Add GDALSetAdbcDriverInitFunc() and use it in OGR ADBC driver

Also no longer make AdbcDriverManager a requirement

autotest/ogr/ogr_adbc.py

@@ -17,7 +17,19 @@
 
 from osgeo import gdal, ogr
 
-pytestmark = pytest.mark.require_driver("ADBC")
+
+def _has_adbc_driver_manager():
+    drv = gdal.GetDriverByName("ADBC")
+    return drv and drv.GetMetadataItem("HAS_ADBC_DRIVER_MANAGER")
+
+
+pytestmark = [
+    pytest.mark.require_driver("ADBC"),
+    pytest.mark.skipif(
+        not _has_adbc_driver_manager(),
+        reason="ADBC driver built without AdbcDriverManager",
+    ),
+]
 
 ###############################################################################
 

doc/source/api/vector_c_api.rst

@@ -14,3 +14,6 @@ ogr_core.h and ogr_api.h: Vector C API
 
 .. doxygenfile:: ogr_api.h
    :project: api
+
+.. doxygenfile:: gdal_adbc.h
+   :project: api

doc/source/drivers/vector/adbc.rst

@@ -7,11 +7,19 @@ ADBC -- Arrow Database Connectivity
 
 .. shortname:: ADBC
 
-.. build_dependencies:: adbc-driver-manager
+ADBC is a set of APIs and libraries for Arrow-native access to database.
 
-ADBC is a set of APIs and libraries for Arrow-native access to database. This
-driver uses the ``adbc-driver-manager`` library to connect to available ADBC
-drivers, and expose content as classic OGR features, or as a ArrowArrayStream.
+This driver has 2 modes:
+
+- either it has been built against the ``adbc-driver-manager`` library. In that
+  case, it can directly be used to connect to available ADBC drivers, and expose
+  content as classic OGR features, or as a ArrowArrayStream.
+  In that mode the driver metadata exposes the ``HAS_ADBC_DRIVER_MANAGER``
+  metadata item.
+- or it has not, in which case applications embedding GDAL must use
+  :cpp:func:`GDALSetAdbcLoadDriverOverride` as detailed in a below paragraph.
+  Note that use of that function can also be done even if the driver has been built
+  against the ``adbc-driver-manager`` library.
 
 Consult the `installation instruction <https://arrow.apache.org/adbc/current/driver/installation.html>`__
 for the various ADBC drivers. At time of writing, there are drivers for
@@ -80,6 +88,16 @@ It returns for each table a OGR feature with the following fields (some
 potentially unset or with an empty string): ``catalog_name``, ``schema_name``,
 ``table_name``, ``table_type``.
 
+Custom driver entry point
+-------------------------
+
+A custom driver entry point can be specified by applications by calling
+:cpp:func:`GDALSetAdbcLoadDriverOverride` (defined in header :file:`gdal_adbc.h`)
+before using the driver. The specified init function will be used by the
+GDAL ADBC driver as a way of specifying the ADBC driver for all calls in the
+same thread. Setting both the init function and the ``ADBC_DRIVER`` open
+option is not supported.
+
 Examples
 --------
 

gcore/CMakeLists.txt

@@ -1,6 +1,7 @@
 # CMake4GDAL project is distributed under MIT license. See accompanying file LICENSE.txt.
 add_library(
   gcore OBJECT
+  gdal_adbc.cpp
   gdalopeninfo.cpp
   gdaldriver.cpp
   gdaldrivermanager.cpp
@@ -194,6 +195,7 @@ target_public_header(
   gdalgeorefpamdataset.h
   gdal_mdreader.h
   gdalsubdatasetinfo.h
+  gdal_adbc.h
 )
 
 set(GDAL_DATA_FILES

gcore/gdal_adbc.cpp

@@ -0,0 +1,49 @@
+/******************************************************************************
+ * Name:     gdal_adbc.h
+ * Project:  GDAL Core
+ * Purpose:  GDAL Core ADBC related declarations.
+ * Author:   Even Rouault <even dot rouault at spatialys.com>
+ *
+ ******************************************************************************
+ * Copyright (c) 2024, Even Rouault <even dot rouault at spatialys.com>
+ * Copyright (c) 2024, Dewey Dunnington <dewey@voltrondata.com>
+ *
+ * SPDX-License-Identifier: MIT
+ ****************************************************************************/
+
+#include "cpl_port.h"
+#include "gdal_adbc.h"
+
+//! ADBC driver initialization function
+static GDALAdbcLoadDriverFunc GDALAdbcLoadDriver = nullptr;
+
+/************************************************************************/
+/*                      GDALSetAdbcLoadDriverOverride()                 */
+/************************************************************************/
+
+/** When set, it is used by the OGR ADBC driver to populate AdbcDriver
+ * callbacks. This provides an embedding application the opportunity to
+ * locate an up-to-date version of a driver or to bundle a driver not
+ * available at the system level.
+ *
+ * Setting it to NULL resets to the the default behaviour of the ADBC driver,
+ * which is use AdbcLoadDriver() from arrow-adbc/adbc_driver_manager.h or
+ * to error if the OGR ADBC driver was not built against a system driver
+ * manager.
+ */
+void GDALSetAdbcLoadDriverOverride(GDALAdbcLoadDriverFunc init_func)
+{
+    GDALAdbcLoadDriver = init_func;
+}
+
+/************************************************************************/
+/*                    GDALGetAdbcLoadDriverOverride()                   */
+/************************************************************************/
+
+/** Gets the ADBC driver load function. This will be NULL if an explicit
+ * override was not specified.
+ */
+GDALAdbcLoadDriverFunc GDALGetAdbcLoadDriverOverride()
+{
+    return GDALAdbcLoadDriver;
+}

