Support CMake VOL builds with FetchContent from local directory (#3455)

* Update VOL CMake for REST VOL

* Prevent linking static libs to VOLs

* index on fetch_local: 5c5c3f1505 Prevent linking static libs to VOLs

* index on (no branch): 9a36d3e7b1 On fetch_local: WIP:add source dir fetch option for vols

* Allow building of VOL from local source

* Move LOCAL_DIR option to HDF5_VOL_ALLOW_EXTERNAL

1 files changed, 54 insertions, 19 deletions

diff --git a/CMakeVOL.cmake b/CMakeVOL.cmake
index 8562106..79afa59 100644
--- a/CMakeVOL.cmake
+++ b/CMakeVOL.cmake
@@ -27,12 +27,12 @@ function (get_generated_cmake_targets out_var dir)
 endfunction ()
 
 # For now, only support building of external VOL connectors with FetchContent
-option (HDF5_VOL_ALLOW_EXTERNAL "Allow building of external HDF5 VOL connectors with FetchContent" OFF)
+option (HDF5_VOL_ALLOW_EXTERNAL "Allow building of external HDF5 VOL connectors with FetchContent" "NO")
 mark_as_advanced (HDF5_VOL_ALLOW_EXTERNAL)
 if (HDF5_VOL_ALLOW_EXTERNAL)
-  if (HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "NO" OR NOT HDF5_ALLOW_EXTERNAL_SUPPORT MATCHES "GIT")
-    message (FATAL_ERROR "HDF5_ALLOW_EXTERNAL_SUPPORT must be set to 'GIT' to allow building of external HDF5 VOL connectors")
-  endif ()
+  if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "NO" OR (NOT HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT" AND NOT HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR"))
+    message (FATAL_ERROR "HDF5_VOL_ALLOW_EXTERNAL must be set to 'GIT' or 'LOCAL_DIR' to allow building of external HDF5 VOL connectors")
+  endif()
 
   # For compatibility, set some variables that projects would
   # typically look for after calling find_package(HDF5)
@@ -51,7 +51,7 @@ if (HDF5_VOL_ALLOW_EXTERNAL)
 
   foreach (vol_idx RANGE 1 ${HDF5_MAX_EXTERNAL_VOLS})
     # Generate fixed-width index number prepended with 0s
-    # so URLs come in order from 1 - HDF5_MAX_EXTERNAL_VOLS
+    # so VOL sources come in order from 1 - HDF5_MAX_EXTERNAL_VOLS
     set (vol_idx_num_digits 2) # Based on HDF5_MAX_EXTERNAL_VOLS
     set (vol_idx_fixed "${vol_idx}")
     string (LENGTH "${vol_idx_fixed}" vol_idx_len)
@@ -60,33 +60,53 @@ if (HDF5_VOL_ALLOW_EXTERNAL)
       math (EXPR vol_idx_len "${vol_idx_len}+1")
     endwhile ()
 
-    set (HDF5_VOL_URL${vol_idx_fixed} "" CACHE STRING "Git repository URL of an external HDF5 VOL connector to build")
-    mark_as_advanced (HDF5_VOL_URL${vol_idx_fixed})
+    if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT")
+      set (HDF5_VOL_URL${vol_idx_fixed} "" CACHE STRING "Git repository URL of an external HDF5 VOL connector to build")
+      mark_as_advanced (HDF5_VOL_URL${vol_idx_fixed})
+      set (HDF5_VOL_SOURCE "${HDF5_VOL_URL${vol_idx_fixed}}")
+    elseif(HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+      set (HDF5_VOL_PATH${vol_idx_fixed} "" CACHE STRING "Path to the source directory of an external HDF5 VOL connector to build")
+      mark_as_advanced (HDF5_VOL_PATH${vol_idx_fixed})
+      set (HDF5_VOL_SOURCE "${HDF5_VOL_PATH${vol_idx_fixed}}")
+    endif()
+
+    if (NOT "${HDF5_VOL_SOURCE}" STREQUAL "")
+      # Deal with trailing slash in path for LOCAL_DIR case
+      if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+        # Erase trailing slash
+        string (REGEX REPLACE "/$" "" HDF5_VOL_SOURCE ${HDF5_VOL_SOURCE})
+      endif()
 
-    if (NOT "${HDF5_VOL_URL${vol_idx_fixed}}" STREQUAL "")
       # Extract the name of the VOL connector
-      string (FIND "${HDF5_VOL_URL${vol_idx_fixed}}" "/" hdf5_vol_name_pos REVERSE)
+      string (FIND "${HDF5_VOL_SOURCE}" "/" hdf5_vol_name_pos REVERSE)
       if (hdf5_vol_name_pos EQUAL -1)
-        message (SEND_ERROR "Invalid URL '${HDF5_VOL_URL${vol_idx_fixed}}' specified for HDF5_VOL_URL${vol_idx_fixed}")
+        if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT")
+          message (SEND_ERROR "Invalid URL '${HDF5_VOL_SOURCE}' specified for HDF5_VOL_URL${vol_idx_fixed}")
+        elseif (HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+          message (SEND_ERROR "Invalid source path '${HDF5_VOL_SOURCE}' specified for HDF5_VOL_PATH${vol_idx_fixed}")
+        endif()
       endif ()
 
       math (EXPR hdf5_vol_name_pos "${hdf5_vol_name_pos}+1")
 
