Fix failure to think clearly about encoding conversion errors in COPY.

We can't regurgitate the unconverted string as I first thought, because
the elog.c mechanisms will assume the error message data is in the server
encoding and attempt a reverse conversion.  Eventually it might be worth
providing a short-circuit path to support this, but for now the simplest
solution is to abandon trying to report back the line contents after a
conversion failure.  Per bug report from Sil Lee, 27-Oct-2004.

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 9c49001b27e73b8bb839fad5bc70ec6a263728ba..c2b2b205aa10f5c1942c713075f544e65b411456 100644 (file)
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.232 2004/09/13 20:06:27 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/copy.c,v 1.233 2004/10/29 19:18:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1401,29 +1401,26 @@ copy_in_error_callback(void *arg)
                else
                {
                        /* error is relevant to a particular line */
-                       if (!line_buf_converted)
+                       if (line_buf_converted ||
+                               client_encoding == server_encoding)
                        {
-                               /* didn't convert the encoding yet... */
-                               line_buf_converted = true;
-                               if (client_encoding != server_encoding)
-                               {
-                                       char       *cvt;
-
-                                       cvt = (char *) pg_client_to_server((unsigned char *) line_buf.data,
-                                                                                                          line_buf.len);
-                                       if (cvt != line_buf.data)
-                                       {
-                                               /* transfer converted data back to line_buf */
-                                               line_buf.len = 0;
-                                               line_buf.data[0] = '\0';
-                                               appendBinaryStringInfo(&line_buf, cvt, strlen(cvt));
-                                       }
-                               }
+                               limit_printout_length(&line_buf);
+                               errcontext("COPY %s, line %d: \"%s\"",
+                                                  copy_relname, copy_lineno,
+                                                  line_buf.data);
+                       }
+                       else
+                       {
+                               /*
+                                * Here, the line buffer is still in a foreign encoding,
+                                * and indeed it's quite likely that the error is precisely
+                                * a failure to do encoding conversion (ie, bad data).  We
+                                * dare not try to convert it, and at present there's no way
+                                * to regurgitate it without conversion.  So we have to punt
+                                * and just report the line number.
+                                */
+                               errcontext("COPY %s, line %d", copy_relname, copy_lineno);
                        }
-                       limit_printout_length(&line_buf);
-                       errcontext("COPY %s, line %d: \"%s\"",
-                                          copy_relname, copy_lineno,
-                                          line_buf.data);
                }
        }
 }
@@ -2175,16 +2172,7 @@ CopyReadLine(void)
 
        /*
         * Done reading the line.  Convert it to server encoding.
-        *
-        * Note: set line_buf_converted to true *before* attempting conversion;
-        * this prevents infinite recursion during error reporting should
-        * pg_client_to_server() issue an error, due to copy_in_error_callback
-        * again attempting the same conversion.  We'll end up issuing the
-        * message without conversion, which is bad but better than nothing
-        * ...
         */
-       line_buf_converted = true;
-
        if (change_encoding)
        {
                cvt = (char *) pg_client_to_server((unsigned char *) line_buf.data,
@@ -2198,6 +2186,9 @@ CopyReadLine(void)
                }
        }
 
+       /* Now it's safe to use the buffer in error messages */
+       line_buf_converted = true;
+
        return result;
 }