Fixed bug #29442.

The SELECT INTO OUTFILE FIELDS ENCLOSED BY digit or minus sign,
followed by the same LOAD DATA INFILE statement, used wrond encoding
of non-string fields contained the enclosed character in their text
representation.

Example:
  SELECT 15, 9 INTO OUTFILE 'text' FIELDS ENCLOSED BY '5';

Old encoded result in the text file:
  5155 595
         ^ was decoded as the 1st enclosing character of the 2nd field;
        ^ was skipped as garbage;
  ^    ^ was decoded as a pair of englosing characters of the 1st field;
      ^   was decoded as traling space of the first field;
    ^^ was decoded as a doubled enclosed character.

New encoded result in the text file:
  51\55 595
  ^   ^ pair of enclosing characters of the 1st field;
    ^^ escaped enclosed character.

2 files changed, 15 insertions, 1 deletions

diff --git a/sql/sql_class.cc b/sql/sql_class.cc
index 117c20352ce..036ba217a9b 100644
--- a/sql/sql_class.cc
+++ b/sql/sql_class.cc
@@ -1210,6 +1210,7 @@ select_export::prepare(List<Item> &list, SELECT_LEX_UNIT *u)
 		   field_term_length ? (*exchange->field_term)[0] : INT_MAX);
   escape_char=	(exchange->escaped->length() ? (*exchange->escaped)[0] : -1);
   is_ambiguous_field_sep= test(strchr(ESCAPE_CHARS, field_sep_char));
+  is_unsafe_field_sep= test(strchr(NUMERIC_CHARS, field_sep_char));
   line_sep_char= (exchange->line_term->length() ?
 		  (*exchange->line_term)[0] : INT_MAX);
   if (!field_term_length)
@@ -1284,7 +1285,8 @@ bool select_export::send_data(List<Item> &items)
 	used_length=min(res->length(),item->max_length);
       else
 	used_length=res->length();
-      if (result_type == STRING_RESULT && escape_char != -1)
+      if ((result_type == STRING_RESULT || is_unsafe_field_sep) &&
+           escape_char != -1)
       {
         char *pos, *start, *end;
         CHARSET_INFO *res_charset= res->charset();
diff --git a/sql/sql_class.h b/sql/sql_class.h
index 23c499aea07..a5cbc21684f 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -1929,6 +1929,12 @@ public:
 #define ESCAPE_CHARS "ntrb0ZN" // keep synchronous with READ_INFO::unescape
 
 
+/*
+ List of all possible characters of a numeric value text representation.
+*/
+#define NUMERIC_CHARS ".0123456789e+-"
+
+
 class select_export :public select_to_file {
   uint field_term_length;
   int field_sep_char,escape_char,line_sep_char;
@@ -1938,6 +1944,12 @@ class select_export :public select_to_file {
     (see the READ_INFO::unescape method and the ESCAPE_CHARS constant value).
   */
   bool is_ambiguous_field_sep;
+  /*
+    The is_unsafe_field_sep field is true if a value of the field_sep_char
+    field is one of the '0'..'9', '+', '-', '.' and 'e' characters
+    (see the NUMERIC_CHARS constant value).
+  */
+  bool is_unsafe_field_sep;
   bool fixed_row_size;
 public:
   select_export(sql_exchange *ex) :select_to_file(ex) {}