On Mon, Jan 25, 2010 at 7:36 AM, Pavel Stehule <pavel.steh...@gmail.com> wrote:
> I hope, so this version is more readable and more clean. I removed
> some not necessary checks.
This still seems overly complicated to me. I spent a few hours today
working up the attached patch. Let me know your thoughts.
...Robert
*** a/doc/src/sgml/ref/psql-ref.sgml
--- b/doc/src/sgml/ref/psql-ref.sgml
***************
*** 658,664 **** testdb=>
<para>
If an unquoted argument begins with a colon (<literal>:</literal>),
it is taken as a <application>psql</> variable and the value of the
! variable is used as the argument instead.
</para>
<para>
--- 658,669 ----
<para>
If an unquoted argument begins with a colon (<literal>:</literal>),
it is taken as a <application>psql</> variable and the value of the
! variable is used as the argument instead. If the variable name is
! surrounded by single quotes (e.g. <literal>:'var'</literal>), it
! will be escaped as an SQL literal and the result will be used as
! the argument. If the variable name is surrounded by double quotes,
! it will be escaped as an SQL identifier and the result will be used
! as the argument.
</para>
<para>
***************
*** 2711,2728 **** bar
<para>
An additional useful feature of <application>psql</application>
variables is that you can substitute (<quote>interpolate</quote>)
! them into regular <acronym>SQL</acronym> statements. The syntax for
! this is again to prepend the variable name with a colon
(<literal>:</literal>):
<programlisting>
testdb=> <userinput>\set foo 'my_table'</userinput>
testdb=> <userinput>SELECT * FROM :foo;</userinput>
</programlisting>
! would then query the table <literal>my_table</literal>. The value of
! the variable is copied literally, so it can even contain unbalanced
! quotes or backslash commands. You must make sure that it makes sense
! where you put it. Variable interpolation will not be performed into
! quoted <acronym>SQL</acronym> entities.
</para>
<para>
--- 2716,2750 ----
<para>
An additional useful feature of <application>psql</application>
variables is that you can substitute (<quote>interpolate</quote>)
! them into regular <acronym>SQL</acronym> statements.
! <application>psql</application> provides special facilities for
! ensuring that values used as SQL literals and identifiers are
! properly escaped. The syntax for interpolating a value without
! any special escaping is again to prepend the variable name with a colon
(<literal>:</literal>):
<programlisting>
testdb=> <userinput>\set foo 'my_table'</userinput>
testdb=> <userinput>SELECT * FROM :foo;</userinput>
</programlisting>
! would then query the table <literal>my_table</literal>. Note that this
! may be unsafe: the value of the variable is copied literally, so it can
! even contain unbalanced quotes or backslash commands. You must make sure
! that it makes sense where you put it.
! </para>
!
! <para>
! When a value is to be used as an SQL literal or identifier, it is
! safest to arrange for it to be escaped. To escape the value of
! a variable as an SQL literal, write a colon followed by the variable
! name in single quotes. To escape the value an SQL identifier, write
! a colon followed by the variable name in double quotes. The previous
! example would be more safely written this way:
! <programlisting>
! testdb=> <userinput>\set foo 'my_table'</userinput>
! testdb=> <userinput>SELECT * FROM :"foo";</userinput>
! </programlisting>
! Variable interpolation will not be performed into quoted
! <acronym>SQL</acronym> entities.
</para>
<para>
***************
*** 2730,2769 **** testdb=> <userinput>SELECT * FROM :foo;</userinput>
copy the contents of a file into a table column. First load the file into a
variable and then proceed as above:
<programlisting>
! testdb=> <userinput>\set content '''' `cat my_file.txt` ''''</userinput>
! testdb=> <userinput>INSERT INTO my_table VALUES (:content);</userinput>
! </programlisting>
! One problem with this approach is that <filename>my_file.txt</filename>
! might contain single quotes. These need to be escaped so that
! they don't cause a syntax error when the second line is processed. This
! could be done with the program <command>sed</command>:
! <programlisting>
! testdb=> <userinput>\set content '''' `sed -e "s/'/''/g" < my_file.txt` ''''</userinput>
! </programlisting>
! If you are using non-standard-conforming strings then you'll also need
! to double backslashes. This is a bit tricky:
! <programlisting>
! testdb=> <userinput>\set content '''' `sed -e "s/'/''/g" -e 's/\\/\\\\/g' < my_file.txt` ''''</userinput>
</programlisting>
! Note the use of different shell quoting conventions so that neither
! the single quote marks nor the backslashes are special to the shell.
