log: add CMD_SYSINFO()

Add a thread-safe and uniform way to retrieve errno values in programs that are
shipped as part of LXC but are not expected to have access to the logging
system.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/log.h b/src/lxc/log.h
index d75d87d4329cf654c7c695177c66619707dfdad9..4654fd918730bae37367fd30f7099730c25a80c5 100644 (file)
--- a/src/lxc/log.h
+++ b/src/lxc/log.h
@@ -435,6 +435,12 @@ ATTR_UNUSED static inline void LXC_##LEVEL(struct lxc_log_locinfo* locinfo,        \
                fprintf(stderr, "%s - " format, ptr, ##__VA_ARGS__); \
        } while (0)
 
+#define CMD_SYSINFO(format, ...)                            \
+       do {                                                \
+               lxc_log_strerror_r;                         \
+               printf("%s - " format, ptr, ##__VA_ARGS__); \
+       } while (0)
+
 extern int lxc_log_fd;
 
 extern int lxc_log_syslog(int facility);