@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / backend / utils / fmgr / dfmgr . c , v 1.87 2006 / 08 / 08 19 : 15 : 0 8tgl Exp $
* $ PostgreSQL : pgsql / src / backend / utils / fmgr / dfmgr . c , v 1.88 2006 / 08 / 15 18 : 26 : 5 8tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -23,12 +23,20 @@
# endif
# include "miscadmin.h"
# include "utils/dynamic_loader.h"
# include "utils/hsearch.h"
/* signatures for PostgreSQL-specific library init/fini functions */
typedef void ( * PG_init_t ) ( void ) ;
typedef void ( * PG_fini_t ) ( void ) ;
/* hashtable entry for rendezvous variables */
typedef struct
{
char varName [ NAMEDATALEN ] ; /* hash key (must be first) */
void * varValue ;
} rendezvousHashEntry ;
/*
* List of dynamically loaded files ( kept in malloc ' d memory ) .
*/
@ -62,10 +70,13 @@ static DynamicFileList *file_tail = NULL;
char * Dynamic_library_path ;
static void * internal_load_library ( const char * libname ) ;
static void internal_unload_library ( const char * libname ) ;
static bool file_exists ( const char * name ) ;
static char * find_in_dynamic_libpath ( const char * basename ) ;
static char * expand_dynamic_library_name ( const char * name ) ;
static void check_restricted_library_name ( const char * name ) ;
static char * substitute_libpath_macro ( const char * name ) ;
static char * find_in_dynamic_libpath ( const char * basename ) ;
/* Magic structure that module needs to match to be accepted */
static const Pg_magic_struct magic_data = PG_MODULE_MAGIC_DATA ;
@ -73,7 +84,7 @@ static const 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 . )
* named funcname in it .
*
* If the function is not found , we raise an error if signalNotFound is true ,
* else return ( PGFunction ) NULL . Note that errors in loading the library
@ -88,37 +99,107 @@ PGFunction
load_external_function ( char * filename , char * funcname ,
bool signalNotFound , void * * filehandle )
{
DynamicFileList * file_scanner ;
char * fullname ;
void * lib_handle ;
PGFunction retval ;
/* Expand the possibly-abbreviated filename to an exact path name */
fullname = expand_dynamic_library_name ( filename ) ;
/* Load the shared library, unless we already did */
lib_handle = internal_load_library ( fullname ) ;
/* Return handle if caller wants it */
if ( filehandle )
* filehandle = lib_handle ;
/* Look up the function within the library */
retval = pg_dlsym ( lib_handle , funcname ) ;
if ( retval = = NULL & & signalNotFound )
ereport ( ERROR ,
( errcode ( ERRCODE_UNDEFINED_FUNCTION ) ,
errmsg ( " could not find function \" %s \" in file \" %s \" " ,
funcname , fullname ) ) ) ;
pfree ( fullname ) ;
return retval ;
}
/*
* This function loads a shlib file without looking up any particular
* function in it . If the same shlib has previously been loaded ,
* unload and reload it .
*
* When ' restrict ' is true , only libraries in the presumed - secure
* directory $ libdir / plugins may be referenced .
*/
void
load_file ( const char * filename , bool restrict )
{
char * fullname ;
/* Apply security restriction if requested */
if ( restrict )
check_restricted_library_name ( filename ) ;
/* Expand the possibly-abbreviated filename to an exact path name */
fullname = expand_dynamic_library_name ( filename ) ;
/* Unload the library if currently loaded */
internal_unload_library ( fullname ) ;
/* Load the shared library */
( void ) internal_load_library ( fullname ) ;
pfree ( fullname ) ;
}
/*
* Lookup a function whose library file is already loaded .
* Return ( PGFunction ) NULL if not found .
*/
PGFunction
lookup_external_function ( void * filehandle , char * funcname )
{
return pg_dlsym ( filehandle , funcname ) ;
}
/*
* Load the specified dynamic - link library file , unless it already is
* loaded . Return the pg_dl * handle for the file .
*
* Note : libname is expected to be an exact name for the library file .
*/
static void *
internal_load_library ( const char * libname )
{
DynamicFileList * file_scanner ;
PGModuleMagicFunction magic_func ;
char * load_error ;
struct stat stat_buf ;
char * fullname ;
PG_init_t PG_init ;
fullname = expand_dynamic_library_name ( filename ) ;
if ( ! fullname )
fullname = pstrdup ( filename ) ;
/* at this point fullname is always freshly palloc'd */
/*
* Scan the list of loaded FILES to see if the file has been loaded .
*/
for ( file_scanner = file_list ;
file_scanner ! = NULL & &
strcmp ( fullname , file_scanner - > filename ) ! = 0 ;
strcmp ( lib name, file_scanner - > filename ) ! = 0 ;
file_scanner = file_scanner - > next )
;
if ( file_scanner = = NULL )
{
/*
* Check for same files - different paths ( ie , symlink or link )
*/
if ( stat ( fullname , & stat_buf ) = = - 1 )
if ( stat ( lib name, & stat_buf ) = = - 1 )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not access file \" %s \" : %m " ,
fullname ) ) ) ;
lib name) ) ) ;
for ( file_scanner = file_list ;
file_scanner ! = NULL & &
@ -133,21 +214,21 @@ load_external_function(char *filename, char *funcname,
* File not loaded yet .