! Backslashes are still special to <command>sed</command>, however, so
! we need to double them. (Perhaps
! at one point you thought it was great that all Unix commands use the
! same escape character.)
</para>
<para>
! Since colons can legally appear in SQL commands, the following rule
! applies: the character sequence
! <quote>:name</quote> is not changed unless <quote>name</> is the name
! of a variable that is currently set. In any case you can escape
! a colon with a backslash to protect it from substitution. (The
! colon syntax for variables is standard <acronym>SQL</acronym> for
embedded query languages, such as <application>ECPG</application>.
The colon syntax for array slices and type casts are
<productname>PostgreSQL</productname> extensions, hence the
! conflict.)
</para>
</refsect3>
--- 2752,2777 ----
copy the contents of a file into a table column. First load the file into a
variable and then proceed as above:
<programlisting>
! testdb=> <userinput>\set content `cat my_file.txt`</userinput>
! testdb=> <userinput>INSERT INTO my_table VALUES (:'content');</userinput>
</programlisting>
! (Note that this still won't work if my_file.txt contains NUL bytes.
! psql does not support embedded NUL bytes in variable values.)
</para>
<para>
! Since colons can legally appear in SQL commands, an apparent attempt
! at interpolation (such as <literal>:name</literal>,
! <literal>:'name'</literal>, or <literal>:"name"</literal>) is not
! changed unless the named variable is currently set. In any case you
! can escape a colon with a backslash to protect it from substitution.
! (The colon syntax for variables is standard <acronym>SQL</acronym> for
embedded query languages, such as <application>ECPG</application>.
The colon syntax for array slices and type casts are
<productname>PostgreSQL</productname> extensions, hence the
! conflict. The colon syntax for escaping a variable's value as an
! SQL literal or identifier is a <application>psql</application>
! extension.)
</para>
</refsect3>
*** a/src/bin/psql/psqlscan.l
--- b/src/bin/psql/psqlscan.l
***************
*** 118,123 **** static YY_BUFFER_STATE prepare_buffer(const char *txt, int len,
--- 118,124 ----
char **txtcopy);
static void emit(const char *txt, int len);
static bool is_utf16_surrogate_first(uint32 c);
+ static void escape_variable(bool as_ident);
#define ECHO emit(yytext, yyleng)
***************
*** 707,712 **** other .
--- 708,721 ----
}
}
+ :'[A-Za-z0-9_]+' {
+ escape_variable(false);
+ }
+
+ :\"[A-Za-z0-9_]+\" {
+ escape_variable(true);
+ }
+
/*
* Back to backend-compatible rules.
*/
***************
*** 927,932 **** other .
--- 936,962 ----
return LEXRES_OK;
}
+ :'[A-Za-z0-9_]+' {
+ if (option_type == OT_VERBATIM)
+ ECHO;
+ else
+ {
+ escape_variable(false);
+ return LEXRES_OK;
+ }
+ }
+
+
+ :\"[A-Za-z0-9_]+\" {
+ if (option_type == OT_VERBATIM)
+ ECHO;
+ else
+ {
+ escape_variable(true);
+ return LEXRES_OK;
+ }
+ }
+
"|" {
ECHO;
if (option_type == OT_FILEPIPE)
***************
*** 1740,1742 **** is_utf16_surrogate_first(uint32 c)
--- 1770,1820 ----
{
return (c >= 0xD800 && c <= 0xDBFF);
}
+
+ static void
+ escape_variable(bool as_ident)
+ {
+ char saved_char;
+ const char *value;
+
+ /* Variable lookup. */
+ saved_char = yytext[yyleng - 1];
+ yytext[yyleng - 1] = '\0';
+ value = GetVariable(pset.vars, yytext + 2);
+
+ /* Escaping. */
+ if (value)
+ {
+ if (!pset.db)
+ psql_error("can't escape without active connection\n");
+ else
+ {
+ char *escaped_value;
+
+ if (as_ident)
+ escaped_value =
+ PQescapeIdentifier(pset.db, value, strlen(value));
+ else
+ escaped_value =
+ PQescapeLiteral(pset.db, value, strlen(value));
+ if (escaped_value == NULL)
+ {
+ const char *error = PQerrorMessage(pset.db);
+ psql_error("%s", error);
+ }
+ else
+ {
+ appendPQExpBufferStr(output_buf, escaped_value);
+ PQfreemem(escaped_value);
+ return;
+ }
+ }
+ }
+
+ /*
+ * If we reach this point, some kind of error has occurred. Emit the
+ * original text into the output buffer.
+ */
+ yytext[yyleng - 1] = saved_char;
+ emit(yytext, yyleng);
+ }
--
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