[tarantool-patches] Re: [PATCH] sql: LIKE & GLOB pattern comparison issue

[Nikita Tatunov <hollow653@gmail.com>]

Alexey requested full diff:

diff --git a/src/box/sql/func.c b/src/box/sql/func.c
index c06e3bd..7f93ef6 100644
--- a/src/box/sql/func.c
+++ b/src/box/sql/func.c
@@ -617,13 +617,17 @@ struct compareInfo {
  u8 noCase; /* true to ignore case differences */
 };

-/*
- * For LIKE and GLOB matching on EBCDIC machines, assume that every
- * character is exactly one byte in size.  Also, provde the Utf8Read()
- * macro for fast reading of the next character in the common case where
- * the next character is ASCII.
+/**
+ * Providing there are symbols in string s this
+ * macro returns UTF-8 code of character and
+ * promotes pointer to the next symbol in the string.
+ * Otherwise return code is SQL_END_OF_STRING.
  */
-#define Utf8Read(s, e)    ucnv_getNextUChar(pUtf8conv, &s, e, &status)
+#define Utf8Read(s, e) (((s) < (e)) ? \
+ ucnv_getNextUChar(pUtf8conv, &(s), (e), &(status)) : 0)
+
+#define SQL_END_OF_STRING        0
+#define SQL_INVALID_UTF8_SYMBOL  0xfffd

 static const struct compareInfo globInfo = { '*', '?', '[', 0 };

@@ -638,19 +642,16 @@ static const struct compareInfo likeInfoNorm = {
'%', '_', 0, 1 };
 static const struct compareInfo likeInfoAlt = { '%', '_', 0, 0 };

 /*
- * Possible error returns from patternMatch()
+ * Possible error returns from sql_utf8_pattern_compare()
  */
 #define SQLITE_MATCH             0
 #define SQLITE_NOMATCH           1
 #define SQLITE_NOWILDCARDMATCH   2
+#define SQL_PROHIBITED_PATTERN   3

-/*
- * Compare two UTF-8 strings for equality where the first string is
- * a GLOB or LIKE expression.  Return values:
- *
- *    SQLITE_MATCH:            Match
- *    SQLITE_NOMATCH:          No match
- *    SQLITE_NOWILDCARDMATCH:  No match in spite of having * or % wildcards.
+/**
+ * Compare two UTF-8 strings for equality where the first string
+ * is a GLOB or LIKE expression.
  *
  * Globbing rules:
  *
@@ -663,92 +664,136 @@ static const struct compareInfo likeInfoAlt = {
'%', '_', 0, 0 };
  *
  *     [^...]     Matches one character not in the enclosed list.
  *
- * With the [...] and [^...] matching, a ']' character can be included
- * in the list by making it the first character after '[' or '^'.  A
- * range of characters can be specified using '-'.  Example:
- * "[a-z]" matches any single lower-case letter.  To match a '-', make
- * it the last character in the list.
+ * With the [...] and [^...] matching, a ']' character can be
+ * included in the list by making it the first character after
+ * '[' or '^'. A range of characters can be specified using '-'.
+ * Example: "[a-z]" matches any single lower-case letter.
+ * To match a '-', make it the last character in the list.
  *
  * Like matching rules:
  *
- *      '%'       Matches any sequence of zero or more characters
+ *      '%'       Matches any sequence of zero or more characters.
  *
- **     '_'       Matches any one character
+ **     '_'       Matches any one character.
  *
  *      Ec        Where E is the "esc" character and c is any other
- *                character, including '%', '_', and esc, match exactly c.
+ *                character, including '%', '_', and esc, match
+ *                exactly c.
  *
  * The comments within this routine usually assume glob matching.
  *
- * This routine is usually quick, but can be N**2 in the worst case.
+ * This routine is usually quick, but can be N**2 in the worst
+ * case.
+ *
+ * @param pattern String containing comparison pattern.
+ * @param string String being compared.
+ * @param compareInfo Information about how to compare.
+ * @param matchOther The escape char (LIKE) or '[' (GLOB).
+ *
+ * @retval SQLITE_MATCH:            Match.
+ *    SQLITE_NOMATCH:          No match.
+ *    SQLITE_NOWILDCARDMATCH:  No match in spite of having *
+ *     or % wildcards.
+ *    SQL_PROHIBITED_PATTERN:  Pattern contains invalid
+ *     symbol.
  */
 static int
-patternCompare(const char * pattern, /* The glob pattern */
-        const char * string, /* The string to compare against the glob */
-        const struct compareInfo *pInfo, /* Information about how to
do the compare */
-        UChar32 matchOther /* The escape char (LIKE) or '[' (GLOB) */
-    )
+sql_utf8_pattern_compare(const char * pattern,
+ const char * string,
+ const struct compareInfo *pInfo,
+ UChar32 matchOther)
 {
- UChar32 c, c2; /* Next pattern and input string chars */
- UChar32 matchOne = pInfo->matchOne; /* "?" or "_" */
- UChar32 matchAll = pInfo->matchAll; /* "*" or "%" */
- UChar32 noCase = pInfo->noCase; /* True if uppercase==lowercase */
- const char *zEscaped = 0; /* One past the last escaped input char */
+ /* Next pattern and input string chars */
+ UChar32 c, c2;
+ /* "?" or "_" */
+ UChar32 matchOne = pInfo->matchOne;
+ /* "*" or "%" */
+ UChar32 matchAll = pInfo->matchAll;
+ /* True if uppercase==lowercase */
+ UChar32 noCase = pInfo->noCase;
+ /* One past the last escaped input char */
+ const char *zEscaped = 0;
  const char * pattern_end = pattern + strlen(pattern);
  const char * string_end = string + strlen(string);
  UErrorCode status = U_ZERO_ERROR;

