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and parsing work in PL/PgSQL: - memory management is now done via palloc(). The compiled representation of each function now has its own memory context. Therefore, the storage consumed by a function can be reclaimed via MemoryContextDelete(). During compilation, the CurrentMemoryContext is the function's memory context. This means that a palloc() is sufficient to allocate memory that will have the same lifetime as the function itself. As a result, code invoked during compilation should be careful to pfree() temporary allocations to avoid leaking memory. Since a lot of the code in the backend is not careful about releasing palloc'ed memory, that means we should switch into a temporary memory context before invoking backend functions. A temporary context appropriate for such allocations is `compile_tmp_cxt'. - The ability to use palloc() allows us to simply a lot of the code in the parser. Rather than representing lists of elements via ad hoc linked lists or arrays, we can use the List type. Rather than doing malloc followed by memset(0), we can just use palloc0(). - We now check that the user has supplied the right number of parameters to a RAISE statement. Supplying either too few or too many results in an error (at runtime). - PL/PgSQL's parser needs to accept arbitrary SQL statements. Since we do not want to duplicate the SQL grammar in the PL/PgSQL grammar, this means we need to be quite lax in what the PL/PgSQL grammar considers a "SQL statement". This can lead to misleading behavior if there is a syntax error in the function definition, since we assume a malformed PL/PgSQL construct is a SQL statement. Furthermore, these errors were only detected at runtime (when we tried to execute the alleged "SQL statement" via SPI). To rectify this, the patch changes the parser to invoke the main SQL parser when it sees a string it believes to be a SQL expression. This means that synctically-invalid SQL will be rejected during the compilation of the PL/PgSQL function. This is only done when compiling for "validation" purposes (i.e. at CREATE FUNCTION time), so it should not impose a runtime overhead. - Fixes for the various buffer overruns I've patched in stable branches in the past few weeks. I've rewritten code where I thought it was warranted (unlike the patches applied to older branches, which were minimally invasive). - Various other minor changes and cleanups. - Updates to the regression tests. |
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