[U-Boot] [PATCH v2 3/3] env: make "env default" selective, check and apply

[Gerlando Falauto]

Changes in the syntax (user API) for "env default":
  -f: override write-once variables
  -a: all (resetting the whole env is NOT the default behavior)

Signed-off-by: Gerlando Falauto <gerlando.falauto at keymile.com>
---
 README                   |    2 ++
 common/cmd_nvedit.c      |   43 ++++++++++++++++++++++++++++++++++++-------
 common/env_common.c      |   31 ++++++++++++++++++++++++++++++-
 include/config_cmd_all.h |    1 +
 include/environment.h    |    5 +++++
 5 files changed, 74 insertions(+), 8 deletions(-)

diff --git a/README b/README
index fda0190..e924575 100644
--- a/README
+++ b/README
@@ -724,6 +724,8 @@ The following options need to be configured:
 		CONFIG_CMD_CONSOLE	  coninfo
 		CONFIG_CMD_CRC32	* crc32
 		CONFIG_CMD_DATE		* support for RTC, date/time...
+		CONFIG_CMD_DEFAULTENV_VARS
+					* Reset individual variables to default
 		CONFIG_CMD_DHCP		* DHCP support
 		CONFIG_CMD_DIAG		* Diagnostics
 		CONFIG_CMD_DS4510	* ds4510 I2C gpio commands
diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index 871b3b1..317bd1c 100644
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -674,14 +674,40 @@ int envmatch(uchar *s1, int i2)
 	return -1;
 }
 
-static int do_env_default(cmd_tbl_t *cmdtp, int flag,
+static int do_env_default(cmd_tbl_t *cmdtp, int __flag,
 			  int argc, char * const argv[])
 {
-	if (argc != 2 || strcmp(argv[1], "-f") != 0)
-		return cmd_usage(cmdtp);
-
-	set_default_env("## Resetting to default environment\n");
-	return 0;
+	int all = 0, flag = 0;
+	debug("Initial value for argc=%d\n", argc);
+	while (--argc > 0 && **++argv == '-') {
+		char *arg = *argv;
+		while (*++arg) {
+			switch (*arg) {
+			case 'a':		/* default all */
+				all = 1;
+				break;
+			case 'f':		/* force */
+				flag |= H_FORCE;
+				break;
+			default:
+				return cmd_usage(cmdtp);
+			}
+		}
+	}
+	debug("Final value for argc=%d\n", argc);
+	if (all && (argc == 0)) {
+		/* Reset the whole environment */
+		set_default_env("## Resetting to default environment\n");
+		return 0;
+	}
+#ifdef CONFIG_CMD_DEFAULTENV_VARS
+	if (!all && (argc > 0)) {
+		/* Reset individual variables */
+		env_default_vars(argc, argv);
+		return 0;
+	}
+#endif
+	return cmd_usage(cmdtp);
 }
 
 static int do_env_delete(cmd_tbl_t *cmdtp, int flag,
@@ -1012,7 +1038,10 @@ U_BOOT_CMD(
 #if defined(CONFIG_CMD_ASKENV)
 	"ask name [message] [size] - ask for environment variable\nenv "
 #endif
-	"default -f - reset default environment\n"
+	"default [-f] -a - [forcibly] reset default environment\n"
+#if defined(CONFIG_CMD_DEFAULTENV_VARS)
+	"env default [-f] var [...] - [forcibly] reset variable(s) to their default values\n"
+#endif
 #if defined(CONFIG_CMD_EDITENV)
 	"env edit name - edit environment variable\n"
 #endif
diff --git a/common/env_common.c b/common/env_common.c
index 7e2bb2f..56719a6 100644
--- a/common/env_common.c
+++ b/common/env_common.c
@@ -157,6 +157,11 @@ const uchar *env_get_addr(int index)
 
 void set_default_env(const char *s)
 {
+	/*
+	 * By default, do not apply changes as they will eventually
+	 * be applied by someone else
+	 */
+	apply_cb apply_function = NULL;
 	if (sizeof(default_environment) > ENV_SIZE) {
 		puts("*** Error - default environment is too large\n\n");
 		return;
@@ -168,6 +173,14 @@ void set_default_env(const char *s)
 				"using default environment\n\n",
 				s + 1);
 		} else {
+			/*
+			 * This set_to_default was explicitly asked for
+			 * by the user, as opposed to being a recovery
+			 * mechanism. Therefore we chack every single
+			 * variable and apply changes to the system
+			 * right away (e.g. baudrate, console).
+			 */
+			apply_function = env_check_apply;
 			puts(s);
 		}
 	} else {
@@ -176,12 +189,28 @@ void set_default_env(const char *s)
 
 	if (himport_r(&env_htab, (char *)default_environment,
 			sizeof(default_environment), '\0', 0,
-			0, NULL, NULL) == 0)
+			0, NULL, apply_function) == 0)
 		error("Environment import failed: errno = %d\n", errno);
 
 	gd->flags |= GD_FLG_ENV_READY;
 }
 
+#ifdef CONFIG_CMD_DEFAULTENV_VARS
+
+/* [re]set individual variables to their value in the default environment */
+int env_default_vars(int nvars, char * const vars[])
+{
+	/*
+	 * Special use-case: import from default environment
+	 * (and use \0 as a separator)
+	 */
+	return himport_r(&env_htab, (const char *)default_environment,
+				sizeof(default_environment), '\0', H_NOCLEAR,
+				nvars, vars, env_check_apply);
+}
+
+#endif /* CONFIG_CMD_DEFAULTENV_VARS */
+
 /*
  * Check if CRC is valid and (if yes) import the environment.
  * Note that "buf" may or may not be aligned.
diff --git a/include/config_cmd_all.h b/include/config_cmd_all.h
index 9716f9c..e728eae 100644
--- a/include/config_cmd_all.h
+++ b/include/config_cmd_all.h
@@ -25,6 +25,7 @@
 #define CONFIG_CMD_CDP		/* Cisco Discovery Protocol	*/
 #define CONFIG_CMD_CONSOLE	/* coninfo			*/
 #define CONFIG_CMD_DATE		/* support for RTC, date/time...*/
+#define CONFIG_CMD_DEFAULTENV_VARS /* default individ variables */
 #define CONFIG_CMD_DHCP		/* DHCP Support			*/
 #define CONFIG_CMD_DIAG		/* Diagnostics			*/
 #define CONFIG_CMD_DISPLAY	/* Display support		*/
diff --git a/include/environment.h b/include/environment.h
index 3a3e6b8..8f0d4db 100644
--- a/include/environment.h
+++ b/include/environment.h
@@ -190,6 +190,11 @@ void env_crc_update(void);
 /* [re]set to the default environment */
 void set_default_env(const char *s);
 
+#ifdef CONFIG_CMD_DEFAULTENV_VARS
+/* [re]set individual variables to their value in the default environment */
+int env_default_vars(int nvars, char * const vars[]);
+#endif
+
 /* Import from binary representation into hash table */
 int env_import(const char *buf, int check);
 
-- 
1.7.1