Fix bugs in contrib/pg_trgm's LIKE pattern analysis code.

Extraction of trigrams did not process LIKE escape sequences properly,
leading to possible misidentification of trigrams near escapes, resulting
in incorrect index search results.

Fujii Masao

diff --git a/contrib/pg_trgm/expected/pg_trgm.out b/contrib/pg_trgm/expected/pg_trgm.out
index e7af7d48902e0c88f7720d5d4dd211cf454288af..81d0ca80b206394799de4a3f1a9bdaba0f124364 100644 (file)
--- a/contrib/pg_trgm/expected/pg_trgm.out
+++ b/contrib/pg_trgm/expected/pg_trgm.out
@@ -3497,6 +3497,12 @@ select * from test2 where t like '%bcd%';
  abcdef
 (1 row)
 
+select * from test2 where t like E'%\\bcd%';
+   t    
+--------
+ abcdef
+(1 row)
+
 select * from test2 where t ilike '%BCD%';
    t    
 --------
@@ -3539,6 +3545,12 @@ select * from test2 where t like '%bcd%';
  abcdef
 (1 row)
 
+select * from test2 where t like E'%\\bcd%';
+   t    
+--------
+ abcdef
+(1 row)
+
 select * from test2 where t ilike '%BCD%';
    t    
 --------

diff --git a/contrib/pg_trgm/sql/pg_trgm.sql b/contrib/pg_trgm/sql/pg_trgm.sql
index ea902f602f9271bb54803ba1a382b5f916560bc5..81ab1e79b17df0c5855b10e01298ab765e95d94d 100644 (file)
--- a/contrib/pg_trgm/sql/pg_trgm.sql
+++ b/contrib/pg_trgm/sql/pg_trgm.sql
@@ -49,6 +49,7 @@ explain (costs off)
   select * from test2 where t ilike '%BCD%';
 select * from test2 where t like '%BCD%';
 select * from test2 where t like '%bcd%';
+select * from test2 where t like E'%\\bcd%';
 select * from test2 where t ilike '%BCD%';
 select * from test2 where t ilike 'qua%';
 drop index test2_idx_gin;
@@ -60,5 +61,6 @@ explain (costs off)
   select * from test2 where t ilike '%BCD%';
 select * from test2 where t like '%BCD%';
 select * from test2 where t like '%bcd%';
+select * from test2 where t like E'%\\bcd%';
 select * from test2 where t ilike '%BCD%';
 select * from test2 where t ilike 'qua%';

diff --git a/contrib/pg_trgm/trgm_op.c b/contrib/pg_trgm/trgm_op.c
index 4e32c6f654c164206fb293fcb3d76f642ed72d38..87dffd1dd2c9b773c91c1243e96f6483735e601d 100644 (file)
--- a/contrib/pg_trgm/trgm_op.c
+++ b/contrib/pg_trgm/trgm_op.c
@@ -272,33 +272,36 @@ get_wildcard_part(const char *str, int lenstr,
        const char *beginword = str;
        const char *endword;
        char       *s = buf;
-       bool            in_wildcard_meta = false;
+       bool            in_leading_wildcard_meta = false;
+       bool            in_trailing_wildcard_meta = false;
        bool            in_escape = false;
        int                     clen;
 
        /*
-        * Find the first word character remembering whether last character was
-        * wildcard meta-character.
+        * Find the first word character, remembering whether preceding character
+        * was wildcard meta-character.  Note that the in_escape state persists
+        * from this loop to the next one, since we may exit at a word character
+        * that is in_escape.
         */
        while (beginword - str < lenstr)
        {
                if (in_escape)
                {
-                       in_escape = false;
-                       in_wildcard_meta = false;
                        if (iswordchr(beginword))
                                break;
+                       in_escape = false;
+                       in_leading_wildcard_meta = false;
                }
                else
                {
                        if (ISESCAPECHAR(beginword))
                                in_escape = true;
                        else if (ISWILDCARDCHAR(beginword))
-                               in_wildcard_meta = true;
+                               in_leading_wildcard_meta = true;
                        else if (iswordchr(beginword))
                                break;
                        else
-                               in_wildcard_meta = false;
+                               in_leading_wildcard_meta = false;
                }
                beginword += pg_mblen(beginword);
        }
@@ -310,11 +313,11 @@ get_wildcard_part(const char *str, int lenstr,
                return NULL;
 
        /*
-        * Add left padding spaces if last character wasn't wildcard
+        * Add left padding spaces if preceding character wasn't wildcard
         * meta-character.
         */
        *charlen = 0;
-       if (!in_wildcard_meta)
+       if (!in_leading_wildcard_meta)
        {
                if (LPADDING > 0)
                {
@@ -333,15 +336,11 @@ get_wildcard_part(const char *str, int lenstr,
         * string boundary.  Strip escapes during copy.
         */
        endword = beginword;
-       in_wildcard_meta = false;
-       in_escape = false;
        while (endword - str < lenstr)
        {
                clen = pg_mblen(endword);
                if (in_escape)
                {
-                       in_escape = false;
-                       in_wildcard_meta = false;
                        if (iswordchr(endword))
                        {
                                memcpy(s, endword, clen);
@@ -349,7 +348,17 @@ get_wildcard_part(const char *str, int lenstr,
                                s += clen;
                        }
                        else
+                       {
+                               /*
+                                * Back up endword to the escape character when stopping at
+                                * an escaped char, so that subsequent get_wildcard_part will
+                                * restart from the escape character.  We assume here that
+                                * escape chars are single-byte.
+                                */
+                               endword--;
                                break;
+                       }
+                       in_escape = false;
                }
                else
                {
@@ -357,7 +366,7 @@ get_wildcard_part(const char *str, int lenstr,
                                in_escape = true;
                        else if (ISWILDCARDCHAR(endword))
                        {
-                               in_wildcard_meta = true;
+                               in_trailing_wildcard_meta = true;
                                break;
                        }
                        else if (iswordchr(endword))
@@ -367,19 +376,16 @@ get_wildcard_part(const char *str, int lenstr,
                                s += clen;
                        }
                        else
-                       {
-                               in_wildcard_meta = false;
                                break;
-                       }
                }
                endword += clen;
        }
 
        /*
-        * Add right padding spaces if last character wasn't wildcard
+        * Add right padding spaces if next character isn't wildcard
         * meta-character.
         */
-       if (!in_wildcard_meta)
+       if (!in_trailing_wildcard_meta)
        {
                if (RPADDING > 0)
                {