- while (pattern < pattern_end){
- c = Utf8Read(pattern, pattern_end);
+ while ((c = Utf8Read(pattern, pattern_end)) != SQL_END_OF_STRING) {
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  if (c == matchAll) { /* Match "*" */
- /* Skip over multiple "*" characters in the pattern.  If there
- * are also "?" characters, skip those as well, but consume a
- * single character of the input string for each "?" skipped
+ /* Skip over multiple "*" characters in
+ * the pattern. If there are also "?"
+ * characters, skip those as well, but
+ * consume a single character of the
+ * input string for each "?" skipped.
  */
- while (pattern < pattern_end){
- c = Utf8Read(pattern, pattern_end);
+ while ((c = Utf8Read(pattern, pattern_end)) !=
+        SQL_END_OF_STRING) {
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  if (c != matchAll && c != matchOne)
  break;
- if (c == matchOne
-     && Utf8Read(string, string_end) == 0) {
+ if (c == matchOne &&
+     (c2 = Utf8Read(string, string_end)) ==
+     SQL_END_OF_STRING)
  return SQLITE_NOWILDCARDMATCH;
- }
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  }
- /* "*" at the end of the pattern matches */
- if (pattern == pattern_end)
+ /*
+ * "*" at the end of the pattern matches.
+ */
+ if (c == SQL_END_OF_STRING) {
+ while ((c2 = Utf8Read(string, string_end)) !=
+        SQL_END_OF_STRING)
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  return SQLITE_MATCH;
+ }
  if (c == matchOther) {
  if (pInfo->matchSet == 0) {
  c = Utf8Read(pattern, pattern_end);
- if (c == 0)
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
+ if (c == SQL_END_OF_STRING)
  return SQLITE_NOWILDCARDMATCH;
  } else {
- /* "[...]" immediately follows the "*".  We have to do a slow
- * recursive search in this case, but it is an unusual case.
+ /* "[...]" immediately
+ * follows the "*". We
+ * have to do a slow
+ * recursive search in
+ * this case, but it is
+ * an unusual case.
  */
- assert(matchOther < 0x80); /* '[' is a single-byte character */
+ assert(matchOther < 0x80);
  while (string < string_end) {
  int bMatch =
-     patternCompare(&pattern[-1],
-    string,
-    pInfo,
-    matchOther);
+     sql_utf8_pattern_compare(
+ &pattern[-1],
+ string,
+ pInfo,
+ matchOther);
  if (bMatch != SQLITE_NOMATCH)
  return bMatch;
- Utf8Read(string, string_end);
+ c = Utf8Read(string, string_end);
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  }
  return SQLITE_NOWILDCARDMATCH;
  }
  }

