meson: Allow CUDA_PATH fallback on linux

That's what we've supported via autotools build

Fixes: https://gitlab.freedesktop.org/gstreamer/gst-plugins-bad/issues/966

sys/meson.build

@@ -27,10 +27,52 @@ cudart_dep = dependency('', required : false)
 cuda_libdir = ''
 cuda_incdir = ''
 
-if host_machine.system() == 'windows'
+cuda_versions = [
-  # On windows, CUDA_PATH env will be set by installer
+    '10.1',
+    '10.0',
+    '9.2',
+    '9.1',
+    '9.0',
+    '8.0',
+    '7.5',
+    '7.0',
+    '6.5',
+  ]
+cuda_ver = ''
+
+# FIXME: use break syntax when we use meson >= '0.49'
+foreach v : cuda_versions
+  if cuda_ver == ''
+    cuda_dep = dependency('cuda-' + v, required: false)
+    cudart_dep = dependency('cudart-' + v, required: false)
+    if cuda_dep.found() and cudart_dep.found()
+      cuda_ver = v
+    endif
+  endif
+endforeach
+
+if cuda_dep.found()
+  cuda_header_found = cc.has_header('cuda.h', dependencies: cuda_dep)
+  cuda_lib_found = cc.has_function('cuInit', dependencies: cuda_dep)
+  if not cuda_header_found or not cuda_lib_found
+    message ('Missing required header and/or function in cuda dependency')
+    cuda_dep = dependency('', required : false)
+  endif
+endif
+
+if cudart_dep.found()
+  cudart_header_found = cc.has_header('cuda_runtime_api.h', dependencies: cudart_dep)
+  cudart_lib_found = cc.has_function('cudaGetErrorString', dependencies: cudart_dep)
+  if not cudart_header_found or not cudart_lib_found
+    message ('Missing required header and/or function in cudart dependency')
+    cudart_dep = dependency('', required : false)
+  endif
+endif
+
+if not cuda_dep.found() or not cudart_dep.found()
   cuda_root = run_command(python3, '-c', 'import os; print(os.environ.get("CUDA_PATH"))').stdout().strip()
   if cuda_root != '' and cuda_root != 'None'
+    if host_machine.system() == 'windows'
       arc = ''
       if build_machine.cpu_family() == 'x86_64'
         arc = 'x64'
@@ -38,9 +80,14 @@ if host_machine.system() == 'windows'
         arc = 'Win32'
       endif
       cuda_libdir = join_paths (cuda_root, 'lib', arc)
+    else
+      cuda_libdir = [join_paths (cuda_root, 'lib'), join_paths (cuda_root, 'lib', 'stubs'),
+                     join_paths (cuda_root, 'lib64'), join_paths (cuda_root, 'lib64', 'stubs')]
+    endif
     cuda_incdir = join_paths (cuda_root, 'include')
     cuda_lib = cc.find_library('cuda', dirs: cuda_libdir, required: false)
     cudart_lib = cc.find_library('cudart', dirs: cuda_libdir, required: false)
+
     if cuda_lib.found()
       cuda_header_found = cc.has_header('cuda.h', args: '-I' + cuda_incdir)
       cuda_lib_found = cc.has_function('cuInit', dependencies: cuda_lib)
@@ -57,48 +104,7 @@ if host_machine.system() == 'windows'
         cudart_dep = declare_dependency(dependencies: cudart_lib)
       endif
     endif
-  endif
-else
-  cuda_versions = [
-    '10.1',
-    '10.0',
-    '9.2',
-    '9.1',
-    '9.0',
-    '8.0',
-    '7.5',
-    '7.0',
-    '6.5',
-  ]
-  cuda_ver = ''
 
-  # FIXME: use break syntax when we use meson >= '0.49'
-  foreach v : cuda_versions
-    if cuda_ver == ''
-      cuda_dep = dependency('cuda-' + v, required: false)
-      cudart_dep = dependency('cudart-' + v, required: false)
-      if cuda_dep.found() and cudart_dep.found()
-        cuda_ver = v
-      endif
-    endif
-  endforeach
-
-  if cuda_dep.found()
-    cuda_header_found = cc.has_header('cuda.h', dependencies: cuda_dep)
-    cuda_lib_found = cc.has_function('cuInit', dependencies: cuda_dep)
-    if not cuda_header_found or not cuda_lib_found
-      message ('Missing required header and/or function in cuda dependency')
-      cuda_dep = dependency('', required : false)
-    endif
-  endif
-
-  if cudart_dep.found()
-    cudart_header_found = cc.has_header('cuda_runtime_api.h', dependencies: cudart_dep)
-    cudart_lib_found = cc.has_function('cudaGetErrorString', dependencies: cudart_dep)
-    if not cudart_header_found or not cudart_lib_found
-      message ('Missing required header and/or function in cudart dependency')
-      cudart_dep = dependency('', required : false)
-    endif
   endif
 endif
 

sys/nvenc/meson.build

@@ -13,7 +13,7 @@ if nvenc_option.disabled()
   subdir_done()
 endif
 
-if host_machine.system() == 'windows'
+if cuda_dep.type_name() == 'internal'
   if cc.has_header('cuda_gl_interop.h', args: '-I' + cuda_incdir)
     use_nvenc_gl = true
   endif