gcore/gdal_adbc.h

@@ -0,0 +1,43 @@
+/******************************************************************************
+ * Name:     gdal_adbc.h
+ * Project:  GDAL Core
+ * Purpose:  GDAL Core ADBC related declarations.
+ * Author:   Even Rouault <even dot rouault at spatialys.com>
+ *
+ ******************************************************************************
+ * Copyright (c) 2024, Even Rouault <even dot rouault at spatialys.com>
+ * Copyright (c) 2024, Dewey Dunnington <dewey@voltrondata.com>
+ *
+ * SPDX-License-Identifier: MIT
+ ****************************************************************************/
+
+#ifndef GDAL_ADBC_H_INCLUDED
+#define GDAL_ADBC_H_INCLUDED
+
+/**
+ * \file gdal_adbc.h
+ *
+ * C GDAL entry points for Arrow Database Connectivity (ADBC)
+ *
+ * These functions provide an opportunity to override the mechanism
+ * that locates and loads ADBC drivers, or provide one if GDAL was
+ * not built with ADBC driver manager support.
+ *
+ * \since GDAL 3.11
+ */
+
+#include "cpl_port.h"
+
+CPL_C_START
+
+typedef uint8_t (*GDALAdbcLoadDriverFunc)(const char *driver_name,
+                                          const char *entrypoint, int version,
+                                          void *driver, void *error);
+
+void CPL_DLL GDALSetAdbcLoadDriverOverride(GDALAdbcLoadDriverFunc init_func);
+
+GDALAdbcLoadDriverFunc CPL_DLL GDALGetAdbcLoadDriverOverride(void);
+
+CPL_C_END
+
+#endif

ogr/ogrsf_frmts/CMakeLists.txt

@@ -84,6 +84,7 @@ ogr_optional_driver(jml JML)
 ogr_optional_driver(vdv "VDV-451/VDV-452/INTREST Data Format")
 ogr_optional_driver(flatgeobuf FlatGeobuf)
 ogr_optional_driver(mapml MapML)
+ogr_optional_driver(adbc ADBC)
 
 if( NOT WORDS_BIGENDIAN )
     ogr_optional_driver(miramon "MiraMonVector")
@@ -113,7 +114,6 @@ ogr_dependent_driver(oapif "OGC API Features service" "GDAL_USE_CURL")
 ogr_dependent_driver(ngw "NextGIS Web" "GDAL_USE_CURL")
 ogr_dependent_driver(elastic "ElasticSearch" "GDAL_USE_CURL")
 ogr_dependent_driver(xodr OpenDRIVE "GDAL_USE_OPENDRIVE;GDAL_USE_GEOS")
-ogr_dependent_driver(adbc ADBC "GDAL_USE_ADBCDRIVERMANAGER")
 
 ogr_dependent_driver(idrisi IDRISI "GDAL_ENABLE_DRIVER_IDRISI")
 

ogr/ogrsf_frmts/adbc/CMakeLists.txt

@@ -10,11 +10,19 @@ add_gdal_driver(
   NO_SHARED_SYMBOL_WITH_CORE
   STRONG_CXX_WFLAGS)
 
+if(TARGET ogr_ADBC_core AND GDAL_USE_ADBCDRIVERMANAGER AND TARGET AdbcDriverManager::adbc_driver_manager_shared)
+    target_compile_definitions(ogr_ADBC_core PRIVATE OGR_ADBC_HAS_DRIVER_MANAGER)
+endif()
+
 if(NOT TARGET ogr_ADBC)
     return()
 endif()
 
 gdal_standard_includes(ogr_ADBC)
 target_include_directories(ogr_ADBC PRIVATE $<TARGET_PROPERTY:ogrsf_generic,SOURCE_DIR>
                                             $<TARGET_PROPERTY:ogr_MEM,SOURCE_DIR>)
-gdal_target_link_libraries(ogr_ADBC PRIVATE AdbcDriverManager::adbc_driver_manager_shared)
+
+if (GDAL_USE_ADBCDRIVERMANAGER AND TARGET AdbcDriverManager::adbc_driver_manager_shared)
+  gdal_target_link_libraries(ogr_ADBC PRIVATE AdbcDriverManager::adbc_driver_manager_shared)
+  target_compile_definitions(ogr_ADBC PRIVATE OGR_ADBC_HAS_DRIVER_MANAGER)
+endif()

ogr/ogrsf_frmts/adbc/ogr_adbc.h

@@ -17,7 +17,8 @@
 #include "ogrsf_frmts.h"
 #include "ogrlayerarrow.h"
 
-#include <arrow-adbc/adbc.h>
+#include "ogr_adbc_internal.h"
+
 
 /************************************************************************/
 /*                 OGRArrowArrayToOGRFeatureAdapterLayer                */
@@ -138,6 +139,7 @@ class OGRADBCDataset final : public GDALDataset
 {
     friend class OGRADBCLayer;
 
+    AdbcDriver m_driver{};
     AdbcDatabase m_database{};
     std::unique_ptr<AdbcConnection> m_connection{};
     std::vector<std::unique_ptr<OGRLayer>> m_apoLayers{};
@@ -179,7 +181,7 @@ struct OGRADBCError
 
     inline OGRADBCError()
     {
-        memset(&error, 0, sizeof(error));
+        error = ADBC_ERROR_INIT;
     }
 
     inline ~OGRADBCError()