Re: [BUGS] BUG #2171: Differences compiling plpgsql in ecpg and psql - Mailing list pgsql-patches

Here is an updated patch.  It fixes things in the places it should be
fixed by handling \n at the time we double-quote, and double single
quotes at the place we are building the $$ string.

I am going to apply this to HEAD.  It is a fix, but I am worried it
might affect ecpg users who might have worked-around these problems and
this might break their work-around.  I am looking for opinions on
applying this to back releases.

---------------------------------------------------------------------------

Andrew Klosterman wrote:
> On Wed, 1 Feb 2006, Bruce Momjian wrote:
>
> >
> > I have researched your report, and you are right, there are two ecpg
> > bugs here.  First, dollar quoting uses single-quotes internally to do
> > the quoting, but it does not double any single-quotes in the
> > dollar-quoted string.
> >
> > Second, when a dollar quoted string or single-quoted string spans
> > multiple lines, ecpg does not escape the newline that is part of the
> > string.  Some compilers will accept an unescaped newline in a string,
> > while others will not:
> >
> >     $ gcc -pedantic -c  -g -Wall tst1.c
> >     tst1.c:5: warning: string constant runs past end of line
> >
> > It isn't standard so I think we need to replace newline in a string with
> > "\n\".
> >
> > Attached is a patch which fixes both of these issues.  This changes ecpg
> > behavior so I am thinking this patch would only appear in 8.2.
> >
> > I am unclear if I fixed the \r case properly.
> >
> > ---------------------------------------------------------------------------
> >
> > andrew5@ece.cmu.edu wrote:
> > >
> > > The following bug has been logged online:
> > >
> > > Bug reference:      2171
> > > Logged by:
> > > Email address:      andrew5@ece.cmu.edu
> > > PostgreSQL version: 8.1.2
> > > Operating system:   Linux (Debian)
> > > Description:        Differences compiling plpgsql in ecpg and psql
> > > Details:
> > >
> > > There appear to be parsing problems with ecpg.  The following example
> > > program shows code snippets that allow for the successful creation of a
> > > function (CREATE FUNCTION) only using two different syntaxes: one when
> > > entered through psql, and another when compiling with ecpg.
> > >
> > > The expectation (and hints from the documentation) indicate that the exact
> > > same method of defining a function should succeed in both cases, but such is
> > > not the case.
> > >
> > > Different quoting and line-wrap behavior is observed between psql and ecpg.
> > >
> > > (Thanks for the attention, I hope this is useful!)
> > >
> > > BEGIN CODE---------------
> > > /* This file is bug.pgc. */
> > > /* Compile as shown:
> > >    ecpg   bug.pgc -o bug.c
> > >    gcc -c -g -std=c99 -I/usr/local/pgsql/include -L/usr/local/pgsql/lib
> > > bug.c -o bug.o
> > >    gcc -I/usr/local/pgsql/include -L/usr/local/pgsql/lib -lecpg bug.o -o bug
> > > */
> > > /* Run as: ./bug */
> > > #include <stdio.h>
> > > #include <stdlib.h>
> > > #include <string.h>
> > >
> > > int main(int argc, char* argv[]) {
> > >
> > >   EXEC SQL CONNECT TO DEFAULT;
> > >
> > >   EXEC SQL SET AUTOCOMMIT TO ON;
> > >   EXEC SQL WHENEVER SQLWARNING SQLPRINT;
> > >   EXEC SQL WHENEVER SQLERROR SQLPRINT;
> > >
> > >   EXEC SQL CREATE TABLE My_Table ( Item1 int, Item2 text );
> > >
> > >   /* Documentation appears to indicate that only single quotes (') are
> > >      needed, but this will not ecpg-compile without double-single ('')
> > >      quotes.  When entered through psql, only the single quotes (')
> > >      are needed. */
> > >   /* doc/html/sql-syntax.html#SQL-SYNTAX-DOLLAR-QUOTING: "It is
> > >      particularly useful when representing string constants inside
> > >      other constants, as is often needed in procedural function
> > >      definitions." */
> > >   /* doc/html/sql-createfunction.html: "Without dollar quoting, any
> > >      single quotes or backslashes in the function definition must be
> > >      escaped by doubling them." */
> > >
> > >   /* Documentation appears to indicate that the body of the funtion
> > >      can be extended across multiple lines in the input file (this
> > >      file) but it will not compile (ecpg) without keeping the function
> > >      body on one line.  Multiple line input works through psql, but
> > >      not here.*/
> > > //bad ecpg,good psql: EXEC SQL CREATE FUNCTION My_Table_Check() RETURNS
> > > trigger
> > > //bad ecpg,good psql:   AS $My_Table_Check$
> > > //bad ecpg,good psql:   BEGIN RAISE NOTICE 'TG_NAME=%, TG WHEN=%', TG_NAME,
> > > TG_WHEN;
> > > //bad ecpg,good psql: RETURN NEW;
> > > //bad ecpg,good psql: END;
> > > //bad ecpg,good psql: $My_Table_Check$
> > > //bad ecpg,good psql:   LANGUAGE 'plpgsql';
> > >   EXEC SQL CREATE FUNCTION My_Table_Check() RETURNS trigger
> > >     AS $My_Table_Check$ BEGIN RAISE NOTICE ''TG_NAME=%, TG WHEN=%'',
> > > TG_NAME, TG_WHEN; RETURN NEW; END; $My_Table_Check$
> > >     LANGUAGE 'plpgsql';
> > >
> > >   EXEC SQL CREATE TRIGGER My_Table_Check_Trigger
> > >     BEFORE INSERT
> > >     ON My_Table
> > >     FOR EACH ROW
> > >     EXECUTE PROCEDURE My_Table_Check();
> > >
> > >   EXEC SQL INSERT INTO My_Table VALUES (1234, 'Some random text');
> > >   EXEC SQL INSERT INTO My_Table VALUES (5678, 'The Quick Brown');
> > >
> > >   EXEC SQL DROP TRIGGER My_Table_Check_Trigger ON My_Table;
> > >   EXEC SQL DROP FUNCTION My_Table_Check();
> > >   EXEC SQL DROP TABLE My_Table;
> > >
> > >   EXEC SQL DISCONNECT ALL;
> > >
> > >   return 0;
> > > }
> > >
> > > END CODE------------------
> > >
> > > ---------------------------(end of broadcast)---------------------------
> > > TIP 9: In versions below 8.0, the planner will ignore your desire to
> > >        choose an index scan if your joining column's datatypes do not
> > >        match
> > >
> >
> > --
> >   Bruce Momjian                        |  http://candle.pha.pa.us
> >   pgman@candle.pha.pa.us               |  (610) 359-1001
> >   +  If your life is a hard drive,     |  13 Roberts Road
> >   +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
> >
>
>
> --Andrew J. Klosterman
> andrew5@ece.cmu.edu
>

