README
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Finding Extension Function Imports
These are commands that can be used to find the functions that an extension imports, so that we know which ones we need to implement for the extension to load.
Windows
On Windows, we make use of dumpbin, which is installed alongside Visual Studio (the full version, not Code). We are generally only interested in the functions under postgres.exe, as the library should load other DLLs as necessary.
dumpbin /imports "C:/Program Files/PostgreSQL/15/lib/LIBRARY_NAME.dll"
Linux
On Linux, we make use of the built-in nm command. We are interested in the U functions that do not have an @ near the end (as those are usually implemented in external libraries).
nm -D -u /usr/lib/postgresql/15/lib/LIBRARY_NAME.so
Documentation
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Index ¶
- Constants
- func Free[T any](val *T)
- func FreeDatum(val Datum)
- func FromDatum[T any](d Datum) *T
- func FromDatumGoBytes(d Datum, n uint) []byte
- func FromDatumGoString(d Datum) string
- func LoadExtensions() (map[string]*ExtensionFiles, error)
- func Malloc[T any]() *T
- func PostgresDirectories() (libDir string, extensionDir string, err error)
- func ZeroMemory[T any](val *T)
- type Control
- type Datum
- type ExtensionFiles
- type FilenameVersions
- type Function
- type InternalLoadedLibrary
- type Library
- type NullableDatum
- type PgFunctionInfo
- type PgMagicStruct
- type Version
Constants ¶
const PLATFORM = "LIN"
PLATFORM specifies which platform applies to the current library loader. This will always be a three-letter string.
Variables ¶
This section is empty.
Functions ¶
func Free ¶
func Free[T any](val *T)
Free frees the given pointer from C heap. Generally, this is paired with a pointer returned from Malloc.
func FreeDatum ¶
func FreeDatum(val Datum)
FreeDatum frees the given Datum. Care should be exercised as datums may refer to static memory, and attempting to free static memory will result in a crash.
func FromDatumGoBytes ¶
FromDatumGoBytes converts the given datum to a byte array of length N.
func FromDatumGoString ¶
FromDatumGoString converts the given datum to a string.
func LoadExtensions ¶
func LoadExtensions() (map[string]*ExtensionFiles, error)
LoadExtensions loads information for all extensions that are in the extensions directory of a local Postgres installation.
func Malloc ¶
func Malloc[T any]() *T
Malloc allocates the given type within the C heap. These should always be followed up with a Free at some point afterward.
func PostgresDirectories ¶
PostgresDirectories returns the installation directories of a local Postgres instance.
func ZeroMemory ¶
func ZeroMemory[T any](val *T)
ZeroMemory writes all zeroes to the memory location occupied by the given pointer.
Types ¶
type Control ¶
type Control struct {
Directory string
DefaultVersion Version
Comment string
Encoding string
ModulePathname string
Requires []string
Superuser bool
Trusted bool
Relocatable bool
Schema string
Extra map[string]string // All entries in here could not be matched to an expected field
}
Control contains the contents of the control file. https://www.postgresql.org/docs/15/extend-extensions.html#id-1.8.3.20.11
type Datum ¶
type Datum uintptr
Datum is a C pointer to some data. Depending on the function being called, it may not be a pointer that should be freed, as some functions return pointers to static memory.
func CallFmgrFunction ¶
func CallFmgrFunction(fn uintptr, args ...NullableDatum) (result Datum, isNotNull bool)
CallFmgrFunction calls the given function and forwards the arguments.
func ToDatumGoBytes ¶
ToDatumGoBytes converts the given byte slice to a Datum.
func ToDatumGoString ¶
ToDatumGoString converts the given string to a Datum.
type ExtensionFiles ¶
type ExtensionFiles struct {
Name string
ControlFileName string
SQLFileNames []string
LibraryFileName string
ControlFileDir string
LibraryFileDir string
Control Control
}
ExtensionFiles contains all of the files that are related to or used by an extension.
func (*ExtensionFiles) LoadLibrary ¶
func (extFile *ExtensionFiles) LoadLibrary() (*Library, error)
LoadLibrary loads the extension as a library.
func (*ExtensionFiles) LoadSQLFiles ¶
func (extFile *ExtensionFiles) LoadSQLFiles() ([]string, error)
LoadSQLFiles loads the contents of the SQL files used by the extension. These will be in the order that they need to be executed.
func (*ExtensionFiles) LoadSQLFunctionNames ¶
func (extFile *ExtensionFiles) LoadSQLFunctionNames() ([]string, error)
LoadSQLFunctionNames loads all of the library function names that are used by the extension.
type FilenameVersions ¶
FilenameVersions returns the versions that were encoded in a filename. `From` is the first number, while `To` is the second number. If a filename only specifies a single version, this both `From` and `To` will equal one another.
func DecodeFilenameVersions ¶
func DecodeFilenameVersions(name string, fileName string) FilenameVersions
DecodeFilenameVersions decodes the version information within the file name. The `sqlFileName` should be the full file name (excluding the path), and the SQL file name should contain only the name as
type InternalLoadedLibrary ¶
InternalLoadedLibrary is an interface that is implemented by the specific platform to handle library operations.
type Library ¶
type Library struct {
Magic PgMagicStruct
Funcs map[string]Function
Version Version
// contains filtered or unexported fields
}
Library is a fully-loaded extension library.
type NullableDatum ¶
NullableDatum is used for arguments to Fmgr function calls.
type PgFunctionInfo ¶
type PgFunctionInfo struct {
APIVersion int32
}
PgFunctionInfo is a stand-in for the C struct that reports the function information.
type PgMagicStruct ¶
type PgMagicStruct struct {
Len int32
Version int32
FuncMaxArgs int32
IndexMaxKeys int32
NameDataLen int32
Float4ByVal int32
Float8ByVal int32
}
PgMagicStruct is a stand-in for the C struct that reports the information of the library.
type Version ¶
type Version uint32
Version specifies the major and minor version numbers for an extension.
Source Files
Directories