[systemd-devel] [PATCH] tmpfiles: try to handle read-only file systems gracefully

[Michael Olbrich]

On read-only filesystems trying to create the target will not fail with
EEXIST but with EROFS. Handle EROFS by checking if the target already
exists, and if empty when truncating.
This avoids reporting errors if tmpfiles doesn't actually needs to do
anything.
---

This is a rework of a patch I wrote some time ago[1]. This time reacting to
EROFS instead of preempting it.

Michael

[1] http://lists.freedesktop.org/archives/systemd-devel/2014-August/022158.html

 src/tmpfiles/tmpfiles.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index 218d55051410..4473bf019911 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -983,9 +983,11 @@ static int write_one_file(Item *i, const char *path) {
                         log_debug_errno(errno, "Not writing \"%s\": %m", path);
                         return 0;
                 }
-
-                log_error_errno(errno, "Failed to create file %s: %m", path);
-                return -errno;
+                r = -errno;
+                if (i->argument || r != -EROFS || stat(path, &st) < 0 || (i->type == TRUNCATE_FILE && st.st_size > 0)) {
+                        log_error_errno(r, "Failed to create file %s: %m", path);
+                        return r;
+                }
         }
 
         if (i->argument) {
@@ -1154,6 +1156,10 @@ static int create_item(Item *i) {
 
                 log_debug("Copying tree \"%s\" to \"%s\".", resolved, i->path);
                 r = copy_tree(resolved, i->path, false);
+
+                if (r == -EROFS && stat(i->path, &st) == 0)
+                        r = -EEXIST;
+
                 if (r < 0) {
                         struct stat a, b;
 
-- 
2.1.4