--
  Bruce Momjian                        |  http://candle.pha.pa.us
  pgman@candle.pha.pa.us               |  (610) 359-1001
  +  If your life is a hard drive,     |  13 Roberts Road
  +  Christ can be your backup.        |  Newtown Square, Pennsylvania 19073
Index: src/interfaces/ecpg/preproc/output.c
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/ecpg/preproc/output.c,v
retrieving revision 1.12
diff -c -c -r1.12 output.c
*** src/interfaces/ecpg/preproc/output.c    13 Oct 2004 01:25:13 -0000    1.12
--- src/interfaces/ecpg/preproc/output.c    3 Feb 2006 05:33:38 -0000
***************
*** 2,7 ****
--- 2,9 ----

  #include "extern.h"

+ static void ouput_escaped_str(char *cmd);
+
  void
  output_line_number(void)
  {
***************
*** 10,30 ****
  }

  void
! output_simple_statement(char *cmd)
  {
!     int            i,
!                 j = strlen(cmd);;
!
!     /* output this char by char as we have to filter '\"' */
!     for (i = 0; i < j; i++)
!     {
!         if (cmd[i] != '"')
!             fputc(cmd[i], yyout);
!         else
!             fputs("\\\"", yyout);
!     }
      output_line_number();
!     free(cmd);
  }

