Don't recurse infinitely until we blow the stack when the debug

file can't be opened in the front-end.  The conversation-type debug
mode will be removed in the future.

lib/util/sudo_debug.c

@@ -122,6 +122,9 @@ static char sudo_debug_pidstr[(((sizeof(int) * 8) + 2) / 3) + 3];
 static size_t sudo_debug_pidlen;
 static const int num_subsystems = NUM_SUBSYSTEMS;
 
+/* Exposed for sudo_printf.c */
+void sudo_debug_write_file(const char *func, const char *file, int line, const char *str, int len, int errno_val);
+
 /*
  * Parse settings string from sudo.conf and open debugfile.
  * Returns 1 on success, 0 if cannot open debugfile.
@@ -331,7 +334,7 @@ sudo_debug_write_conv(const char *func, const char *file, int lineno,
     }
 }
 
-static void
+void
 sudo_debug_write_file(const char *func, const char *file, int lineno,
     const char *str, int len, int errnum)
 {

lib/util/sudo_printf.c

@@ -33,6 +33,9 @@
 #include "sudo_plugin.h"
 #include "sudo_debug.h"
 
+/* Not exported outside libsudo_util */
+void sudo_debug_write_file(const char *func, const char *file, int line, const char *str, int len, int errno_val);
+
 __dso_public int
 _sudo_printf(int msg_type, const char *fmt, ...)
 {
@@ -57,7 +60,7 @@ _sudo_printf(int msg_type, const char *fmt, ...)
 	len = vasprintf(&buf, fmt, ap);
 	va_end(ap);
 	if (len != -1)
-	    sudo_debug_write(buf, len, 0);
+	    sudo_debug_write_file(NULL, NULL, 0, buf, len, 0);
 	break;
     default:
 	errno = EINVAL;