MDEV-31117 clean up spider connection info parsing

Spider connection string is a comma-separated parameter definitions,
where each definition is of the form "<param_title> <param_value>",
where <param_value> is quote delimited on both ends, with backslashes
acting as an escaping prefix.

The code however treated param title the same way as param value when
assigning, and have nonsensical fields like delim_title_len and
delim_title. We remove these.

We also clean up the spider comment connection string parsing,
including:

- Factoring out some code from the parsing function
- Rewriting the struct `st_spider_param_string_parse`, including
  replacing its messy methods with cleaner ones
- And any necessary changes caused by the above changes

storage/spider/mysql-test/spider/bugfix/r/mdev_31117.result

+#
+# MDEV-31117 Spider UBSAN runtime error: applying non-zero offset x to null pointer in st_spider_param_string_parse::restore_delims
+#
+for master_1
+for child2
+for child3
+CREATE TABLE t (c INT) ENGINE=Spider COMMENT='abc';
+ERROR HY000: The connect info 'abc' is invalid
+ALTER TABLE mysql.help_topic ENGINE=Spider;
+ERROR HY000: The connect info 'help topics' is invalid
+CREATE SERVER srv FOREIGN DATA WRAPPER MYSQL OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (c int);
+create table t1 (c int) ENGINE=Spider COMMENT='WRAPPER "mysql", "srv" "srv",TABLE "t2"';
+ERROR HY000: The connect info '"srv" "srv",TABLE "t2"' is invalid
+create table t1 (c int) ENGINE=Spider CONNECTION='WRAPPER "mysql", srv \'srv\',TABLE "t2", password "say \\"hello\\ world!\\""';
+drop table t1, t2;
+for master_1
+for child2
+for child3

storage/spider/mysql-test/spider/bugfix/t/mdev_31117.test

+--echo #
+--echo # MDEV-31117 Spider UBSAN runtime error: applying non-zero offset x to null pointer in st_spider_param_string_parse::restore_delims
+--echo #
+
+--disable_query_log
+--disable_result_log
+--source ../../t/test_init.inc
+--enable_result_log
+--enable_query_log
+
+--error 12501
+CREATE TABLE t (c INT) ENGINE=Spider COMMENT='abc';
+
+--error 12501
+ALTER TABLE mysql.help_topic ENGINE=Spider;
+
+evalp CREATE SERVER srv FOREIGN DATA WRAPPER MYSQL OPTIONS (SOCKET "$MASTER_1_MYSOCK", DATABASE 'test',user 'root');
+create table t2 (c int);
+# param title should not have delimiter
+--error 12501
+create table t1 (c int) ENGINE=Spider COMMENT='WRAPPER "mysql", "srv" "srv",TABLE "t2"';
+# test escaping
+create table t1 (c int) ENGINE=Spider CONNECTION='WRAPPER "mysql", srv \'srv\',TABLE "t2", password "say \\"hello\\ world!\\""';
+drop table t1, t2;
+
+--disable_query_log
+--disable_result_log
+--source ../t/test_deinit.inc
+--enable_query_log
+--enable_result_log