  /*
--- 12,22 ----
  }

  void
! output_simple_statement(char *stmt)
  {
!     ouput_escaped_str(stmt);
      output_line_number();
!     free(stmt);
  }

  /*
***************
*** 106,125 ****
  void
  output_statement(char *stmt, int mode, char *con)
  {
-     int            i,
-                 j = strlen(stmt);
-
      fprintf(yyout, "{ ECPGdo(__LINE__, %d, %d, %s, \"", compat, force_indicator, con ? con : "NULL");
!
!     /* output this char by char as we have to filter '\"' */
!     for (i = 0; i < j; i++)
!     {
!         if (stmt[i] != '"')
!             fputc(stmt[i], yyout);
!         else
!             fputs("\\\"", yyout);
!     }
!
      fputs("\", ", yyout);

      /* dump variables to C file */
--- 98,105 ----
  void
  output_statement(char *stmt, int mode, char *con)
  {
      fprintf(yyout, "{ ECPGdo(__LINE__, %d, %d, %s, \"", compat, force_indicator, con ? con : "NULL");
!     ouput_escaped_str(stmt);
      fputs("\", ", yyout);

      /* dump variables to C file */
***************
*** 135,137 ****
--- 115,135 ----
      if (connection != NULL)
          free(connection);
  }
+
+
+ static void
+ ouput_escaped_str(char *str)
+ {
+     int            i, len = strlen(str);
+
+     /* output this char by char as we have to filter " and \n */
+     for (i = 0; i < len; i++)
+     {
+         if (str[i] == '"')
+             fputs("\\\"", yyout);
+         else if (str[i] == '\n')
+             fputs("\\n\\\n", yyout);
+         else
+             fputc(str[i], yyout);
+     }
+ }
Index: src/interfaces/ecpg/preproc/pgc.l
===================================================================
RCS file: /cvsroot/pgsql/src/interfaces/ecpg/preproc/pgc.l,v
retrieving revision 1.140
diff -c -c -r1.140 pgc.l
*** src/interfaces/ecpg/preproc/pgc.l    2 Feb 2006 03:51:41 -0000    1.140
--- src/interfaces/ecpg/preproc/pgc.l    3 Feb 2006 05:33:38 -0000
***************
*** 152,158 ****
  dolq_cont        [A-Za-z\200-\377_0-9]
  dolqdelim        \$({dolq_start}{dolq_cont}*)?\$
  dolqfailed        \${dolq_start}{dolq_cont}*
! dolqinside        [^$]+

  /* Double quote
   * Allows embedded spaces and other special characters into identifiers.
--- 152,158 ----
  dolq_cont        [A-Za-z\200-\377_0-9]
  dolqdelim        \$({dolq_start}{dolq_cont}*)?\$
  dolqfailed        \${dolq_start}{dolq_cont}*
! dolqinside        [^$']+

  /* Double quote
   * Allows embedded spaces and other special characters into identifiers.
***************
*** 476,482 ****
  <xdolq>{dolqinside}     { addlit(yytext, yyleng); }
  <xdolq>{dolqfailed}    { addlit(yytext, yyleng); }
  <xdolq>.    {
!                 /* This is only needed for $ inside the quoted text */
                  addlitchar(yytext[0]);
              }
  <xdolq><<EOF>> { yyerror("unterminated dollar-quoted string"); }
--- 476,485 ----
  <xdolq>{dolqinside}     { addlit(yytext, yyleng); }
  <xdolq>{dolqfailed}    { addlit(yytext, yyleng); }
  <xdolq>.    {
!                 /* $$ is implemented as a single-quoted string, so double it? */
!                 if (yytext[0] == '\'')
!                     addlitchar(yytext[0]);
!                 /* single quote or dollar sign */
                  addlitchar(yytext[0]);
              }
  <xdolq><<EOF>> { yyerror("unterminated dollar-quoted string"); }