- /* At this point variable c contains the first character of the
- * pattern string past the "*".  Search in the input string for the
- * first matching character and recursively continue the match from
- * that point.
+ /* At this point variable c contains the
+ * first character of the pattern string
+ * past the "*". Search in the input
+ * string for the first matching
+ * character and recursively continue the
+ * match from that point.
  *
- * For a case-insensitive search, set variable cx to be the same as
- * c but in the other case and search the input string for either
- * c or cx.
+ * For a case-insensitive search, set
+ * variable cx to be the same as c but in
+ * the other case and search the input
+ * string for either c or cx.
  */

  int bMatch;
@@ -756,14 +801,18 @@ patternCompare(const char * pattern, /* The glob
pattern */
  c = u_tolower(c);
  while (string < string_end){
  /**
- * This loop could have been implemented
- * without if converting c2 to lower case
- * (by holding c_upper and c_lower), however
- * it is implemented this way because lower
- * works better with German and Turkish
- * languages.
+ * This loop could have been
+ * implemented without if
+ * converting c2 to lower case
+ * by holding c_upper and
+ * c_lower,however it is
+ * implemented this way because
+ * lower works better with German
+ * and Turkish languages.
  */
  c2 = Utf8Read(string, string_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  if (!noCase) {
  if (c2 != c)
  continue;
@@ -771,9 +820,10 @@ patternCompare(const char * pattern, /* The glob pattern */
  if (c2 != c && u_tolower(c2) != c)
  continue;
  }
- bMatch =
-     patternCompare(pattern, string,
-    pInfo, matchOther);
+ bMatch = sql_utf8_pattern_compare(pattern,
+   string,
+   pInfo,
+   matchOther);
  if (bMatch != SQLITE_NOMATCH)
  return bMatch;
  }
@@ -782,7 +832,9 @@ patternCompare(const char * pattern, /* The glob pattern */
  if (c == matchOther) {
  if (pInfo->matchSet == 0) {
  c = Utf8Read(pattern, pattern_end);
- if (c == 0)
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
+ if (c == SQL_END_OF_STRING)
  return SQLITE_NOMATCH;
  zEscaped = pattern;
  } else {
@@ -790,23 +842,33 @@ patternCompare(const char * pattern, /* The glob
pattern */
  int seen = 0;
  int invert = 0;
  c = Utf8Read(string, string_end);
+ if (c == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  if (string == string_end)
  return SQLITE_NOMATCH;
  c2 = Utf8Read(pattern, pattern_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  if (c2 == '^') {
  invert = 1;
  c2 = Utf8Read(pattern, pattern_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  }
  if (c2 == ']') {
  if (c == ']')
  seen = 1;
  c2 = Utf8Read(pattern, pattern_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  }
- while (c2 && c2 != ']') {
+ while (c2 != SQL_END_OF_STRING && c2 != ']') {
  if (c2 == '-' && pattern[0] != ']'
      && pattern < pattern_end
      && prior_c > 0) {
  c2 = Utf8Read(pattern, pattern_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  if (c >= prior_c && c <= c2)
  seen = 1;
  prior_c = 0;
@@ -817,29 +879,36 @@ patternCompare(const char * pattern, /* The glob
pattern */
  prior_c = c2;
  }
  c2 = Utf8Read(pattern, pattern_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQL_PROHIBITED_PATTERN;
  }
- if (pattern == pattern_end || (seen ^ invert) == 0) {
+ if (pattern == pattern_end ||
+     (seen ^ invert) == 0) {
  return SQLITE_NOMATCH;
  }
  continue;
  }
  }
  c2 = Utf8Read(string, string_end);
+ if (c2 == SQL_INVALID_UTF8_SYMBOL)
+ return SQLITE_NOMATCH;
  if (c == c2)
  continue;
  if (noCase){
  /**
- * Small optimisation. Reduce number of calls
- * to u_tolower function.
- * SQL standards suggest use to_upper for symbol
- * normalisation. However, using to_lower allows to
- * respect Turkish 'İ' in default locale.
+ * Small optimisation. Reduce number of
+ * calls to u_tolower function. SQL
+ * standards suggest use to_upper for
+ * symbol normalisation. However, using
+ * to_lower allows to respect Turkish 'İ'
+ * in default locale.
  */
  if (u_tolower(c) == c2 ||
      c == u_tolower(c2))
  continue;
  }
- if (c == matchOne && pattern != zEscaped && c2 != 0)
+ if (c == matchOne && pattern != zEscaped &&
+     c2 != SQL_END_OF_STRING)
  continue;
  return SQLITE_NOMATCH;
  }
@@ -853,8 +922,7 @@ patternCompare(const char * pattern, /* The glob pattern */
 int
 sqlite3_strglob(const char *zGlobPattern, const char *zString)
 {
- return patternCompare(zGlobPattern, zString, &globInfo,
-       '[');
+ return sql_utf8_pattern_compare(zGlobPattern, zString, &globInfo, '[');
 }

