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>

userns: handle delayed write errors at fclose
e4ccd113 · Serge Hallyn · dba104c8 · e4ccd113
Commit e4ccd113 authored Mar 04, 2013 by Serge Hallyn
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Showing with 6 additions and 4 deletions

conf.c src/lxc/conf.c +6 -4

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--- 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");
+		SYSERROR("writing id mapping");
-	fclose(f);
+	closeret = fclose(f);
-	return ret < 0 ? ret : 0;
+	if (closeret)
+		SYSERROR("writing id mapping");
+	return ret < 0 ? ret : closeret;
 }
 int lxc_map_ids(struct lxc_list *idmap, pid_t pid)