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Prevent "\g filename" from affecting subsequent commands after an error.

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In the previous coding, psql's state variable saying that output should
go to a file was only reset after successful completion of a query
returning tuples.  Thus for example,

regression=# select 1/0
regression-# \g somefile
ERROR:  division by zero
regression=# select 1/2;
regression=#

... huh, I wonder where that output went.  Even more oddly, the state
was not reset even if it's the file that's causing the failure:

regression=# select 1/2 \g /foo
/foo: Permission denied
regression=# select 1/2;
/foo: Permission denied
regression=# select 1/2;
/foo: Permission denied

This seems to me not to satisfy the principle of least surprise.
\g is certainly not documented in a way that suggests its effects are
at all persistent.

To fix, adjust the code so that the flag is reset at exit from SendQuery
no matter what happened.

Noted while reviewing the \gset patch, which had comparable issues.
Arguably this is a bug fix, but I'll refrain from back-patching for now.
This commit is contained in:
Tom Lane 2013-02-02 14:21:24 -05:00
parent 84725aa5ef
commit 101d6ae755
3 changed files with 27 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
doc/src/sgml/ref/psql-ref.sgml
View File

@ -1608,9 +1608,13 @@ Tue Oct 26 21:40:57 CEST 1999
optionally stores the query's output in <replaceable
class="parameter">filename</replaceable> or pipes the output
into a separate Unix shell executing <replaceable
class="parameter">command</replaceable>. A bare
<literal>\g</literal> is virtually equivalent to a semicolon. A
<literal>\g</literal> with argument is a <quote>one-shot</quote>
class="parameter">command</replaceable>. The file or command is
written to only if the query successfully returns zero or more tuples,
not if the query fails or is a non-data-returning SQL command.
</para>
<para>
A bare <literal>\g</literal> is essentially equivalent to a semicolon.
A <literal>\g</literal> with argument is a <quote>one-shot</quote>
alternative to the <command>\o</command> command.
</para>
</listitem>

2
src/bin/psql/command.c
View File

@ -731,7 +731,7 @@ exec_command(const char *cmd,
free(fname);
}
/* \g means send query */
/* \g [filename] means send query, optionally with output to file/pipe */
else if (strcmp(cmd, "g") == 0)
{
char *fname = psql_scan_slash_option(scan_state,

32
src/bin/psql/common.c
View File

@ -607,9 +607,6 @@ PrintQueryTuples(const PGresult *results)
pset.queryFout = queryFout_copy;
pset.queryFoutPipe = queryFoutPipe_copy;
free(pset.gfname);
pset.gfname = NULL;
}
else
printQuery(results, &my_popt, pset.queryFout, pset.logfile);
@ -835,14 +832,14 @@ SendQuery(const char *query)
PGresult *results;
PGTransactionStatusType transaction_status;
double elapsed_msec = 0;
bool OK,
on_error_rollback_savepoint = false;
bool OK = false;
bool on_error_rollback_savepoint = false;
static bool on_error_rollback_warning = false;
if (!pset.db)
{
psql_error("You are currently not connected to a database.\n");
return false;
goto sendquery_cleanup;
}
if (pset.singlestep)
@ -856,7 +853,7 @@ SendQuery(const char *query)
fflush(stdout);
if (fgets(buf, sizeof(buf), stdin) != NULL)
if (buf[0] == 'x')
return false;
goto sendquery_cleanup;
}
else if (pset.echo == PSQL_ECHO_QUERIES)
{
@ -887,7 +884,7 @@ SendQuery(const char *query)
psql_error("%s", PQerrorMessage(pset.db));
PQclear(results);
ResetCancelConn();
return false;
goto sendquery_cleanup;
}
PQclear(results);
transaction_status = PQtransactionStatus(pset.db);
@ -912,7 +909,7 @@ SendQuery(const char *query)
psql_error("%s", PQerrorMessage(pset.db));
PQclear(results);
ResetCancelConn();
return false;
goto sendquery_cleanup;
}
PQclear(results);
on_error_rollback_savepoint = true;
@ -1008,10 +1005,11 @@ SendQuery(const char *query)
{
psql_error("%s", PQerrorMessage(pset.db));
PQclear(svptres);
OK = false;
PQclear(results);
ResetCancelConn();
return false;
goto sendquery_cleanup;
}
PQclear(svptres);
}
@ -1037,6 +1035,17 @@ SendQuery(const char *query)
PrintNotifications();
/* perform cleanup that should occur after any attempted query */
sendquery_cleanup:
/* reset \g's output-to-filename trigger */
if (pset.gfname)
{
free(pset.gfname);
pset.gfname = NULL;
}
return OK;
}
@ -1218,9 +1227,6 @@ ExecQueryUsingCursor(const char *query, double *elapsed_msec)
pset.queryFout = queryFout_copy;
pset.queryFoutPipe = queryFoutPipe_copy;
free(pset.gfname);
pset.gfname = NULL;
}
else if (did_pager)
{