read-cache.c: refactor --ignore-missing implementation

Move lstat ENOENT handling from refresh_index to refresh_cache_ent and
activate it with a new CE_MATCH_IGNORE_MISSING option.  This will allow
other call paths into refresh_cache_ent to use the feature.

Signed-off-by: Brad King <brad.king@kitware.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -488,6 +488,8 @@ extern void *read_blob_data_from_index(struct index_state *, const char *, unsig
 #define CE_MATCH_RACY_IS_DIRTY		02
 /* do stat comparison even if CE_SKIP_WORKTREE is true */
 #define CE_MATCH_IGNORE_SKIP_WORKTREE	04
+/* ignore non-existent files during stat update  */
+#define CE_MATCH_IGNORE_MISSING		0x08
 extern int ie_match_stat(const struct index_state *, const struct cache_entry *, struct stat *, unsigned int);
 extern int ie_modified(const struct index_state *, const struct cache_entry *, struct stat *, unsigned int);
 

read-cache.c

@@ -1031,6 +1031,7 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 	int changed, size;
 	int ignore_valid = options & CE_MATCH_IGNORE_VALID;
 	int ignore_skip_worktree = options & CE_MATCH_IGNORE_SKIP_WORKTREE;
+	int ignore_missing = options & CE_MATCH_IGNORE_MISSING;
 
 	if (ce_uptodate(ce))
 		return ce;
@@ -1050,6 +1051,8 @@ static struct cache_entry *refresh_cache_ent(struct index_state *istate,
 	}
 
 	if (lstat(ce->name, &st) < 0) {
+		if (ignore_missing && errno == ENOENT)
+			return ce;
 		if (err)
 			*err = errno;
 		return NULL;
@@ -1126,7 +1129,8 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
 	int ignore_submodules = (flags & REFRESH_IGNORE_SUBMODULES) != 0;
 	int first = 1;
 	int in_porcelain = (flags & REFRESH_IN_PORCELAIN);
-	unsigned int options = really ? CE_MATCH_IGNORE_VALID : 0;
+	unsigned int options = ((really ? CE_MATCH_IGNORE_VALID : 0) |
+				(not_new ? CE_MATCH_IGNORE_MISSING : 0));
 	const char *modified_fmt;
 	const char *deleted_fmt;
 	const char *typechange_fmt;
@@ -1175,8 +1179,6 @@ int refresh_index(struct index_state *istate, unsigned int flags, const char **p
 		if (!new) {
 			const char *fmt;
 
-			if (not_new && cache_errno == ENOENT)
-				continue;
 			if (really && cache_errno == EINVAL) {
 				/* If we are doing --really-refresh that
 				 * means the index is not valid anymore.