Merge pull request #19647 from ddstreet/test-oomd-failure

handle lack of kernel support for some cgroup files

src/basic/fileio.c

@@ -371,8 +371,6 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
         int n_retries;
         bool truncated = false;
 
-        assert(ret_contents);
-
         /* Virtual filesystems such as sysfs or procfs use kernfs, and kernfs can work with two sorts of
          * virtual files. One sort uses "seq_file", and the results of the first read are buffered for the
          * second read. The other sort uses "raw" reads which always go direct to the device. In the latter
@@ -486,7 +484,9 @@ int read_virtual_file(const char *filename, size_t max_size, char **ret_contents
                 return -EBADMSG;
 
         buf[n] = 0;
-        *ret_contents = TAKE_PTR(buf);
+
+        if (ret_contents)
+                *ret_contents = TAKE_PTR(buf);
 
         return !truncated;
 }

src/basic/log.h

@@ -236,6 +236,29 @@ int log_emergency_level(void);
 #define log_error_errno(error, ...)     log_full_errno(LOG_ERR,     error, __VA_ARGS__)
 #define log_emergency_errno(error, ...) log_full_errno(log_emergency_level(), error, __VA_ARGS__)
 
+/* This logs at the specified level the first time it is called, and then
+ * logs at debug. If the specified level is debug, this logs only the first
+ * time it is called. */
+#define log_once(level, ...)                                             \
+        ({                                                               \
+                if (ONCE)                                                \
+                        log_full(level, __VA_ARGS__);                    \
+                else if (LOG_PRI(level) != LOG_DEBUG)                    \
+                        log_debug(__VA_ARGS__);                          \
+        })
+
+#define log_once_errno(level, error, ...)                                \
+        ({                                                               \
+                int _err = (error);                                      \
+                if (ONCE)                                                \
+                        _err = log_full_errno(level, _err, __VA_ARGS__); \
+                else if (LOG_PRI(level) != LOG_DEBUG)                    \
+                        _err = log_debug_errno(_err, __VA_ARGS__);       \
+                else                                                     \
+                        _err = -ERRNO_VALUE(_err);                       \
+                _err;                                                    \
+        })
+
 #if LOG_TRACE
 #  define log_trace(...) log_debug(__VA_ARGS__)
 #else