 /*
@@ -864,7 +932,7 @@ sqlite3_strglob(const char *zGlobPattern, const
char *zString)
 int
 sqlite3_strlike(const char *zPattern, const char *zStr, unsigned int esc)
 {
- return patternCompare(zPattern, zStr, &likeInfoNorm, esc);
+ return sql_utf8_pattern_compare(zPattern, zStr, &likeInfoNorm, esc);
 }

 /*
@@ -910,8 +978,9 @@ likeFunc(sqlite3_context * context, int argc,
sqlite3_value ** argv)
  zB = (const char *) sqlite3_value_text(argv[0]);
  zA = (const char *) sqlite3_value_text(argv[1]);

- /* Limit the length of the LIKE or GLOB pattern to avoid problems
- * of deep recursion and N*N behavior in patternCompare().
+ /* Limit the length of the LIKE or GLOB pattern to avoid
+ * problems of deep recursion and N*N behavior in
+ * sql_utf8_pattern_compare().
  */
  nPat = sqlite3_value_bytes(argv[0]);
  testcase(nPat == db->aLimit[SQLITE_LIMIT_LIKE_PATTERN_LENGTH]);
@@ -947,7 +1016,12 @@ likeFunc(sqlite3_context * context, int argc,
sqlite3_value ** argv)
  sqlite3_like_count++;
 #endif
  int res;
- res = patternCompare(zB, zA, pInfo, escape);
+ res = sql_utf8_pattern_compare(zB, zA, pInfo, escape);
+ if (res == SQL_PROHIBITED_PATTERN) {
+ sqlite3_result_error(context, "LIKE or GLOB pattern can only"
+      " contain UTF-8 characters", -1);
+ return;
+ }
  sqlite3_result_int(context, res == SQLITE_MATCH);
 }

diff --git a/test-run b/test-run
index 77e9327..95562e9 160000
--- a/test-run
+++ b/test-run
@@ -1 +1 @@
-Subproject commit 77e93279210f8c5c1fd0ed03416fa19a184f0b6d
+Subproject commit 95562e95401fef4e0b755ab0bb430974b5d1a29a
diff --git a/test/sql-tap/e_expr.test.lua b/test/sql-tap/e_expr.test.lua
index 13d3a96..9780d2c 100755
--- a/test/sql-tap/e_expr.test.lua
+++ b/test/sql-tap/e_expr.test.lua
@@ -1,6 +1,6 @@
 #!/usr/bin/env tarantool
 test = require("sqltester")
-test:plan(12431)
+test:plan(10665)

