Add rules_license and improve link flexibility
Change-Id: If4eb2b6851187ecf2c5e5cb974304f95656e40c7
diff --git a/BUILD.bazel b/BUILD.bazel
index 6084c64..ccfcf72 100644
--- a/BUILD.bazel
+++ b/BUILD.bazel
@@ -12,6 +12,8 @@
# See the License for the specific language governing permissions and
# limitations under the License.
+load("@bazel_skylib//rules:common_settings.bzl", "bool_flag")
+
package(default_visibility = ["//visibility:public"])
cc_library(
@@ -30,3 +32,16 @@
"//conditions:default": [],
}),
)
+
+# Forces libusb to always be dynamically linked. This defaults to True since
+# libusb is LGPL and that is usually the right thing. Be cautious when
+# statically linking and distributing binaries, as libusb is LGPL.
+bool_flag(
+ name = "force_dynamic_linkage",
+ build_setting_default = True,
+)
+
+config_setting(
+ name = "force_dynamic_linkage_enabled",
+ flag_values = {":force_dynamic_linkage": "True"},
+)
diff --git a/MODULE.bazel b/MODULE.bazel
index 9896d23..8cdba89 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -4,6 +4,8 @@
)
bazel_dep(name = "platforms", version = "0.0.8")
+bazel_dep(name = "rules_license", version = "0.0.8")
+bazel_dep(name = "bazel_skylib", version = "1.5.0")
# If your project has versioning requirements for libusb, you'll need to specify
# this in your project's MODULE.bazel.
diff --git a/README.md b/README.md
index 8a15f5d..a4d428c 100644
--- a/README.md
+++ b/README.md
@@ -20,18 +20,45 @@
use_repo(libusb, "libusb")
```
+Note: `source_release` constraints follow bzlmod behavior of minimal version
+selection.
+
Then add to the tool that requires libusb:
```
cc_binary(
name = "my_tool",
srcs = ["main.cpp"],
- deps = ["@libusb//:libusb_core"], # Required for headers.
- dynamic_deps = ["@libusb//:libusb"], # Link against shared lib.
+ deps = ["@libusb//:libusb"],
)
```
-Note: `source_release` constraints follow bzlmod behavior of minimal version
-selection.
+## Linking libusb
+
+The libusb build file offers two targets to help guide link behavior:
+
+* `//:libusb`: The generic `cc_library` for libusb. Most build targets should
+ just use this.
+* `//:libusb_dynamic`: The actual libusb dynamic/shared library (e.g.
+ `libusb-1.0.so`).
+
+By default, `@libusb//:libusb` will always dynamically link. This can be
+disabled by toggling the flag that controls this:
+```
+bazel build //... --@rules_libusb//:force_dynamic_linkage=False
+```
+
+When `@rules_libusb//:force_dynamic_linkage` is disabled, the link behavior is
+fully controlled by your build system, and can be controlled on a per-binary
+basis by specifying `dynamic_deps` on build targets that require dynamic
+linkage of libusb:
+```
+cc_binary(
+ name = "my_tool",
+ srcs = ["main.cpp"],
+ deps = ["@libusb//:libusb"],
+ dynamic_deps = ["@libusb//:libusb_dynamic"],
+)
+```
## Building this repo
diff --git a/libusb.BUILD b/libusb.BUILD
index 318c468..1c8c60b 100644
--- a/libusb.BUILD
+++ b/libusb.BUILD
@@ -12,26 +12,32 @@
# See the License for the specific language governing permissions and
# limitations under the License.
-# Be careful about only depending on :libusb_core without specifying
-# :libusb in dynamic_deps! If you forget, libusb will be statically linked.
-cc_library(
- name = "libusb_core",
- srcs = glob(["libusb/*.c"]),
+load("@rules_license//rules:license.bzl", "license")
+
+package(
+ default_applicable_licenses = [":license"],
+ default_visibility = ["//visibility:private"],
+)
+
+license(
+ name = "license",
+ package_name = "libusb",
+ license_kinds = ["@rules_license//licenses/spdx:LGPL-2.1"],
+ license_text = "COPYING",
+)
+
+alias(
+ name = "libusb",
+ actual = select({
+ "@rules_libusb//:force_dynamic_linkage_enabled": ":libusb_force_dynamic",
+ "//conditions:default": ":libusb_core",
+ }),
visibility = ["//visibility:public"],
- deps = select({
- "@platforms//os:linux": [":libusb_linux"],
- "@platforms//os:macos": [":libusb_macos"],
- "@platforms//os:windows": [":libusb_windows"],
- "//conditions:default": ["@platforms//:incompatible"],
- }) + [
- ":libusb_config",
- ":libusb_headers",
- ],
)
cc_shared_library(
- name = "libusb",
- # Always use exactly this name.
+ name = "libusb_dynamic",
+ # Always use exactly these names.
shared_lib_name = select({
"@platforms//os:macos": "libusb-1.0.dylib",
"@platforms//os:windows": "libusb-1.0.dll",
@@ -45,6 +51,32 @@
deps = [":libusb_core"],
)
+# This intermediate helper forces libusb to be dynamically linked.
+cc_library(
+ name = "libusb_force_dynamic",
+ srcs = [":libusb_dynamic"],
+ visibility = ["//visibility:private"],
+ deps = [
+ ":libusb_config",
+ ":libusb_headers",
+ ],
+)
+
+cc_library(
+ name = "libusb_core",
+ srcs = glob(["libusb/*.c"]),
+ visibility = ["//visibility:private"],
+ deps = select({
+ "@platforms//os:linux": [":libusb_linux"],
+ "@platforms//os:macos": [":libusb_macos"],
+ "@platforms//os:windows": [":libusb_windows"],
+ "//conditions:default": ["@platforms//:incompatible"],
+ }) + [
+ ":libusb_config",
+ ":libusb_headers",
+ ],
+)
+
label_flag(
name = "libusb_config",
build_setting_default = "@rules_libusb//:default_libusb_config",
