userns: handle delayed write errors at fclose

As Kees pointed out, write() errors can be delayed and returned as
close() errors.  So don't ignore error on close when writing the
userns id mapping.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/conf.c b/src/lxc/conf.c
index 04ab8b86de16aed80bb4d684e0683b4633285ae7..7d70c97aa3d1b27af293e2d02350b175bea61234 100644 (file)
--- a/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@ -2447,7 +2447,7 @@ int lxc_assign_network(struct lxc_list *network, pid_t pid)
 int add_id_mapping(enum idtype idtype, pid_t pid, uid_t host_start, uid_t ns_start, int range)
 {
        char path[PATH_MAX];
-       int ret;
+       int ret, closeret;
        FILE *f;
 
        ret = snprintf(path, PATH_MAX, "/proc/%d/%cid_map", pid, idtype == ID_TYPE_UID ? 'u' : 'g');
@@ -2462,9 +2462,11 @@ int add_id_mapping(enum idtype idtype, pid_t pid, uid_t host_start, uid_t ns_sta
        }
        ret = fprintf(f, "%d %d %d", ns_start, host_start, range);
        if (ret < 0)
-               perror("write");
-       fclose(f);
-       return ret < 0 ? ret : 0;
+               SYSERROR("writing id mapping");
+       closeret = fclose(f);
+       if (closeret)
+               SYSERROR("writing id mapping");
+       return ret < 0 ? ret : closeret;
 }
 
 int lxc_map_ids(struct lxc_list *idmap, pid_t pid)