MDEV-8682 - CSV engine does not properly process "", in quotes

Added per-table boolean IETF_QUOTES variable to CSV storage engine. It allows to
enable IETF-compatible parsing of embedded quote and comma characters. Disabled
by default.

This patch is based on Percona revision:
https://github.com/percona/percona-server/commit/b32fbf02766f8db00f9ff4e6dc05a1df97c10ff7

Note that original patch adds server variable, while this patch adds per-table
variable.

mysql-test/suite/csv/csv.result

@@ -5493,3 +5493,57 @@ RENAME TABLE t1 TO t2;
 SELECT * FROM t2;
 a
 DROP TABLE t2;
+#
+# MDEV-8664 - plugins.show_all_plugins --embedded fails in buildbot
+#
+CREATE TABLE t1(c1 TEXT NOT NULL, c2 TEXT NOT NULL) ENGINE=CSV IETF_QUOTES=yes;
+INSERT INTO t1 VALUES("a\"b,c","d");
+INSERT INTO t1 VALUES("d","a\"b,c");
+INSERT INTO t1 VALUES(",\"a","e");
+INSERT INTO t1 VALUES("e",",\"a");
+INSERT INTO t1 VALUES("\"","f");
+INSERT INTO t1 VALUES("f","\"");
+INSERT INTO t1 VALUES(",","g");
+INSERT INTO t1 VALUES("g",",");
+SELECT * FROM t1;
+c1	c2
+a"b,c	d
+d	a"b,c
+,"a	e
+e	,"a
+"	f
+f	"
+,	g
+g	,
+CSV file contents:
+"a""b,c","d"
+"d","a""b,c"
+",""a","e"
+"e",",""a"
+"""","f"
+"f",""""
+",","g"
+"g",","
+DROP TABLE t1;
+CREATE TABLE t1(c1 TEXT NOT NULL, c2 TEXT NOT NULL) ENGINE=CSV IETF_QUOTES=yes;
+Replacing t1.CSV
+SELECT * FROM t1;
+c1	c2
+a	b
+a	b
+a"b,c	d
+d	,"a
+a",	e
+e	"
+,	f
+ALTER TABLE t1 IETF_QUOTES=no;
+SELECT * FROM t1;
+c1	c2
+a	b
+a	b
+a"b,c	d
+d	,"a
+a",	e
+e	"
+,	f
+DROP TABLE t1;

mysql-test/suite/csv/csv.test

@@ -1926,3 +1926,46 @@ move_file $MYSQLD_DATADIR/test/t1.CSV $MYSQLD_DATADIR/test/t2.CSV;
 RENAME TABLE t1 TO t2;
 SELECT * FROM t2;
 DROP TABLE t2;
+
+--echo #
+--echo # MDEV-8664 - plugins.show_all_plugins --embedded fails in buildbot
+--echo #
+CREATE TABLE t1(c1 TEXT NOT NULL, c2 TEXT NOT NULL) ENGINE=CSV IETF_QUOTES=yes;
+
+INSERT INTO t1 VALUES("a\"b,c","d");
+INSERT INTO t1 VALUES("d","a\"b,c");
+INSERT INTO t1 VALUES(",\"a","e");
+INSERT INTO t1 VALUES("e",",\"a");
+INSERT INTO t1 VALUES("\"","f");
+INSERT INTO t1 VALUES("f","\"");
+INSERT INTO t1 VALUES(",","g");
+INSERT INTO t1 VALUES("g",",");
+
+SELECT * FROM t1;
+
+--echo CSV file contents:
+--cat_file $MYSQLD_DATADIR/test/t1.CSV
+
+DROP TABLE t1;
+
+CREATE TABLE t1(c1 TEXT NOT NULL, c2 TEXT NOT NULL) ENGINE=CSV IETF_QUOTES=yes;
+
+--echo Replacing t1.CSV
+--remove_file $MYSQLD_DATADIR/test/t1.CSV
+--write_file $MYSQLD_DATADIR/test/t1.CSV
+a,b
+"a","b"
+"a""b,c","d"
+"d",",""a"
+"a"",",e
+e,""""
+",",f
+EOF
+
+SELECT * FROM t1;
+
+ALTER TABLE t1 IETF_QUOTES=no;
+
+SELECT * FROM t1;
+
+DROP TABLE t1;

storage/csv/ha_tina.cc

@@ -61,6 +61,16 @@ TODO:
 #define CSN_EXT ".CSN"               // Files used during repair and update
 #define CSM_EXT ".CSM"               // Meta file
 
