Per feedback, here is an updated version. As was pointed out, the prior
version was checking stuff that either changed too often to be useful
or was never going to change at all. The error reporting is cleaned up
too, it now releases the module before throwing the error. It now only
checks four things:
Major version number (7.4 or 8.1 for example)
NAMEDATALEN
FUNC_MAX_ARGS
INDEX_MAX_KEYS
The three constants were chosen because:
1. We document them in the config page in the docs
2. We mark them as changable in pg_config_manual.h
3. Changing any of these will break some of the more popular modules:
FUNC_MAX_ARGS changes fmgr interface, every module uses this
NAMEDATALEN changes syscache interface, every PL as well as tsearch uses this
INDEX_MAX_KEYS breaks tsearch and anything using GiST.
I considered others but ultimatly rejected them. For example,
HAVE_INT64_TIMESTAMP, while changing the way timestamps are stored and
being configurable by a configure option, doesn't actually break
anything important (only the btree_gist example in contrib).
Any more comments?
Have a nice day,
--
Martijn van Oosterhout kleptog@svana.org http://svana.org/kleptog/
From each according to his ability. To each according to his ability to
litigate.
Index: doc/src/sgml/xfunc.sgml
===
RCS file: /projects/cvsroot/pgsql/doc/src/sgml/xfunc.sgml,v
retrieving revision 1.112
diff -c -r1.112 xfunc.sgml
*** doc/src/sgml/xfunc.sgml 23 Apr 2006 03:39:52 - 1.112
--- doc/src/sgml/xfunc.sgml 8 May 2006 17:41:33 -
***
*** 1149,1154
--- 1149,1161
/para
para
+ After the module has been found, PostgreSQL looks for its magic block.
+ This block contains information about the environment a module was
+ compiled in. The server uses this to verify the module was compiled
+ under the same assumptions and environment as the backend.
+/para
+
+para
The user ID the productnamePostgreSQL/productname server runs
as must be able to traverse the path to the file you intend to
load. Making the file or a higher-level directory not readable
***
*** 1953,1958
--- 1960,1985
listitem
para
+ To ensure your module is not loaded into an incompatible backend, it
+ is recommended to include a magic block. To do this you must include
+ the header filenamepgmagic.h/filename and declare the block as
+ follows:
+/para
+
+ programlisting
+ #include pgmagic.h
+
+ PG_MODULE_MAGIC;
+ /programlisting
+
+para
+ If the module consists of multiple source files, this only needs to
+ be done in one of them.
+/para
+ /listitem
+
+ listitem
+para
Symbol names defined within object files must not conflict
with each other or with symbols defined in the
productnamePostgreSQL/productname server executable. You
Index: src/backend/utils/fmgr/dfmgr.c
===
RCS file: /projects/cvsroot/pgsql/src/backend/utils/fmgr/dfmgr.c,v
retrieving revision 1.82
diff -c -r1.82 dfmgr.c
*** src/backend/utils/fmgr/dfmgr.c 5 Mar 2006 15:58:46 - 1.82
--- src/backend/utils/fmgr/dfmgr.c 8 May 2006 17:41:33 -
***
*** 20,26
#include dynloader.h
#include miscadmin.h
#include utils/dynamic_loader.h
!
/*
* List of dynamically loaded files (kept in malloc'd memory).
--- 20,26
#include dynloader.h
#include miscadmin.h
#include utils/dynamic_loader.h
! #include pgmagic.h
/*
* List of dynamically loaded files (kept in malloc'd memory).
***
*** 60,65
--- 60,68
static char *expand_dynamic_library_name(const char *name);
static char *substitute_libpath_macro(const char *name);
+ /* Magic structure that module needs to match to be accepted */
+ static Pg_magic_struct magic_data = PG_MODULE_MAGIC_DATA;
+
/*
* Load the specified dynamic-link library file, and look for a function
* named funcname in it. (funcname can be NULL to just load the file.)
***
*** 116,121
--- 119,125
if (file_scanner == NULL)
{
+ PGModuleMagicFunction magic_func;
/*
* File not loaded yet.
*/
***
*** 146,151
--- 150,194
fullname, load_error)));
}
+ /* Check the magic function to determine compatability */
+ magic_func = pg_dlsym( file_scanner-handle,
PG_MAGIC_FUNCTION_NAME_STRING );
+ if( magic_func )
+ {
+ Pg_magic_struct *module_magic_data = magic_func();
+ if( module_magic_data-len != magic_data.len ||
+ memcmp(