storage/spider/spd_table.h

@@ -30,281 +30,21 @@
 
 typedef struct st_spider_param_string_parse
 {
-  char *start_ptr;         /* Pointer to the start of the parameter string */
-  char *end_ptr;           /* Pointer to the end   of the parameter string */
-  char *start_title_ptr;   /* Pointer to the start of the current parameter
-                              title */
-  char *end_title_ptr;     /* Pointer to the end   of the current parameter
-                              title */
-  char *start_value_ptr;   /* Pointer to the start of the current parameter
-                              value */
-  char *end_value_ptr;     /* Pointer to the end   of the current parameter
-                              value */
-  int  error_num;          /* Error code of the error message to print when
-                              an error is detected */
-  uint delim_title_len;    /* Length of the paramater title's delimiter */
-  uint delim_value_len;    /* Length of the paramater value's delimiter */
-  char delim_title;        /* Current parameter title's delimiter character */
-  char delim_value;        /* Current parameter value's delimiter character */
-
-  /**
-    Initialize the parameter string parse information.
-
-    @param  param_string      Pointer to the parameter string being parsed.
-    @param  error_code        Error code of the error message to print when
-                              an error is detected.
-  */
-
-  inline void init(char *param_string, int error_code)
-  {
-    start_ptr = param_string;
-    end_ptr = start_ptr + strlen(start_ptr);
-
-    init_param_title();
-    init_param_value();
-
-    error_num = error_code;
-  }
-
-  /**
-    Initialize the current parameter title.
-  */
-
-  inline void init_param_title()
-  {
-    start_title_ptr = end_title_ptr = NULL;
-    delim_title_len = 0;
-    delim_title = '\0';
-  }
-
-  /**
-    Save pointers to the start and end positions of the current parameter
-    title in the parameter string.  Also save the parameter title's
-    delimiter character.
-
-    @param  start_value       Pointer to the start position of the current
-                              parameter title.
-    @param  end_value         Pointer to the end   position of the current
-                              parameter title.
-  */
-
-  inline void set_param_title(char *start_title, char *end_title)
-  {
-    start_title_ptr = start_title;
-    end_title_ptr = end_title;
-
-    if (*start_title == '"' ||
-        *start_title == '\'')
-    {
-      delim_title = *start_title;
-
-      if (start_title >= start_ptr && *--start_title == '\\')
-        delim_title_len = 2;
-      else
-        delim_title_len = 1;
-    }
-  }
-
-  /**
-    Initialize the current parameter value.
-  */
-
-  inline void init_param_value()
-  {
-    start_value_ptr = end_value_ptr = NULL;
-    delim_value_len = 0;
-    delim_value = '\0';
-  }
-
-  /**
-    Save pointers to the start and end positions of the current parameter
-    value in the parameter string.  Also save the parameter value's
-    delimiter character.
-
-    @param  start_value       Pointer to the start position of the current
-                              parameter value.
-    @param  end_value         Pointer to the end   position of the current
-                              parameter value.
-  */
-
-  inline void set_param_value(char *start_value, char *end_value)
-  {
-    start_value_ptr = start_value--;
-    end_value_ptr = end_value;
-
-    if (*start_value == '"' ||
-        *start_value == '\'')
-    {
-      delim_value = *start_value;
-
-      if (*--start_value == '\\')
-        delim_value_len = 2;
-      else
-        delim_value_len = 1;
-    }
-  }
-
-  /**
-    Determine whether the current parameter in the parameter string has
-    extra parameter values.
-
-    @return   0               Current parameter value in the parameter string
-                              does not have extra parameter values.
-              <> 0            Error code indicating that the current parameter
-                              value in the parameter string has extra
-                              parameter values.
-  */
-
-  inline int has_extra_parameter_values()
-  {
-    int error_num = 0;
-    DBUG_ENTER("has_extra_parameter_values");
-
-    if (end_value_ptr)
-    {
-      /* There is a current parameter value */
-      char *end_param_ptr =  end_value_ptr;
-
-      while (end_param_ptr < end_ptr &&