-      string (SUBSTRING "${HDF5_VOL_URL${vol_idx_fixed}}" ${hdf5_vol_name_pos} -1 hdf5_vol_name)
+      string (SUBSTRING "${HDF5_VOL_SOURCE}" ${hdf5_vol_name_pos} -1 hdf5_vol_name)
       string (REPLACE ".git" "" hdf5_vol_name "${hdf5_vol_name}")
       string (STRIP "${hdf5_vol_name}" hdf5_vol_name)
       string (TOUPPER "${hdf5_vol_name}" hdf5_vol_name_upper)
       string (TOLOWER "${hdf5_vol_name}" hdf5_vol_name_lower)
 
-      message (VERBOSE "Building VOL connector '${hdf5_vol_name}' with FetchContent")
+      message (VERBOSE "Building VOL connector '${hdf5_vol_name}' with FetchContent from source ${HDF5_VOL_SOURCE}")
 
       # Set some cache variables that can be set by users when building
+      if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT")
+        set ("HDF5_VOL_${hdf5_vol_name_upper}_BRANCH" "main" CACHE STRING "Git branch (or tag) to use when building VOL connector '${hdf5_vol_name}'")
+        mark_as_advanced ("HDF5_VOL_${hdf5_vol_name_upper}_BRANCH")
+      endif()
+
       set ("HDF5_VOL_${hdf5_vol_name_upper}_NAME" "" CACHE STRING "Name of VOL connector to set for the HDF5_VOL_CONNECTOR environment variable")
-      set ("HDF5_VOL_${hdf5_vol_name_upper}_BRANCH" "main" CACHE STRING "Git branch (or tag) to use when building VOL connector '${hdf5_vol_name}'")
       option ("HDF5_VOL_${hdf5_vol_name_upper}_TEST_PARALLEL" "Whether to test VOL connector '${hdf5_vol_name}' against the parallel API tests" OFF)
 
       mark_as_advanced ("HDF5_VOL_${hdf5_vol_name_upper}_NAME")
-      mark_as_advanced ("HDF5_VOL_${hdf5_vol_name_upper}_BRANCH")
       mark_as_advanced ("HDF5_VOL_${hdf5_vol_name_upper}_TEST_PARALLEL")
 
       if (HDF5_TEST_API)
@@ -95,21 +115,36 @@ if (HDF5_VOL_ALLOW_EXTERNAL)
         endif ()
       endif ()
 
-      if ("${HDF5_VOL_${hdf5_vol_name_upper}_BRANCH}" STREQUAL "")
+      if ((HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT") AND ("${HDF5_VOL_${hdf5_vol_name_upper}_BRANCH}" STREQUAL ""))
         message (SEND_ERROR "HDF5_VOL_${hdf5_vol_name_upper}_BRANCH must be set to a valid git branch name (or git tag) to build VOL connector '${hdf5_vol_name}'")
       endif ()
 
-      FetchContent_Declare (HDF5_VOL_${hdf5_vol_name_lower}
-        GIT_REPOSITORY "${HDF5_VOL_URL${vol_idx_fixed}}"
+      if ((HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+        AND NOT (EXISTS ${HDF5_VOL_SOURCE} AND IS_DIRECTORY ${HDF5_VOL_SOURCE}))
+          message (FATAL_ERROR "HDF5_VOL_PATH${vol_idx_fixed} must be an absolute path to a valid directory")
+      endif ()
+
+      if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT")
+        FetchContent_Declare (HDF5_VOL_${hdf5_vol_name_lower}
+        GIT_REPOSITORY "${HDF5_VOL_SOURCE}"
         GIT_TAG "${HDF5_VOL_${hdf5_vol_name_upper}_BRANCH}"
-      )
+        )
+      elseif(HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+        FetchContent_Declare (HDF5_VOL_${hdf5_vol_name_lower}
+        SOURCE_DIR "${HDF5_VOL_SOURCE}"
+        )
+      endif()
 
       FetchContent_GetProperties(HDF5_VOL_${hdf5_vol_name_lower})
       if (NOT hdf5_vol_${hdf5_vol_name_lower}_POPULATED)
         FetchContent_Populate(HDF5_VOL_${hdf5_vol_name_lower})
 
         if (NOT EXISTS "${hdf5_vol_${hdf5_vol_name_lower}_SOURCE_DIR}/CMakeLists.txt")
-          message (SEND_ERROR "The git repository branch '${HDF5_VOL_${hdf5_vol_name_upper}_BRANCH}' for VOL connector '${hdf5_vol_name}' does not appear to contain a CMakeLists.txt file")
+          if (HDF5_VOL_ALLOW_EXTERNAL MATCHES "GIT")
+            message (SEND_ERROR "The git repository branch '${HDF5_VOL_${hdf5_vol_name_upper}_BRANCH}' for VOL connector '${hdf5_vol_name}' does not appear to contain a CMakeLists.txt file")
+          elseif (HDF5_VOL_ALLOW_EXTERNAL MATCHES "LOCAL_DIR")
+            message(SEND_ERROR "The local directory '${HDF5_VOL_SOURCE}' for VOL connector '${hdf5_vol_name}' does not appear to contain a CMakeLists.txt file")
+          endif()
         endif ()
 
         # If there are any calls to find_package(HDF5) in the connector's