reflog: fix bogus removal of reflog entries

src/reflog.c

@@ -469,18 +469,18 @@ int git_reflog_drop(
 	if (!rewrite_previous_entry)
 		return 0;
 
-	/* No need to rewrite anything when removing the first entry */
-	if (idx == 0)
+	/* No need to rewrite anything when removing the most recent entry */
+	if (idx == entrycount - 1)
 		return 0;
 
 	/* There are no more entries in the log */
 	if (entrycount == 1)
 		return 0;
 
-	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);
+	entry = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
 
-	/* If the last entry has just been removed... */
-	if (idx == entrycount - 1) {
+	/* If the oldest entry has just been removed... */
+	if (idx == 0) {
 		/* ...clear the oid_old member of the "new" last entry */
 		if (git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO) < 0)
 			return -1;
@@ -488,7 +488,7 @@ int git_reflog_drop(
 		return 0;
 	}
 
-	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx);
+	previous = (git_reflog_entry *)git_reflog_entry_byindex(reflog, idx - 1);
 	git_oid_cpy(&entry->oid_old, &previous->oid_cur);
 
 	return 0;

tests-clar/refs/reflog/drop.c

@@ -43,57 +43,48 @@ void test_refs_reflog_drop__can_drop_an_entry(void)
 
 void test_refs_reflog_drop__can_drop_an_entry_and_rewrite_the_log_history(void)
 {
-	const git_reflog_entry *before_previous, *before_next;
-	const git_reflog_entry *after_next;
-	git_oid before_next_old_oid;
+	const git_reflog_entry *before_current;
+	const git_reflog_entry *after_current;
+	git_oid before_current_old_oid, before_current_cur_oid;
 
 	cl_assert(entrycount > 4);
 
-	before_previous = git_reflog_entry_byindex(g_reflog, 3);
-	before_next = git_reflog_entry_byindex(g_reflog, 1);
-	git_oid_cpy(&before_next_old_oid, &before_next->oid_old);
+	before_current = git_reflog_entry_byindex(g_reflog, 2);
+	git_oid_cpy(&before_current_old_oid, &before_current->oid_old);
+	git_oid_cpy(&before_current_cur_oid, &before_current->oid_cur);
 
 	cl_git_pass(git_reflog_drop(g_reflog, 2, 1));
 	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
 
-	after_next = git_reflog_entry_byindex(g_reflog, 1);
+	after_current = git_reflog_entry_byindex(g_reflog, 2);
 
-	cl_assert_equal_i(0, git_oid_cmp(&before_next->oid_cur, &after_next->oid_cur));
-	cl_assert(git_oid_cmp(&before_next_old_oid, &after_next->oid_old) != 0);
-	cl_assert_equal_i(0, git_oid_cmp(&before_previous->oid_cur, &after_next->oid_old));
+	cl_assert_equal_i(0, git_oid_cmp(&before_current_old_oid, &after_current->oid_old));
+	cl_assert(0 != git_oid_cmp(&before_current_cur_oid, &after_current->oid_cur));
 }
 
-void test_refs_reflog_drop__can_drop_the_first_entry(void)
-{
-	cl_assert(entrycount > 2);
-
-	cl_git_pass(git_reflog_drop(g_reflog, 0, 0));
-	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
-}
-
-void test_refs_reflog_drop__can_drop_the_last_entry(void)
+void test_refs_reflog_drop__can_drop_the_oldest_entry(void)
 {
 	const git_reflog_entry *entry;
 
 	cl_assert(entrycount > 2);
 
-	cl_git_pass(git_reflog_drop(g_reflog, entrycount - 1, 0));
+	cl_git_pass(git_reflog_drop(g_reflog, 0, 0));
 	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
 
-	entry = git_reflog_entry_byindex(g_reflog, entrycount - 2);
+	entry = git_reflog_entry_byindex(g_reflog, 0);
 	cl_assert(git_oid_streq(&entry->oid_old, GIT_OID_HEX_ZERO) != 0);
 }
 
-void test_refs_reflog_drop__can_drop_the_last_entry_and_rewrite_the_log_history(void)
+void test_refs_reflog_drop__can_drop_the_oldest_entry_and_rewrite_the_log_history(void)
 {
 	const git_reflog_entry *entry;
 
 	cl_assert(entrycount > 2);
 
-	cl_git_pass(git_reflog_drop(g_reflog, entrycount - 1, 1));
+	cl_git_pass(git_reflog_drop(g_reflog, 0, 1));
 	cl_assert_equal_i(entrycount - 1, git_reflog_entrycount(g_reflog));
 
-	entry = git_reflog_entry_byindex(g_reflog, entrycount - 2);
+	entry = git_reflog_entry_byindex(g_reflog, 0);
 	cl_assert(git_oid_streq(&entry->oid_old, GIT_OID_HEX_ZERO) == 0);
 }