Re: [PATCH v4 6/8] dir: fix checks on common prefix directory

[Jeff King <peff@peff.net>]

On Thu, Dec 19, 2019 at 12:23:29PM -0800, Elijah Newren wrote:

> > >       while (len && path[len - 1] == '/')
> > >               len--;
> > >       if (!len)
> > >               return 1;
> > > +
> > > +     de = xcalloc(1, sizeof(struct dirent)+len+1);
> >
> > That "+len+1" may deserve a comment?
> 
> Good point, I'll add one and send a re-roll.

Please use st_add3() while you are at it.

I'd also usually suggest FLEX_ALLOC_MEM() for even more simplicity, but
it looks like filling the string is handled separately (and done many
times).

I have to wonder, though, if it wouldn't be simpler to move away from
"struct dirent" here (and it looks like Junio suggested the same earlier
in the thread). I don't know this code very well, but it looks
like it could easily get by passing around a name pointer and a dtype
through the cached_dir. The patch below seems like it's not too bad a
cleanup, but possibly the names could be better.

---
 dir.c | 48 ++++++++++++++++++-----------------
 1 file changed, 25 insertions(+), 23 deletions(-)

diff --git a/dir.c b/dir.c
index 43e2f47f66..e1cba688f3 100644
--- a/dir.c
+++ b/dir.c
@@ -41,7 +41,8 @@ struct cached_dir {
 	int nr_files;
 	int nr_dirs;
 
-	struct dirent *de;
+	const char *d_name;
+	int d_type;
 	const char *file;
 	struct untracked_cache_dir *ucd;
 };
@@ -50,8 +51,8 @@ static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 	struct index_state *istate, const char *path, int len,
 	struct untracked_cache_dir *untracked,
 	int check_only, int stop_at_first_file, const struct pathspec *pathspec);
-static int get_dtype(struct dirent *de, struct index_state *istate,
-		     const char *path, int len);
+static int resolve_dtype(int dtype, struct index_state *istate,
+			 const char *path, int len);
 
 int count_slashes(const char *s)
 {
@@ -1050,8 +1051,7 @@ static struct path_pattern *last_matching_pattern_from_list(const char *pathname
 		int prefix = pattern->nowildcardlen;
 
 		if (pattern->flags & PATTERN_FLAG_MUSTBEDIR) {
-			if (*dtype == DT_UNKNOWN)
-				*dtype = get_dtype(NULL, istate, pathname, pathlen);
+			*dtype = resolve_dtype(*dtype, istate, pathname, pathlen);
 			if (*dtype != DT_DIR)
 				continue;
 		}
@@ -1639,10 +1639,9 @@ static int get_index_dtype(struct index_state *istate,
 	return DT_UNKNOWN;
 }
 
-static int get_dtype(struct dirent *de, struct index_state *istate,
-		     const char *path, int len)
+static int resolve_dtype(int dtype, struct index_state *istate,
+			 const char *path, int len)
 {
-	int dtype = de ? DTYPE(de) : DT_UNKNOWN;
 	struct stat st;
 
 	if (dtype != DT_UNKNOWN)
@@ -1667,14 +1666,13 @@ static enum path_treatment treat_one_path(struct dir_struct *dir,
 					  struct strbuf *path,
 					  int baselen,
 					  const struct pathspec *pathspec,
-					  int dtype, struct dirent *de)
+					  int dtype)
 {
 	int exclude;
 	int has_path_in_index = !!index_file_exists(istate, path->buf, path->len, ignore_case);
 	enum path_treatment path_treatment;
 
-	if (dtype == DT_UNKNOWN)
-		dtype = get_dtype(de, istate, path->buf, path->len);
+	dtype = resolve_dtype(dtype, istate, path->buf, path->len);
 
 	/* Always exclude indexed files */
 	if (dtype != DT_DIR && has_path_in_index)
@@ -1782,21 +1780,18 @@ static enum path_treatment treat_path(struct dir_struct *dir,
 				      int baselen,
 				      const struct pathspec *pathspec)
 {
-	int dtype;
-	struct dirent *de = cdir->de;
-
-	if (!de)
+	if (!cdir->d_name)
 		return treat_path_fast(dir, untracked, cdir, istate, path,
 				       baselen, pathspec);
-	if (is_dot_or_dotdot(de->d_name) || !fspathcmp(de->d_name, ".git"))
+	if (is_dot_or_dotdot(cdir->d_name) || !fspathcmp(cdir->d_name, ".git"))
 		return path_none;
 	strbuf_setlen(path, baselen);
-	strbuf_addstr(path, de->d_name);
+	strbuf_addstr(path, cdir->d_name);
 	if (simplify_away(path->buf, path->len, pathspec))
 		return path_none;
 
-	dtype = DTYPE(de);
-	return treat_one_path(dir, untracked, istate, path, baselen, pathspec, dtype, de);
+	return treat_one_path(dir, untracked, istate, path, baselen, pathspec,
+			      cdir->d_type);
 }
 
 static void add_untracked(struct untracked_cache_dir *dir, const char *name)
@@ -1884,10 +1879,17 @@ static int open_cached_dir(struct cached_dir *cdir,
 
 static int read_cached_dir(struct cached_dir *cdir)
 {
+	struct dirent *de;
+
 	if (cdir->fdir) {
-		cdir->de = readdir(cdir->fdir);
-		if (!cdir->de)
+		de = readdir(cdir->fdir);
+		if (!de) {
+			cdir->d_name = NULL;
+			cdir->d_type = DT_UNKNOWN;
 			return -1;
+		}
+		cdir->d_name = de->d_name;
+		cdir->d_type = DTYPE(de);
 		return 0;
 	}
 	while (cdir->nr_dirs < cdir->untracked->dirs_nr) {
@@ -1970,7 +1972,7 @@ static enum path_treatment read_directory_recursive(struct dir_struct *dir,
 		/* recurse into subdir if instructed by treat_path */
 		if ((state == path_recurse) ||
 			((state == path_untracked) &&
-			 (get_dtype(cdir.de, istate, path.buf, path.len) == DT_DIR) &&
+			 (resolve_dtype(cdir.d_type, istate, path.buf, path.len) == DT_DIR) &&
 			 ((dir->flags & DIR_SHOW_IGNORED_TOO) ||
 			  (pathspec &&
 			   do_match_pathspec(istate, pathspec, path.buf, path.len,
@@ -2103,7 +2105,7 @@ static int treat_leading_path(struct dir_struct *dir,
 		if (simplify_away(sb.buf, sb.len, pathspec))
 			break;
 		if (treat_one_path(dir, NULL, istate, &sb, baselen, pathspec,
-				   DT_DIR, NULL) == path_none)
+				   DT_DIR) == path_none)
 			break; /* do not recurse into it */
 		if (len <= baselen) {
 			rc = 1;