-        (*end_param_ptr == ' ' || *end_param_ptr == '\r' ||
-         *end_param_ptr == '\n' || *end_param_ptr == '\t'))
-        end_param_ptr++;
-
-      if (end_param_ptr < end_ptr && *end_param_ptr != '\0')
-      {
-        /* Extra values in parameter definition */
-        error_num = print_param_error();
-      }
-    }
-
-    DBUG_RETURN(error_num);
-  }
-
-  inline int get_next_parameter_head(char *st, char **nx)
-  {
-    DBUG_ENTER("get_next_parameter_head");
-    char *sq = strchr(st, '\'');
-    char *dq = strchr(st, '"');
-    if (!sq && !dq)
-    {
-      DBUG_RETURN(print_param_error());
-    }
-
-    if (dq && (!sq || sq > dq))
-    {
-      while (1)
-      {
-        ++dq;
-        if (*dq == '\\')
-        {
-          ++dq;
-        }
-        else if (*dq == '"')
-        {
-          break;
-        }
-        else if (*dq == '\0')
-        {
-          DBUG_RETURN(print_param_error());
-        }
-      }
-      while (1)
-      {
-        ++dq;
-        if (*dq == '\0')
-        {
-          *nx = dq;
-          break;
-        }
-        else if (*dq == ',')
-        {
-          *dq = '\0';
-          *nx = dq + 1;
-          break;
-        }
-        else if (*dq != ' ' && *dq != '\r' && *dq != '\n' && *dq != '\t')
-        {
-          DBUG_RETURN(print_param_error());
-        }
-      }
-    }
-    else /* sq && (!dq || sq <= dq) */
-    {
-      while (1)
-      {
-        ++sq;
-        if (*sq == '\\')
-        {
-          ++sq;
-        }
-        else if (*sq == '\'')
-        {
-          break;
-        }
-        else if (*sq == '\0')
-        {
-          DBUG_RETURN(print_param_error());
-        }
-      }
-      while (1)
-      {
-        ++sq;
-        if (*sq == '\0')
-        {
-          *nx = sq;
-          break;
-        }
-        else if (*sq == ',')
-        {
-          *sq = '\0';
-          *nx = sq + 1;
-          break;
-        }
-        else if (*sq != ' ' && *sq != '\r' && *sq != '\n' && *sq != '\t')
-        {
-          DBUG_RETURN(print_param_error());
-        }
-      }
-    }
-    DBUG_RETURN(0);
-  }
-
-  /**
-    Restore the current parameter's input delimiter characters in the
-    parameter string.  They were NULLed during parameter parsing.
-  */
-
-  inline void restore_delims()
-  {
-    char *end = end_title_ptr - 1;
-
-    switch (delim_title_len)
-    {
-    case 2:
-      *end++ = '\\';
-      /* Fall through */
-    case 1:
-      *end = delim_title;
-    }
-
-    end = end_value_ptr - 1;
-    switch (delim_value_len)
-    {
-    case 2:
-      *end++ = '\\';
-      /* Fall through */
-    case 1:
-      *end = delim_value;
-    }
-  }
-
-  /**
-    Print a parameter string error message.
-
-    @return                   Error code.
-  */
-
-  int print_param_error();
+  char *start_title;   /* Pointer to the start of the current parameter
+                         title */
+  char *end_title;     /* Pointer to the end   of the current
+                         parameter value */
+  char *start_value;   /* Pointer to the start of the current parameter
+                         value */
+  char *end_value;     /* Pointer to the end   of the current parameter
+                         value */
+  char delim_value;    /* Current parameter value's delimiter
+                         character, either a single or a double quote */
+  int  error_num;      /* Error code of the error message to print when
+                         an error is detected */
+
+  int fail(bool restore_delim);
+  bool locate_param_def(char*& start_param);
 } SPIDER_PARAM_STRING_PARSE;
 
 uchar *spider_tbl_get_key(
@@ -344,19 +84,12 @@ void spider_free_tmp_share_alloc(
   SPIDER_SHARE *share
 );
 
-char *spider_get_string_between_quote(
-  char *ptr,
-  bool alloc,
-  SPIDER_PARAM_STRING_PARSE *param_string_parse = NULL
-);
-
 int spider_create_string_list(
   char ***string_list,
   uint **string_length_list,
   uint *list_length,
   char *str,
-  uint length,
-  SPIDER_PARAM_STRING_PARSE *param_string_parse
+  uint length
 );
 
 int spider_create_long_list(
@@ -365,8 +98,7 @@ int spider_create_long_list(
   char *str,
   uint length,
   long min_val,
-  long max_val,
-  SPIDER_PARAM_STRING_PARSE *param_string_parse
+  long max_val
 );
 
 int spider_create_longlong_list(
@@ -375,8 +107,7 @@ int spider_create_longlong_list(
   char *str,
   uint length,
   longlong min_val,
-  longlong max_val,
-  SPIDER_PARAM_STRING_PARSE *param_string_parse
+  longlong max_val
 );
 
 int spider_increase_string_list(