On Fri, Oct 21, 2011 at 05:31:41PM -0400, Robert Haas wrote:
> On Fri, Oct 21, 2011 at 7:24 AM, Richard Huxton <d...@archonet.com> wrote:
> > It looks like \copy is just passing the text of the query unadjusted to
> > "COPY". I get a syntax error on ":x" with the \copy below on both 9.0 and
> > 9.1
> >
> > === test script ===
> > \set x '''HELLO'''
> > -- Works
> > \echo :x
> > -- Works
> > \o '/tmp/test1.txt'
> > COPY (SELECT :x) TO STDOUT;
> > -- Doesn't work
> > \copy (SELECT :x) TO '/tmp/test2.txt'
> > === end script ===
>
> I'm not sure whether that's a bug per se, but I can see where a
> behavior change might be an improvement.
I did some research on this and learned a little more about flex rules.
Turns out we can allow variable substitution in psql whole-line
commands, like \copy and \!, by sharing the variable expansion flex
rules with the code that does argument processing.
What we can't easily do is to allow quotes to prevent variable
substitution in these whole-line commands because we can't process the
quotes because that will remove them.
Here are some examples; \copy and \! behave the same:
test=> \set x abc
test=> \echo :x
abc
test=> \echo ":x"
--> ":x"
test=> \! echo :x
abc
test=> \! echo ":x"
--> abc
Notice the last line has expanded :x even though it is in quotes.
So, what do we want? The attached patch is pretty short.
--
Bruce Momjian <br...@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
diff --git a/src/bin/psql/psqlscan.l b/src/bin/psql/psqlscan.l
new file mode 100644
index 1208c8f..3732dc5
*** a/src/bin/psql/psqlscan.l
--- b/src/bin/psql/psqlscan.l
*************** other .
*** 934,949 ****
}
! <xslasharg>{
/*
* Default processing of text in a slash command's argument.
*
* Note: unquoted_option_chars counts the number of characters at the
* end of the argument that were not subject to any form of quoting.
* psql_scan_slash_option needs this to strip trailing semicolons safely.
*/
! {space}|"\\" {
/*
* Unquoted space is end of arg; do not eat. Likewise
* backslash is end of command or next command, do not eat
--- 934,956 ----
}
!
/*
* Default processing of text in a slash command's argument.
+ * It shares token actions with xslasharg and xslashwholeline.
*
* Note: unquoted_option_chars counts the number of characters at the
* end of the argument that were not subject to any form of quoting.
* psql_scan_slash_option needs this to strip trailing semicolons safely.
*/
! <xslashwholeline>{space}+ {
! /* process entire line, but suppress leading whitespace */
! if (output_buf->len > 0)
! ECHO;
! }
!
! <xslasharg>{space}|"\\" {
/*
* Unquoted space is end of arg; do not eat. Likewise
* backslash is end of command or next command, do not eat
*************** other .
*** 957,982 ****
return LEXRES_OK;
}
! {quote} {
! *option_quote = '\'';
! unquoted_option_chars = 0;
! BEGIN(xslashquote);
! }
!
! "`" {
backtick_start_offset = output_buf->len;
*option_quote = '`';
unquoted_option_chars = 0;
BEGIN(xslashbackquote);
}
! {dquote} {
ECHO;
*option_quote = '"';
unquoted_option_chars = 0;
BEGIN(xslashdquote);
}
:{variable_char}+ {
/* Possible psql variable substitution */
if (option_type == OT_NO_EVAL)
--- 964,1005 ----
return LEXRES_OK;
}
! <xslasharg>"`" {
! /* Only in xslasharg, so backticks are potentially passed to the shell */
backtick_start_offset = output_buf->len;
*option_quote = '`';
unquoted_option_chars = 0;
BEGIN(xslashbackquote);
}
! <xslasharg>{quote} {
! *option_quote = '\'';
! unquoted_option_chars = 0;
! BEGIN(xslashquote);
! }
!
! <xslasharg>{dquote} {
ECHO;
*option_quote = '"';
unquoted_option_chars = 0;
BEGIN(xslashdquote);
}
+ <xslasharg>{other} {
+ unquoted_option_chars++;
+ ECHO;
+ }
+
+ <xslashwholeline>{other} { ECHO; }
+
+ /*
+ * This code allows variable processing in slasharg and wholeline
+ * modes. wholeline does not allow quoting to prevent variable
+ * subtitution because quote detection would remove the quotes.
+ */
+
+ <xslasharg,xslashwholeline>{
+
:{variable_char}+ {
/* Possible psql variable substitution */
if (option_type == OT_NO_EVAL)
*************** other .
*** 1044,1054 ****
ECHO;
}
- {other} {
- unquoted_option_chars++;
- ECHO;
- }
-
}
<xslashquote>{
--- 1067,1072 ----
*************** other .
*** 1115,1133 ****
}
- <xslashwholeline>{
- /* copy everything until end of input line */
- /* but suppress leading whitespace */
-
- {space}+ {
- if (output_buf->len > 0)
- ECHO;
- }
-
- {other} { ECHO; }
-
- }
-
<xslashend>{
/* at end of command, eat a double backslash, but not anything else */
--- 1133,1138 ----
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
