svn commit: r284614 - head/sys/boot/uboot/lib

[Maxim Sobolev]

Author: sobomax
Date: Fri Jun 19 22:24:58 2015
New Revision: 284614
URL: https://svnweb.freebsd.org/changeset/base/284614

Log:
  Provide bug4bug workaround for certain dumbiness of the u-boot's API_env_enum
  function, which is expected to set returned env to NULL upon reaching the end
  of the environment list but fails to do so in certain cases. The respective
  u-boot code looks like the following (HEAD at the time of this commit):
  
  --- api.c ---
   496 static int API_env_enum(va_list ap)
   ...
   510                 *next = last;
   511
   512                 for (i = 0; env_get_char(i) != '\0'; i = n + 1) {
   513                         for (n = i; env_get_char(n) != '\0'; ++n) {
   514                                 if (n >= CONFIG_ENV_SIZE) {
   515                                         /* XXX shouldn't we set *next = NULL?? */
   516                                         return 0;
   517                                 }
   518                         }
  -------------
  
  The net result is that any unfortunate user of the loader's ub_env_enum()
  function hitting this condition would be trapped in the infinite loop, as
  the main use pattern of ub_env_enum() is basically the following:
  
  while ((env = ub_env_enum(env)) != NULL) { DO STUFF }
  
  Which would stuck forever with the last element.

Modified:
  head/sys/boot/uboot/lib/glue.c

Modified: head/sys/boot/uboot/lib/glue.c
==============================================================================
--- head/sys/boot/uboot/lib/glue.c	Fri Jun 19 21:55:12 2015	(r284613)
+++ head/sys/boot/uboot/lib/glue.c	Fri Jun 19 22:24:58 2015	(r284614)
@@ -513,7 +513,7 @@ ub_env_enum(const char *last)
 	if (!syscall(API_ENV_ENUM, NULL, (uint32_t)last, (uint32_t)&env))
 		return (NULL);
 
-	if (env == NULL)
+	if (env == NULL || last == env)
 		/* no more env. variables to enumerate */
 		return (NULL);