Fix de-escaping checks so that we will reject \000 as well as other invalidly

encoded sequences.  Per discussion of a couple of days ago.

1 files changed, 20 insertions, 18 deletions

diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index a3d4d857c89..8551cd27538 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.150 2009/04/14 22:18:47 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.151 2009/04/19 21:08:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -60,7 +60,7 @@ bool			escape_string_warning = true;
 bool			standard_conforming_strings = false;
 
 static bool		warn_on_first_escape;
-static bool     saw_high_bit = false;
+static bool		saw_non_ascii = false;
 
 /*
  * literalbuf is used to accumulate literal values when multiple rules
@@ -453,7 +453,7 @@ other			.
 
 {xqstart}		{
 					warn_on_first_escape = true;
-					saw_high_bit = false;
+					saw_non_ascii = false;
 					SET_YYLLOC();
 					if (standard_conforming_strings)
 						BEGIN(xq);
@@ -463,7 +463,7 @@ other			.
 				}
 {xestart}		{
 					warn_on_first_escape = false;
-					saw_high_bit = false;
+					saw_non_ascii = false;
 					SET_YYLLOC();
 					BEGIN(xe);
 					startlit();
@@ -477,10 +477,11 @@ other			.
 <xq,xe>{quotefail} {
 					yyless(1);
 					BEGIN(INITIAL);
-					/* check that the data remains valid if it might have been
+					/*
+					 * check that the data remains valid if it might have been
 					 * made invalid by unescaping any chars.
 					 */
-					if (saw_high_bit)
+					if (saw_non_ascii)
 						pg_verifymbstr(literalbuf, literallen, false);
 					yylval.str = litbufdup();
 					return SCONST;
@@ -526,16 +527,16 @@ other			.
 
 					check_escape_warning();
 					addlitchar(c);
-					if (IS_HIGHBIT_SET(c))
-						saw_high_bit = true;
+					if (c == '\0' || IS_HIGHBIT_SET(c))
+						saw_non_ascii = true;
 				}
 <xe>{xehexesc}  {
 					unsigned char c = strtoul(yytext+2, NULL, 16);
 
 					check_escape_warning();
 					addlitchar(c);
-					if (IS_HIGHBIT_SET(c))
-						saw_high_bit = true;
+					if (c == '\0' || IS_HIGHBIT_SET(c))
+						saw_non_ascii = true;
 				}
 <xq,xe,xus>{quotecontinue} {
 					/* ignore */
@@ -1083,6 +1084,11 @@ litbuf_udeescape(unsigned char escape)
 	}
 
 	*out = '\0';
+	/*
+	 * We could skip pg_verifymbstr if we didn't process any non-7-bit-ASCII
+	 * codes; but it's probably not worth the trouble, since this isn't
+	 * likely to be a performance-critical path.
+	 */
 	pg_verifymbstr(new, out - new, false);
 	return new;
 }
@@ -1090,14 +1096,6 @@ litbuf_udeescape(unsigned char escape)
 static unsigned char
 unescape_single_char(unsigned char c)
 {
-	/* Normally we wouldn't expect to see \n where n has its high bit set
-	 * but we set the flag to check the string if we do get it, so
-	 * that this doesn't become a way of getting around the coding validity
-	 * checks.
-	 */
-	if (IS_HIGHBIT_SET(c))
-		saw_high_bit = true;
-
 	switch (c)
 	{
 		case 'b':
@@ -1111,6 +1109,10 @@ unescape_single_char(unsigned char c)
 		case 't':
 			return '\t';
 		default:
+			/* check for backslash followed by non-7-bit-ASCII */
+			if (c == '\0' || IS_HIGHBIT_SET(c))
+				saw_non_ascii = true;
+
 			return c;
 	}
 }