Bug#18908: ERROR 1406 (22001): Data too long for column :: using utf8

Problem: Too confusing error message when cannot convert
between string and column character sets on INSERT and UPDATE.
Fix: producing a better error message, instead of "Data too long"
in such cases
Additional changes: Adding "DROP TABLE IF EXISTS" into several
tests to be safe against failures in previous tests. 


mysql-test/include/strict_autoinc.inc:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/ctype_recoding.result:
  Fixing test results
mysql-test/r/ctype_utf8.result:
  Fixing test results
mysql-test/r/fulltext.result:
  Fixing test results
mysql-test/r/strict_autoinc_1myisam.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_2innodb.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_3heap.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_4bdb.result:
  Adding DROP TABLE to be safe against previous tests failure.
mysql-test/r/strict_autoinc_5ndb.result:
  Adding DROP TABLE to be safe against previous tests failure.
sql/field.cc:
  - producing better error messages than
    "DATA TRUNCATED" or "DATA TOO LONG" (in strict mode)
    in case of "not well formed source" and
    "cannot convert to field character set"
  - Performance improvements: copying directly to
    the target, instead of using an intermediate
    String.
  - Moving duplicate code into report_data_too_long() function.
sql/sql_string.cc:
  Adding a new function to convert strings between character sets,
  but not more than "nchar" characters - a helper function for
  Field_string::store(), Field_varstring::store() and Field_blob::store().
sql/sql_string.h:
  Adding new function prototype.

1 files changed, 156 insertions, 0 deletions

diff --git a/sql/sql_string.cc b/sql/sql_string.cc
index 7aaca809113..85ff1fddc45 100644
--- a/sql/sql_string.cc
+++ b/sql/sql_string.cc
@@ -854,6 +854,162 @@ outp:
 }
 
 
+/*
+  copy a string,
+  with optional character set conversion,
+  with optional left padding (for binary -> UCS2 conversion)
+  
+  SYNOPSIS
+    well_formed_copy_nhars()
+    to			     Store result here
+    to_length                Maxinum length of "to" string
+    to_cs		     Character set of "to" string
+    from		     Copy from here
+    from_length		     Length of from string
+    from_cs		     From character set
+    nchars                   Copy not more that nchars characters
+    well_formed_error_pos    Return position when "from" is not well formed
+                             or NULL otherwise.
+    cannot_convert_error_pos Return position where a not convertable
+                             character met, or NULL otherwise.
+    from_end_pos             Return position where scanning of "from"
+                             string stopped.
+  NOTES
+
+  RETURN
+    length of bytes copied to 'to'
+*/
+
+
+uint32
+well_formed_copy_nchars(CHARSET_INFO *to_cs,
+                        char *to, uint to_length,
+                        CHARSET_INFO *from_cs,
+                        const char *from, uint from_length,
+                        uint nchars,
+                        const char **well_formed_error_pos,
+                        const char **cannot_convert_error_pos,
+                        const char **from_end_pos)
+{
+  uint res;
+
+  if ((to_cs == &my_charset_bin) || 
+      (from_cs == &my_charset_bin) ||
+      (to_cs == from_cs) ||
+      my_charset_same(from_cs, to_cs))
+  {
+    if (to_length < to_cs->mbminlen || !nchars)
+    {
+      *from_end_pos= from;
+      *cannot_convert_error_pos= NULL;
+      *well_formed_error_pos= NULL;
+      return 0;
+    }
+
+    if (to_cs == &my_charset_bin)
+    {
+      res= min(min(nchars, to_length), from_length);
+      memmove(to, from, res);
+      *from_end_pos= from + res;
+      *well_formed_error_pos= NULL;
+      *cannot_convert_error_pos= NULL;
+    }
+    else
+    {
+      int well_formed_error;
+      uint from_offset;
+
+      if ((from_offset= (from_length % to_cs->mbminlen)) &&
+          (from_cs == &my_charset_bin))
+      {
+        /*
+          Copying from BINARY to UCS2 needs to prepend zeros sometimes:
+          INSERT INTO t1 (ucs2_column) VALUES (0x01);
+          0x01 -> 0x0001
+        */
+        uint pad_length= to_cs->mbminlen - from_offset;
+        bzero(to, pad_length);
+        memmove(to + pad_length, from, from_offset);
+        nchars--;
+        from+= from_offset;
+        from_length-= from_offset;
+        to+= to_cs->mbminlen;
+        to_length-= to_cs->mbminlen;
+      }
+
+      set_if_smaller(from_length, to_length);
+      res= to_cs->cset->well_formed_len(to_cs, from, from + from_length,
+                                        nchars, &well_formed_error);
+      memmove(to, from, res);
+      *from_end_pos= from + res;
+      *well_formed_error_pos= well_formed_error ? from + res : NULL;
+      *cannot_convert_error_pos= NULL;
+      if (from_offset)
+        res+= to_cs->mbminlen;
+    }
+  }
+  else
+  {
+    int cnvres;
+    my_wc_t wc;
+    int (*mb_wc)(struct charset_info_st *, my_wc_t *,
+                 const uchar *, const uchar *)= from_cs->cset->mb_wc;
+    int (*wc_mb)(struct charset_info_st *, my_wc_t,
+                 uchar *s, uchar *e)= to_cs->cset->wc_mb;
+    const uchar *from_end= (const uchar*) from + from_length;
+    uchar *to_end= (uchar*) to + to_length;
+    char *to_start= to;
+    *well_formed_error_pos= NULL;
+    *cannot_convert_error_pos= NULL;
+
+    for ( ; nchars; nchars--)
+    {
+      const char *from_prev= from;
+      if ((cnvres= (*mb_wc)(from_cs, &wc, (uchar*) from, from_end)) > 0)
+        from+= cnvres;
+      else if (cnvres == MY_CS_ILSEQ)
+      {
+        if (!*well_formed_error_pos)
+          *well_formed_error_pos= from;
+        from++;
+        wc= '?';
+      }
+      else if (cnvres > MY_CS_TOOSMALL)
+      {
+        /*
+          A correct multibyte sequence detected
+          But it doesn't have Unicode mapping.
+        */
+        if (!*cannot_convert_error_pos)
+          *cannot_convert_error_pos= from;
+        from+= (-cnvres);
+        wc= '?';
+      }
+      else
+        break;  // Not enough characters
+
+outp:
+      if ((cnvres= (*wc_mb)(to_cs, wc, (uchar*) to, to_end)) > 0)
+        to+= cnvres;
+      else if (cnvres == MY_CS_ILUNI && wc != '?')
+      {
+        if (!*cannot_convert_error_pos)
+          *cannot_convert_error_pos= from_prev;
+        wc= '?';
+        goto outp;
+      }
+      else
+        break;
+    }
+    *from_end_pos= from;
+    res= to - to_start;
+  }
+  return (uint32) res;
+}
+
+
+
+
 void String::print(String *str)
 {
   char *st= (char*)Ptr, *end= st+str_length;