 --!./tcltestrunner.lua
 -- 2010 July 16
@@ -77,8 +77,10 @@ local operations = {
     {"<>", "ne1"},
     {"!=", "ne2"},
     {"IS", "is"},
-    {"LIKE", "like"},
-    {"GLOB", "glob"},
+-- NOTE: This test needs refactoring after deletion of GLOB &
+-- type restrictions for LIKE. (See #3572)
+--    {"LIKE", "like"},
+--    {"GLOB", "glob"},
     {"AND", "and"},
     {"OR", "or"},
     {"MATCH", "match"},
@@ -96,7 +98,12 @@ operations = {
     {"+", "-"},
     {"<<", ">>", "&", "|"},
     {"<", "<=", ">", ">="},
-    {"=", "==", "!=", "<>", "LIKE", "GLOB"}, --"MATCH", "REGEXP"},
+-- NOTE: This test needs refactoring after deletion of GLOB &
+-- type restrictions for LIKE. (See #3572)
+-- Another NOTE: MATCH & REGEXP aren't supported in Tarantool &
+-- are waiting for their hour, don't confuse them
+-- being commented with ticket above.
+    {"=", "==", "!=", "<>"}, --"LIKE", "GLOB"}, --"MATCH", "REGEXP"},
     {"AND"},
     {"OR"},
 }
@@ -475,6 +482,7 @@ for _, op in ipairs(oplist) do
         end
     end
 end
+
 ---------------------------------------------------------------------------
 -- Test the IS and IS NOT operators.
 --
diff --git a/test/sql-tap/gh-3251-string-pattern-comparison.test.lua
b/test/sql-tap/gh-3251-string-pattern-comparison.test.lua
new file mode 100755
index 0000000..2a787f2
--- /dev/null
+++ b/test/sql-tap/gh-3251-string-pattern-comparison.test.lua
@@ -0,0 +1,213 @@
+#!/usr/bin/env tarantool
+test = require("sqltester")
+test:plan(128)
+
+local prefix = "like-test-"
+
+-- Unicode byte sequences.
+local valid_testcases = {
+    '\x01',
+    '\x09',
+    '\x1F',
+    '\x7F',
+    '\xC2\x80',
+    '\xC2\x90',
+    '\xC2\x9F',
+    '\xE2\x80\xA8',
+    '\x20\x0B',
+    '\xE2\x80\xA9',
+}
+
+-- Non-Unicode byte sequences.
+local invalid_testcases = {
+    '\xE2\x80',
+    '\xFE\xFF',
+    '\xC2',
+    '\xED\xB0\x80',
+    '\xD0',
+}
+
+local like_test_cases =
+{
+    {"1.1",
+        "SELECT 'AB' LIKE '_B';",
+        {0, {1}} },
+    {"1.2",
+        "SELECT 'CD' LIKE '_B';",
+        {0, {0}} },
+    {"1.3",
+        "SELECT '' LIKE '_B';",
+        {0, {0}} },
+    {"1.4",
+        "SELECT 'AB' LIKE '%B';",
+        {0, {1}} },
+    {"1.5",
+        "SELECT 'CD' LIKE '%B';",
+        {0, {0}} },
+    {"1.6",
+        "SELECT '' LIKE '%B';",
+        {0, {0}} },
+    {"1.7",
+        "SELECT 'AB' LIKE 'A__';",
+        {0, {0}} },
+    {"1.8",
+        "SELECT 'CD' LIKE 'A__';",
+        {0, {0}} },
+    {"1.9",
+        "SELECT '' LIKE 'A__';",
+        {0, {0}} },
+    {"1.10",
+        "SELECT 'AB' LIKE 'A_';",
+        {0, {1}} },
+    {"1.11",
+        "SELECT 'CD' LIKE 'A_';",
+        {0, {0}} },
+    {"1.12",
+        "SELECT '' LIKE 'A_';",
+        {0, {0}} },
+    {"1.13",
+        "SELECT 'AB' LIKE 'A';",
+        {0, {0}} },
+    {"1.14",
+        "SELECT 'CD' LIKE 'A';",
+        {0, {0}} },
+    {"1.15",
+        "SELECT '' LIKE 'A';",
+        {0, {0}} },
+    {"1.16",
+        "SELECT 'AB' LIKE '_';",
+        {0, {0}} },
+    {"1.17",
+        "SELECT 'CD' LIKE '_';",
+        {0, {0}} },
+    {"1.18",
+        "SELECT '' LIKE '_';",
+        {0, {0}} },
+    {"1.19",
+        "SELECT 'AB' LIKE '__';",
+        {0, {1}} },
+    {"1.20",
+        "SELECT 'CD' LIKE '__';",
+        {0, {1}} },
+    {"1.21",
+        "SELECT '' LIKE '__';",
+        {0, {0}} },
+    {"1.22",
+        "SELECT 'AB' LIKE '%A';",
+        {0, {0}} },
+    {"1.23",
+        "SELECT 'AB' LIKE '%C';",
+        {0, {0}} },
+    {"1.24",
+        "SELECT 'ab' LIKE '%df';",
