bug in parsing escaped characters in dquoted string

* bug in parsing escaped characters in dquoted string
@ 2009-11-05  8:33 BVK
  2009-11-06 15:24 ` BVK
  0 siblings, 1 reply; 3+ messages in thread
From: BVK @ 2009-11-05  8:33 UTC (permalink / raw)
  To: The development of GRUB 2

[-- Attachment #1: Type: text/plain, Size: 416 bytes --]

Hi,


Current parsers (rescue-mode and sh-mode) parses don't seem to handle
escape characters in double quoted strings like the way bash does.
For example, in bash

echo "\""

prints single double quote character with escape processing and

echo "\a"

prints two characters without escape processing.


But grub parsers are not handling the first case.  Attached patch
fixes this issue.



thanks,
-- 
bvk-chaitanya

[-- Attachment #2: escaped-dquote-in-dquote-string.patch --]
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Index: kern/parser.c
===================================================================

--- kern/parser.c	(revision 2682)
+++ kern/parser.c	(working copy)
@@ -39,7 +39,10 @@
 
   { GRUB_PARSER_STATE_DQUOTE, GRUB_PARSER_STATE_TEXT, '\"', 0},
   { GRUB_PARSER_STATE_DQUOTE, GRUB_PARSER_STATE_QVAR, '$', 0},
+  { GRUB_PARSER_STATE_DQUOTE, GRUB_PARSER_STATE_DQESC, '\\', 1},
 
+  { GRUB_PARSER_STATE_DQESC, GRUB_PARSER_STATE_DQUOTE, 0, 1},
+
   { GRUB_PARSER_STATE_VAR, GRUB_PARSER_STATE_VARNAME2, '{', 0},
   { GRUB_PARSER_STATE_VAR, GRUB_PARSER_STATE_VARNAME, 0, 1},
   { GRUB_PARSER_STATE_VARNAME, GRUB_PARSER_STATE_TEXT, ' ', 1},
@@ -182,6 +185,14 @@
 		      (*argc)++;
 		    }
 		}
+	      else if (state == GRUB_PARSER_STATE_DQESC
+		       && newstate == GRUB_PARSER_STATE_DQUOTE && use == '"')
+		{
+		  /* If escaped double quote in double quoted string
+		     is found, overwrite it on backslash character at
+		     top.  */
+		  *(bp - 1) = use;
+		}
 	      else if (use)
 		*(bp++) = use;
 	    }
Index: include/grub/parser.h
===================================================================
--- include/grub/parser.h	(revision 2682)
+++ include/grub/parser.h	(working copy)
@@ -29,6 +29,7 @@
   {
     GRUB_PARSER_STATE_TEXT = 1,
     GRUB_PARSER_STATE_ESC,
+    GRUB_PARSER_STATE_DQESC,
     GRUB_PARSER_STATE_QUOTE,
     GRUB_PARSER_STATE_DQUOTE,
     GRUB_PARSER_STATE_VAR,
Index: script/sh/lexer.c
===================================================================
--- script/sh/lexer.c	(revision 2682)
+++ script/sh/lexer.c	(working copy)
@@ -298,6 +298,13 @@
 		  if (breakout)
 		    break;
 		}
+	      /* If escaped double quote in double quoted string is
+		 found, remove backslash character from top.  */
+	      else if (newstate == GRUB_PARSER_STATE_DQUOTE
+		       && state->state == GRUB_PARSER_STATE_DQESC && use == '"')
+		{
+		  bufpos--;
+		}
 
 	      if (use)
 		{

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