Allow printf to be used on signal handlers

libc function dprintf is meant to be signal safe for as long you obey
the documented constrains.

diff --git a/include/c.h b/include/c.h
index 3b921ab33b15d570f3faf5ba8efe341e75228a97..d060a4d89eb34497438afeb71a76ffbe5ffcbb66 100644 (file)
--- a/include/c.h
+++ b/include/c.h
@@ -427,18 +427,16 @@ static inline int xusleep(useconds_t usec)
 #endif
 }
 
-
-#define ul_err_write(_m) ignore_result( write(STDERR_FILENO, _m, strlen(_m)) )
+/* ul_sig_printf is signal safe as long you don't use floating point formats,
+   positional arguments or wide characters.*/
+#define ul_sig_printf(fmt, ...) ignore_result(dprintf(STDERR_FILENO, fmt, __VA_ARGS__))
 
 /*
  * warn() for signal handlers
  */
 static inline void ul_sig_warn(const char *mesg)
 {
-       ul_err_write(program_invocation_short_name);
-       ul_err_write(": ");
-       ul_err_write(mesg);
-       ul_err_write("\n");
+       ul_sig_printf("%s: %s\n", program_invocation_short_name, mesg);
 }
 
 /*