+struct ha_table_option_struct
+{
+  bool ietf_quotes;
+};
+
+ha_create_table_option csv_table_option_list[]=
+{
+  HA_TOPTION_BOOL("IETF_QUOTES", ietf_quotes, 0),
+  HA_TOPTION_END
+};
 
 static TINA_SHARE *get_share(const char *table_name, TABLE *table);
 static int free_share(TINA_SHARE *share);
@@ -164,6 +174,7 @@ static int tina_init_func(void *p)
   tina_hton->flags= (HTON_CAN_RECREATE | HTON_SUPPORT_LOG_TABLES | 
                      HTON_NO_PARTITION);
   tina_hton->tablefile_extensions= ha_tina_exts;
+  tina_hton->table_options= csv_table_option_list;
   return 0;
 }
 
@@ -513,7 +524,7 @@ int ha_tina::encode_quote(uchar *buf)
   char attribute_buffer[1024];
   String attribute(attribute_buffer, sizeof(attribute_buffer),
                    &my_charset_bin);
-
+  bool ietf_quotes= table_share->option_struct->ietf_quotes;
   my_bitmap_map *org_bitmap= dbug_tmp_use_all_columns(table, table->read_set);
   buffer.length(0);
 
@@ -556,7 +567,7 @@ int ha_tina::encode_quote(uchar *buf)
       {
         if (*ptr == '"')
         {
-          buffer.append('\\');
+          buffer.append(ietf_quotes ? '"' : '\\');
           buffer.append('"');
         }
         else if (*ptr == '\r')
@@ -648,6 +659,7 @@ int ha_tina::find_current_row(uchar *buf)
   my_bitmap_map *org_bitmap;
   int error;
   bool read_all;
+  bool ietf_quotes= table_share->option_struct->ietf_quotes;
   DBUG_ENTER("ha_tina::find_current_row");
 
   free_root(&blobroot, MYF(0));
@@ -681,8 +693,10 @@ int ha_tina::find_current_row(uchar *buf)
                      a) If end of current field is reached, move
                         to next field and jump to step 2.3
                      b) If current character is a \\ handle
-                        \\n, \\r, \\, \\"
-                     c) else append the current character into the buffer
+                        \\n, \\r, \\, and \\" if not in ietf_quotes mode
+                     c) if in ietf_quotes mode and the current character is
+                        a ", handle ""
+                     d) else append the current character into the buffer
                         before checking that EOL has not been reached.
           2.2) If the current character does not begin with a quote
                2.2.1) Until EOL has not been reached
@@ -723,15 +737,25 @@ int ha_tina::find_current_row(uchar *buf)
           curr_offset+= 2;
           break;
         }
-        if (curr_char == '\\' && curr_offset != (end_offset - 1))
+        if (ietf_quotes && curr_char == '"'
+            && file_buff->get_value(curr_offset + 1) == '"')
+        {
+          /* Embedded IETF quote */
+          curr_offset++;
+          buffer.append('"');
+        }
+        else if (curr_char == '\\' && curr_offset != (end_offset - 1))
         {
+          /* A quote followed by something else than a comma, end of line, or
+          (in IETF mode) another quote will be handled as a regular
+          character. */
           curr_offset++;
           curr_char= file_buff->get_value(curr_offset);
           if (curr_char == 'r')
             buffer.append('\r');
           else if (curr_char == 'n' )
             buffer.append('\n');
-          else if (curr_char == '\\' || curr_char == '"')
+          else if (curr_char == '\\' || (!ietf_quotes && curr_char == '"'))
             buffer.append(curr_char);
           else  /* This could only happed with an externally created file */
           {
@@ -1744,6 +1768,10 @@ int ha_tina::reset(void)
 bool ha_tina::check_if_incompatible_data(HA_CREATE_INFO *info_arg,
 					   uint table_changes)
 {
+  if (info_arg->option_struct->ietf_quotes !=
+      table_share->option_struct->ietf_quotes)
+    return COMPATIBLE_DATA_NO;
+
   return COMPATIBLE_DATA_YES;
 }