commit: fix duplication regression in permission error output

Fix a regression in the error output emitted when .git/objects can't
be written to. Before 9c4d6c0297 (cache-tree: Write updated
cache-tree after commit, 2014-07-13) we'd emit only one "insufficient
permission" error, now we'll do so again.

The cause is rather straightforward, we've got WRITE_TREE_SILENT for
the use-case of wanting to prepare an index silently, quieting any
permission etc. error output. Then when we attempt to update to
that (possibly broken) index we'll run into the same errors again.

But with 9c4d6c0297 the gap between the cache-tree API and the object
store wasn't closed in terms of asking write_object_file() to be
silent. I.e. post-9c4d6c0297b the first call is to prepare_index(),
and after that we'll call prepare_to_commit(). We only want verbose
error output from the latter.

So let's add and use that facility with a corresponding HASH_SILENT
flag, its only user is cache-tree.c's update_one(), which will set it
if its "WRITE_TREE_SILENT" flag is set.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache-tree.c

@@ -440,8 +440,9 @@ static int update_one(struct cache_tree *it,
 	} else if (dryrun) {
 		hash_object_file(the_hash_algo, buffer.buf, buffer.len,
 				 tree_type, &it->oid);
-	} else if (write_object_file(buffer.buf, buffer.len, tree_type,
+	} else if (write_object_file_flags(buffer.buf, buffer.len, tree_type,
-				     &it->oid)) {
+					   &it->oid, flags & WRITE_TREE_SILENT
+					   ? HASH_SILENT : 0)) {
 		strbuf_release(&buffer);
 		return -1;
 	}

cache.h

@@ -887,6 +887,7 @@ int ie_modified(struct index_state *, const struct cache_entry *, struct stat *,
 #define HASH_WRITE_OBJECT 1
 #define HASH_FORMAT_CHECK 2
 #define HASH_RENORMALIZE  4
+#define HASH_SILENT 8
 int index_fd(struct index_state *istate, struct object_id *oid, int fd, struct stat *st, enum object_type type, const char *path, unsigned flags);
 int index_path(struct index_state *istate, struct object_id *oid, const char *path, struct stat *st, unsigned flags);
 

object-file.c

@@ -1915,7 +1915,7 @@ static int create_tmpfile(struct strbuf *tmp, const char *filename)
 
 static int write_loose_object(const struct object_id *oid, char *hdr,
 			      int hdrlen, const void *buf, unsigned long len,
-			      time_t mtime)
+			      time_t mtime, unsigned flags)
 {
 	int fd, ret;
 	unsigned char compressed[4096];
@@ -1929,7 +1929,9 @@ static int write_loose_object(const struct object_id *oid, char *hdr,
 
 	fd = create_tmpfile(&tmp_file, filename.buf);
 	if (fd < 0) {
-		if (errno == EACCES)
+		if (flags & HASH_SILENT)
+			return -1;
+		else if (errno == EACCES)
 			return error(_("insufficient permission for adding an object to repository database %s"), get_object_directory());
 		else
 			return error_errno(_("unable to create temporary file"));
@@ -1979,7 +1981,8 @@ static int write_loose_object(const struct object_id *oid, char *hdr,
 		struct utimbuf utb;
 		utb.actime = mtime;
 		utb.modtime = mtime;
-		if (utime(tmp_file.buf, &utb) < 0)
+		if (utime(tmp_file.buf, &utb) < 0 &&
+		    !(flags & HASH_SILENT))
 			warning_errno(_("failed utime() on %s"), tmp_file.buf);
 	}
 
@@ -2004,8 +2007,9 @@ static int freshen_packed_object(const struct object_id *oid)
 	return 1;
 }
 
-int write_object_file(const void *buf, unsigned long len, const char *type,
+int write_object_file_flags(const void *buf, unsigned long len,
-		      struct object_id *oid)
+			    const char *type, struct object_id *oid,
+			    unsigned flags)
 {
 	char hdr[MAX_HEADER_LEN];
 	int hdrlen = sizeof(hdr);
@@ -2017,7 +2021,7 @@ int write_object_file(const void *buf, unsigned long len, const char *type,
 				  &hdrlen);
 	if (freshen_packed_object(oid) || freshen_loose_object(oid))
 		return 0;
-	return write_loose_object(oid, hdr, hdrlen, buf, len, 0);
+	return write_loose_object(oid, hdr, hdrlen, buf, len, 0, flags);
 }
 
 int hash_object_file_literally(const void *buf, unsigned long len,
@@ -2037,7 +2041,7 @@ int hash_object_file_literally(const void *buf, unsigned long len,
 		goto cleanup;
 	if (freshen_packed_object(oid) || freshen_loose_object(oid))
 		goto cleanup;
-	status = write_loose_object(oid, header, hdrlen, buf, len, 0);
+	status = write_loose_object(oid, header, hdrlen, buf, len, 0, 0);
 
 cleanup:
 	free(header);
@@ -2059,7 +2063,7 @@ int force_object_loose(const struct object_id *oid, time_t mtime)
 	if (!buf)
 		return error(_("cannot read object for %s"), oid_to_hex(oid));
 	hdrlen = xsnprintf(hdr, sizeof(hdr), "%s %"PRIuMAX , type_name(type), (uintmax_t)len) + 1;
-	ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime);
+	ret = write_loose_object(oid, hdr, hdrlen, buf, len, mtime, 0);
 	free(buf);
 
 	return ret;

object-store.h

@@ -222,8 +222,14 @@ int hash_object_file(const struct git_hash_algo *algo, const void *buf,
 		     unsigned long len, const char *type,
 		     struct object_id *oid);
 
-int write_object_file(const void *buf, unsigned long len,
+int write_object_file_flags(const void *buf, unsigned long len,
-		      const char *type, struct object_id *oid);
+			    const char *type, struct object_id *oid,
+			    unsigned flags);
+static inline int write_object_file(const void *buf, unsigned long len,
+				    const char *type, struct object_id *oid)
+{
+	return write_object_file_flags(buf, len, type, oid, 0);
+}
 
 int hash_object_file_literally(const void *buf, unsigned long len,
 			       const char *type, struct object_id *oid,

t/t0004-unwritable.sh

@@ -37,7 +37,7 @@ test_expect_success POSIXPERM,SANITY 'commit should notice unwritable repository
 '
 
 test_lazy_prereq COMMIT_OUT 'test -e "$TRASH_DIRECTORY"/out.commit'
-test_expect_failure COMMIT_OUT 'commit output on unwritable repository' '
+test_expect_success COMMIT_OUT 'commit output on unwritable repository' '
 	cat >expect <<-\EOF &&
 	error: insufficient permission for adding an object to repository database .git/objects
 	error: Error building trees