[cmdline] Expand settings within each command-line token individually

Perform settings expansion after tokenisation, and only at the point
of executing each command.  This allows statements such as

   dhcp && echo ${net0/ip}

to work correctly.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/core/exec.c b/src/core/exec.c
index 217ed039e8643447add1232f9ca922da72a9e11d..8da288271128c602872036886910c837a6fb7725 100644 (file)
--- a/src/core/exec.c
+++ b/src/core/exec.c
@@ -216,6 +216,45 @@ int shell_stopped ( int stop ) {
        return stopped;
 }
 
+/**
+ * Expand settings within a token list
+ *
+ * @v argc             Argument count
+ * @v tokens           Token list
+ * @v argv             Argument list to fill in
+ * @ret rc             Return status code
+ */
+static int expand_tokens ( int argc, char **tokens, char **argv ) {
+       int i;
+
+       /* Expand each token in turn */
+       for ( i = 0 ; i < argc ; i++ ) {
+               argv[i] = expand_settings ( tokens[i] );
+               if ( ! argv[i] )
+                       goto err_expand_settings;
+       }
+
+       return 0;
+
+ err_expand_settings:
+       assert ( argv[i] == NULL );
+       for ( ; i >= 0 ; i-- )
+               free ( argv[i] );
+       return -ENOMEM;
+}
+
+/**
+ * Free an expanded token list
+ *
+ * @v argv             Argument list
+ */
+static void free_tokens ( char **argv ) {
+
+       /* Free each expanded argument */
+       while ( *argv )
+               free ( *(argv++) );
+}
+
 /**
  * Execute command line
  *
@@ -225,58 +264,63 @@ int shell_stopped ( int stop ) {
  * Execute the named command and arguments.
  */
 int system ( const char *command ) {
+       int count = split_command ( ( char * ) command, NULL );
+       char *all_tokens[ count + 1 ];
        int ( * process_next ) ( int rc );
-       char *expcmd;
-       char **argv;
+       char *command_copy;
+       char **tokens;
        int argc;
-       int count;
        int process;
        int rc = 0;
 
-       /* Perform variable expansion */
-       expcmd = expand_settings ( command );
-       if ( ! expcmd )
+       /* Create modifiable copy of command */
+       command_copy = strdup ( command );
+       if ( ! command_copy )
                return -ENOMEM;
 
-       /* Count tokens */
-       count = split_command ( expcmd, NULL );
-
-       /* Create token array */
-       if ( count ) {
-               char * tokens[count + 1];
-               
-               split_command ( expcmd, tokens );
-               tokens[count] = NULL;
-               process = 1;
+       /* Split command into tokens */
+       split_command ( command_copy, all_tokens );
+       all_tokens[count] = NULL;
 
-               for ( argv = tokens ; ; argv += ( argc + 1 ) ) {
+       /* Process individual commands */
+       process = 1;
+       for ( tokens = all_tokens ; ; tokens += ( argc + 1 ) ) {
 
-                       /* Find command terminator */
-                       argc = command_terminator ( argv, &process_next );
+               /* Find command terminator */
+               argc = command_terminator ( tokens, &process_next );
 
-                       /* Execute command */
-                       if ( process ) {
-                               argv[argc] = NULL;
-                               rc = execv ( argv[0], argv );
-                       }
+               /* Expand tokens and execute command */
+               if ( process ) {
+                       char *argv[ argc + 1 ];
 
-                       /* Stop processing, if applicable */
-                       if ( shell_stopped ( SHELL_STOP_COMMAND ) )
+                       /* Expand tokens */
+                       if ( ( rc = expand_tokens ( argc, tokens, argv ) ) != 0)
                                break;
+                       argv[argc] = NULL;
 
-                       /* Stop processing if we have reached the end
-                        * of the command.
-                        */
-                       if ( ! process_next )
-                               break;
+                       /* Execute command */
+                       rc = execv ( argv[0], argv );
 
-                       /* Determine whether or not to process next command */
-                       process = process_next ( rc );
+                       /* Free tokens */
+                       free_tokens ( argv );
                }
+
+               /* Stop processing, if applicable */
+               if ( shell_stopped ( SHELL_STOP_COMMAND ) )
+                       break;
+
+               /* Stop processing if we have reached the end of the
+                * command.
+                */
+               if ( ! process_next )
+                       break;
+
+               /* Determine whether or not to process next command */
+               process = process_next ( rc );
        }
 
-       /* Free expanded command */
-       free ( expcmd );
+       /* Free modified copy of command */
+       free ( command_copy );
 
        return rc;
 }