+        {0, {0}} },
+    {"1.25",
+        "SELECT 'abCDF' LIKE '%df';",
+        {0, {1}} },
+    {"1.26",
+        "SELECT 'CDF' LIKE '%df';",
+        {0, {1}} },
+    {"1.27",
+        "SELECT 'ab' LIKE 'a_';",
+        {0, {1}} },
+    {"1.28",
+        "SELECT 'abCDF' LIKE 'a_';",
+        {0, {0}} },
+    {"1.29",
+        "SELECT 'CDF' LIKE 'a_';",
+        {0, {0}} },
+    {"1.30",
+        "SELECT 'ab' LIKE 'ab%';",
+        {0, {1}} },
+    {"1.31",
+        "SELECT 'abCDF' LIKE 'ab%';",
+        {0, {1}} },
+    {"1.32",
+        "SELECT 'CDF' LIKE 'ab%';",
+        {0, {0}} },
+    {"1.33",
+        "SELECT 'ab' LIKE 'abC%';",
+        {0, {0}} },
+    {"1.34",
+        "SELECT 'abCDF' LIKE 'abC%';",
+        {0, {1}} },
+    {"1.35",
+        "SELECT 'CDF' LIKE 'abC%';",
+        {0, {0}} },
+    {"1.36",
+        "SELECT 'ab' LIKE 'a_%';",
+        {0, {1}} },
+    {"1.37",
+        "SELECT 'abCDF' LIKE 'a_%';",
+        {0, {1}} },
+    {"1.38",
+        "SELECT 'CDF' LIKE 'a_%';",
+        {0, {0}} },
+}
+
+test:do_catchsql_set_test(like_test_cases, prefix)
+
+-- Invalid testcases.
+for i, tested_string in ipairs(invalid_testcases) do
+
+    -- We should raise an error in case
+    -- pattern contains invalid characters.
+
+    local test_name = prefix .. "2." .. tostring(i)
+    local test_itself = "SELECT 'abc' LIKE 'ab" .. tested_string .. "';"
+    test:do_catchsql_test(test_name, test_itself,
+                          {1, "LIKE or GLOB pattern can only contain
UTF-8 characters"})
+
+    test_name = prefix .. "3." .. tostring(i)
+    test_itself = "SELECT 'abc' LIKE 'abc" .. tested_string .. "';"
+    test:do_catchsql_test(test_name, test_itself,
+                          {1, "LIKE or GLOB pattern can only contain
UTF-8 characters"})
+
+    test_name = prefix .. "4." .. tostring(i)
+    test_itself = "SELECT 'abc' LIKE 'ab" .. tested_string .. "c';"
+    test:do_catchsql_test(test_name, test_itself,
+                          {1, "LIKE or GLOB pattern can only contain
UTF-8 characters"})
+
+    -- Just skipping if row value predicand contains invalid character.
+
+    test_name = prefix .. "5." .. tostring(i)
+    test_itself = "SELECT 'ab" .. tested_string .. "' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "6." .. tostring(i)
+    test_itself = "SELECT 'abc" .. tested_string .. "' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "7." .. tostring(i)
+    test_itself = "SELECT 'ab" .. tested_string .. "c' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+end
+
+-- Valid testcases.
+for i, tested_string in ipairs(valid_testcases) do
+    test_name = prefix .. "8." .. tostring(i)
+    local test_itself = "SELECT 'abc' LIKE 'ab" .. tested_string .. "';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "9." .. tostring(i)
+    test_itself = "SELECT 'abc' LIKE 'abc" .. tested_string .. "';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "10." .. tostring(i)
+    test_itself = "SELECT 'abc' LIKE 'ab" .. tested_string .. "c';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "11." .. tostring(i)
+    test_itself = "SELECT 'ab" .. tested_string .. "' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "12." .. tostring(i)
+    test_itself = "SELECT 'abc" .. tested_string .. "' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+
+    test_name = prefix .. "13." .. tostring(i)
+    test_itself = "SELECT 'ab" .. tested_string .. "c' LIKE 'abc';"
+    test:do_execsql_test(test_name, test_itself, {0})
+end
+
+test:finish_test()