Add feature to default to using .init_array

dtolnay · Jan 26, 2024 · df8cd24 · df8cd24
1 parent 2f9fa4b
commit df8cd24
Show file tree

Hide file tree

Showing 3 changed files with 81 additions and 24 deletions.
diff --git a/Cargo.toml b/Cargo.toml
@@ -11,13 +11,19 @@ license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/inventory"
 rust-version = "1.62"
 
+[dependencies]
+cfg-if = "1.0"
+
 [dev-dependencies]
 rustversion = "1.0"
 trybuild = { version = "1.0.89", features = ["diff"] }
 
 [lib]
 doc-scrape-examples = false
 
+[features]
+default-to-init-array-section = []
+
 [package.metadata.docs.rs]
 targets = ["x86_64-unknown-linux-gnu"]
 rustdoc-args = ["--generate-link-to-definition"]
diff --git a/README.md b/README.md
@@ -104,7 +104,9 @@ registered at the time that dlopen occurs.
 
 Platform support includes Linux, macOS, iOS, FreeBSD, Android, Windows, and a
 few others. Beyond this, other platforms will simply find that no plugins have
-been registered.
+been registered. Alternatively, unsupported platforms may enable the
+`default-to-init-array-section` feature to assign constructors to the
+`.init_array` section.
 
 For a different approach to plugin registration that *does not* involve
 life-before-main, see the [`linkme`] crate.

diff --git a/src/lib.rs b/src/lib.rs
@@ -433,29 +433,10 @@ macro_rules! __do_submit {
                 unsafe { $crate::ErasedNode::submit(__INVENTORY.value, &__INVENTORY) }
             }
 
-            // Linux/ELF: https://www.exploit-db.com/papers/13234
-            //
-            // macOS: https://blog.timac.org/2016/0716-constructor-and-destructor-attributes/
-            //
-            // Why .CRT$XCU on Windows? https://www.cnblogs.com/sunkang/archive/2011/05/24/2055635.html
-            // 'I'=C init, 'C'=C++ init, 'P'=Pre-terminators and 'T'=Terminators
-            $($used)+
-            #[cfg_attr(
-                any(
-                    target_os = "linux",
-                    target_os = "android",
-                    target_os = "dragonfly",
-                    target_os = "freebsd",
-                    target_os = "haiku",
-                    target_os = "illumos",
-                    target_os = "netbsd",
-                    target_os = "openbsd",
-                ),
-                link_section = ".init_array",
-            )]
-            #[cfg_attr(any(target_os = "macos", target_os = "ios"), link_section = "__DATA,__mod_init_func")]
-            #[cfg_attr(windows, link_section = ".CRT$XCU")]
-            static __CTOR: unsafe extern "C" fn() = __ctor;
+            $crate::__assign_static_to_section! {
+                $($used)+
+                static __CTOR: unsafe extern "C" fn() = __ctor;
+            }
         };
     };
 
@@ -473,3 +454,71 @@ macro_rules! __do_submit {
         }
     };
 }
+
+// Linux/ELF: https://www.exploit-db.com/papers/13234
+//
+// macOS: https://blog.timac.org/2016/0716-constructor-and-destructor-attributes/
+//
+// Why .CRT$XCU on Windows? https://www.cnblogs.com/sunkang/archive/2011/05/24/2055635.html
+// 'I'=C init, 'C'=C++ init, 'P'=Pre-terminators and 'T'=Terminators
+cfg_if::cfg_if! {
+    if #[cfg(any(
+        target_os = "linux",
+        target_os = "android",
+        target_os = "dragonfly",
+        target_os = "freebsd",
+        target_os = "haiku",
+        target_os = "illumos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+    ))] {
+        // Not public API.
+        #[doc(hidden)]
+        #[macro_export]
+        macro_rules! __assign_static_to_section {
+            ($item:stmt) => {
+                #[link_section = ".init_array"]
+                $item
+            };
+        }
+    } else if #[cfg(any(target_os = "macos", target_os = "ios"))] {
+        // Not public API.
+        #[doc(hidden)]
+        #[macro_export]
+        macro_rules! __assign_static_to_section {
+            ($item:stmt) => {
+                #[link_section = "__DATA,__mod_init_func"]
+                $item
+            };
+        }
+    } else if #[cfg(windows)] {
+        // Not public API.
+        #[doc(hidden)]
+        #[macro_export]
+        macro_rules! __assign_static_to_section {
+            ($item:stmt) => {
+                #[link_section = ".CRT$XCU"]
+                $item
+            };
+        }
+    } else if #[cfg(feature = "default-to-init-array-section")] {
+        // Not public API.
+        #[doc(hidden)]
+        #[macro_export]
+        macro_rules! __assign_static_to_section {
+            ($item:stmt) => {
+                #[link_section = ".init_array"]
+                $item
+            };
+        }
+    } else {
+        // Not public API.
+        #[doc(hidden)]
+        #[macro_export]
+        macro_rules! __assign_static_to_section {
+            ($item:stmt) => {
+                $item
+            };
+        }
+    }
+}