Clean up error cases in psql's COPY TO STDOUT/FROM STDIN code.

Adjust handleCopyOut() to stop trying to write data once it's failed
one time.  For typical cases such as out-of-disk-space or broken-pipe,
additional attempts aren't going to do anything but waste time, and
in any case clean truncation of the output seems like a better behavior
than randomly dropping blocks in the middle.

Also remove dubious (and misleadingly documented) attempt to force our way
out of COPY_OUT state if libpq didn't do that.  If we did have a situation
like that, it'd be a bug in libpq and would be better fixed there, IMO.
We can hope that commit fa4440f51628d692f077d54b8313aea31af087ea took care
of any such problems, anyway.

Also fix longstanding bug in handleCopyIn(): PQputCopyEnd() only supports
a non-null errormsg parameter in protocol version 3, and will actively
fail if one is passed in version 2.  This would've made our attempts
to get out of COPY_IN state after a failure into infinite loops when
talking to pre-7.4 servers.

Back-patch the COPY_OUT state change business back to 9.2 where it was
introduced, and the other two fixes into all supported branches.

diff --git a/src/bin/psql/copy.c b/src/bin/psql/copy.c
index 6d291099b1f6c04f3f8f27c19663028fae97d22d..045ad927278d21e00df2fb2525a59495b5dfea30 100644 (file)
--- a/src/bin/psql/copy.c
+++ b/src/bin/psql/copy.c
@@ -573,7 +573,9 @@ do_copy(const char *args)
                                   PQresultStatus(result));
                /* if still in COPY IN state, try to get out of it */
                if (PQresultStatus(result) == PGRES_COPY_IN)
-                       PQputCopyEnd(pset.db, _("trying to exit copy mode"));
+                       PQputCopyEnd(pset.db,
+                                                (PQprotocolVersion(pset.db) < 3) ? NULL :
+                                                _("trying to exit copy mode"));
                PQclear(result);
        }
 
@@ -620,15 +622,15 @@ handleCopyOut(PGconn *conn, FILE *copystream)
                ret = PQgetCopyData(conn, &buf, 0);
 
                if (ret < 0)
-                       break;                          /* done or error */
+                       break;                          /* done or server/connection error */
 
                if (buf)
                {
-                       if (fwrite(buf, 1, ret, copystream) != ret)
+                       if (OK && fwrite(buf, 1, ret, copystream) != ret)
                        {
-                               if (OK)                 /* complain only once, keep reading data */
-                                       psql_error("could not write COPY data: %s\n",
-                                                          strerror(errno));
+                               psql_error("could not write COPY data: %s\n",
+                                                  strerror(errno));
+                               /* complain only once, keep reading data from server */
                                OK = false;
                        }
                        PQfreemem(buf);
@@ -692,7 +694,9 @@ handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary)
                /* got here with longjmp */
 
                /* Terminate data transfer */
-               PQputCopyEnd(conn, _("canceled by user"));
+               PQputCopyEnd(conn,
+                                        (PQprotocolVersion(conn) < 3) ? NULL :
+                                        _("canceled by user"));
 
                /* Check command status and return to normal libpq state */
                res = PQgetResult(conn);
@@ -820,7 +824,8 @@ handleCopyIn(PGconn *conn, FILE *copystream, bool isbinary)
 
        /* Terminate data transfer */
        if (PQputCopyEnd(conn,
-                                        OK ? NULL : _("aborted because of read failure")) <= 0)
+                                        (OK || PQprotocolVersion(conn) < 3) ? NULL :
+                                        _("aborted because of read failure")) <= 0)
                OK = false;
 
        /* Check command status and return to normal libpq state */