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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2024-04-16 12:31:32 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2024-04-16 12:31:42 -0400 |
| commit | 6f0cef9353fcef50e74c31bb06c96c40207fd535 (patch) | |
| tree | b05dcc5af44da01e8b52d2cb259a2fd4531c5f89 /doc/src | |
| parent | c62d2ebd9e6f94758f5ed3a28cf08861229ae421 (diff) | |
| download | postgresql-6f0cef9353fcef50e74c31bb06c96c40207fd535.tar.gz postgresql-6f0cef9353fcef50e74c31bb06c96c40207fd535.zip | |
Fix assorted bugs in ecpg's macro mechanism.
The code associated with EXEC SQL DEFINE was unreadable and full of
bugs, notably:
* It'd attempt to free a non-malloced string if the ecpg program
tries to redefine a macro that was defined on the command line.
* Possible memory stomp if user writes "-D=foo".
* Undef'ing or redefining a macro defined on the command line would
change the state visible to the next file, when multiple files are
specified on the command line. (While possibly that could have been
an intentional choice, the code clearly intends to revert to the
original macro state; it's just failing to consider this interaction.)
* Missing "break" in defining a new macro meant that redefinition
of an existing name would cause an extra entry to be added to the
definition list. While not immediately harmful, a subsequent undef
would result in the prior entry becoming visible again.
* The interactions with input buffering are subtle and were entirely
undocumented.
It's not that surprising that we hadn't noticed these bugs,
because there was no test coverage at all of either the -D
command line switch or multiple input files. This patch adds
such coverage (in a rather hacky way I guess).
In addition to the code bugs, the user documentation was confused
about whether the -D switch defines a C macro or an ecpg one, and
it failed to mention that you can write "-Dsymbol=value".
These problems are old, so back-patch to all supported branches.
Discussion: https://postgr.es/m/998011.1713217712@sss.pgh.pa.us
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ecpg.sgml | 8 | ||||
| -rw-r--r-- | doc/src/sgml/ref/ecpg-ref.sgml | 6 |
2 files changed, 12 insertions, 2 deletions
diff --git a/doc/src/sgml/ecpg.sgml b/doc/src/sgml/ecpg.sgml index b332aa435df..e7a53f3c9d0 100644 --- a/doc/src/sgml/ecpg.sgml +++ b/doc/src/sgml/ecpg.sgml @@ -5793,6 +5793,14 @@ EXEC SQL UPDATE Tbl SET col = MYNUMBER; embedded SQL query because in this case the embedded SQL precompiler is not able to see this declaration. </para> + + <para> + If multiple input files are named on the <command>ecpg</command> + preprocessor's command line, the effects of <literal>EXEC SQL + DEFINE</literal> and <literal>EXEC SQL UNDEF</literal> do not carry + across files: each file starts with only the symbols defined + by <option>-D</option> switches on the command line. + </para> </sect2> <sect2 id="ecpg-ifdef"> diff --git a/doc/src/sgml/ref/ecpg-ref.sgml b/doc/src/sgml/ref/ecpg-ref.sgml index f3b6034f42a..43f2d8bdaa7 100644 --- a/doc/src/sgml/ref/ecpg-ref.sgml +++ b/doc/src/sgml/ref/ecpg-ref.sgml @@ -93,10 +93,12 @@ PostgreSQL documentation </varlistentry> <varlistentry> - <term><option>-D <replaceable>symbol</replaceable></option></term> + <term><option>-D <replaceable>symbol</replaceable>[=<replaceable>value</replaceable>]</option></term> <listitem> <para> - Define a C preprocessor symbol. + Define a preprocessor symbol, equivalently to the <command>EXEC SQL + DEFINE</command> directive. If no <replaceable>value</replaceable> is + specified, the symbol is defined with the value <literal>1</literal>. </para> </listitem> </varlistentry> |