meson: Don't confuse the install and search paths for dri drivers

Currently there is not a separate option for setting the search path of
DRI drivers in meson, like there is in scons and autotools. This is an
oversight and needs to be fixed. This adds an extra option
`dri-search-path`, which will default to the value of
`dri-drivers-path`, like autotools does.

v2: - Split input list before joining.
v3: - use : instead of ; as the delimiter. The autotools help string
      incorrectly says ; but the code uses :
v4: - Take list in pre : delimited form (Ilia)
    - Ensure that the dri-search-path is absolute when using
      dri_drivers_path

Fixes: db9788420d ("meson: Add support for configuring dri drivers directory.")
Reported-by: Ilia Mirkin <imirkin@alum.mit.edu>
Signed-off-by: Dylan Baker <dylan.c.baker@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net> (v2)
Reviewed-by: Eric Engestrom <eric@engestrom.ch> (v3)

meson.build

@@ -57,6 +57,10 @@ dri_drivers_path = get_option('dri-drivers-path')
 if dri_drivers_path == ''
   dri_drivers_path = join_paths(get_option('libdir'), 'dri')
 endif
+dri_search_path = get_option('dri-search-path')
+if dri_search_path == ''
+  dri_search_path = join_paths(get_option('prefix'), dri_drivers_path)
+endif
 
 with_gles1 = get_option('gles1')
 with_gles2 = get_option('gles2')

meson_options.txt

@@ -41,7 +41,13 @@ option(
   'dri-drivers-path',
   type : 'string',
   value : '',
-  description : 'Location of dri drivers. Default: $libdir/dri.'
+  description : 'Location to install dri drivers. Default: $libdir/dri.'
+)
+option(
+  'dri-search-path',
+  type : 'string',
+  value : '',
+  description : 'Locations to search for dri drivers, passed as colon separated list. Default: dri-drivers-path.'
 )
 option(
   'gallium-drivers',

src/egl/meson.build

@@ -160,7 +160,7 @@ libegl = shared_library(
   c_args : [
     c_vis_args,
     c_args_for_egl,
-    '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_driver_dir),
+    '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path),
     '-D_EGL_BUILT_IN_DRIVER_DRI2',
     '-D_EGL_NATIVE_PLATFORM=_EGL_PLATFORM_@0@'.format(egl_native_platform.to_upper()),
   ],

src/gbm/meson.build

@@ -38,7 +38,7 @@ incs_gbm = [
 if with_dri2
   files_gbm += files('backends/dri/gbm_dri.c', 'backends/dri/gbm_driint.h')
   deps_gbm += dep_libdrm # TODO: pthread-stubs
-  args_gbm += '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_driver_dir)
+  args_gbm += '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path)
 endif
 if with_platform_wayland
   deps_gbm += dep_wayland_server

src/glx/meson.build

@@ -113,7 +113,6 @@ elif with_dri_platform == 'windows'
   extra_ld_args_libgl = '-Wl,--disable-stdcall-fixup'
 endif
 
-dri_driver_dir = join_paths(get_option('prefix'), dri_drivers_path)
 if not with_glvnd
   gl_lib_name = 'GL'
   gl_lib_version = '1.2.0'
@@ -130,7 +129,8 @@ else
 endif
 
 gl_lib_cargs = [
-  '-D_REENTRANT', '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_driver_dir),
+  '-D_REENTRANT',
+  '-DDEFAULT_DRIVER_DIR="@0@"'.format(dri_search_path),
 ]
 
 if dep_xxf86vm != [] and dep_xxf86vm.found()