Make %p print '(null)' for NULL pointers

Before, when we only ever printed out the pointer value itself, a NULL pointer would never cause issues and might as well be printed out as just its numeric value. However, with the extended %p formats, especially %pR, we might validly want to print out resources for debugging. And sometimes they don't even exist, and the resource pointer is just NULL. Print it out as such, rather than oopsing. This is a more generic version of a patch done by Trent Piepho (catching all %p cases rather than just %pR, and using "(null)" instead of "[NULL]" to match glibc). Requested-by: Trent Piepho <[email protected]> Acked-by: Harvey Harrison <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
berg · Jan 3, 2009 · d97106a · d97106a
1 parent 3bfacef
commit d97106a
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
@@ -661,6 +661,9 @@ static char *ip4_addr_string(char *buf, char *end, u8 *addr, int field_width,
  */
 static char *pointer(const char *fmt, char *buf, char *end, void *ptr, int field_width, int precision, int flags)
 {
+	if (!ptr)
+		return string(buf, end, "(null)", field_width, precision, flags);
+
 	switch (*fmt) {
 	case 'F':
 		ptr = dereference_function_descriptor(ptr);