Re: [PATCH 09/14] update submodules: add submodule_go_from_to

[brian m. carlson]

On Tue, Feb 14, 2017 at 04:34:18PM -0800, Stefan Beller wrote:
> + prepare_submodule_repo_env_no_git_dir(_array);
> +
> + cp.git_cmd = 1;
> + cp.no_stdin = 1;
> + cp.dir = path;
> +
> + argv_array_pushf(, "--super-prefix=%s/", path);
> + argv_array_pushl(, "read-tree", NULL);
> +
> + if (!dry_run)
> + argv_array_push(, "-u");
> + else
> + argv_array_push(, "-n");

I might write this as

if (dry_run)
argv_array_push(, "-n");
else
argv_array_push(, "-u");

In other words, avoiding the negation when you have an else branch.  I
can also see an argument for keeping the condition identical to the
other branches, though.
-- 
brian m. carlson / brian with sandals: Houston, Texas, US
+1 832 623 2791 | https://www.crustytoothpaste.net/~bmc | My opinion only
OpenPGP: https://keybase.io/bk2204


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[PATCH 09/14] update submodules: add submodule_go_from_to

[Stefan Beller]

In later patches we introduce the options and flag for commands
that modify the working directory, e.g. git-checkout.

This piece of code will be used universally for
all these working tree modifications as it
* supports dry run to answer the question:
  "Is it safe to change the submodule to this new state?"
  e.g. is it overwriting untracked files or are there local
  changes that would be overwritten?
* supports a force flag that can be used for resetting
  the tree.

Signed-off-by: Stefan Beller 
---
 submodule.c | 151 
 submodule.h |   5 ++
 2 files changed, 156 insertions(+)

diff --git a/submodule.c b/submodule.c
index d3fc6c2a75..194cba9535 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1252,6 +1252,157 @@ int bad_to_remove_submodule(const char *path, unsigned 
flags)
return ret;
 }
 
+static int submodule_has_dirty_index(const struct submodule *sub)
+{
+   ssize_t len;
+   struct child_process cp = CHILD_PROCESS_INIT;
+   struct strbuf buf = STRBUF_INIT;
+   int ret = 0;
+
+   prepare_submodule_repo_env_no_git_dir(_array);
+
+   cp.git_cmd = 1;
+   argv_array_pushl(, "diff-index", "--cached", "HEAD", NULL);
+   cp.no_stdin = 1;
+   cp.out = -1;
+   cp.dir = sub->path;
+   if (start_command())
+   die("could not recurse into submodule %s", sub->path);
+
+   len = strbuf_read(, cp.out, 1024);
+   if (len > 2)
+   ret = 1;
+
+   close(cp.out);
+   if (finish_command())
+   die("could not recurse into submodule %s", sub->path);
+
+   strbuf_release();
+   return ret;
+}
+
+void submodule_clean_index(const char *path)
+{
+   struct child_process cp = CHILD_PROCESS_INIT;
+   prepare_submodule_repo_env_no_git_dir(_array);
+
+   cp.git_cmd = 1;
+   cp.no_stdin = 1;
+   cp.dir = path;
+
+   argv_array_pushf(, "--super-prefix=%s/", path);
+   argv_array_pushl(, "read-tree", "-u", "--reset", NULL);
+
+   argv_array_push(, EMPTY_TREE_SHA1_HEX);
+
+   if (run_command())
+   die("could not clean submodule index");
+}
+
+/**
+ * Moves a submodule at a given path from a given head to another new head.
+ * For edge cases (a submodule coming into existence or removing a submodule)
+ * pass NULL for old or new respectively.
+ *
+ * TODO: move dryrun and forced to flags.
+ */
+int submodule_go_from_to(const char *path,
+const char *old,
+const char *new,
+int dry_run,
+int force)
+{
+   int ret = 0;
+   struct child_process cp = CHILD_PROCESS_INIT;
+   const struct submodule *sub;
+
+   sub = submodule_from_path(null_sha1, path);
+
+   if (!sub)
+   die("BUG: could not get submodule information for '%s'", path);
+
+   if (!dry_run) {
+   if (old) {
+   if (!submodule_uses_gitfile(path))
+   absorb_git_dir_into_superproject("", path,
+   ABSORB_GITDIR_RECURSE_SUBMODULES);
+   } else {
+   struct strbuf sb = STRBUF_INIT;
+   strbuf_addf(, "%s/modules/%s",
+   get_git_common_dir(), sub->name);
+   connect_work_tree_and_git_dir(path, sb.buf);
+   strbuf_release();
+
+   /* make sure the index is clean as well */
+   submodule_clean_index(path);
+   }
+   }
+
+   if (old && !force) {
+   /* Check if the submodule has a dirty index. */
+   if (submodule_has_dirty_index(sub)) {
+   /* print a thing here? */
+   return -1;
+   }
+   }
+
+   prepare_submodule_repo_env_no_git_dir(_array);
+
+   cp.git_cmd = 1;
+   cp.no_stdin = 1;
+   cp.dir = path;
+
+   argv_array_pushf(, "--super-prefix=%s/", path);
+   argv_array_pushl(, "read-tree", NULL);
+
+   if (!dry_run)
+   argv_array_push(, "-u");
+   else
+   argv_array_push(, "-n");
+
+   if (force)
+   argv_array_push(, "--reset");
+   else
+   argv_array_push(, "-m");
+
+   argv_array_push(, old ? old : EMPTY_TREE_SHA1_HEX);
+   argv_array_push(, new ? new : EMPTY_TREE_SHA1_HEX);
+
+   if (run_command()) {
+   ret = -1;
+   goto out;
+   }
+
+   if (!dry_run) {
+   if (new) {
+   struct child_process cp1 = CHILD_PROCESS_INIT;
+   /* also set the HEAD accordingly */
+   cp1.git_cmd = 1;
+   cp1.no_stdin = 1;
+   cp1.dir = path;
+
+   argv_array_pushl(, "update-ref", "HEAD",
+