Linux: create a library loader code generator for dlopen and use it for libpci.

build/linux/system.gyp

Index: build/linux/system.gyp
diff --git a/build/linux/system.gyp b/build/linux/system.gyp
index 2eacbdbaaba56db8f5633e7a63ef3d78dc8cae5c..17fe73b978fb8032ecda5e89dc185e6470899edc 100644
--- a/build/linux/system.gyp
+++ b/build/linux/system.gyp
@@ -11,6 +11,8 @@
         'pkg-config': 'pkg-config'
       }]
     ],
+
+    'linux_link_libpci%': 0,
   },
   'conditions': [
     [ 'os_posix==1 and OS!="mac"', {
@@ -275,6 +277,65 @@
       ],
     },
     {
+      'target_name': 'libpci',
+      'type': 'static_library',
+      'cflags': [
+        '<!@(<(pkg-config) --cflags libpci)',
+      ],
+      'sources': [
+        '<(SHARED_INTERMEDIATE_DIR)/libpci_loader/libpci_loader.cc',

[Mark Mentovai, 2012/11/27 20:10:20]

The .cc doesn’t need to be in the shared dir, it can just go into the normal
intermediate dir.

[Paweł Hajdan Jr., 2012/11/27 22:27:24]

Done.

+      ],
+      'include_dirs': [
+        '../..',
+        '<(SHARED_INTERMEDIATE_DIR)/libpci_loader',
+      ],
+      'direct_dependent_settings': {
+        'include_dirs': [
+          '<(SHARED_INTERMEDIATE_DIR)/libpci_loader',

[Mark Mentovai, 2012/11/27 20:10:20]

I’d rather see includers #include something that has a path in it, rather than
having them include just the basename and forcing this pretty specific directory
into their path.

[Paweł Hajdan Jr., 2012/11/27 22:27:24]

Done.

+        ],
+        'conditions': [
+          ['linux_link_libpci==1', {
+            'link_settings': {
+              'ldflags': [
+                '<!@(<(pkg-config) --libs-only-L --libs-only-other libpci)',
+              ],
+              'libraries': [
+                '<!@(<(pkg-config) --libs-only-l libpci)',
+              ],
+            }
+          }],
+        ],
+      },
+      'hard_dependency': 1,

[Mark Mentovai, 2012/11/27 20:10:20]

If this was inline in content_gpu, I don’t think it would need to be hard at
all.

[Paweł Hajdan Jr., 2012/11/27 22:27:24]

I think even when it was inline, it still needed hard. By the way, I think it's
going to serve as a better example here than in content_gpu.gypi file (other
generated loaders would be in system.gyp).

[Mark Mentovai, 2012/11/27 23:09:11]

Paweł Hajdan Jr. wrote:
It shouldn’t have needed hard, the generators are all supposed to run actions
before trying to compile anything in a target.

+      'actions': [
+        {
+          'action_name': 'generate_libpci_loader',
+          'inputs': [
+            '../../tools/generate_library_loader/generate_library_loader.py',
+          ],
+          'outputs': [
+            '<(SHARED_INTERMEDIATE_DIR)/libpci_loader/libpci_loader.cc',

[Mark Mentovai, 2012/11/27 20:10:20]

If you used process_outputs_as_sources, you wouldn’t need to list this as a
distinct source.

[Paweł Hajdan Jr., 2012/11/27 22:27:24]

Done.

+            '<(SHARED_INTERMEDIATE_DIR)/libpci_loader/libpci_loader.h',
+          ],
+          'action': ['python',
+                     '../../tools/generate_library_loader/generate_library_loader.py',
+                     '--name', 'LibPciLoader',
+                     '--output', '<(SHARED_INTERMEDIATE_DIR)/libpci_loader/libpci_loader',
+                     '--header', '<pci/pci.h>',
+                     '--use-extern-c',
+                     '--link-directly=<(linux_link_libpci)',
+                     'pci_alloc',
+                     'pci_init',
+                     'pci_cleanup',
+                     'pci_scan_bus',
+                     'pci_fill_info',
+                     'pci_lookup_name',
+          ],
+          'message': 'Generating libpci library loader.',
+        },
+      ],
+    },
+    {
       'target_name': 'x11',
       'type': 'none',
       'toolsets': ['host', 'target'],