Horton

Re: ECPG cleanup and fix for clang compile-time problem

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alexander Lakhin <exclusion@gmail.com>
Cc: John Naylor <johncnaylorls@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, Andres Freund <andres@anarazel.de>, Michael Paquier <michael.paquier@gmail.com>
Date: 2024-10-17T19:42:41Z
Lists: pgsql-hackers 
Alexander Lakhin <exclusion@gmail.com> writes:
> I've spent a day testing ecpg preprocessor and found another couple of
> bugs:

Thanks for the report!  The first couple of these seem simple
enough to fix, so I've done so.  As for

> Also, processing of .../ecpg/test/sql/include.pgc, containing only:
> EXEC SQL INCLUDE ../sql;
> emits merely:
> input in flex scanner failed

what we have here is an attempt to read a directory.  On Linux
it seems that fopen() is okay with that but then fread() fails
with EISDIR.  The fread() occurs in code emitted by flex that
is totally failing to produce a useful error report:

        while ( (result = (int) fread(buf, 1, (yy_size_t) max_size, base_yyin)) == 0 && ferror(base_yyin)) \
            { \
            if( errno != EINTR) \
                { \
                YY_FATAL_ERROR( "input in flex scanner failed" ); \
                break; \
                } \

It looks like YY_FATAL_ERROR can only accept a literal string,
so I can see why this isn't including strerror(errno), but still
I'd say that this is their poor error reporting not ours.  The
only thing we could really do about it is fstat the fopen's FD
and see if it's a directory, but that would only improve matters
for EISDIR not any other error cause.  I don't believe we've done
that anywhere else we use flex, so I'm not inclined to do it here.

> I think that's all that can be found here without extra efforts.

Thanks for poking at it!  I don't feel a huge need to search out
ecpg bugs in advance of field reports, but we might as well fix
things we do stumble across.

			regards, tom lane

Commits

  1. ecpg: clean up some other assorted memory leaks.

  2. ecpg: fix some memory leakage of data-type-related structures.

  3. ecpg: put all string-valued tokens returned by pgc.l in local storage.

  4. ecpg: fix more minor mishandling of bad input in preprocessor.

  5. ecpg: fix some minor mishandling of bad input in preprocessor.

  6. ecpg: avoid breaking the IDENT precedence level in two.

  7. ecpg: improve preprocessor's memory management.

  8. ecpg: move some functions into a new file ecpg/preproc/util.c.

  9. ecpg: re-implement preprocessor's string management.

  10. ecpg: major cleanup, simplification, and documentation of parse.pl.

  11. ecpg: remove check_rules.pl.

  12. ecpg: clean up documentation of parse.pl, and add more input checking.

  13. Clean up indentation and whitespace inconsistencies in ecpg.

  14. Exclude flex-generated code from coverage testing