nsh env variables expanding

1 files changed, 50 insertions, 5 deletions

diff --git a/apps/nshlib/nsh_envcmds.c b/apps/nshlib/nsh_envcmds.c
index 07b775517..5e7f3e7b6 100644
--- a/apps/nshlib/nsh_envcmds.c
+++ b/apps/nshlib/nsh_envcmds.c
@@ -137,6 +137,48 @@ static inline char *nsh_getdirpath(FAR struct nsh_vtbl_s *vtbl,
   return alloc;
 }
 
+static int expand_env(const char *src, char *res, int res_size)
+{
+	unsigned int src_idx = 0;
+	unsigned int res_idx = 0;
+	int var_idx = -1;
+	char var_name[32];
+	while (res_idx < res_size) {
+	  char c = src[src_idx++];
+	  if (var_idx >= 0) {
+		  // parsing variable name
+	  	  if (var_idx == 0 && c == '{') {
+	  		  continue;
+	  	  } else if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_') {
+	  		  // variable name
+			  var_name[var_idx++] = c;
+			  continue;
+	  	  } else {
+	  		  // end of variable name
+			  var_name[var_idx] = '\0';
+			  char *var_value = getenv(var_name);
+			  for (unsigned int i = 0; res_idx < res_size && var_value[i] != 0; i++) {
+				  res[res_idx++] = var_value[i];
+			  }
+			  var_idx = -1;
+			  if (c == '}')
+				  continue;
+		  }
+	  }
+	  if (c == '$') {
+		  // start parsing variable
+		  var_idx = 0;
+		  continue;
+	  }
+	  // normal string
+	  res[res_idx++] = c;
+	  if (c == '\0')
+		  break;
+	}
+	if (res_idx >= res_size)
+		return -1;
+	return 0;
+}
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -309,11 +351,14 @@ int cmd_pwd(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv)
 #ifndef CONFIG_NSH_DISABLE_SET
 int cmd_set(FAR struct nsh_vtbl_s *vtbl, int argc, char **argv)
 {
-  int ret = setenv(argv[1], argv[2], TRUE);
-  if (ret < 0)
-    {
-      nsh_output(vtbl, g_fmtcmdfailed, argv[0], "setenv", NSH_ERRNO);
-    }
+  char value[256];
+  int ret = expand_env(argv[2], value, sizeof(value));
+  if (ret == 0) {
+    ret = setenv(argv[1], value, TRUE);
+  }
+  if (ret < 0) {
+    nsh_output(vtbl, g_fmtcmdfailed, argv[0], "setenv", NSH_ERRNO);
+  }
   return ret;
 }
 #endif