Rework checkout with new strategy options

This is a major reworking of checkout strategy options.  The
checkout code is now sensitive to the contents of the HEAD tree
and the new options allow you to update the working tree so that
it will match the index content only when it previously matched
the contents of the HEAD.  This allows you to, for example, to
distinguish between removing files that are in the HEAD but not
in the index, vs just removing all untracked files.

Because of various corner cases that arise, etc., this required
some additional capabilities in rmdir and other utility functions.

This includes the beginnings of an implementation of code to read
a partial tree into the index based on a pathspec, but that is
not enabled because of the possibility of creating conflicting
index entries.

1 files changed, 45 insertions, 3 deletions

diff --git a/src/fileops.c b/src/fileops.c
index d2cbd046d..5eebc5057 100644
--- a/src/fileops.c
+++ b/src/fileops.c
@@ -351,6 +351,7 @@ int git_futils_mkdir_r(const char *path, const char *base, const mode_t mode)
 }
 
 typedef struct {
+	const char *base;
 	uint32_t flags;
 	int error;
 } futils__rmdir_data;
@@ -366,11 +367,52 @@ static int futils__error_cannot_rmdir(const char *path, const char *filemsg)
 	return -1;
 }
 
+static int futils__rm_first_parent(git_buf *path, const char *ceiling)
+{
+	int error = GIT_ENOTFOUND;
+	struct stat st;
+
+	while (error == GIT_ENOTFOUND) {
+		git_buf_rtruncate_at_char(path, '/');
+
+		if (!path->size || git__prefixcmp(path->ptr, ceiling) != 0)
+			error = 0;
+		else if (p_lstat(path->ptr, &st) == 0) {
+			if (S_ISREG(st.st_mode) || S_ISLNK(st.st_mode))
+				error = p_unlink(path->ptr);
+			else if (!S_ISDIR(st.st_mode))
+				error = -1; /* fail to remove non-regular file */
+		} else if (errno != ENOTDIR)
+			error = -1;
+	}
+
+	if (error)
+		futils__error_cannot_rmdir(path->ptr, "cannot remove parent");
+
+	return error;
+}
+
 static int futils__rmdir_recurs_foreach(void *opaque, git_buf *path)
 {
+	struct stat st;
 	futils__rmdir_data *data = opaque;
 
-	if (git_path_isdir(path->ptr) == true) {
+	if ((data->error = p_lstat(path->ptr, &st)) < 0) {
+		if (errno == ENOENT)
+			data->error = 0;
+		else if (errno == ENOTDIR) {
+			/* asked to remove a/b/c/d/e and a/b is a normal file */
+			if ((data->flags & GIT_RMDIR_REMOVE_BLOCKERS) != 0)
+				data->error = futils__rm_first_parent(path, data->base);
+			else
+				futils__error_cannot_rmdir(
+					path->ptr, "parent is not directory");
+		}
+		else
+			futils__error_cannot_rmdir(path->ptr, "cannot access");
+	}
+
+	else if (S_ISDIR(st.st_mode)) {
 		int error = git_path_direach(path, futils__rmdir_recurs_foreach, data);
 		if (error < 0)
 			return (error == GIT_EUSER) ? data->error : error;
@@ -393,9 +435,8 @@ static int futils__rmdir_recurs_foreach(void *opaque, git_buf *path)
 			futils__error_cannot_rmdir(path->ptr, "cannot be removed");
 	}
 
-	else if ((data->flags & GIT_RMDIR_SKIP_NONEMPTY) == 0) {
+	else if ((data->flags & GIT_RMDIR_SKIP_NONEMPTY) == 0)
 		data->error = futils__error_cannot_rmdir(path->ptr, "still present");
-	}
 
 	return data->error;
 }
@@ -434,6 +475,7 @@ int git_futils_rmdir_r(
 	if (git_path_join_unrooted(&fullpath, path, base, NULL) < 0)
 		return -1;
 
+	data.base  = base ? base : "";
 	data.flags = flags;
 	data.error = 0;