stash: add git_stash_drop()

include/git2/stash.h

@@ -102,6 +102,21 @@ GIT_EXTERN(int) git_stash_foreach(
 	stash_cb callback,
 	void *payload);
 
+/**
+ * Remove a single stashed state from the stash list.
+ *
+ * @param repo The owning repository.
+ *
+ * @param index The position within the stash list. 0 points to the
+ * most recent stashed state.
+ *
+ * @return 0 on success, or error code
+ */
+
+GIT_EXTERN(int) git_stash_drop(
+	git_repository *repo,
+	size_t index);
+
 /** @} */
 GIT_END_DECL
 #endif

src/reflog.c

@@ -481,7 +481,7 @@ int git_reflog_drop(
 
 	/* If the oldest entry has just been removed... */
 	if (idx == 0) {
-		/* ...clear the oid_old member of the "new" last entry */
+		/* ...clear the oid_old member of the "new" oldest entry */
 		if (git_oid_fromstr(&entry->oid_old, GIT_OID_HEX_ZERO) < 0)
 			return -1;
 		

src/stash.c

@@ -617,3 +617,43 @@ cleanup:
 	git_reflog_free(reflog);
 	return error;
 }
+
+int git_stash_drop(
+	git_repository *repo,
+	size_t index)
+{
+	git_reference *stash;
+	git_reflog *reflog = NULL;
+	size_t max;
+	int error;
+
+	if ((error = git_reference_lookup(&stash, repo, GIT_REFS_STASH_FILE)) < 0)
+		return error;
+
+	if ((error = git_reflog_read(&reflog, stash)) < 0)
+		goto cleanup;
+
+	max = git_reflog_entrycount(reflog);
+
+	if (index > max - 1) {
+		error = GIT_ENOTFOUND;
+		giterr_set(GITERR_STASH, "No stashed state at position %" PRIuZ, index);
+		goto cleanup;
+	}
+
+	if ((error = git_reflog_drop(reflog, max - index - 1, true)) < 0)
+		goto cleanup;
+
+	if ((error = git_reflog_write(reflog)) < 0)
+		goto cleanup;
+
+	if (max == 1) {
+		error = git_reference_delete(stash);
+		stash = NULL;
+	}
+
+cleanup:
+	git_reference_free(stash);
+	git_reflog_free(reflog);
+	return error;
+}

tests-clar/stash/drop.c

@@ -0,0 +1,126 @@
+#include "clar_libgit2.h"
+#include "fileops.h"
+#include "stash_helpers.h"
+
+static git_repository *repo;
+static git_signature *signature;
+
+void test_stash_drop__initialize(void)
+{
+	cl_git_pass(git_repository_init(&repo, "stash", 0));
+	cl_git_pass(git_signature_new(&signature, "nulltoken", "emeric.fermas@gmail.com", 1323847743, 60)); /* Wed Dec 14 08:29:03 2011 +0100 */
+}
+
+void test_stash_drop__cleanup(void)
+{
+	git_signature_free(signature);
+	git_repository_free(repo);
+	cl_git_pass(git_futils_rmdir_r("stash", NULL, GIT_DIRREMOVAL_FILES_AND_DIRS));
+}
+
+void test_stash_drop__cannot_drop_from_an_empty_stash(void)
+{
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 0));
+}
+
+static void push_three_states(void)
+{
+	git_oid oid;
+	git_index *index;
+
+	cl_git_mkfile("stash/zero.txt", "content\n");
+	cl_git_pass(git_repository_index(&index, repo));
+	cl_git_pass(git_index_add(index, "zero.txt", 0));
+	commit_staged_files(&oid, index, signature);
+
+	cl_git_mkfile("stash/one.txt", "content\n");
+	cl_git_pass(git_stash_save(&oid, repo, signature, "First", GIT_STASH_INCLUDE_UNTRACKED));
+
+	cl_git_mkfile("stash/two.txt", "content\n");
+	cl_git_pass(git_stash_save(&oid, repo, signature, "Second", GIT_STASH_INCLUDE_UNTRACKED));
+
+	cl_git_mkfile("stash/three.txt", "content\n");
+	cl_git_pass(git_stash_save(&oid, repo, signature, "Third", GIT_STASH_INCLUDE_UNTRACKED));
+
+	git_index_free(index);
+}
+
+void test_stash_drop__cannot_drop_a_non_existing_stashed_state(void)
+{
+	push_three_states();
+
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 666));
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 42));
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 3));
+}
+
+void test_stash_drop__can_purge_the_stash_from_the_top(void)
+{
+	push_three_states();
+
+	cl_git_pass(git_stash_drop(repo, 0));
+	cl_git_pass(git_stash_drop(repo, 0));
+	cl_git_pass(git_stash_drop(repo, 0));
+
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 0));
+}
+
+void test_stash_drop__can_purge_the_stash_from_the_bottom(void)
+{
+	push_three_states();
+
+	cl_git_pass(git_stash_drop(repo, 2));
+	cl_git_pass(git_stash_drop(repo, 1));
+	cl_git_pass(git_stash_drop(repo, 0));
+
+	cl_assert_equal_i(GIT_ENOTFOUND, git_stash_drop(repo, 0));
+}
+
+void test_stash_drop__dropping_an_entry_rewrites_reflog_history(void)
+{
+	git_reference *stash;
+	git_reflog *reflog;
+	const git_reflog_entry *entry;
+	git_oid oid;
+	size_t count;
+
+	push_three_states();
+
+	cl_git_pass(git_reference_lookup(&stash, repo, "refs/stash"));
+	
+	cl_git_pass(git_reflog_read(&reflog, stash));
+	entry = git_reflog_entry_byindex(reflog, 1);
+
+	git_oid_cpy(&oid, git_reflog_entry_oidold(entry));
+	count = git_reflog_entrycount(reflog);
+	
+	git_reflog_free(reflog);
+
+	cl_git_pass(git_stash_drop(repo, 1));
+
+	cl_git_pass(git_reflog_read(&reflog, stash));
+	entry = git_reflog_entry_byindex(reflog, 1);
+
+	cl_assert_equal_i(0, git_oid_cmp(&oid, git_reflog_entry_oidold(entry)));
+	cl_assert_equal_i(count - 1, git_reflog_entrycount(reflog));
+
+	git_reflog_free(reflog);
+
+	git_reference_free(stash);
+}
+
+void test_stash_drop__dropping_the_last_entry_removes_the_stash(void)
+{
+	git_reference *stash;
+
+	push_three_states();
+
+	cl_git_pass(git_reference_lookup(&stash, repo, "refs/stash"));
+	git_reference_free(stash);
+
+	cl_git_pass(git_stash_drop(repo, 0));
+	cl_git_pass(git_stash_drop(repo, 0));
+	cl_git_pass(git_stash_drop(repo, 0));
+
+	cl_assert_equal_i(GIT_ENOTFOUND, git_reference_lookup(&stash, repo, "refs/stash"));
+}