[PATCH] cmd_reset: don't trash uncommitted changes unless told to

[Steven Walter <stevenrwalter@gmail.com>]

Give "reset --hard" a -f (force) flag, without which it will refuse to
proceed if there are changes in the index or working tree.

Signed-off-by: Steven Walter <stevenrwalter@gmail.com>
---
 builtin-reset.c |   24 +++++++++++++++++++++++-
 1 files changed, 23 insertions(+), 1 deletions(-)

diff --git a/builtin-reset.c b/builtin-reset.c
index f34acb1..6ee8448 100644
--- a/builtin-reset.c
+++ b/builtin-reset.c
@@ -11,8 +11,10 @@
 #include "tag.h"
 #include "object.h"
 #include "commit.h"
+#include "diff.h"
 #include "run-command.h"
 #include "refs.h"
+#include "revision.h"
 #include "diff.h"
 #include "diffcore.h"
 #include "tree.h"
@@ -165,12 +167,26 @@ static void prepend_reflog_action(const char *action, char *buf, size_t size)
 		warning("Reflog action message too long: %.*s...", 50, buf);
 }
 
+/* Stolen from builtin-revert.c... */
+static int index_is_dirty(void)
+{
+	struct rev_info rev;
+        read_cache();
+	init_revisions(&rev, NULL);
+	setup_revisions(0, NULL, &rev, "HEAD");
+	DIFF_OPT_SET(&rev.diffopt, QUIET);
+	DIFF_OPT_SET(&rev.diffopt, EXIT_WITH_STATUS);
+	run_diff_files(&rev, 1);
+	return !!DIFF_OPT_TST(&rev.diffopt, HAS_CHANGES);
+}
+
 enum reset_type { MIXED, SOFT, HARD, NONE };
 static const char *reset_type_names[] = { "mixed", "soft", "hard", NULL };
 
 int cmd_reset(int argc, const char **argv, const char *prefix)
 {
-	int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0;
+	int i = 0, reset_type = NONE, update_ref_status = 0, quiet = 0,
+            force = 0;
 	const char *rev = "HEAD";
 	unsigned char sha1[20], *orig = NULL, sha1_orig[20],
 				*old_orig = NULL, sha1_old_orig[20];
@@ -184,6 +200,8 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 				"reset HEAD, index and working tree", HARD),
 		OPT_BOOLEAN('q', NULL, &quiet,
 				"disable showing new HEAD in hard reset and progress message"),
+		OPT_BOOLEAN('f', NULL, &force,
+				"proceed even if there are uncommitted changes"),
 		OPT_END()
 	};
 
@@ -225,6 +243,10 @@ int cmd_reset(int argc, const char **argv, const char *prefix)
 	if (reset_type == HARD && is_bare_repository())
 		die("hard reset makes no sense in a bare repository");
 
+        if (reset_type == HARD && !force && index_is_dirty()) {
+                die("Uncommitted changes; re-run with -f to trash them");
+        }
+
 	/* 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. */
-- 
1.5.6.dirty