$(git diff --cached)"
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     C       C     C    D     --merge  D       D     D
+# file2:     C       C     D    D     --merge  D       D     D
+test_expect_success 'reset --merge discards changes added to index (2)' '
+    git reset --hard second &&
+    echo "line 4" >> file2 &&
+    git add file2 &&
+    git reset --merge HEAD^ &&
+    ! grep 4 file2 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse initial)" &&
+    test -z "$(git diff)" &&
+    test -z "$(git diff --cached)"
+'
+
+test_expect_success 'reset --merge is ok again when switching back (2)' '
+    git reset --hard initial &&
+    git reset --merge second &&
+    ! grep 4 file2 &&
+    grep 4 file1 &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse second)" &&
+    test -z "$(git diff --cached)"
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     A       B     B    C     --merge  (disallowed)
+test_expect_success 'reset --merge fails with changes in file it touches' '
+    git reset --hard second &&
+    echo "line 5" >> file1 &&
+    test_tick &&
+    git commit -m "add line 5" file1 &&
+    sed -e "s/line 1/changed line 1/" <file1 >file3 &&
+    mv file3 file1 &&
+    test_must_fail git reset --merge HEAD^ 2>err.log &&
+    grep file1 err.log | grep "not uptodate"
+'
+
+test_expect_success 'setup 3 different branches' '
+    git reset --hard second &&
+    git branch branch1 &&
+    git branch branch2 &&
+    git branch branch3 &&
+    git checkout branch1 &&
+    echo "line 5 in branch1" >> file1 &&
+    test_tick &&
+    git commit -a -m "change in branch1" &&
+    git checkout branch2 &&
+    echo "line 5 in branch2" >> file1 &&
+    test_tick &&
+    git commit -a -m "change in branch2" &&
+    git tag third &&
+    git checkout branch3 &&
+    echo a new file >file3 &&
+    rm -f file1 &&
+    git add file3 &&
+    test_tick &&
+    git commit -a -m "change in branch3"
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     X       U     B    C     --merge  C       C     C
+test_expect_success '"reset --merge HEAD^" is ok with pending merge' '
+    git checkout third &&
+    test_must_fail git merge branch1 &&
+    git reset --merge HEAD^ &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse second)" &&
+    test -z "$(git diff --cached)" &&
+    test -z "$(git diff)"
+'
+
+# The next test will test the following:
+#
+#           working index HEAD target         working index HEAD
+#           ----------------------------------------------------
+# file1:     X       U     B    B     --merge  B       B     B
+test_expect_success '"reset --merge HEAD" is ok with pending merge' '
+    git reset --hard third &&
+    test_must_fail git merge branch1 &&
+    git reset --merge HEAD &&
+    test "$(git rev-parse HEAD)" = "$(git rev-parse third)" &&
+    test -z "$(git diff --cached)" &&
+    test -z "$(git diff)"
+'
+
+test_expect_success '--merge with added/deleted' '
+    git reset --hard third &&
+    rm -f file2 &&
+    test_must_fail git merge branch3 &&
+    ! test -f file2 &&
+    test -f file3 &&
+    git diff --exit-code file3 &&
+    git diff --exit-code branch3 file3 &&
+    git reset --merge HEAD &&
+    ! test -f file3 &&
+    ! test -f file2 &&
+    git diff --exit-code --cached
+'
+
+test_done
diff --git a/t/t7111-reset-table.sh b/t/t7111-reset-table.sh
new file mode 100755
index 0000000000..0a362a12bf
--- /dev/null
+++ b/t/t7111-reset-table.sh
@@ -0,0 +1,113 @@
+#!/bin/sh
+#
+# Copyright (c) 2010 Christian Couder
+#
+
+test_description='Tests to check that "reset" options follow a known table'
+
+. ./test-lib.sh
+
+
+test_expect_success 'creating initial commits' '
+    test_commit E file1 &&
+    test_commit D file1 &&
