InnoDB: Fix ALTER TABLE t DISCARD TABLESPACE (Bug #5851)

innobase/include/ut0mem.h:
  Improve documentation of ut_strlenq(), ut_strcpyq() and ut_memcpyq()
innobase/include/ut0mem.ic:
  Improve documentation of ut_strlenq()
innobase/row/row0mysql.c:
  row_discard_tablespace_for_mysql(): Add quotes around table_name
  in DISCARD_TABLESPACE_PROC (Bug #5851)
innobase/ut/ut0mem.c:
  Improve documentation of ut_strcpyq() and ut_memcpyq()

innobase/include/ut0mem.h

@@ -117,7 +117,7 @@ int
 ut_strcmp(const void* str1, const void* str2);
 
 /**************************************************************************
-Determine the length of a string when it is quoted with ut_strcpyq(). */
+Compute strlen(ut_strcpyq(str, q)). */
 UNIV_INLINE
 ulint
 ut_strlenq(
@@ -127,7 +127,9 @@ ut_strlenq(
 	char		q);	/* in: the quote character */
 
 /**************************************************************************
-Make a quoted copy of a string. */
+Make a quoted copy of a NUL-terminated string.  Leading and trailing
+quotes will not be included; only embedded quotes will be escaped.
+See also ut_strlenq() and ut_memcpyq(). */
 
 char*
 ut_strcpyq(
@@ -138,7 +140,9 @@ ut_strcpyq(
 	const char*	src);	/* in: null-terminated string */
 
 /**************************************************************************
-Make a quoted copy of a fixed-length string. */
+Make a quoted copy of a fixed-length string.  Leading and trailing
+quotes will not be included; only embedded quotes will be escaped.
+See also ut_strlenq() and ut_strcpyq(). */
 
 char*
 ut_memcpyq(

innobase/include/ut0mem.ic

@@ -49,7 +49,7 @@ ut_strcmp(const void* str1, const void* str2)
 }
 
 /**************************************************************************
-Determine the length of a string when it is quoted with ut_strcpyq(). */
+Compute strlen(ut_strcpyq(str, q)). */
 UNIV_INLINE
 ulint
 ut_strlenq(

innobase/row/row0mysql.c

@@ -1988,9 +1988,9 @@ row_discard_tablespace_for_mysql(
 	"new_id_high INT;\n"
 	"table_name CHAR;\n"
 	"BEGIN\n"
-	"table_name := ";
+	"table_name := '";
 	static const char discard_tablespace_proc2[] =
-	";\n"
+	"';\n"
 	"new_id_high := %lu;\n"
 	"new_id_low := %lu;\n"
    "new_id := CONCAT(TO_BINARY(new_id_high, 4), TO_BINARY(new_id_low, 4));\n"

innobase/ut/ut0mem.c

@@ -313,7 +313,9 @@ ut_free_all_mem(void)
 }
 
 /**************************************************************************
-Make a quoted copy of a string. */
+Make a quoted copy of a NUL-terminated string.  Leading and trailing
+quotes will not be included; only embedded quotes will be escaped.
+See also ut_strlenq() and ut_memcpyq(). */
 
 char*
 ut_strcpyq(
@@ -333,7 +335,9 @@ ut_strcpyq(
 }
 
 /**************************************************************************
-Make a quoted copy of a fixed-length string. */
+Make a quoted copy of a fixed-length string.  Leading and trailing
+quotes will not be included; only embedded quotes will be escaped.
+See also ut_strlenq() and ut_strcpyq(). */
 
 char*
 ut_memcpyq(