Bug#23924 general_log truncates queries with character set introducers.

Problem: logging of utf8-incompatible binary strings didn't work
Fix: hex-encoding of incompatible sequences.

mysql-test/r/log_tables.result

@@ -107,6 +107,17 @@ Database	Table	In_use	Name_locked
 SET GLOBAL GENERAL_LOG=ON;
 SET GLOBAL SLOW_QUERY_LOG=ON;
 truncate table mysql.general_log;
+set names binary;
+select _koi8r'' as test;
+test
+
+select * from mysql.general_log;
+event_time	user_host	thread_id	server_id	command_type	argument
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	set names binary
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select _koi8r'\xD4\xC5\xD3\xD4' as test
+TIMESTAMP	USER_HOST	THREAD_ID	1	Query	select * from mysql.general_log
+set names utf8;
+truncate table mysql.general_log;
 set names utf8;
 create table bug16905 (s char(15) character set utf8 default 'пусто');
 insert into bug16905 values ('новое');

mysql-test/t/log_tables.test

@@ -130,6 +130,16 @@ show open tables;
 SET GLOBAL GENERAL_LOG=ON;
 SET GLOBAL SLOW_QUERY_LOG=ON;
 
+#
+# Bug#23924 general_log truncates queries with character set introducers.
+#
+truncate table mysql.general_log;
+set names binary;
+select _koi8r'' as test;
+--replace_column 1 TIMESTAMP 2 USER_HOST 3 THREAD_ID
+select * from mysql.general_log;
+set names utf8;
+
 #
 # Bug #16905    Log tables: unicode statements are logged incorrectly
 #

sql/field.cc

@@ -7644,6 +7644,17 @@ int Field_blob::store(const char *from,uint length,CHARSET_INFO *cs)
   if (value.alloc(new_length))
     goto oom_error;
 
+
+  if (f_is_hex_escape(flags))
+  {
+    copy_length= my_copy_with_hex_escaping(field_charset,
+                                           (char*) value.ptr(), new_length,
+                                            from, length);
+    Field_blob::store_length(copy_length);
+    tmp= value.ptr();
+    bmove(ptr + packlength, (uchar*) &tmp, sizeof(char*));
+    return 0;
+  }
   /*
     "length" is OK as "nchars" argument to well_formed_copy_nchars as this
     is never used to limit the length of the data. The cut of long data

sql/field.h

@@ -2069,6 +2069,7 @@ int set_field_to_null_with_conversions(Field *field, bool no_conversions);
 #define FIELDFLAG_NO_DEFAULT		16384   /* sql */
 #define FIELDFLAG_SUM			((uint) 32768)// predit: +#fieldflag
 #define FIELDFLAG_MAYBE_NULL		((uint) 32768)// sql
+#define FIELDFLAG_HEX_ESCAPE		((uint) 0x10000)
 #define FIELDFLAG_PACK_SHIFT		3
 #define FIELDFLAG_DEC_SHIFT		8
 #define FIELDFLAG_MAX_DEC		31
@@ -2094,3 +2095,4 @@ int set_field_to_null_with_conversions(Field *field, bool no_conversions);
 #define f_maybe_null(x)		(x & FIELDFLAG_MAYBE_NULL)
 #define f_no_default(x)		(x & FIELDFLAG_NO_DEFAULT)
 #define f_bit_as_char(x)        ((x) & FIELDFLAG_TREAT_BIT_AS_CHAR)
+#define f_is_hex_escape(x)      ((x) & FIELDFLAG_HEX_ESCAPE)

sql/log.cc

@@ -418,6 +418,7 @@ bool Log_to_csv_event_handler::
     A positive return value in store() means truncation.
     Still logging a message in the log in this case.
   */
+  table->field[5]->flags|= FIELDFLAG_HEX_ESCAPE;
   if (table->field[5]->store(sql_text, sql_text_len, client_cs) < 0)
     goto err;
 

sql/sql_string.cc

@@ -840,6 +840,68 @@ outp:
 }
 
 
+/**
+  Copy string with HEX-encoding of "bad" characters.
+
+  @details This functions copies the string pointed by "src"
+  to the string pointed by "dst". Not more than "srclen" bytes
+  are read from "src". Any sequences of bytes representing
+  a not-well-formed substring (according to cs) are hex-encoded,
+  and all well-formed substrings (according to cs) are copied as is.
+  Not more than "dstlen" bytes are written to "dst". The number 
+  of bytes written to "dst" is returned.
+  
+   @param      cs       character set pointer of the destination string
+   @param[out] dst      destination string
+   @param      dstlen   size of dst
+   @param      src      source string
+   @param      srclen   length of src
+
+   @retval     result length
+*/
+
+size_t
+my_copy_with_hex_escaping(CHARSET_INFO *cs,
+                          char *dst, size_t dstlen,
+                          const char *src, size_t srclen)
+{
+  const char *srcend= src + srclen;
+  char *dst0= dst;
+
+  for ( ; src < srcend ; )
+  {
+    size_t chlen;
+    if ((chlen= my_ismbchar(cs, src, srcend)))
+    {
+      if (dstlen < chlen)
+        break; /* purecov: inspected */
+      memcpy(dst, src, chlen);
+      src+= chlen;
+      dst+= chlen;
+      dstlen-= chlen;
+    }
+    else if (*src & 0x80)
+    {
+      if (dstlen < 4)
+        break; /* purecov: inspected */
+      *dst++= '\\';
+      *dst++= 'x';
+      *dst++= _dig_vec_upper[((unsigned char) *src) >> 4];
+      *dst++= _dig_vec_upper[((unsigned char) *src) & 15];
+      src++;
+      dstlen-= 4;
+    }
+    else
+    {
+      if (dstlen < 1)
+        break; /* purecov: inspected */
+      *dst++= *src++;
+      dstlen--;
+    }
+  }
+  return dst - dst0;
+}
+
 /*
   copy a string,
   with optional character set conversion,

sql/sql_string.h

@@ -37,6 +37,9 @@ uint32 well_formed_copy_nchars(CHARSET_INFO *to_cs,
                                const char **well_formed_error_pos,
                                const char **cannot_convert_error_pos,
                                const char **from_end_pos);
+size_t my_copy_with_hex_escaping(CHARSET_INFO *cs,
+                                 char *dst, size_t dstlen,
+                                 const char *src, size_t srclen);
 
 class String
 {