[PATCH v2] clean: use warning_errno() when appropriate

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

All these warning() calls are preceded by a system call. Report the
actual error to help the user understand why we fail to remove
something.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 v2 dances with errno

 builtin/clean.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/builtin/clean.c b/builtin/clean.c
index d6bc3aaae..3569736f6 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -154,6 +154,7 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 	struct strbuf quoted = STRBUF_INIT;
 	struct dirent *e;
 	int res = 0, ret = 0, gone = 1, original_len = path->len, len;
+	int saved_errno;
 	struct string_list dels = STRING_LIST_INIT_DUP;
 
 	*dir_gone = 1;
@@ -173,9 +174,11 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 	if (!dir) {
 		/* an empty dir could be removed even if it is unreadble */
 		res = dry_run ? 0 : rmdir(path->buf);
+		saved_errno = errno;
 		if (res) {
 			quote_path_relative(path->buf, prefix, &quoted);
-			warning(_(msg_warn_remove_failed), quoted.buf);
+			errno = saved_errno;
+			warning_errno(_(msg_warn_remove_failed), quoted.buf);
 			*dir_gone = 0;
 		}
 		return res;
@@ -204,12 +207,14 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 			continue;
 		} else {
 			res = dry_run ? 0 : unlink(path->buf);
+			saved_errno = errno;
 			if (!res) {
 				quote_path_relative(path->buf, prefix, &quoted);
 				string_list_append(&dels, quoted.buf);
 			} else {
 				quote_path_relative(path->buf, prefix, &quoted);
-				warning(_(msg_warn_remove_failed), quoted.buf);
+				errno = saved_errno;
+				warning_errno(_(msg_warn_remove_failed), quoted.buf);
 				*dir_gone = 0;
 				ret = 1;
 			}
@@ -227,11 +232,13 @@ static int remove_dirs(struct strbuf *path, const char *prefix, int force_flag,
 
 	if (*dir_gone) {
 		res = dry_run ? 0 : rmdir(path->buf);
+		saved_errno = errno;
 		if (!res)
 			*dir_gone = 1;
 		else {
 			quote_path_relative(path->buf, prefix, &quoted);
-			warning(_(msg_warn_remove_failed), quoted.buf);
+			errno = saved_errno;
+			warning_errno(_(msg_warn_remove_failed), quoted.buf);
 			*dir_gone = 0;
 			ret = 1;
 		}
@@ -853,7 +860,7 @@ static void interactive_main_loop(void)
 
 int cmd_clean(int argc, const char **argv, const char *prefix)
 {
-	int i, res;
+	int i, res, saved_errno;
 	int dry_run = 0, remove_directories = 0, quiet = 0, ignored = 0;
 	int ignored_only = 0, config_set = 0, errors = 0, gone = 1;
 	int rm_flags = REMOVE_DIR_KEEP_NESTED_GIT;
@@ -980,9 +987,11 @@ int cmd_clean(int argc, const char **argv, const char *prefix)
 			}
 		} else {
 			res = dry_run ? 0 : unlink(abs_path.buf);
+			saved_errno = errno;
 			if (res) {
 				qname = quote_path_relative(item->string, NULL, &buf);
-				warning(_(msg_warn_remove_failed), qname);
+				errno = saved_errno;
+				warning_errno(_(msg_warn_remove_failed), qname);
 				errors++;
 			} else if (!quiet) {
 				qname = quote_path_relative(item->string, NULL, &buf);
-- 
2.11.0.157.gd943d85