Do not strip the dylink.0 section from libdl.so (#1490)

The `dylink.0` section is required to correctly layout the main memory
space and provide `__memory_base` and `__table_base` symbols. The
section was being stripped by the `strip` tool, and it led to the
unpredictable corruption of `LIBRARIES` global variable.

Author: kateinoigakukun

crates/wit-component/dl/build.sh

@@ -7,4 +7,5 @@
 
 CARGO_PROFILE_RELEASE_LTO=true RUSTFLAGS="-C relocation-model=pic" cargo build --release --target=wasm32-wasi
 $WASI_SDK_PATH/bin/clang -shared -o $1 -Wl,--whole-archive ../../../target/wasm32-wasi/release/libdl.a -Wl,--no-whole-archive
-cargo run --manifest-path ../../../Cargo.toml -- strip -a $1 -o $1
+cargo run --manifest-path ../../../Cargo.toml -- strip $1 -o $1
+cargo run --manifest-path ../../../Cargo.toml -- strip --delete name $1 -o $1

crates/wit-component/libdl.so

@@ -16,7 +16,7 @@
     (global (;4;) i32 i32.const 4)
     (global (;5;) i32 i32.const 1048704)
     (global (;6;) i32 i32.const 4)
-    (global (;7;) (mut i32) i32.const 1048704)
+    (global (;7;) (mut i32) i32.const 1048864)
     (global (;8;) (mut i32) i32.const 1114112)
     (export "__stack_pointer" (global 0))
     (export "foo:memory_base" (global 1))
@@ -72,6 +72,10 @@
     (start $start)
   )
   (core module (;2;)
+    (@dylink.0
+      (mem-info (memory 152 2))
+      (needed "libc.so")
+    )
     (type (;0;) (func (param i32) (result i32)))
     (type (;1;) (func (param i32 i32 i32) (result i32)))
     (type (;2;) (func))

crates/wit-component/tests/components/link-dl-openable-builtin-libdl-with-unused/component.wat

