[script] Allow for backslash continuation of script lines

Allow long script lines to be broken up using backslash continuation.
For example:

   choose --default linux --timeout 3000 os \
   	  && goto boot_${os} || goto cancelled

Requested-by: Robin Smidsrød <robin@smidsrod.no>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/image/script.c b/src/image/script.c
index e83180ab55f55ec9f830c4125334f8b10c570c18..8ef058545e8b49ccf74266ed289afe2e2db94d73 100644 (file)
--- a/src/image/script.c
+++ b/src/image/script.c
@@ -57,9 +57,11 @@ static size_t script_offset;
 static int process_script ( struct image *image,
                            int ( * process_line ) ( const char *line ),
                            int ( * terminate ) ( int rc ) ) {
+       size_t len = 0;
+       char *line = NULL;
        off_t eol;
-       size_t len;
-       char *line;
+       size_t frag_len;
+       char *tmp;
        int rc;
 
        script_offset = 0;
@@ -71,28 +73,54 @@ static int process_script ( struct image *image,
                                    ( image->len - script_offset ) );
                if ( eol < 0 )
                        eol = image->len;
-               len = ( eol - script_offset );
+               frag_len = ( eol - script_offset );
 
                /* Allocate buffer for line */
-               line = zalloc ( len + 1 /* NUL */ );
-               if ( ! line )
-                       return -ENOMEM;
+               tmp = realloc ( line, ( len + frag_len + 1 /* NUL */ ) );
+               if ( ! tmp ) {
+                       rc = -ENOMEM;
+                       goto err_alloc;
+               }
+               line = tmp;
 
                /* Copy line */
-               copy_from_user ( line, image->data, script_offset, len );
+               copy_from_user ( ( line + len ), image->data, script_offset,
+                                frag_len );
+               len += frag_len;
+
+               /* Move to next line in script */
+               script_offset += ( frag_len + 1 );
+
+               /* Strip trailing CR, if present */
+               if ( line[ len - 1 ] == '\r' )
+                       len--;
+
+               /* Handle backslash continuations */
+               if ( line[ len - 1 ] == '\\' ) {
+                       len--;
+                       rc = -EINVAL;
+                       continue;
+               }
+
+               /* Terminate line */
+               line[len] = '\0';
                DBG ( "$ %s\n", line );
 
-               /* Move to next line */
-               script_offset += ( len + 1 );
-
-               /* Process and free line */
+               /* Process line */
                rc = process_line ( line );
-               free ( line );
                if ( terminate ( rc ) )
-                       return rc;
+                       goto err_process;
+
+               /* Free line */
+               free ( line );
+               line = NULL;
+               len = 0;
 
        } while ( script_offset < image->len );
 
+ err_process:
+ err_alloc:
+       free ( line );
        return rc;
 }