*/
file_scanner = ( DynamicFileList * )
malloc ( sizeof ( DynamicFileList ) + strlen ( full name) ) ;
malloc ( sizeof ( DynamicFileList ) + strlen ( lib name) ) ;
if ( file_scanner = = NULL )
ereport ( ERROR ,
( errcode ( ERRCODE_OUT_OF_MEMORY ) ,
errmsg ( " out of memory " ) ) ) ;
MemSet ( file_scanner , 0 , sizeof ( DynamicFileList ) ) ;
strcpy ( file_scanner - > filename , full name) ;
strcpy ( file_scanner - > filename , lib name) ;
file_scanner - > device = stat_buf . st_dev ;
# ifndef WIN32
file_scanner - > inode = stat_buf . st_ino ;
# endif
file_scanner - > next = NULL ;
file_scanner - > handle = pg_dlopen ( full name ) ;
file_scanner - > handle = pg_dlopen ( file_scanner - > file name ) ;
if ( file_scanner - > handle = = NULL )
{
load_error = ( char * ) pg_dlerror ( ) ;
@ -156,7 +237,7 @@ load_external_function(char *filename, char *funcname,
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not load library \" %s \" : %s " ,
full name, load_error ) ) ) ;
lib name, load_error ) ) ) ;
}
/* Check the magic function to determine compatibility */
@ -184,7 +265,7 @@ load_external_function(char *filename, char *funcname,
if ( module_magic_data . version ! = magic_data . version )
ereport ( ERROR ,
( errmsg ( " incompatible library \" %s \" : version mismatch " ,
full name) ,
lib name) ,
errdetail ( " Server is version %d.%d, library is version %d.%d. " ,
magic_data . version / 100 ,
magic_data . version % 100 ,
@ -192,7 +273,7 @@ load_external_function(char *filename, char *funcname,
module_magic_data . version % 100 ) ) ) ;
ereport ( ERROR ,
( errmsg ( " incompatible library \" %s \" : magic block mismatch " ,
full name) ) ) ;
lib name) ) ) ;
}
}
else
@ -203,7 +284,7 @@ load_external_function(char *filename, char *funcname,
/* complain */
ereport ( ERROR ,
( errmsg ( " incompatible library \" %s \" : missing magic block " ,
full name) ,
lib name) ,
errhint ( " Extension libraries are now required to use the PG_MODULE_MAGIC macro. " ) ) ) ;
}
@ -222,77 +303,48 @@ load_external_function(char *filename, char *funcname,
file_tail = file_scanner ;
}
/* Return handle if caller wants it. */
if ( filehandle )
* filehandle = file_scanner - > handle ;
/*
* If funcname is NULL , we only wanted to load the file .
*/
if ( funcname = = NULL )
{
pfree ( fullname ) ;
return NULL ;
}
retval = pg_dlsym ( file_scanner - > handle , funcname ) ;
if ( retval = = NULL & & signalNotFound )
ereport ( ERROR ,
( errcode ( ERRCODE_UNDEFINED_FUNCTION ) ,
errmsg ( " could not find function \" %s \" in file \" %s \" " ,
funcname , fullname ) ) ) ;
pfree ( fullname ) ;
return retval ;
return file_scanner - > handle ;
}
/*
* This function loads a shlib file without looking up any particular
* function in it . If the same shlib has previously been loaded ,
* unload and reload it .
* Unload the specified dynamic - link library file , if it is loaded .
*
* Note : libname is expected to be an exact name for the library file .
*/
void
load_file ( char * file name)
static void
internal_unload_library ( const char * libname )
{
DynamicFileList * file_scanner ,
* prv ,
* nxt ;
struct stat stat_buf ;
char * fullname ;
PG_fini_t PG_fini ;
fullname = expand_dynamic_library_name ( filename ) ;
if ( ! fullname )
fullname = pstrdup ( filename ) ;
/* at this point fullname is always freshly palloc'd */
/*
* We need to do stat ( ) in order to determine whether this is the same
* file as a previously loaded file ; it ' s also handy so as to give a good
* error message if bogus file name given .
*/
if ( stat ( full name, & stat_buf ) = = - 1 )
if ( stat ( libname , & stat_buf ) = = - 1 )
ereport ( ERROR ,
( errcode_for_file_access ( ) ,
errmsg ( " could not access file \" %s \" : %m " , full name) ) ) ;
errmsg ( " could not access file \" %s \" : %m " , lib name) ) ) ;
/*
* We have to zap all entries in the list that match on either filename or
* inode , else load_external_function ( ) won ' t do anything .
* inode , else internal_load_library ( ) will still think it ' s present .
