cmd_nvedit.c: Add env exists command

env exists is a way to test (in hush) if an environment variable
exists.  A workaround existed using printenv but this new command
doesn't require all the stdout/stderr redirection to prevent
printing information to the screen.

Example:
$ set testexists 1
$ env exists testexists && echo "yes"
yes
$ env exists testexists || echo "no"
$ set testexists
$ env exists testexists && echo "yes"
$ env exists testexists || echo "no"
no
$

Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>

diff --git a/README b/README
index 91c3ac0fa729fcb011a8faaf51713c550e1ecc3c..a4a450efeec89302e96ad10e4c3dfdae91a363fc 100644 (file)
--- a/README
+++ b/README
@@ -848,6 +848,7 @@ The following options need to be configured:
                CONFIG_CMD_ELF          * bootelf, bootvx
                CONFIG_CMD_ENV_CALLBACK * display details about env callbacks
                CONFIG_CMD_ENV_FLAGS    * display details about env flags
+               CONFIG_CMD_ENV_EXISTS   * check existence of env variable
                CONFIG_CMD_EXPORTENV    * export the environment
                CONFIG_CMD_EXT2         * ext2 command support
                CONFIG_CMD_EXT4         * ext4 command support

diff --git a/common/cmd_nvedit.c b/common/cmd_nvedit.c
index ba9ba16972cda0c3502fd24399f2666f20544046..0d4d02cfe0a1eb91ecd39bb6c9edfcc502e8225a 100644 (file)
--- a/common/cmd_nvedit.c
+++ b/common/cmd_nvedit.c
@@ -1059,6 +1059,23 @@ sep_err:
 }
 #endif
 
+#if defined(CONFIG_CMD_ENV_EXISTS)
+static int do_env_exists(cmd_tbl_t *cmdtp, int flag, int argc,
+                      char * const argv[])
+{
+       ENTRY e, *ep;
+
+       if (argc < 2)
+               return CMD_RET_USAGE;
+
+       e.key = argv[1];
+       e.data = NULL;
+       hsearch_r(e, FIND, &ep, &env_htab, 0);
+
+       return (ep == NULL) ? 1 : 0;
+}
+#endif
+
 /*
  * New command line interface: "env" command with subcommands
  */
@@ -1094,6 +1111,9 @@ static cmd_tbl_t cmd_env_sub[] = {
        U_BOOT_CMD_MKENT(save, 1, 0, do_env_save, "", ""),
 #endif
        U_BOOT_CMD_MKENT(set, CONFIG_SYS_MAXARGS, 0, do_env_set, "", ""),
+#if defined(CONFIG_CMD_ENV_EXISTS)
+       U_BOOT_CMD_MKENT(exists, 2, 0, do_env_exists, "", ""),
+#endif
 };
 
 #if defined(CONFIG_NEEDS_MANUAL_RELOC)
@@ -1136,6 +1156,9 @@ static char env_help_text[] =
 #if defined(CONFIG_CMD_EDITENV)
        "env edit name - edit environment variable\n"
 #endif
+#if defined(CONFIG_CMD_ENV_EXISTS)
+       "env exists name - tests for existence of variable\n"
+#endif
 #if defined(CONFIG_CMD_EXPORTENV)
        "env export [-t | -b | -c] [-s size] addr [var ...] - export environment\n"
 #endif