@@ -16,24 +16,57 @@
     (global (;4;) i32 i32.const 4)
     (global (;5;) i32 i32.const 1048688)
     (global (;6;) i32 i32.const 4)
-    (global (;7;) (mut i32) i32.const 1048688)
-    (global (;8;) (mut i32) i32.const 1114112)
+    (global (;7;) i32 i32.const 1048840)
+    (global (;8;) i32 i32.const 4)
+    (global (;9;) (mut i32) i32.const 1048848)
+    (global (;10;) (mut i32) i32.const 1114112)
     (export "__stack_pointer" (global 0))
     (export "foo:memory_base" (global 1))
     (export "foo:table_base" (global 2))
-    (export "libdl.so:memory_base" (global 3))
-    (export "libdl.so:table_base" (global 4))
-    (export "wit-component:stubs:memory_base" (global 5))
-    (export "wit-component:stubs:table_base" (global 6))
-    (export "__heap_base" (global 7))
-    (export "__heap_end" (global 8))
+    (export "libc.so:memory_base" (global 3))
+    (export "libc.so:table_base" (global 4))
+    (export "libdl.so:memory_base" (global 5))
+    (export "libdl.so:table_base" (global 6))
+    (export "wit-component:stubs:memory_base" (global 7))
+    (export "wit-component:stubs:table_base" (global 8))
+    (export "__heap_base" (global 9))
+    (export "__heap_end" (global 10))
     (export "__indirect_function_table" (table 0))
     (export "memory" (memory 0))
     (@producers
       (processed-by "wit-component" "$CARGO_PKG_VERSION")
     )
   )
   (core module (;1;)
+    (@dylink.0
+      (mem-info (memory 0 4))
+    )
+    (type (;0;) (func))
+    (type (;1;) (func (param i32) (result i32)))
+    (import "GOT.mem" "__heap_base" (global $__heap_base (;0;) (mut i32)))
+    (import "GOT.mem" "__heap_end" (global $__heap_end (;1;) (mut i32)))
+    (func $start (;0;) (type 0)
+      global.get $__heap_base
+      global.set $heap
+    )
+    (func $malloc (;1;) (type 1) (param i32) (result i32)
+      global.get $heap
+      global.get $heap
+      local.get 0
+      i32.add
+      global.set $heap
+    )
+    (func $abort (;2;) (type 0)
+      unreachable
+    )
+    (global $errno (;2;) i32 i32.const 0)
+    (global $heap (;3;) (mut i32) i32.const 0)
+    (export "malloc" (func $malloc))
+    (export "abort" (func $abort))
+    (export "errno" (global $errno))
+    (start $start)
+  )
+  (core module (;2;)
     (type (;0;) (func (param i32 i32 i32) (result i32)))
     (type (;1;) (func (param i32) (result i32)))
     (func (;0;) (type 0) (param i32 i32 i32) (result i32)
@@ -48,7 +81,11 @@
       (processed-by "wit-component" "$CARGO_PKG_VERSION")
     )
   )
-  (core module (;2;)
+  (core module (;3;)
+    (@dylink.0
+      (mem-info (memory 152 2))
+      (needed "libc.so")
+    )
     (type (;0;) (func (param i32) (result i32)))
     (type (;1;) (func (param i32 i32 i32) (result i32)))
     (type (;2;) (func))
@@ -478,7 +515,7 @@
     (export "__wasm_set_libraries" (func 10))
     (data (;0;) (global.get 0) "invalid library handle\00library not found\00dlopen flags not yet supported\00symbol not found\00dlsym RTLD_NEXT and RTLD_DEFAULT not yet supported\00\00\00\00\00\00\00\00\00\00\00\00\00")
   )
-  (core module (;3;)
+  (core module (;4;)
     (@dylink.0
       (mem-info (memory 0 4))
     )
@@ -495,7 +532,7 @@
     (export "baz" (func $foo))
     (export "what" (global $what))
   )
-  (core module (;4;)
+  (core module (;5;)
     (type (;0;) (func))
     (type (;1;) (func (param i32)))
     (type (;2;) (func (param i32) (result i32)))
@@ -542,8 +579,8 @@
   (alias core export 0 "memory" (core memory (;1;)))
   (alias core export 0 "__indirect_function_table" (core table (;0;)))
   (alias core export 0 "__stack_pointer" (core global (;2;)))
-  (alias core export 0 "wit-component:stubs:memory_base" (core global (;3;)))
-  (alias core export 0 "wit-component:stubs:table_base" (core global (;4;)))
+  (alias core export 0 "libc.so:memory_base" (core global (;3;)))
+  (alias core export 0 "libc.so:table_base" (core global (;4;)))
   (core instance (;3;)
     (export "memory" (memory 1))
     (export "__indirect_function_table" (table 0))
@@ -567,18 +604,14 @@
   (alias core export 0 "memory" (core memory (;2;)))
   (alias core export 0 "__indirect_function_table" (core table (;1;)))
   (alias core export 0 "__stack_pointer" (core global (;7;)))
-  (alias core export 0 "libdl.so:memory_base" (core global (;8;)))
-  (alias core export 0 "libdl.so:table_base" (core global (;9;)))
-  (alias core export 4 "memcmp" (core func (;0;)))
-  (alias core export 4 "strlen" (core func (;1;)))