+    test_commit C file1
+'
+
+while read W1 I1 H1 T opt W2 I2 H2
+do
+    test_expect_success "check: $W1 $I1 $H1 $T --$opt $W2 $I2 $H2" '
+	git reset --hard C &&
+	if test "$I1" != "$H1"
+	then
+	    echo "$I1" >file1 &&
+	    git add file1
+	fi &&
+	if test "$W1" != "$I1"
+	then
+	    echo "$W1" >file1
+	fi &&
+	if test "$W2" != "XXXXX"
+	then
+	    git reset --$opt $T &&
+	    test "$(cat file1)" = "$W2" &&
+	    git checkout-index -f -- file1 &&
+	    test "$(cat file1)" = "$I2" &&
+	    git checkout -f HEAD -- file1 &&
+	    test "$(cat file1)" = "$H2"
+	else
+	    test_must_fail git reset --$opt $T
+	fi
+    '
+done <<\EOF
+A B C D soft   A B D
+A B C D mixed  A D D
+A B C D hard   D D D
+A B C D merge  XXXXX
+A B C C soft   A B C
+A B C C mixed  A C C
+A B C C hard   C C C
+A B C C merge  XXXXX
+B B C D soft   B B D
+B B C D mixed  B D D
+B B C D hard   D D D
+B B C D merge  D D D
+B B C C soft   B B C
+B B C C mixed  B C C
+B B C C hard   C C C
+B B C C merge  C C C
+B C C D soft   B C D
+B C C D mixed  B D D
+B C C D hard   D D D
+B C C D merge  XXXXX
+B C C C soft   B C C
+B C C C mixed  B C C
+B C C C hard   C C C
+B C C C merge  B C C
+EOF
+
+test_expect_success 'setting up branches to test with unmerged entries' '
+    git reset --hard C &&
+    git branch branch1 &&
+    git branch branch2 &&
+    git checkout branch1 &&
+    test_commit B1 file1 &&
+    git checkout branch2 &&
+    test_commit B2 file1
+'
+
+while read W1 I1 H1 T opt W2 I2 H2
+do
+    test_expect_success "check: $W1 $I1 $H1 $T --$opt $W2 $I2 $H2" '
+	git reset --hard B2 &&
+	test_must_fail git merge branch1 &&
+	cat file1 >X_file1 &&
+	if test "$W2" != "XXXXX"
+	then
+	    git reset --$opt $T &&
+	    if test "$W2" = "X"
+	    then
+		test_cmp file1 X_file1
+	    else
+		test "$(cat file1)" = "$W2"
+	    fi &&
+	    git checkout-index -f -- file1 &&
+	    test "$(cat file1)" = "$I2" &&
+	    git checkout -f HEAD -- file1 &&
+	    test "$(cat file1)" = "$H2"
+	else
+	    test_must_fail git reset --$opt $T
+	fi
+    '
+done <<\EOF
+X U C D soft   XXXXX
+X U C D mixed  X D D
+X U C D hard   D D D
+X U C D merge  D D D
+X U C C soft   XXXXX
+X U C C mixed  X C C
+X U C C hard   C C C
+X U C C merge  C C C
+EOF
+
+test_done
diff --git a/unpack-trees.c b/unpack-trees.c
index 7570475b45..acdd311737 100644
--- a/unpack-trees.c
+++ b/unpack-trees.c
@@ -550,6 +550,8 @@ static int same(struct cache_entry *a, struct cache_entry *b)
 		return 0;
 	if (!a && !b)
 		return 1;
+	if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
+		return 0;
 	return a->ce_mode == b->ce_mode &&
 	       !hashcmp(a->sha1, b->sha1);
 }
@@ -809,7 +811,11 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 {
 	int update = CE_UPDATE;
 
-	if (old) {
+	if (!old) {
+		if (verify_absent(merge, "overwritten", o))
+			return -1;
+		invalidate_ce_path(merge, o);
+	} else if (!(old->ce_flags & CE_CONFLICTED)) {
 		/*
 		 * See if we can re-use the old CE directly?
 		 * That way we get the uptodate stat info.
@@ -827,11 +833,12 @@ static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 				update |= CE_SKIP_WORKTREE;
 			invalidate_ce_path(old, o);
 		}
-	}
-	else {
-		if (verify_absent(merge, "overwritten", o))
-			return -1;
-		invalidate_ce_path(merge, o);
+	} else {
+		/*
+		 * Previously unmerged entry left as an existence
+		 * marker by read_index_unmerged();
+		 */
+		invalidate_ce_path(old, o);
 	}
 
 	add_entry(o, merge, update, CE_STAGEMASK);
@@ -847,7 +854,7 @@ static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 			return -1;
 		return 0;
 	}
-	if (verify_uptodate(old, o))
+	if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
 		return -1;
 	add_entry(o, ce, CE_REMOVE, 0);
 	invalidate_ce_path(ce, o);