*/
prv = NULL ;
for ( file_scanner = file_list ; file_scanner ! = NULL ; file_scanner = nxt )
{
nxt = file_scanner - > next ;
if ( strcmp ( full name, file_scanner - > filename ) = = 0 | |
if ( strcmp ( lib name, file_scanner - > filename ) = = 0 | |
SAME_INODE ( stat_buf , * file_scanner ) )
{
if ( prv )
prv - > next = nxt ;
else
file_list = nxt ;
clear_external_function_hash ( file_scanner - > handle ) ;
/*
* If the library has a _PG_fini ( ) function , call it .
@ -301,6 +353,7 @@ load_file(char *filename)
if ( PG_fini )
( * PG_fini ) ( ) ;
clear_external_function_hash ( file_scanner - > handle ) ;
pg_dlclose ( file_scanner - > handle ) ;
free ( ( char * ) file_scanner ) ;
/* prv does not change */
@ -308,23 +361,8 @@ load_file(char *filename)
else
prv = file_scanner ;
}
load_external_function ( fullname , NULL , false , NULL ) ;
pfree ( fullname ) ;
}
/*
* Lookup a function whose library file is already loaded .
* Return ( PGFunction ) NULL if not found .
*/
PGFunction
lookup_external_function ( void * filehandle , char * funcname )
{
return pg_dlsym ( filehandle , funcname ) ;
}
static bool
file_exists ( const char * name )
{
@ -353,9 +391,9 @@ file_exists(const char *name)
* the name . Else ( no slash ) try to expand using search path ( see
* find_in_dynamic_libpath below ) ; if that works , return the fully
* expanded file name . If the previous failed , append DLSUFFIX and
* try again . If all fails , return NULL .
* try again . If all fails , just return the original name .
*
* A non - NULL result will always be freshly palloc ' d .
* The result will always be freshly palloc ' d .
*/
static char *
expand_dynamic_library_name ( const char * name )
@ -402,9 +440,28 @@ expand_dynamic_library_name(const char *name)
pfree ( full ) ;
}
return NULL ;
/*
* If we can ' t find the file , just return the string as - is .
* The ensuing load attempt will fail and report a suitable message .
*/
return pstrdup ( name ) ;
}
/*
* Check a restricted library name . It must begin with " $libdir/plugins/ "
* and there must not be any directory separators after that ( this is
* sufficient to prevent " .. " style attacks ) .
*/
static void
check_restricted_library_name ( const char * name )
{
if ( strncmp ( name , " $libdir/plugins/ " , 16 ) ! = 0 | |
first_dir_separator ( name + 16 ) ! = NULL )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
errmsg ( " access to library \" %s \" is not allowed " ,
name ) ) ) ;
}
/*
* Substitute for any macros appearing in the given string .
@ -418,6 +475,7 @@ substitute_libpath_macro(const char *name)
AssertArg ( name ! = NULL ) ;
/* Currently, we only recognize $libdir at the start of the string */
if ( name [ 0 ] ! = ' $ ' )
return pstrdup ( name ) ;
@ -428,7 +486,8 @@ substitute_libpath_macro(const char *name)
strncmp ( name , " $libdir " , strlen ( " $libdir " ) ) ! = 0 )
ereport ( ERROR ,
( errcode ( ERRCODE_INVALID_NAME ) ,
errmsg ( " invalid macro name in dynamic library path: %s " , name ) ) ) ;
errmsg ( " invalid macro name in dynamic library path: %s " ,
name ) ) ) ;
ret = palloc ( strlen ( pkglib_path ) + strlen ( sep_ptr ) + 1 ) ;
@ -513,3 +572,58 @@ find_in_dynamic_libpath(const char *basename)
return NULL ;
}
/*
* Find ( or create ) a rendezvous variable that one dynamically
* loaded library can use to meet up with another .
*
* On the first call of this function for a particular varName ,
* a " rendezvous variable " is created with the given name .
* The value of the variable is a void pointer ( initially set to NULL ) .
* Subsequent calls with the same varName just return the address of
* the existing variable . Once created , a rendezvous variable lasts
* for the life of the process .
*
* Dynamically loaded libraries can use rendezvous variables
* to find each other and share information : they just need to agree
* on the variable name and the data it will point to .
*/
void * *
find_rendezvous_variable ( const char * varName )
{
static HTAB * rendezvousHash = NULL ;
char key [ NAMEDATALEN ] ;
rendezvousHashEntry * hentry ;
bool found ;
/* Create a hashtable if we haven't already done so in this process */
if ( rendezvousHash = = NULL )
{
HASHCTL ctl ;
MemSet ( & ctl , 0 , sizeof ( ctl ) ) ;
ctl . keysize = NAMEDATALEN ;
ctl . entrysize = sizeof ( rendezvousHashEntry ) ;
rendezvousHash = hash_create ( " Rendezvous variable hash " ,
16 ,
& ctl ,
HASH_ELEM ) ;
}
/* Turn the varName into a fixed-size string */
StrNCpy ( key , varName , sizeof ( key ) ) ;
/* Find or create the hashtable entry for this varName */
hentry = ( rendezvousHashEntry * ) hash_search ( rendezvousHash ,
key ,
HASH_ENTER ,
& found ) ;
/* Initialize to NULL if first time */
if ( ! found )
hentry - > varValue = NULL ;
return & hentry - > varValue ;
}
Tom Lane
19 years ago