+  (alias core export 0 "wit-component:stubs:memory_base" (core global (;8;)))
+  (alias core export 0 "wit-component:stubs:table_base" (core global (;9;)))
   (core instance (;7;)
     (export "memory" (memory 2))
     (export "__indirect_function_table" (table 1))
     (export "__stack_pointer" (global 7))
     (export "__memory_base" (global 8))
     (export "__table_base" (global 9))
-    (export "memcmp" (func 0))
-    (export "strlen" (func 1))
   )
   (core instance (;8;) (instantiate 2
       (with "GOT.mem" (instance 5))
@@ -596,38 +629,68 @@
   (alias core export 0 "memory" (core memory (;3;)))
   (alias core export 0 "__indirect_function_table" (core table (;2;)))
   (alias core export 0 "__stack_pointer" (core global (;12;)))
-  (alias core export 0 "foo:memory_base" (core global (;13;)))
-  (alias core export 0 "foo:table_base" (core global (;14;)))
-  (alias core export 8 "dlopen" (core func (;2;)))
+  (alias core export 0 "libdl.so:memory_base" (core global (;13;)))
+  (alias core export 0 "libdl.so:table_base" (core global (;14;)))
+  (alias core export 8 "memcmp" (core func (;0;)))
+  (alias core export 8 "strlen" (core func (;1;)))
   (core instance (;11;)
     (export "memory" (memory 3))
     (export "__indirect_function_table" (table 2))
     (export "__stack_pointer" (global 12))
     (export "__memory_base" (global 13))
     (export "__table_base" (global 14))
+    (export "memcmp" (func 0))
+    (export "strlen" (func 1))
+  )
+  (core instance (;12;) (instantiate 3
+      (with "GOT.mem" (instance 9))
+      (with "GOT.func" (instance 10))
+      (with "env" (instance 11))
+    )
+  )
+  (alias core export 0 "__heap_base" (core global (;15;)))
+  (alias core export 0 "__heap_end" (core global (;16;)))
+  (core instance (;13;)
+    (export "__heap_base" (global 15))
+    (export "__heap_end" (global 16))
+  )
+  (core instance (;14;))
+  (alias core export 0 "memory" (core memory (;4;)))
+  (alias core export 0 "__indirect_function_table" (core table (;3;)))
+  (alias core export 0 "__stack_pointer" (core global (;17;)))
+  (alias core export 0 "foo:memory_base" (core global (;18;)))
+  (alias core export 0 "foo:table_base" (core global (;19;)))
+  (alias core export 12 "dlopen" (core func (;2;)))
+  (core instance (;15;)
+    (export "memory" (memory 4))
+    (export "__indirect_function_table" (table 3))
+    (export "__stack_pointer" (global 17))
+    (export "__memory_base" (global 18))
+    (export "__table_base" (global 19))
     (export "dlopen" (func 2))
   )
   (alias export 0 "foo" (func (;0;)))
   (core func (;3;) (canon lower (func 0)))
-  (core instance (;12;)
+  (core instance (;16;)
     (export "foo" (func 3))
   )
-  (core instance (;13;) (instantiate 3
-      (with "GOT.mem" (instance 9))
-      (with "GOT.func" (instance 10))
-      (with "env" (instance 11))
-      (with "test:test/test" (instance 12))
+  (core instance (;17;) (instantiate 4
+      (with "GOT.mem" (instance 13))
+      (with "GOT.func" (instance 14))
+      (with "env" (instance 15))
+      (with "test:test/test" (instance 16))
     )
   )
-  (core instance (;14;) (instantiate 4
+  (core instance (;18;) (instantiate 5
       (with "env" (instance 0))
-      (with "foo" (instance 13))
-      (with "libdl.so" (instance 8))
-      (with "wit-component:stubs" (instance 4))
+      (with "foo" (instance 17))
+      (with "libc.so" (instance 4))
+      (with "libdl.so" (instance 12))
+      (with "wit-component:stubs" (instance 8))
     )
   )
   (type (;1;) (func (param "v" s32) (result s32)))
-  (alias core export 13 "test:test/test#foo" (core func (;4;)))
+  (alias core export 17 "test:test/test#foo" (core func (;4;)))
   (func (;1;) (type 1) (canon lift (core func 4)))
   (component (;0;)
     (type (;0;) (func (param "v" s32) (result s32)))

crates/wit-component/tests/components/link-dl-openable-builtin-libdl/component.wat

@@ -46,8 +46,11 @@ impl Opts {
                 return to_delete.is_match(name);
             }
 
-            // Finally default strip everything but the `name` and any `component-type` sections.
-            name != "name" && !name.starts_with("component-type:")
+            // Finally default strip everything but:
+            // * the `name` section
+            // * any `component-type` sections
+            // * the `dylink.0` section
+            name != "name" && !name.starts_with("component-type:") && name != "dylink.0"
         };
 
         let mut output = Vec::new();