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

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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.
This commit is contained in:
Tom Lane 2014-02-13 18:45:23 -05:00
parent 170590261c
commit 7182bd2394
1 changed files with 13 additions and 8 deletions
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17
src/bin/psql/copy.c
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@ -350,7 +350,9 @@ 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);
}
@ -397,15 +399,15 @@ 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));
/* complain only once, keep reading data from server */
OK = false;
}
PQfreemem(buf);
@ -469,7 +471,9 @@ 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);
@ -597,7 +601,8 @@ 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 */